Well, with the first post and a response to criticisms out of the way, I'll conclude with the graphs on some ideas that are gaining in popularity in the study of mankind. Where it says "social sciences," I've only searched JSTOR for the following journal categories: anthropology, economics, education, political science, psychology, and sociology. The social sciences, basically. (And I've used appropriate neutral comparisons as before.) The reason is that if "heritability" increases in usage, that could be due to its use in genetics -- I want to see how popular it is when talking about humans. (As before, graphs have simple titles, while the full search terms are listed in an Appendix.)










Contrary to what you might think, since about 1950 academics have become increasingly interested in the genetic influence on human nature, reversing a period of decline from roughly 1930 to 1950. There is also an apparent cyclical pattern on top of the increasing trend. Just make sure you refer to the heritability of "cognitive ability" rather than of "IQ" (see below).

I've broken up the graphs on Darwin in the social sciences to make the trends clearer. There is an early phase in Victorian times when Darwin's thoughts were everywhere, especially in discussing human beings. Around the turn of the century, his ideas become less popular, as mentioned above. Around 1940, when his ideas come back due to the modern synthesis in biology, they become more popular in the social sciences as well. Indeed, since the mid-1940s, his ideas have only become more important to social scientists -- whether they like it or not.

Notice that while "IQ" goes through cycles about an increasing trend, its synonym "cognitive ability" shows exponential increase. I assume that this is because "cognitive ability" is not a politicized term, while "IQ" is, resulting in outbreaks of hysteria where many more people of any ideological background begin talking a lot about it.

The same is true of "sociobiology," which Leftist academics such as the Sociobiology Study Group tainted with negative political associations, compared to its synonym "evolutionary psychology." Now, someone will say that evolutionary psychology is different -- that it studies the mental, psychological processes rather than just observed behavior. But that's nonsense -- if you've read one of the many evolutionary psychology articles about digit ratios, waist-to-hip ratios, whether the female orgasm is adaptive, and so on, you know that mental processes and cognitive science models rarely come up, except in the study of vision.

Indeed, "evolutionary psychology" increases at just the time when "sociobiology" decreases, in the mid-1980s, showing that the former is simply replacing the latter as the preferred term.

As further evidence that a decline in usage means a decline in popularity, "evolutionary psychology" gets lots of hits in the 1890s when pioneers of psychology like William James were obsessed with integrating evolution and the study of the human mind, and takes a nosedive and lies dead once behaviorism takes over in psychology around the 1920s.

Because "evolutionary psychology" and "cognitive ability" are safe terms politically, these are the obvious choices for people who don't want to have water poured over their head at a conference -- and the data show this rational choice. Interest has continued to skyrocket, although people use different codewords. Nothing like this turned up in the first post because it is not political suicide to talk about postmodernism or Marxism in academia -- but just try bringing up "IQ". It is fascinating that academics can adhere to the ideas of Marx, Lenin, Trotsky, or Stalin and be taken seriously, while anyone who would do so for the ideas of Mussolini or Hitler would be made a total pariah. I wouldn't take either numbskull seriously, but most educated people will, perhaps grudgingly, give a free pass to those who revere the ideological or political figures associated with The Other Great Dictatorships and Mass Murders.

I've already made general observations in the first post, and they carry over here, especially the fact that the history of ideas seems so unaffected by the history of the entire outside world -- one more idea that Marx got wrong. There is clearly change, struggle between groups, and so on, but they are largely internal to academia. The future -- or the near-future anyway -- looks pretty bright for those interested in the biological approach to studying humans and their ways, and who believe things like IQ are important. Any students who are still considering the social constructionist, Marxist, feminist, or Whateverist approach should at least learn the new theories, if for no other reason than to be employable in 5 to 10 years. Hell, you might even consider it a kind of Pascal's Wager.

APPENDIX

Here are the search terms I used, once again searching the full text of articles and reviews:

"cognitive ability" OR "cognitive abilities"

"darwin*" NOT "social darwinism" NOT "social darwinist" NOT "social darwinists"

"evolutionary psychology" OR "evolutionary psychologist" OR "evolutionary psychologists"

"heritability" OR "heritable"

"IQ"

"sociobiolog*"

Labels: culture, intellectual history

My first post detailed the demise of wooly-headed theories in academia. In this post, I'll also address some common criticisms that have come up so far. In the third post, just above this one, I will look at a rival class of theories, namely the scientific and in particular biological approaches to studying humanity. The take-home message is that, while the Blank Slate theories are slowly being driven out of academia, new ones based on the biological sciences are becoming ever more popular. But let's start with the criticisms:

1) You're confusing popularity with accuracy, truth, etc.

I never said anything to this effect. I am just interested in whether certain theories are becoming more or less prevalent. Now, I happen to believe that in the case of, say, psychoanalysis or Marxism, the theories are becoming less popular because people realize that they're not very insightful. And certainly what I think is a great theory could become unfashionable for whatever reason. Whether you're celebrating or mourning the death of some theory, I don't care -- I just want to show whether it is or is not dying.

2) You didn't account for the lag between when an article is published and when it is archived in JSTOR.

I did do that, but I was only explicit about it in the comments to the first post. Journals in JSTOR have a "moving wall" between original and archived dates, with most having a lag of 3 to 5 years. Here is the distribution of lag times. By excluding data from 2003 onward, I've taken care of 88% of journals. And I don't want to hear a non-quantitative objection that "the remainder could be affecting the results" -- tell me what you think the data-point should be for, say 2001, and then derive how large of an effect the 12% of journals would have to have in order to get that value. We'll see how reasonable that sounds. Moreover, since no moving wall is greater than 10 years, any decline that started before 1998 is not subject to even this vague objection -- for example, Marxism, feminism, and psychoanalysis.

3) You don't have a neutral control case to show that Marxism is "really" decreasing in popularity.

I did admit in the first post that ideally we'd have the total number of articles that JSTOR has for a given year, and that we'd divide the number of articles with Marxism by the total number of articles to get a frequency or prevalence. We can estimate the total by searching for articles with some highly frequent word, such as "the", so that the number returned is very close to the total. For "the", this approach is almost guaranteed to work, since almost no article would slip through the net.

However, JSTOR has a list of highly frequent words that it doesn't allow. Still, not all common words are blocked. I consulted a frequency list compiled by Oxford Online, and chose the highest-ranking words there which are not blocked by JSTOR, though I excluded the personal pronouns and "people," since I don't expect those to show up much in hard science or social science journals. This gives the variants of "time," "know," "good," and "look."

So, I've estimated the total number of articles for a year by searching for "time" OR "know*" OR "good*" OR "look*", where the asterisk means the word-ending can vary. How closely this estimates the true total is not of interest -- the point is that it serves as a common, neutral yardstick to measure the change from one year to the next.

Interestingly, using this control has almost no effect on the shape of the graphs from the first post. That is because the increase in the total number of articles increases only linearly from about 1940 onward, whereas the articles on postmodernism increase or decrease exponentially -- and an exponential divided by a linear is still growing or dying very fast. I've redrawn the original graphs and posted them here because it's easier for me; sometime soon, I'll substitute them into the first post for the record.

The only change I make to my original observations is that social constructionism is not so obviously declining anymore, although it is plateauing and apparently declining since 1998. If I had to guess about its behavior after 2002, I would say it's downward simply because none of the other theories plateaued for very long -- they quickly hit a peak and declined, so a steady high value does not appear to be stable for such theories.

4) You're mistaking a decline in usage with a decline in belief -- once the idea becomes taken for granted, practitioners stop referring to it explicitly.

Just on an intuitive level, we know this is horseshit -- do physicists not use the words "gravity" or "electricity" anymore, or no longer refer to Newton? This objection exemplifies the problem with the average arts and humanities major: he is content to build a logically coherent argument without doing a quick reality check for its explanatory plausibility. I guess that's why they end up in law firms.

But to provide evidence that usage tracks belief, here are some graphs for hard science keywords. In the case of Darwin, I excluded articles on "social Darwinism," which appears to be a, er, social construction in academia. See here. I have data on academic scarewords like "biological determinism," and perhaps in a future post I'll show those. Right now, I want to focus on articles that are at least somewhat level-headed. For ease of inspection, I've given each graph a simple title, and list the search terms at the end of this post in an Appendix.






As the disciplines of population genetics and sociobiology have become staples of biology, mentioning them by name has not declined -- just the opposite. Because they are such thriving fields, writing about them explicitly has shot up. Darwin's thoughts were immensely popular in Victorian times, but they languished because no one could tell how to unite them with the study of heredity. That was, until the modern evolutionary synthesis, which began in the late 1930s -- since then, interest has exploded. The same goes for Mendel's thoughts -- no one knew what the physical basis for his "gene" idea was, until the relationship between the genetic code and DNA was laid out in the late 1950s.

This shows that even hard science ideas can rise and fall and rise again, in these cases probably because some key aspect was found unsatisfying, until a later discovery fixed the problem, allowing the idea to become popular again. So there's hope for the unemployed psychoanalyst yet, assuming he can stick around for a half-century.

APPENDIX

Here are the search terms I used:

"population genetic" OR "population genetics" OR "genetics of populations"

"sociobiolog*"

"darwin*" NOT "social darwinism" NOT "social darwinist" NOT "social darwinists"

"mendel" OR "mendelian*" OR "mendelis*" NOT "mendelss*"

I put the last restriction on the Mendel search because I got a lot of results about the composer Felix Mendelssohn.

As with the first post, I searched the full text for both articles and reviews.

Labels: culture, intellectual history

Nature Genetics this week has published a genome-wide association study of narcolepsy in the Japanese population. The finding in the paper is a variant that confers a modest risk of narcolepsy, but personally, I was blown away by Figure 1, reproduced above. The figure shows the strength of association of each of 500,000 SNPs with narcolespy, and the novel reproducible finding is on chromosome 22 (ie, it doesn't stand out all that impressively in this plot). The major signal, absolutely swamping everything else, is in fact in the MHC region (called HLA in humans).

This region, of course, contains risk factors for type I diabetes, crohn's disease, and most (all?) other autoimmune diseases. A quick google confirms that, indeed, thinking of narcolepsy as an autoimmune disease is not new, but it's definitely new to me, and it's pretty striking to see just how much more important the risk factors in HLA are compared to everything else.

Labels: disease, Genetics

In my note on Sewall Wright's concept of the Adaptive Landscape I said that I would later discuss R. A Fisher's views on the subject. Some commentators have claimed that Fisher held a definite view on the 'shape' of the landscape. For example, a book by Sergey Gavrilets includes a section on 'Fisher's single-peak fitness landscapes', with the claim that:

In contrast to Wright, Fisher... suggested that as the number of dimensions in a fitness landscape increases, local peaks in lower dimensions will tend to become saddle points in higher dimensions. In this case, according to Fisher, natural selection will be able to move the population without the need for genetic drift or other factors. A typical fitness landscape implied by Fisher's views has a single peak. - Gavrilets, p.36

I think this goes beyond anything that Fisher actually says about Wright's adaptive landscape. There is of course room for debate about what an author's views imply. My own interpretation is that Fisher was sceptical about the value of the landscape concept as such, because both environmental and genetic conditions were too changeable for the metaphor of a 'landscape' to be useful. For Fisher the question of the 'shape' of the landscape therefore did not arise as a major issue, and he had no need to take a firm view on it. I discuss this interpretation below the fold.


Sources

As I pointed out in my earlier note, Wright himself seldom if ever used the term 'landscape', so we should not expect to find the term in Fisher either. Wright usually referred to a 'field' of gene combinations, and a 'surface' of selective values. He used these concepts mainly to illustrate his shifting balance theory of evolution. Any comments by Fisher that are relevant to the shifting balance theory could therefore also be relevant to the landscape concept. Even with this broad scope, I can find few published comments by Fisher on the subject. The main ones are in his 1932 review of Wright's paper on 'Evolution in Mendelian Populations', reprinted in Bennett (ed.), his 1941 paper on 'Average excess and average effect of a gene substitution', his 1953 paper on 'Population genetics', and his 1958 paper on 'Polymorphism and natural selection', all available at the Fisher Archives here.

In addition to Fisher's published writings, his correspondence contains a few relevant remarks. Most of his correspondence is accessible at the Fisher Archives, and a good selection of his letters on evolution and genetics is published in Bennett (ed.) Two letters are especially relevant. In February 1931 Wright outlined his landscape concept in a letter to Fisher, quoted in Provine's biography of Wright (p.272). In a reply Fisher made some sceptical comments. Then in 1938 Fisher's colleague E. B. Ford described Wright's concept in a popular book on genetics. In a letter of 2 May 1938 to Ford, commenting on his book, Fisher gave what is probably his longest critique of the landscape concept. The letter is published in Bennett (ed.) (p.201-2) and available at the Fisher Archives, so I will not quote it in full, but it should certainly be read by anyone interested in this issue.

From Fisher's published and unpublished writings we can extract a number of criticisms of Wright's theory.

The interpretation of the dimensions of the landscape

In his biography of Wright, William B. Provine has pointed out that Wright in various places used two different interpretations of the genetic 'dimensions' of the landscape, which in Provine's view are inconsistent (Provine, p.313). In one interpretation the dimensions represent the number of alleles of a given type in an individual genome, while in the other interpretation they represent the frequency of those alleles in a population. Provine points out that in the first interpretation there is properly speaking no continuous surface, but only a lattice of discrete points. He also argues that there is no way of validly transferring conclusions from one interpretation to the other. I believe that these criticisms are somewhat overstated, but it is interesting to find that they are both anticipated by Fisher. In his letter to Ford, Fisher comments that either Ford's description of Wright's views, or the views themselves, are confused, and points out that 'so far as individuals are concerned, there is only a discontinuous aggregate of lattice points, each having its own selective value. There is no continuum of possible values in which we might speak of peaks or maxima.' In his article of 1941, Fisher also criticises one of Wright's own accounts, remarking that Wright 'confuses the number of genotypes, e.g. 3^1000, which may be distinguished among individuals, with the continuous field of variation of gene frequencies.... the large number of genotypes gives no reason for thinking that even one peak, maximal for variations of all gene ratios should occur in this field of variation' (1941, p.378). It is surprising that no-one else seems to have picked up on the apparent confusion in Wright's accounts until Provine's book in 1986.

The number of peaks

As discussed in my earlier post, Wright believed that there are usually a very large number of local fitness maxima in the landscape. Fisher, on the other hand, believed that this was unproven. As noted above, he thought that Wright's view was partly due to confusion between optimal genotypes and optimal frequencies. There is no easy transition from the existence of multiple optima among genotypes to multiple optima among frequencies. I have suggested in my earlier post that in some circumstances (notably where the optimal genotype is homozygous at all loci, and fitness is not frequency-dependent) there can be such a transition, but this is a special case. In general Fisher was correct to regard Wright's argument as inconclusive.

Fisher makes another criticism in his letters to Wright and Ford. In the letter to Wright he says:

In one dimension a curve gives a series of alternative maxima and minima, but in two dimensions two inequalities must be satisfied for a true maximum, and I suppose that only about one fourth of the stationary points will satisfy both. Roughly I would guess that with n factors only 2^-n of the stationary points would be stable for all types of displacement, and any new mutation will have a half chance of destroying the stability. This suggests that true stability in the case of many interacting genes may be of rare occurrence, though its consequence when it does occur is especially interesting and important.

In his letter to Ford, Fisher writes:

In one dimension, as in a road, we pass over an alternative series of hills and dips, so that half of the level points are maxima. In two dimensions, in addition to peaks and bottoms we have cols [i.e. saddle points], which may be regarded as the lowest points on ridges or the highest points on valleys, the curvature of the ground being positive in one direction and negative in another, and the peaks are only about a quarter of the level spots. In n dimensions only about one in 2^n can be expected to be surrounded by lower ground in all directions.

Disregarding for a moment the important comment in the first letter about new mutations, Fisher's thinking seems to be as follows. In each dimension of gene frequencies, only about half of the level points will be maxima. Assuming that the location of the maxima in each dimension is independent of the other dimensions, the probability that a level point will be simultaneously maximal in all dimensions will only be about (1/2)^n, or 1 in 2^n.

As these are just comments in private letters, it is difficult to know how much weight we should put on them. Fisher uses the words 'roughly', 'guess', and 'about', which do not suggest a dogmatic position. The validity of the two key assumptions - that about half of the level points in each dimension will be maxima, and that these will be independent of each other - could be discussed at length. But even at best, Fisher's argument only goes to show that the proportion of the level points which are all-round maxima will fall as the number of dimensions increases (which, incidentally, Wright himself accepted, e.g. at ESP p.226). It does not follow that the number of all-round maxima will remain small. If Fisher believed that this was necessarily the case (which is not clear), he was mistaken. It is quite possible that with an increasing number of dimensions the number of level points may increase faster than the proportion of all-round maxima declines. Indeed, it has been claimed that this is generally the case, but this is also unproven. (I will discuss this more fully in a separate post.)

I have not found any definite statement by Fisher either accepting or denying the existence of multiple optima. As I pointed out in my post on Fisher's views on epistasis, he accepted that there could be alternative stable allele frequencies at particular loci. As far as I can see, Fisher would not have denied in principle the possibility of multiple optima for the genome as a whole, and indeed his 1931 letter to Wright might be interpreted as accepting them as an important if rare phenomenon. But overall I think Fisher's position should be described as deeply sceptical. Wright himself said that Fisher 'did not accept the concept of multiple selective peaks' (Wright,1970, p.23), which is literally true, provided it is not taken as implying outright rejection either.

The mean fitness of the population

In Wright's theory, a population is expected to 'climb' up the slope of the fitness landscape under the influence of natural selection, implying that the mean fitness of the population increases. (Selection may however be offset by migration, recurrent mutation, or genetic drift.) In his publications from 1935 onwards (e.g. ESP p.239, 366) Wright uses a formula which may be expressed as delta-q = [q(1 - q)/2W][dW/dq], where q and (1 - q) are the frequencies of two alleles, delta-q is the single-generation change in q, W is the mean fitness of the population, and dW/dq is the partial derivative of W with respect to changes in q. The formula may be interpreted as saying that the effect of selection on the frequency of a particular allele is proportional to its effect on the mean fitness of the population (as well as to the current frequency distribution q(1 - q)).

In his 1941 paper Fisher strongly criticised this formulation, showing by a somewhat roundabout argument that it depends on the assumption of random mating, and claiming that any attempt to relate selection pressure to mean fitness is 'foredoomed to failure just so soon as the simplifying, but unrealistic, assumption of random mating is abandoned' (p.378). Wright's derivation of his formula, e.g. at ESP p.239, does indeed assume random mating. But Fisher's objection is not just technical: 'In regard to selection theory, objection should be taken to Wright's equation principally because it represents natural selection, which in reality acts upon individuals, as though it were governed by the average condition of the species or inter-breeding group. Early selectionists, following in this respect the language of the earlier theological writers on organic adaptation, often speak of selection as directed 'for the good of the species'. In reality it is always directed to the good, as measured by descendants, of the individual. Unless individual advantage can be shown, natural selection offers no explanation of structures or instincts which appear to be beneficial to the species. Yet in Wright's equation the whole evolutionary sequence would appear to be governed by the principle of increasing the 'general good'.' (p.378) I think this is somewhat unfair to Wright, who did not ascribe any causal efficacy to the fitness of the population as such, but Fisher's statement is important as his first general criticism of 'good of the species' thinking. He makes similar criticisms in his 1953 and 1958 papers. In the 1958 edition of GTNS a section on 'The Benefit of the Species' is added, which has become highly influential on modern evolutionary thinking. Although this new section does not refer to Wright, it is plausible that Fisher's sharpening of his hostility to 'good of the species' thinking was stimulated by his objections to Wright's equation.

New Mutations

As already mentioned, in his 1931 letter to Wright, Fisher argues that 'any new mutation will have a half chance of destroying the stability' of an optimal gene frequency. He makes a similar point in his published review of Wright's 1931 paper on 'Evolution in Mendelian Populations', saying that 'even under static conditions, unless it is postulated that the organism is as well adapted as it could possibly be (in which case, obviously, evolutionary improvement is impossible), the equilibrium will be broken by the occurrence of any favourable mutation, of which a steady stream will doubtless occur in one or other of the very numerous individuals produced in each generation. The advantage of the large populations in picking up mutations of excessively low mutation rate seems to be overlooked [by Wright]'.

Their attitude towards new mutations is one of the fundamental dividing lines between Wright and Fisher. Wright repeatedly played down the importance of favourable new mutations, on the grounds that their chance of occurring would be negligible even over long periods (see e.g. ESP pp.150, 165, and 321). He seems to have believed that all possible mutations would already have occurred often enough to be selected if they were favourable, so that the possibility of improvement through new mutations would already have been exhausted. Fisher, in contrast, believed that in large populations even very low mutation rates (say, of one in a thousand million per generation) could not be neglected, and that on an evolutionary time-scale of hundreds or thousands of generations they would provide scope for continuing evolution. It may of course be thought that neither Wright nor Fisher, in the 1930s, knew enough about the nature of genes to have any good basis for their opinions.

Changing Environment

Wright's concept of the adaptive landscape is explicitly based on the assumption of constant environmental conditions. Any change in those conditions involves a change in the landscape itself. Wright was of course aware that environments could change, but he seems to have regarded the 'landscape' as having an underlying continuity of existence even if environmental fluctuations might temporarily change its shape. (I will consider Wright's views on this further in my final post on the shifting balance theory.)

Fisher, on the other hand, believed that environmental change was in one sense irreversible. In the section 'Deterioration of the Environment' in GTNS he emphasised especially the organic environment of competitors, etc:

For the majority of organisms... the physical environment may be regarded as constantly deteriorating... Probably more important than the changes in climate will be the evolutionary changes in progress in associated organisms. As each organism increases in fitness, so will its enemies and competitors increase in fitness; and this will have the same effect, perhaps in a much more important degree, in impairing the environment, from the point of view of each organism concerned. - The Genetical Theory of Natural Selection, Variorum Edition, ed. Henry Bennett, 1999 p.41-2

In his review of Wright's 'Evolution in Mendelian Populations' (reprinted in Bennett, ed.) Fisher again emphasised environmental change:

Professor Wright considers that: 'In too large a freely interbreeding population there is great variability, but such a close approximation to complete equilibrium of all gene frequencies that there is no evolution under static conditions'. He therefore argues that the subdivision of species into partially isolated local races of small size is an important condition not merely, as is obvious, for fission into distinct species, but for progressive evolution. This conclusion is much more debatable [Fisher then makes his point about the importance of new mutations even under static conditions]... Moreover, static conditions in the evolutionary sense certainly do not occur, for, apart from geological and climatological changes, the evolutionary progress of associated organisms ensures that the organic environment shall be continually changing

In short, as several recent commentators have noted, Fisher held a 'Red Queen' conception of evolution, in which organisms have to keep constantly running just to keep up with the competition. This is quite alien to Wright's conception, in which under the influence of selection alone the organic world would soon grind to an evolutionary halt. The extent to which either of these views is correct is a matter for empirical observation. Genetic studies of living populations tend to show continual change, at least at a microevolutionary level, which might seem to support Fisher's view, whereas paleontologists often claim to observe long-term stasis in morphological traits, which might support Wright. This is of course one of the points at issue in the debate over 'punctuated equilibrium', which seems to have petered out through boredom (and the death of some key participants) rather than being resolved. A possible explanation of the apparent conflict of evidence is that traits in hard body parts may be more tightly constrained by stabilising selection than biochemical and behavioural traits. For other suggestions see Williams, Chapter 9.

Refs:
J. H. Bennett, ed.: Natural Selection, Heredity and Eugenics: Including selected correspondence of R. A. Fisher with Leonard Darwin and others, 1983.
Sergey Gavrilets, Fitness Landscapes and the Origin of Species, 2004.
William B. Provine, Sewall Wright and Evolutionary Biology, 1986.
Sewall Wright: Evolution: Selected Papers (ESP), ed. William B.Provine, 1986.
George C. Williams: Natural Selection: Domains, Levels, and Challenges, 1992.
Sewall Wright: 'Random drift and the shifting balance theory of evolution', in Mathematical Topics in Population Genetics, ed. Kojima, 1970.

Labels: Burbridge, Population genetics

Parag Khanna is the author of The Second World: Empires and Influence in the New Global Order. He is also Director of the Global Governance Initiative and Senior Research Fellow in the American Strategy Program at the New America Foundation. His website is Paragkhanna.com, where one can find a repository of articles, videos and interviews. Below are 10 questions. (in case readers are curious, I did read The Second World in one sitting)


1) Another recent work which I think one can compare to your book, "The Second World: Empires and Influence in the New Global Order," is Fareed Zakaria's "The Post-American World." If I had to contrast the two I would suggest that Fareed's narrative is both broader in scope and thinner in detail. "The Post-American World" attempts to describe a possible future trajectory for the whole world while you focus specifically on the Second World (albeit, a rather a large canvas in and of itself). And while Fareed tends to utilize simple and general frameworks (e.g., China and India do not believe in God), you seem to rely on more thick description empirically (balancing both quantitative statistical data with on-the-ground observation) as well as a more scholarly theoretical superstructure (such as H. L. Mackinder's "Heartland" model). Would you say this is a fair description of the differences?

*** My "Second World" is certainly broader in scope than "Post-American World" in that it covers literally the entire planet (but with some areas like Central America and Sub-Saharan Africa getting very short treatment). He gives more space to India than I do, and we both accord much attention to China, while I add in China's role in key regions like Latin America, the Middle East, and Central Asis as well. Even though my book is a travelogue with micro-detail, Fareed and I have nearly identical conclusions about the growing confidence of "The East" and the Second World more broadly (which he calls "the rest"). I wanted to have the scholarly superstructure in my book because in addition to providing descriptive detail, I wanted to be predictive about what the rise of new powers will do to geopolitical transition, the balance of power, the future constraints on American foreign policy, and so on.


2) You make copious reference to geographer H. L. Mackinder and those who responded to his hypothesis about the centrality of the Eurasian core in world domination (e.g., Nicholas J. Spykman and the "Rimland"). As a self-identified geography-nerd I can say that your references to grand theoretical frameworks were deftly integrated into the narrative. On the other hand, can you expand on the value which these sorts of models may give to the typical lay reader? Specifically, do you believe that the theory allows one to plausibly stitch together the copious data which you present within your narrative a more comprehensible manner?

*** Even in the age of technology and globalization, geography is still destiny for most. I try to demonstrate just how important the regional context is for evaluating a country's situation and options -- it is more important than the global in most cases. So indeed, Mackinder and geopolitics' emphasis on population, resources, location, sea access, natural barriers, and other features of geography remain absolutely pivotal to understand a country's prospects. Let's take the biggest debate in Asia today (from America's point of view), namely India vs. China. Just because they both have over 1 billion people, that does not make them equal. Even if they both had efficient regimes (which China does and India doesn't), or even if the regimes were reversed, and India had the "better" government, India would still face the reality that it is hemmed in by the Himalayan mountains (the world's tallest) and vast oceans, and has acrimonious relations (at best) with all its neighbors. This severely limits its power projection capability. China, on the other hand, borders more countries than any other in the world, which is extremely useful when spreading influence by either economic, demographic, military, or infrastructural means.


3) I recently read "After Tamerlane: The Global History of Empire Since 1405," which seems to argue there was a fundamental shift in the rise and fall of polities around this period. Specifically, the author seems to be making the case that the Gunpowder Empires fundamentally reversed the power dynamic which had long privileged the peoples of Mackinder's Heartland over the settled societies of Spykman's "Rimland." The defeat of the Dzunghar Confederacy by the Manchus and the rollback of the Tatar by the Russian Empire come to mind. Since I am not fluent in Mackinder's ideas at anything more than a caricature level, am I right to believe that he his argument was one of strategic control of territory, as opposed to the dynamic forces of history being driven by peoples shaped by the ecology of the Heartland itself?

*** "After Tamerlane" is a wonderful work of scholarship. Both the factors you identify -- strategic control of territory and the ecology of the Heartland -- were important for Mackinder. It wasn't just that the Heartland would be impervious to naval attack/control, but also that it possessed rich natural resources (water, timber, etc.) In fact, based on differing understandings of Mackinder's emphasis, scholars have come up with different geographies for the precise location of "Heartland" and "Pivot", Mackinder's other key geographic concept.


4) Reading "The Second World" I felt the shadow of books such as "Guns, Germs and Steel" and "The Wealth and Poverty of Nations." In other words, fixed geographical parameters interact dynamically with historical contingencies to shape the patterns of variation we see around us. For example, geography does not mean that Argentina is a wealthy land, but, if history is a guide it suggests that it can be a wealthy land because of the potential productivity of agriculture in its particular climate. I believe these coarse marco-level parameters are critical and do add value in our attempt to model the reasons for the shape of the past, the nature of the present, and the possible trajectories of the future. But I also have an interest in biology, and I am of the opinion that economists for example would gain value by deviating from the uniform Homo economicus assumption and take into account individual and group differences. There are strong indications for example that Toxoplasma gondii, a parasite which one may catch from cats, can change personality and predisposition and generate between-cultural differences. There is also data which suggests that personality variation may be controlled by genes which modulate dopamine pathways. Finally, there are also new avenues of research suggesting genetic variation which controls differences between individuals in behavioral economics experiments. These are simply three examples. I believe in the importance of geography as a major macroscale parameter, but, I am also one who suspects that many of these coarse differences we see across the world may be rooted in microscale variation. Some economists are moving into this domain and attempting to find causal connections between the micro and macroscale. Do you know if scholars in international relations community have taken notice? Or are there just too many other low hanging fruit to analyze so that it is impractical at this moment to integrate these domains into the field?

*** You might have noticed that I try to pitch the book as a work of "geopolitical psychology" and I use quite a few metaphors from sociology as well. I strongly avoid any rational actor models/biases in the book, and in fact try to highlight "irrational" behavior wherever possible and show it as a product of history/culture/geography: just take Chavez in Venezuela, Gaddafi in Libya, and Putin in Russia, three examples I delve into in the book. I also argue that a nation's psychology is schizophrenic (particularly in the Second World), and that nations can be satiated in a manner that tracks to Maslow's famous "hierarchy of need". But yes, beyond game theory there is increasing amounts of work in political science that looks at such non-social sciene approaches to undetstanding behavior in the political arena as well.


5) I was struck a bit by the Sinocentric focus of much of the book. China looms large. In contrast, you don't spend much time on India, asserting that it is basically a Third World nation, and will remain one for some time. This seems plausible to me skimming over the data on any human development index (or, the fact that it seems likely that the majority of the world's mentally retarded due to nutritional deficiency, cretins, reside on the Indian subcontinent). Nevertheless, the media in the United States has constructed a China vs. India narrative. Good copy? Or do some people actually think in these terms? (as I suggest above, it seems that the comparison is laughable looking at the bottom-line statistics on most vital indices)

*** In addition to my answer above about how geography impacts the China vs. India debate, it should be added, in agreement with you, that it makes good copy. After all, how else could one come up with an acronym like "Chindia" or "BRICS", both of which actually speak against the argument of rivalry. In any case, a 19th-century view of the balance of power would certainly suggest that India would make for a strong, populous, democratic, industrial, nuclear, naval superpower partner in the quest to contain China, and thus it's a very useful construction on the part of the U.S. Pentagon. That said, a great deal more depth has been added to the US-India relationship over the years, especially in the IT and now biotech and other areas, so there is a pattern of growing trust between the two since the end of the Cold War, and independent of the military relationship.


6) Your book was published last year. Events move fast. You spend some time on Georgia, and it is not a particularly flattering picture. A friend of mine told me several weeks ago the basic outline you present, which I would characterize by suggesting that Georgia lay somewhere in the great middle between Bangladesh and Finland in corruption and the robustness of civil society. But during the recent course of events I heard little detail of the nation of Georgia as opposed to the specific blow-by-blow of events (or what we know) involving South Ossetia, Russia and Georgia. Is simply an unchangeable feature of the media, or a bug which might be fixed in future releases? Is there any way we can prevent this? Geographical knowledge isn't a top priority now...but it seems that a little data would go a long way in making more informed foreign policy decisions.

*** It certainly would! And that is why my book attempts to be an inside-out look at Georgia. I present Mikhael Saakashvili as a corrupt, power-hungry and pugnacious semi-autocrat, and Georgia as a West African micro-state in the Caucasus. I talk about the poor roads, the belching buses, the squalid villages and the arrogant government. If more foreign policy experts and the general public understood these things earlier on, we would have heard less bullish talk about Georgia I think.


7) You lived in the United Arab Emirates at some point and profile Dubai. So quick question, is Dubai sustainable over the next decade? There are some questions about how over-leveraged and how it is being bankrolled by taking on debt. Additionally, as you allude to in "The Second World" it also extracts labor productivity rather cheaply out of most of its South Asian workforce and it seems there is a likelihood that at some point in the near future the cost of this labor might increase because of the imposition of what we in the States would term humane working conditions.

*** I do believe that Dubai is sustainable over the next decade - and the entire UAE even more so. The country has quickly taken up an essential place as a node in the globalized world, both financial (think SWFs), geographical (a key re-export zone located between Europe and Asia), and political (a neutral and safe place in a turbulent region). There is an outside view of labor conditions and an inside view. The outside view equates third world/Asian labor conditions as tantamount to slavery. The inside view shows that they're considering a proper minimum wage, are aquiring low-cost but energy-efficient housing in the labor camps, and that the workers are there because they want to be there and earn enoughto make the UAE/Gulf the second largest source of global remittances (behind the US). So there will be bumps in the road, but Dubai is the Arab world's first "global city" and absolutely essential for the region and now the world.


8) Speaking of working conditions and cheap labor, in the closing of the book you make reference to immigration in the United States. There are some, quite often economists, who make a case for the enriching value of open borders and free movement of labor, while others would like to close borders in the interests of cultural homogeneity and tightening labor supply to increase wages. Immigration has been a major flashpoint here in the United States over the past few years, and we haven't really resolved anything and seem to be tabling the issue for now. If you could design a system of immigration for the United States what would it look like?

**** The notion of closed borders vs. total free movement represent two extreme bookends, neither of which is realistic. The balance has to be found between bringing in sufficient low-cost Latin labor to do the work that Americans won't do, while also bringing the workers up the value chain so that real wages are pulled down. I do think bringing the currently illegal population "above board" as Schwarzeneggar proposed a while back is a good idea - it will help to get a better accounting of numbers of immigrants/workers in the country and legitimize their presence.


9) Empires loom large in the actions of Second World powers, the United States, China and the EU. I get the sense from the book that you think that the EU has acquitted itself rather well in the world of late in terms of advancing its own interests, both in terms of realpolitik and in the domain of spreading its normative outlook. Additionally, you observe that the EU allows for both unity and diversity; nations can preserve their language and culture upon admission, though obviously centralizing and homogenizing trends are also apparent. Of late some scholars have been looking back to empires of the past as models for diversity existing cheek-by-jowl with political unity. But I would assert that despite diversity most empires of the past were dominated by one identity. For example, Polybius famously observed that the power of the Roman state was its assimilative capacity, but Anastasius in the late 5th century was probably the first emperor who self-identify as a Hellene. Emperors of "exotic" lineage such as Philip the Arab or Septimius Severus (Punic on his father's side) were Latinized. In "The Fall of the Roman Empire: A New History of Rome and the Barbarians" the author asserts that the liberal education which was the norm among Roman aristocrats was essential in inculcating not just specific values, but an upper class Latin accent which could mark one's social origins through life immediately upon first contact. So my point is that these diverse empires had herrenvolk. You seem to point to China's Han ethnicity as something of this sort, but the Han are on the order of 90% of the population of their state. In contrast, there is no such preponderance of ethnicities in the EU. Could it be that past exemplars are simply not applicable to the present? In "The Great Upheaval: America and the Birth of the Modern World, 1788-1800" Jay Winik contends that it was a common assumption during the 18th century that popular governmental forms such as republics and democracies were simply not scalable beyond the city-state, and yet here we are over 200 years later.

*** In her excellent book "Day of Empire," Amy Chua explains how tolerance of diversity was a renewing force for major historical empires and becomes the lifeblood of sustainability, even as it eventually can bring down an empire. The interplay of technology and historical learning is what has allowed the EU to become the modern day Holy Roman Empire so successfully.


10) You offer that you've traveled to over 100 nations in "The Second World." Certainly impressive, but I'm curious as to the range of linguistic fluency necessary make yourself understood. Was English sufficient, or did you have to lean on languages which you'd learned or already knew besides English? Were there interregional differences?

*** One needs a different linguistic strategy for each region. In Eastern Europe I got by with a mix of German (which I speak fluently), English, and some translators for Ukrainian and Russian. I speak Spanish so was okay in South America. In the Mideast I used basic Arabic to get by on the street, but did interviews either in English or with translators. And in China I needed translators all the time. If I could have done it all over again it would have been nice to speak Russian given all time I spent in Central Asia, but I wouldn't recommend to young students today to learn Russian. I think it is best to learn Arabic or Chinese (or both) today.

Labels: 10 questions

If you have Netflix, the Paskowitz family documentary Surfwise is now watchable online.

It's up, How Jews Became Smart: Anti-"Natural History of Ashkenazi Intelligence" (big PDF). The long-awaited rebuttal to the Natural History of Ashkenazi Intelligence.

Labels: culture, IQ

Economists are getting into the twin-study game more often. The latest entry is forthcoming in the Harvard-MIT run Quarterly Journal of Economics. They ran tests on a bunch of Swedish twins, tests that involved real money. The goal: See how altruistic they were (how much money did they share with a pro-homeless charity?) and see how risk-tolerant they were (how big does the reward have to be before they'd take a risky gamble?).

Key quote:

[W]e have used standard behavior genetic techniques to decompose variation in preferences for giving and risk-taking into environmental and genetic components. We document a significant genetic effect on risk taking and giving, with genes explaining approximately 20% of phenotypic variation in the best fitting models. The estimated effect of common environment, by contrast, is smaller.

So E>A>C, a common result. Since economists have spent a fair amount of time arguing for the social construction of preferences, it's good to have some evidence that shared family environment--presumably one important kind of "social construction"--apparently has only a modest association with routine economic preferences.

Note: This is the same group of researchers that found that 40% of "responder" behavior in an ultimatum game was heritable.

Conclusions: 1. The Swedish Twin Registry is a treasure. 2. Responder behavior (basically, willingness to punish even when it's expensive to punish) seems about twice as heritable as risk-taking and altruism. We're only going on two studies here, but that's an interesting result: Perhaps "Desire for justice/revenge" is more heritable than "Fear of loss" and "Kindness."

Labels: Behavior Genetics

Dienekes posted a bunch of abstracts from a meeting of the American Society of Human Genetics. This one jumped out at me:

Seven selection-nominated candidate genes (COL11A1, LMNA, FGFR1, FGFR2, TRPS, BRAF, FLNA) known to be involved in Mendelian craniofacial dysmorphologies and to have high allele frequency differences between West African and European populations were tested for admixture linkage to normal facial feature traits. The sample consists of 254 subjects (n=131 African Americans, n=123 Brazilians) of West African and European genetic ancestry. Each individual was genotyped at 176 ancestry informative markers (AIMs), which allowed for proportional estimation of genetic ancestry from four parental populations and adjustments for admixture stratification.

3D images of faces were acquired using the 3dMDface imaging system. 3D coordinate data were collected from 22 landmarks placed on each image using the 3dMDPatient software. The 231 possible pairwise landmark distances were scaled to the geometric mean and then analyzed using Euclidean Distance Matrix Analysis.

We used both ANOVA and ADMIXMAP to control for admixture stratification and to test for associations between the 231 pairwise landmark distances and 183 AIMs, using sex, height and BMI as covariates. We used a four-population model (West African, European, East Asian, and Native American).

There is a strong concordance between the ANOVA and ADMIXMAP results. Many landmark distances, particularly on the mouth and nose, were significantly associated with genetic ancestry. Additionally, three of the candidate genes show no effects on pairwise landmark distances while four show distinct patterns of association. For example, FGFR2 is associated primarily with the length of the face. These results represent the first identification of the first genes affecting normal variation in facial features.

A definite new twist possible on DNA forensics.

Labels: Genetics

W. D. Hamilton is rightly given the main credit for establishing the concept of inclusive fitness. He gave it its name, developed its mathematical theory, and examined a wide range of empirical evidence for it.

There had of course been occasional anticipations of inclusive fitness, going back to Darwin's treatment of neuter social insects in the Origin. Hamilton himself mentioned three such partial anticipations: by G. C. Williams, by J. B. S. Haldane, and by R. A. Fisher in his treatment of the evolution of distastefulness among insects (Hamilton, Narrow Roads of Gene Land, vol. 1, pp.49-50).

Curiously, neither Hamilton nor many other commentators seem to have noticed a more general and prominent formulation of the concept by Fisher in the Genetical Theory of Natural Selection......


In Chapter 2 of that book, on the 'Fundamental Theorem of Natural Selection', there is a section headed 'Reproductive Value', which contains the following passage (with emphasis added):

We may ask, not only about the newly born, but about persons of any chosen age, what is the present value of their future offspring; and if present value is calculated at the rate determined before [in the section on the 'Malthusian Parameter'], the question has a definite meaning - To what extent will persons of this age, on average, contribute to the ancestry of future generations? The question is one of some interest, since the direct action of Natural Selection must be proportional to this contribution. There will also, no doubt, be indirect effects in cases in which an animal favours or impedes the survival or reproduction of its relatives; as a suckling mother assists the survival of her child, as in mankind a mother past bearing may greatly promote the reproduction of her children, as a foetus and in less measure a sucking child inhibits conception, and most strikingly of all in the services of neuter insects to their queen. - The Genetical Theory of Natural Selection, Variorum Edition, ed. Henry Bennett, 1999 p.27

What Fisher here describes as 'indirect effects' may be considered a concise but very general statement of what was later defined by Hamilton as inclusive fitness. Fisher's brief remark may have been overlooked, not only because the statement is not mathematically quantified, but because Fisher immediately goes on to say that 'such indirect effects will in very many cases be unimportant compared to the effects of personal reproduction', and he does not discuss them further. He therefore treats them essentially as a complication to be mentioned but cleared out of the way. Nevertheless, he does recognise the existence of such indirect effects (both positive and negative) and mentions several examples which have later been extensively treated by Hamilton and other sociobiologists.

I dare say that someone somewhere has already noticed and mentioned this passage of Fisher, but as it does not seem to be widely known it will do no harm to mention it again.

Labels: Burbridge, Population genetics

Recently Charles Murray has promoted the idea that too many people are seeking 4 year degrees: "Let's stop this business of the B.A., this meaningless credential". Last year he wrote in the Wall Street Journal:

If you want to do well [in college], you should have an IQ of 115 or higher. Put another way, it makes sense for only about 15% of the population, 25% if one stretches it, to get a college education. And yet more than ... 40% of all persons in their late teens are trying to go to a four-year college--enough people to absorb everyone down through an IQ of 104.

Several months ago, the Inductivist found this to be a canny estimate: in the 1960s the average college graduate had an IQ very close to 115, and today the average college graduate has an IQ of 105.

But what does this mean for the individual? Murray suggests that college debt, lack of relevant job training, and years of lost workforce wages and experience await those below the 85th percentile:

They are in college to improve their chances of making a good living ... and would do better in vocational training ... two-year colleges ... [are] about right for learning many technical specialties, while four years is unnecessarily long ... Finding a good lawyer or physician is easy. Finding a good carpenter, painter, electrician, plumber, glazier, mason--the list goes on and on--is difficult, and it is a seller's market. Journeymen craftsmen routinely make incomes in the top half of the income distribution while master craftsmen can make six figures.

I find the thinking here plausible, and these seem like testable enough ideas. Luckily, all the relevant variables are included in the General Social Survey.

It's graph day on gnxp. The x axis in the figure below represents the number of correct answers on the 10 question WORDSUM mini IQ test included in the GSS. The y axis represents the respondent's income in constant dollars. The colored lines represent five educational categories, and one occupational category. Moving left to right we see the average income of people in each category as their IQ score increases from 0-10 correct answers. 'Junior college' represents the two-year vocational degree Murray references. And 'Craft and Trade Workers' covers over 50 skilled trade categories like electrician, mason, plumber, carpenter, and mechanic, coded by the survey.


The first observation here is that educational degrees, whether they confer skills or credentials, are more important to income than IQ when minimum thresholds are met. Trade workers, and 2 and 4-year college graduates are not significantly represented in the lowest three IQ categories. Graduate holders have an even higher minimum IQ. Second, income rises within 5 of the 6 categories as IQ increases. Higher IQ generates the biggest pay-off differences between those with advanced degrees, which is consistent with IQ increasing in importance as jobs become more complex. Third, merely earning a Bachelor's degree is a golden ticket. People with average and below average IQs are getting just as much of a financial return out of their 4-year degree as those above the 85th percentile. This suggests many more people of marginal ability should be seeking a Bachelor's degree, not less. Fourth, the two lines for junior college and trade occupations overlap substantially, as we would expect if most people in trade occupations went to trade school. Fifth, and most directly related to Murray's argument, people with 4-year degrees earn much more than people with 2-year degrees and trade jobs at every level of IQ. Average IQ people will get a much, much larger monetary reward from completing a 4 year school than a 2 year school. So the BA is far from being a "meaningless credential" when it comes to "chances of making a good living".

It's possible people with average IQs who complete college are exceptional in other ways. But there is no other empirical evidence that vocational school is better at generating income for those <85th percentile.

Also, secular trends could distort data in the first graph, which combines all survey data from 1972-2006. So the second graph below represents only people who were 35 and older and surveyed between 2000-2006. Fortunately, the results are not too different from the first graph. The IQ categories are condensed and transformed, and we see that 96 is about the minimum to complete 2 and 4 year college, and 111 the minimum for graduate degrees. Again we find that IQ shows no relationship to income for those with a BA, and, in fact, those with lower IQs might profit the most. For those without advanced degrees, people who are moderately above and moderately below average intelligence might earn the most (this balance might be because other socially valued personality traits, like masculinity, are inversely associated with IQ).



So, while I have yet to read Real Education -- which may address these issues -- it would appear that Murray is mistaken in some of his crucial premises.

Still undetermined is if people with 4 year degrees earn a lot more money because they actually acquire important skills, or if inefficient laws/taboos against employee IQ testing, sustain a comically messy and tragically expensive employment screening method. If the latter was true Murray could still be partially correct: 4 year college could be worthless for the <85th percentile, if employers began to use 20 minutes of psychometric testing, instead of 4 year degrees, as their screening filter.

But, ceteris paribus, college is still the best pay-off.

Labels: education, GSS, IQ

[Note: I'm rushing this out before the school week starts, as I need sleep, so if it seems unedited, that's why.]

We are living in very exciting times -- at long last, we've broken the stranglehold that a variety of silly Blank Slate theories have held on the arts, humanities, and social sciences. To some, this may sound strange, but things have decisively changed within the past 10 years, and these so-called theories are now moribund. To let those out-of-the-loop in on the news, and to quantify what insiders have already suspected, I've drawn graphs of the rise and fall of these fashions.

I searched the archives of JSTOR, which houses a cornucopia of academic journals, for certain keywords that appear in the full text of an article or review (since sometimes the big ideas appear in books rather than journals). This provides an estimate of how popular the idea is -- not only the true believers, but their opponents too, will use the term. Once no one believes it anymore, then the adherents, opponents, and neutral spectators will have less occasion to use the term. I excluded data from 2003 onward because most JSTOR journals don't deposit their articles in JSTOR until 3 to 5 years after the original publication. Still, most of the declines are visible even as of 2002.

Admittedly, a better estimate would be to measure the number of articles with the term in a given year, divided by the total number of articles that JSTOR has for that year, to yield a frequency. But I don't have the data on total articles. However, on time-scales when we don't expect a huge change in the total number of articles published -- say, over a few decades -- then we can take the total to be approximately constant and use only the raw counts of articles with the keyword. Crucially, although this may warp our view of an increasing trend -- which could be due to more articles being written in total, while the frequency of those of interest stays the same -- a sustained decline must be real.

Here are the graphs (an asterisk means the word endings could vary):













Some thoughts:

First, there are two exceptions to the overall pattern of decline -- orientalism and post-colonialism. The former may be declining, but it's hard to say one way or the other. The latter, though, was holding steady in 2002, although its growth rate had clearly slowed down, so its demise seems to be only a matter of time -- by 2010 at the latest, it should show a down-turn.

Second, aside from Marxism, which peaked in 1988, and social constructionism, which declined starting in 2002 *, the others began to fall from roughly 1993 to 1998. It is astonishing that such a narrow time frame saw the fall of fashions that varied so much in when they were founded. Marxism, psychoanalysis, and feminism are very old compared to deconstruction or postmodernism, yet it was as though during the 1990s an academia-wide clean-up swept away all the bullshit, no matter how long it had been festering there.

If we wanted to model this, we would probably use an S-I-R type model for the spread of infectious diseases. But we'd have to include an exogenous shock sometime during the 1990s since it's unlikely that epidemics that had begun 100 years apart would, of their own inner workings, decline at the same time. It's as if we started to live in sparser population densities, where diseases old and new could not spread so easily, or if we wandered onto an antibiotic that cured of us diseases, some of which had plagued us for much longer than others.

Third, notice how simple most of the curves look -- few show lots of noise, or the presence of smaller-scale cycles. That's despite the vicissitudes of politics, economics, and other social changes -- hardly any of it made an impact on the world of ideas. I guess they don't call it the Ivory Tower for nothing. About the only case you could make is for McCarthyism halting the growth of Marxist ideas during most of the 1950s. The fall of the Berlin Wall does not explain why Marxism declined then -- its growth rate was already grinding to a halt for the previous decade, compared to its explosion during the 1960s and '70s.

Still, it could be that there was a general anti-communist zeitgeist in the 1950s, so that academics would have cooled off to Marxism of their own accord, not because they were afraid of McCarthy or whoever else. Importantly, that's only one plausible link -- there are a billion others that don't pan out, so it may be that our plausible link happened due to chance: when you test 1000 correlations, 5 of them will be significant at the 0.005 level, even though they're only the result of chance.

This suggests that a "great man theory" of intellectual history is wrong. Surely someone needs to invent the theory, and it may be complex enough that if that person hadn't existed, the theory wouldn't have existed (contra the view that somebody or other would've invented Marxism). After that, though, we write a system of differential equations to model the dynamics of the classes of individuals involved -- perhaps just two, believers and non-believers -- and these interactions between individuals are all that matter. How many persuasive tracts were there against postmodernism or Marxism, for example? And yet none of those convinced the believers since the time wasn't right. Postmodernism was already growing at a slower rate in 1995 when the Sokal Affair put its silliness in the spotlight, and even then its growth rate didn't decline even faster as a result. Kind of depressing for iconoclasts -- but at least you can rest assured that at some point, the fuckers will get theirs.

Fourth, the sudden decline of all the big-shot theories you'd study in a literary theory or critical theory class is certainly behind the recent angst of arts and humanities grad students. Without a big theory, you can't pretend you have specialized training and shouldn't be treated as such -- high school English teachers may be fine with that, but if you're in grad school, that's admitting you failed as an academic. You want a good reputation. Isn't it strange, though, that no replacement theories have filled the void? That's because everyone now understands that the whole thing was a big joke, and aren't going to be suckered again anytime soon. Now the generalizing and biological approaches to the humanities and social sciences are dominant -- but that's for another post.

Also, as you sense all of the big theories are dying, you must realize that you have no future: you'll be increasingly unable to publish articles -- or have others cite you -- and even if you became a professor, you wouldn't be able to recruit grad students into your pyramid scheme, or enroll students in your classes, since their interest would be even lower than among current students. Someone who knows more about intellectual history should compare arts and humanities grad students today to the priestly caste that was becoming obsolete as Europe became more rational and secular. I'm sure they rationalized their angst as a spiritual or intellectual crisis, just like today's grad students might say that they had an epiphany -- but in reality, they're just recognizing how bleak their economic prospects are and are opting for greener pastures.

Fifth and last, I don't know about the rest of you, but I find young people today very refreshing. Let's look at 18 year-olds -- the impressionable college freshmen, who could be infected by their dopey professors. If they begin freshman year just 1 year after the theory's peak, the idea is still very popular, so they'll get infected. If we allow, say 5 years of cooling off and decay, professors won't talk about it so much, or will be use a less strident tone of voice, so that only the students who were destined to latch on to some stupid theory will get infected. Depending on the trend, this makes the safe cohort born in 1975 at the oldest (for Marxism), or 1989 at the youngest (for social constructionism). And obviously even among safe cohorts, some are safer than others -- people my age (27) may not go in for Marxism much, but have heard of it or taken it seriously at some point (even if to argue against it intellectually). But 18 year-olds today weren't even born when Marxism had already started to die.

It's easy to fossilize your picture of the world from your formative years of 15 to 24, but things change. If you turned off the radio in the mid-late '90s, you missed four years of great rock and rap music that came out from 2003 to 2006 (although now you can keep it off again). If you write off dating a 21 year-old grad student on the assumption that they're mostly angry feminist hags, you're missing out. And if you'd rather socialize with people your own age because younger people are too immature to have an intelligent discussion -- ask yourself when the last time was that you didn't have to dance around all kinds of topics with Gen-X or Baby Boomer peers because of the moronic beliefs they've been infected with since their young adult years? Try talking to a college student about human evolution -- they're pretty open-minded. My almost-30 housemate, by comparison, was eager to hear that what I'm studying would show that there's no master race after all. What a loser.

* I started the graph of social constructionism at 1960, even though it extends back to 1876, since it was always at a very low level before then (less than 5 per year, often 0). Including these points didn't make the recent decline so apparent in the graph, so out they went.

Labels: culture, intellectual history

Young and Arab in Land of Mosques and Bars is an article about a few young Egyptian men who moved to Dubai and how it changed them. The piece is an illustration of a very narrow slice of Dubai life; after all most young men in the city are not Arab, but South Asian (Pakistani, Indian, Bangladeshi, etc.). Nevertheless, there are particular points which align with broader trends which we have discussed on this weblog. For example:

This economically vital, socially freewheeling yet unmistakably Muslim state has had a transforming effect on young men. Religion has become more of a personal choice and Islam less of a common bond than national identity.

I have already mentioned several times the cross-cultural sex differences in religiosity. The article makes it clear that freedom and choice result in a drifting away of many young men from traditional religious norms. Not all of course. I believe that the "traditional" institutions which have constrained, channeled and sometimes altered species-typical urges and biases are features of the Post-Neolithic mass society. These mass societies, what we term "civilizations," are characterized by powerful male packs who generate within group cohesion by reducing internal variance in norms, behavior and symbolic markers. The variation is to some extent generated by genetic variation (personality differences, etc.), so without constant social pressure the extant phenotypic variation in behavior starts to show up again. Of course even in a modern economy where "rational actors" are individual agents who operate within a fluid market of goods and services these packs remain (social networks and connections), but the bureaucratic meritocracy breaks down their determinative power. The packs are a parameter in your success in life, but they are not the parameter. Man exists apart from the pack as a selfish consumer and personal producer, and to some extent these individual identities are given notional primacy. But it is not just a modern capitalist economy which allows this individualism to flourish. As documented in Benjamin Friedman's The Moral Consequences of Economic Growth the norms which we might define as broadly liberal individualism seem contingent upon a regime where one perceives that the future will be characterized by greater prosperity than the present. Which bring us back to Dubai; its prosperity is to a large extent built upon debt. I suspect that there's a good chance that when its economic growth is curtailed Dubai will become much less free-wheeling.

Addendum: Though in this post I allude to the constricting effect of the pack norms, obviously many people receive psychological utility from packishness. The cognitive "hooks" for pack behavior vs. individual consumer behavior are different, but they're both there in various proportions in all of us. Unfortunately I think that the modern liberal individualist society has inverted the totalism of the pre-modern traditionalist culture in terms of prioritizing only one aspect of our psychological predispositions. While in a traditional setting many who were by nature individualists chaffed at the social controls, today those who might benefit and find particular comfort in packs are marked off as somewhat deviant (e.g., women who are raised with liberal values but convert to a very traditionalist religion and immerse themselves in a subculture where their personal choices are constrained and channeled).

Note: The relationship between the main individual profiled in the piece and his girlfriend reminded me of the South Park episode Raisins. Ergo, the image.

Labels: culture

It's widely accepted that many of the differences between species are due to changes in gene regulation, rather than in protein sequences themselves. It's plausible, however, that changes in the sequences of transcription factors could lead to large-scale changes in gene regulation in a relatively simple manner--just a single nucleotide substitution could alter transcription factor binding across the whole genome.

Is this how evolution has worked? A new study takes advantage of a pretty cool resource--a mouse carrying human chromosome 21--to answer no, it doesn't appear so.

The authors begin by noting that several transcription factors bind different spots in human and mouse livers. With the mouse carrying human chromosome 21, they can pretty definitively test whether this difference in binding is due to changes in the transcription factors themselves or to changes in binding site sequence. Remarkably, it doesn't seem to matter whether the human chromosome is located in a mouse or a human--the same human regulatory sequences are bound. Similarly, the locations of an epigentic mark they test seems to depend almost solely on the species the chromosome belongs to rather than the species in which it's located.

This has enormous implications--as the authors write:

Here we show that each layer of transcriptional regulation within the adult hepatocyte, from the binding of liver master regulators and chromatin remodeling complexes to the output of the transcriptional machinery, is directed primarily by DNA sequence. Although conservation of motifs alone cannot predict transcription factor binding, we show that within the genetic sequence there must be embedded adequate instructions to direct species-specific transcription.

Now it's "just" a question of deciphering those instructions.

Labels: Genetics

Thank god for animals and their resemblance to humans to elucidate general patterns and relationships. Missense Mutation in Exon 2 of SLC36A1 Responsible for Champagne Dilution in Horses:

The purpose of this study was to uncover the molecular basis for the champagne hair color dilution phenotype in horses. Here, we report a DNA base substitution in the second exon of the horse gene SLC36A1 that changes an amino acid in the transmembrane domain of the protein from threonine to arginine. The phenotypic effect of this base change is a diminution of hair and skin color intensity for both red and black pigment in horses, and the resulting dilution has become known as champagne. This is the first genetic variant reported for SLC36A1 and the first evidence for its effect on eye, skin, and hair pigmentation. So far, no other phenotypic effects have been attributed to this gene. This discovery of the base substitution provides a molecular test for horse breeders to test their animals for the Champagne gene (CH).

Is horse color a big deal in terms of value? I wonder what the reason why there are so many horse pigmentation papers as opposed to a cheaper multi-colored animal like dog or cat.

Related: White horses and blonde humans: a genetic connection? KITLG makes you whiter.

Labels: Genetics, Pigmentation

At the Freakonomics blog. Nothing too original.

At The Atlantic. I assume regular readers will have some opinions about Ross' opinions....

Here is a nice follow-up to the Herbert and Coates study on London floor traders where they study the profitability of traders and testosterone levels. In this new paper, "Testosterone and Financial Risk Preferences", available on the website on one of the authors, a Harvard-led team of researchers report that men with higher T make more financially risky decisions. They are careful to note that it is merely an association. But it is a start. The slam dunk paper that remains to be written is one with exogenous administration of testosterone (and placebo). That would hopefully settle the causality issue (and might therefore excite the imaginations of some economists!). There are some interesting ideas in the manuscript about financial-risk taking as a form of male-male competition.

Labels: Biological Psychology, Economics

Selective Breeding for a Behavioral Trait Changes Digit Ratio:

The ratio of the length of the second digit (index finger) divided by the fourth digit (ring finger) tends to be lower in men than in women. This 2D:4D digit ratio is often used as a proxy for prenatal androgen exposure in studies of human health and behavior. For example, 2D:4D ratio is lower (i.e. more 'masculinized') in both men and women of greater physical fitness and/or sporting ability. Lab mice have also shown variation in 2D:4D as a function of uterine environment, and mouse digit ratios seem also to correlate with behavioral traits, including daily activity levels. Selective breeding for increased rates of voluntary exercise (wheel running) in four lines of mice has caused correlated increases in aerobic exercise capacity, circulating corticosterone level, and predatory aggression. Here, we show that this selection regime has also increased 2D:4D. This apparent 'feminization' in mice is opposite to the relationship seen between 2D:4D and physical fitness in human beings. The present results are difficult to reconcile with the notion that 2D:4D is an effective proxy for prenatal androgen exposure; instead, it may more accurately reflect effects of glucocorticoids, or other factors that regulate any of many genes.

A while ago I posted two notes on R. A. Fisher's views on population size: Part 1 here and Part 2 here. I assembled some evidence from The Genetical Theory of Natural Selection suggesting that Fisher believed the population size of a species was usually between a million and a million million, with the latter figure being a realistic possibility for some species of small invertebrates.

In writing that post I could not find any more direct evidence, so I am pleased to have come across a letter from Fisher to C. Tate Regan, dated 7 February 1927, containing the following explicit statement:

The population number of 10^6 [1,000,000] parents in each generation represents a somewhat small species. I suppose most species lie between 10^6 and 10^12 [1,000,000,000,000], although some, such as some of the millipedes, certainly exceed the latter figure. The larger the population the less frequent need mutations be to maintain a given stock of segregating factors, or in other words, with the same mutation rates the larger will the variance (when equilibrium is attained) be. (Bennett, ed., p.255)

Earlier in the letter Fisher makes it clear that he is thinking about genes that are nearly neutral in their effect, so that variance is maintained by a balance between mutation and drift.

A population of a million million does seem very large, but Fisher's reference to millipedes confirms that he was thinking of small inverterbrates, where very large populations are quite possible. For example, a population of a million million would only require an average density of one per square metre over an area of about a tenth the size of the United States.

Ref:
J. H. Bennett, ed., Natural Selection, Heredity and Eugenics: Including selected correspondence of R. A. Fisher with Leonard Darwin and others1983

Labels: Burbridge, Population genetics

S knows that P, iff:
1. P is true,
2. S believes that P is true, and
3. S is justified in believing that P.

Winner of the thread for the most clear exposition of what's wrong with this and how to improve it.

Labels: philosophy of knowledge

Attraction 'down to testosterone':

Dr Ben Jones, a psychology lecturer, said: "People preferred different types of face in the session where their testosterone level was highest than in the session where it was lowest.

"When men's testosterone levels were high, they were more attracted to feminine women. When women's testosterone levels were high, they were more attracted to masculine men.

"Since masculine men and feminine women are thought to produce the healthiest children and sex drive is higher when testosterone levels are also high, these findings suggest that men and women in hormonal states where their interest in sex is highest, show stronger attraction to high quality - or healthy - mates."

They used a survey. Is there any way that fMRI would add more value or precision? This hasn't been published yet, but since it's about hotitude of course it will get a lot of play. Since I don't know how strong the effect was from this report I'll hold off on the judging the evolutionary explanation. But I wonder if the constant stream of these sorts of evolutionary psychology results are a function of the British press, or is evolutionary psychology just really popular on that side of the pond?

Labels: Biological Psychology, Evolutionary Psychology

In response to a recent paper detailing how to identify an individual from aggregate allele frequency data, the NIH has removed all such data under its control from the public eye.

This is obviously overkill (to identify an individual from such data, one would have to have genotyped them independently), but it's easier to inconvenience a few scientists than risk a PR backlash. Stories like this make it clear that expectations of privacy in terms of genetic data need a major rethinking; the open consent model of the Personal Genome Project is worth a very close look.

Labels: Genetics

These are numbers from July. More recent months have gotten "launches" from blogs like Andrew Sullivan's. As you note, there are many transients coming in through search engines, but a substantial number of "core" readers. Some of the repeats are just due to comments of course. I was prompted to check after noting Arnold Kling's request for some of his readers to subscribe. I'm pretty happy with our numbers, so no reason for Arnold to feel any guilt.

At least on the state level. A bold Swede who is not shy about plotting data took a stab at checking to see if the results in the personality variation paper could also show trends in GDP per capita:

Extroversion correlated weakly positive (0.16), agreeableness moderately (0.31), conscientiousness moderately (0.34), neuroticism weakly (0.13) and openness negatively (-0.26). That seems odd.

I have plotted the different factors vs GDP below (click for a larger version), with a bundle of regression lines added (each corresponds to the data minus one state, thus showing a bit how stable the estimates are).

Here's my explanation: the same state which has Silicon Valley also has Fresno (no offense to Fresno). The correlations I reported yesterday between Openness and something like patent production would only be generated by the tails of the social distribution. Silicon Valley, not Fresno. There's a reason that The Audacious Epigone looked at both high school graduation rates and college degree holding rates. The two don't always go in the same direction....

Update: From the comments::

He's interpreted the data wrong. Specifically, he plotted the state rank, not the z-value, and so the lowest valued states have the highest openness. The graph then does in fact show that higher openness produces higher per capita GDP. In fact all his correlations have the wrong sign because of this.

Still, he should plot the z-value instead.

If Anders doesn't do this, I might instead....

Labels: culture, Finn baiting

ORMDL3 variants associated with asthma susceptibility in North Americans of European ancestry. ScienceDaily has a summary:

Asthma researchers have found that a gene variant known to raise the risk of childhood asthma in European children plays a similar role in white American children, but not in African American children.
...
Researchers from The Children's Hospital of Philadelphia found that variants in the ORMDL3 gene were associated with childhood-onset asthma among U.S. patients of European ancestry. In 2007 a study team based in Europe had identified the ORMDL3 gene, located on chromosome 17, as contributing to childhood asthma among British and German children.

Labels: Genetics

Update: Another post where I've transcribed the highest correlations for each trait.

Jason pointed me to this Guardian piece, US personalities vary by region, say researchers. It's pretty thin on the details, but luckily the original paper can be found online in full, A Theory of the Emergence, Persistence, and Expression of Geographic Variation in Psychological Characteristics. I haven't read the whole thing, nor do I know much about personality, so I have put the maps which illustrate regional variation in traits below the fold. But I do want to note the correlations between Openness and the following metrics on the state level:

% Arts and entertainment = 0.23
% Computer and mathematical = 0.24
Patent production per capita = 0.28

* Controlling for income, race, sex, college degree, and proportion of state population living in city with one million or more residents. p < 0.05.

Labels: Personality, Psychology

This week's Science has a nice article mapping the hairless phenotype in dogs to a small deletion in a poorly-characterized transcription factor. One of the hairless breeds used in mapping is the Chinese Crested, members of which are perennial contenders in the World's Ugliest Dog Competition. As more dog phenotypes are mapped, one imagines that this competition will be taken over by hideous genetically-modified freaks with the hair/tooth-lessness of the Chinese Crested, the slobber of a Newfoundland, the legs of a Daschund, and the rage of a Springer Spaniel. The horror.

Labels: Genetics

I recall once in high school history my teacher telling us that the average American lived like a king compared to Henry VIII. Not implausible considering the conveniences which were the products of only the past few generations, let alone centuries. That being said, people were in abundance during Henry's period, at least when it came to the whims of the king. So I was surprised when I was skimming over some original documents detailing the English Reformation that several contemporary observers note that Ann Boleyn was rather average in attractiveness. Her exceptionality in appearence was her rather dark complexion for an Englishwoman. In any case, I decided to check out the paintings of Henry's other wives, and was shocked that they seemed rather unexceptional by an large. I left out Anne of Cleves because she wasn't picked by Henry, though I suppose Catherine of Aragon is a borderline case since Henry was young enough that he had little choice in the matter. Anyway, makes you wonder about what people actually do when they have power to do what they want to do, and what they value.

Labels: Roissy

The Epigone, Half Sigma and Inductivist look at a lot of American state-level data. But I have started to get curious about other countries. I've heard weird things like the claim that at some point in the 1990s northern Italy was the wealthiest part of Europe. I don't know about Italy yet (Italy at one point had a higher per capita GDP than the UK though), but I was curious at inequality in the German states and how it might relate to confession (Protestant or Catholic). I didn't find any religious trend of major note, but the gap between the former East German Lander and those of the West in per capita GDP as late as 2001 shocking (more recent data is welcome, I might look myself). To get a sense of, it looks that as if the between-lander differences are on the order of what you might see across American states, from Connecticut to Mississippi. To be fair to the komrades, the economically and socially dynamic regions of Germany have often been to the southwest near the Rhine and mineral resources, so it seems likely that Baden-Wurttemberg had a head start even before World War II.

State	GDP per capita 2001 (EURO)	Protestant	Catholic	Protestant + Catholic
Saxon-Anhalt	16.18	15.7	4.1	19.8
Brandenburg	16.27	19.2	3.1	22.3
Mecklenburg-Vorpommern	16.29	18.4	3.4	21.8
Thuringia	16.41	26.1	8.1	34.2
Saxony	16.79	21.6	3.7	25.3
Berlin	22.39	22	9.2	31.2
Schleswig-Holstein	22.57	56.3	6.1	62.4
Lower-Saxony	22.63	52	17.9	69.9
Rhineland-Palatinate	22.75	31.9	46.9	78.8
Saarland	22.96	20	65.3	85.3
North Rhine-Westphalia	25.52	28.6	43	71.6
Baden-Wurttemberg	28.75	34	38	72
Bavaria	29.22	21.7	58	79.7
Hesse	30.56	41.3	25.6	66.9
Bremen	33.92	44.1	12.2	56.3
Hamburg	42.88	32.2	10.1	42.3

Labels: culture

Individual differences in non-verbal number acuity correlate with maths achievement. If you're interested in this sort of thing, I would recommend The Number Sense: How the Mind Creates Mathematics. It's actually not much about mathematics, but more about numeracy. H/T Jonah

In Obama's unexciting review of the Bell Curve, he remarked:

no one disputes that children whose mothers smoke crack when they're pregnant are going to have developmental problems.

The relevant studies reveal a more complex picture, though. The effects of prenatal cocaine exposure on IQ remain heavily contested to this day. However, recent evidence from Bennett et al points to a 3 to 5 IQ point drop, on average. This is the most recent study on this subject that I'm aware of.

Interestingly, in following with a few previous studies, it was found that boys suffer a greater cognitive loss from prenatal cocaine exposure than girls. Also, the study found that 9 year olds had equally fewer IQ points as their 4 year old counterparts, countering to a certain extent the idea that the IQ loss goes away as development progresses.

If Bennett's numbers are correct, they have small-- but significant-- implications for the Black-White IQ gap. Unlike tobacco and alcohol, which are used by pregnant white and black women at about equal rates and intensities on average*[1], black women are much more[2] likely than white women to use cocaine or crack while pregnant. This is relevant to behavioral genetic studies-- both past and present-- which have aimed to understand the relative contributions of genetics and environment to the IQ gaps. There is no way, as far as I know, to extract prenatal factors like cocaine use from measures of heritability without explicitly measuring such inputs. As far as adoption studies in particular, it stands to reason that women who place their babies up for adoption exceed the rest of the US population in pregnant cocaine use. An interesting thing about the Scarr adoption study is that all of the mothers of the half-black kids were white.

[1] Today, that is. 1989 was the earliest year I could find data for, and in that year the pattern is starkly different from today-- the black-white ratio in fetal alcohol syndrom for this year has way more alcohol use by pregnant black women than pregnant white women, and also much higher rates of fetal alcohol syndrome among black babies. I'm not sure if the rates were comparable in say the 70's, when the Scarr adoption study was performed. That would be interesting data if anyone happens to have it.

[2]~12 times more in the second link, from 1994

*Source for the alcohol/tobacco/fetal alcohol syndrome rates is the CDC.

Labels: IQ

Related: Wayne Allyn Root smarter that Barack Obama?.

Jason's comment deserves promotion so that Google picks it up:

NPR
October 28, 1994
SHOW: All Things Considered (NPR 4:30 pm ET)

Charles Murray's Political Expediency Denounced
BYLINE: BARACK OBAMA
SECTION: News; Domestic
LENGTH: 635 words

HIGHLIGHT: Commentator Barack Obama finds that Charles Murray, author of the controversial "The Bell Curve," demonstrates not scientific expertise but spurious political motivation in his conclusions about race and IQ.

BARACK OBAMA, Commentator: Charles Murray is inviting American down a dangerous path.

NOAH ADAMS, Host: Civil rights lawyer, Barack Obama.

Mr. OBAMA: The idea that inferior genes account for the problems of the poor in general, and blacks in particular, isn't new, of course. Racial supremacists have been using IQ tests to support their theories since the turn of the century. The arguments against such dubious science aren't new either. Scientists have repeatedly told us that genes don't vary much from one race to another, and psychologists have pointed out the role that language and other cultural barriers can play in depressing minority test scores, and no one disputes that children whose mothers smoke crack when they're pregnant are going to have developmental problems.

Now, it shouldn't take a genius to figure out that with early intervention such problems can be prevented. But Mr. Murray isn't interested in prevention. He's interested in pushing a very particular policy agenda, specifically, the elimination of affirmative action and welfare programs aimed at the poor. With one finger out to the political wind, Mr. Murray has apparently decided that white America is ready for a return to good old-fashioned racism so long as it's artfully packaged and can admit for exceptions like Colin Powell. It's easy to see the basis for Mr. Murray's calculations. After watching their income stagnate or decline over the past decade, the majority of Americans are in an ugly mood and deeply resent any advantages, realor perceived, that minorities may enjoy.

I happen to think Mr. Murray's wrong, not just in his estimation of black people, but in his estimation of the broader American public. But I do think Mr. Murray's right about the growing distance between the races. The violence and despair of the inner city are real. So's the problem of street crime. The longer we allow these problems to fester, the easier it becomes for white America to see all blacks as menacing and for black America to see all whites as racist. To close that gap, we're going to have to do more than denounce Mr. Murray's book. We're going to have to take concrete and deliberate action. For blacks, that means taking greater responsibility for the state of our own communities. Too many of us use white racism as an excuse for self-defeating behavior. Too many of our young people think education is a white thing and that the values of hard work and discipline andself-respect are somehow outdated.

That being said, it's time for all of us, and now I'm talking about the larger American community, to acknowledge that we've never even come close to providing equal opportunity to the majority of black children. Real opportunity would mean quality prenatal care for all women and well-funded and innovative public schools for all children. Real opportunity would mean a job at a living wage for everyone who was willing to work, jobs that can return some structure and dignity to people's lives and give inner-city children something more than a basketball rim to shoot for. In the short run, such ladders of opportunity are going to cost more, not less, than either welfare or affirmative action. But, in the long run, our investment should payoff handsomely. That we fail to make this investment is just plain stupid. It's not the result of an intellectual deficit. It's theresult of a moral deficit.

ADAMS: Barack Obama is a civil rights lawyer and writer. He lives in Chicago.

Labels: IQ

Steve points me to a John Tierney column, As Barriers Disappear, Some Gender Gaps Widen:

"Humanity's jaunt into monotheism, agriculturally based economies and the monopolization of power and resources by a few men was 'unnatural' in many ways," Dr. Schmitt says, alluding to evidence that hunter-gatherers were relatively egalitarian. "In some ways modern progressive cultures are returning us psychologically to our hunter-gatherer roots," he argues. "That means high sociopolitical gender equality over all, but with men and women expressing predisposed interests in different domains. Removing the stresses of traditional agricultural societies could allow men's, and to a lesser extent women's, more 'natural' personality traits to emerge."

I've made this precise argument on this weblog for several years now. The preoccupation with self-actualization and personal fulfillment which is the true religion of the mass consumer society is not something that I think is historically contingent or a random act of cultural evolution. It is an expression of a very deep rooted modal psychological predisposition that has echoed down from the Paleolithic and has simply been evoked by the modern context.

With all the talk about recent human evolution and the effect of agriculture obviously we've deemphasized the whole Pleistocene Mind model which was in the vogue with Evolutionary Psychologists. But these sorts of distinctions of emphasis highlight that variations of truth are often quantitative, not qualitative. Reality is a mix of various elements, not a set of stark alternatives. Agricultural peoples may carry more copies of AMY1, but they still enjoy the taste of meat. And it is illustrative that the elites of many agricultural societies allocated much of their marginal time to the sport of hunting.

After The Great Divergence and the transition to mass wealth societies we saw unleashed these ancient pent up preferences on a broader level. Today hunting is no longer the purview of rentier aristocracies who engage in their pleasures by capturing the surplus production of the peasantry. But we have not gone back to the past in some Eternal Recurrence. Rather, elements of pre-Neolithic psychology that have come to the fore and become explicit aspects of our cultural framework remain embedded in a matrix riddled with the great residual institutions of the traditional post-Neolithic world (e.g., religion, monarchies, formal law, etc.). And of course though we live in a culture where individuality is prized, we are not fragmented into small hunter-gatherer brands. Instead, the post-Industrial society dwarfs the post-Neolithic in the potential scope of social networks and scale of our tribes to such an extent that even the aforementioned institutions which arose to grapple with the complexities of the pan-tribal world have been stretched to their breaking points.

Labels: anthropology, culture

Wrote a small script which totes up how White one is using the full list of Stuff White People Like.

So while skimming this paper on a genome-wide association study of leukemia, I noticed one of their hits falls in the gene IRF4. What other phenotype has variation in this same region been associated with? Pigmentation. Of course, the actual causal polymorphisms in each case aren't known, but still, kind of an interesting fact.

Labels: Genetics

Update: Added populations.

Update: Added 1980 vintage language data. Note that Italians are the largest foreign population traditionally.

Update II: I tried to plot the 1980 language proportions against 2005 per capita income. I know, not kosher, but doesn't matter, almost none of the income variation can be accounted for by language variation (around 5%, with a slight positive relation between Germanity and wealth). Using the 1980 language data and 2005 per capita cantonal GDP the nominal per capita GDP would be 56,000 for German speakers and 51,000 for French speakers.

A commenter asked about Switzerland. I'd been meaning to look deeper into the issue for a long time, so I decided to give it a try. Below the fold are the Swiss Cantons organized by the variables you see in the title. I had to collect the information from various sources, explaining the obviously non-Anglicized names of some of the Cantons (I've just finished looking up the language and religious proportions in a somewhat time consuming manner, so I am not inclined to change the names since they're rather intelligible). I ran into some papers relating factors such as government expenditure and economic productivity and Protestantism, but I'll leave the data without comment and as a reference for readers. I also included a map below which can give you a sense of where the Cantons are and the distributed. One thing to note, several sources noted that in Switzerland Protestantism historically tended to be urban, which I thing goes a long way toward explaining what seems to be a difference in per capita GDP.

Canton	Per capita*	Language	Religion	Population	German	French	Italian	Romansch
Basle-Town	115178	German	Protestant	193100	81	3	8
Zoug	93753	German	Catholic	95100	87	1	7
Nidwald	73286	German	Catholic	37200	94	1	2
Glaris	73236	German	Protestant	38700	83		10
Zurich	68804	German	Protestant	1181600	83	2	8
Geneve	62839	French	Protestant, Catholic	396600	9	65	9
Schaffhouse	55126	German	Protestant	73700	85	1	6
Basle-Land	53502	German	Protestant	255300	85	2	7
Vaud	52901	French	Protestant	608200	9	75	7
Schwyz	50170	German	Catholic	125200	91		5
Neuchatel	49775	French	2/3 Protestant	165400	8	77	9
Grisons	49355	55% German, 30% Romansh, 15% Italian	1/2 Catholic, 1/2 Protestant	38700	60	1	13	22
Argovie	49209	German	Mixed	579400
Soleure	46844	German	3/5 Catholic	241600	87	1	7
Appenzel Rh-I	45936	German	Catholic	14900
Uri	45712	German	Catholic	35800	91	1	4
Berne	45644	German, French	Protestant	938600	84	8	4
Thurgovie	44918	German	2/3 Protestant	225400	87		7
St-Gall	44866	German	Mixed	443900	89		5
Appenzell Rh-E	44215	German	Protestant	54000	90		5
Lucerne	43910	German	Catholic	342900	91	1	4
Tessin	39646	Italian	Catholic	305600	11	2	84
Obwald	39559	German	Catholic	31800	94	1	2
Valais	38385	2/3 French, 1/3 German	Catholic	273400	32	61	3
Fribourg	38385	2/.3 French, 1/3 German	Catholic	229900	32	61	3
Jura	38070	French	Catholic	69222	9	86	4

* Nominal per capita GDP 20005, swiss franc

Labels: culture, Economics

I randomly decided to click The Audacious Epigone's Sitemeter. Its magnitude was far too modest. I encourage GNXP readers to add it to their RSS. I get irritated by commenters with great thoughts who never seem to set aside any marginal time to do some digging themselves. No problems on that front from the Epigone. Also, if you want to know why Sarah Palin is a prole for liking sweet drinks, Half Sigma is your bet for the next week or so. It's all-Palin-all-the-time there....

Cliodynamics, a science of history?  Peter Turchin pops up in the comments via Massimo, and offers a link where you can get a full copy of his next book, Secular Cycles, in pdf form.

On the most recent bloggingheads.tv Brian Ferguson says he will place a rebuttal to The Natural History of Ashkenazi Intelligence on his website, it will be titled "How Jews Became Smart," within a week (it's 70 pages).

Multiple Advantageous Amino Acid Variants in the NAT2 Gene in Human Populations:

Data on the structure of haplotypes and their frequencies are compatible with a model in which slow-causing variants were present in widely dispersed populations before major shifts to pastoralism and/or agriculture. In this model, slow-causing mutations gained a selective advantage in populations shifting from hunting-gathering to pastoralism/agriculture. We suggest the diminished dietary availability of folates resulting from the nutritional shift, as the possible cause of the fitness increase associated to haplotypes carrying mutations that reduce enzymatic activity.

Shorter version: a bunch of loss of function mutations which effect enzymatic activity in the ancestral genetic background shot up in frequency across disparate populations with the Neolithic revolution due to dietary changes. The paper is kind of a hodge-podge (e.g., not statistically significant, so let's hand wave :-). Also the appeal to balancing selection generally makes me suspicious...exactly how much balancing selection was their in our species? If there's a lot of it I assume it has more to do with frequency dependence and environmental heterogeneity than heterozygote advantage. Nevertheless, perhaps this is going to go down with amylase and lactase persistence as a recent adaptation driven by the shock of agriculture. I'm certainly not averse to the idea that nutritional deficiences due to the switch to agriculture drove a lot of recent human evolution.

H/T Dienekes

Labels: Genetics, Human Evolution

Thinking People Eat Too Much: Intellectual Work Found To Induce Excessive Calorie Intake. No surprise, right?

Significance Of Milk In Development Of Culture To Be Studied:

"The oldest pottery shards shown to contain milk were found in southeastern Europe, more precisely in what today is northeastern Greece. We believe that the mutation once grew common there and then became fundamental to the development of agrarian culture," says Anders Gotherstam, who will be coordinating the project.

The researchers will follow the tracks of milk throughout Europe, making use of a model for the spread of genes in order to follow the dissemination of the mutation. In this model the frequency of the mutation increases along the 'frontline' of the dissemination-that is, we in Scandinavia, on the periphery, should thus have the highest frequency of the specific gene.

OK, if I'm reading this right...the hypothesis is that lactase persistence due to a mutation around LCT will be highest frequency in regions which experience agriculture, but haven't experienced it that long? In other words, perhaps the "end state" of agriculture societies is more like China, as milk culture gets squeezed on the Malthusian margins? If this is what they're saying I doubt I believe it.

Labels: culture, Genetics, Human Evolution

Many readers of this weblog are familiar with Robert Putnam's research showing that communitarianism may be inversely correlated with diversity. In the American context we're likely to view this through the prism of race and ethnicity. But Peter Turchin in his work tends to focus on religion and other ideologies as the group identities around which humans coalesce. Humans obviously have a need for conformity and solidarity; I recall as a child a Steelers fan getting into a fight with a Browns fan. So it should not be hard to observe the problems which ideological diversity produce even in an ethnically and racially homogeneous nation such as South Korea.

Last week there were mass demonstrations of Buddhists in South Korea against the religious parochialism of the current president, a Presbyterian elder. The president is already unpopular for other reasons, so I don't personally believe that this unrest is a necessary outcome of religious tension. Rather, as documented in books such as The Moral Consequences of Economic Growth, a social context where individuals feel under stress and insecure will often produce intergroup conflict. In an age of plenty there is elbow room between factions because of the growing pie, but when we smell the Malthusian trap in the air group level affinities come to the fore as you don't want to become isolated as an individual without communal capital which you can leverage.

South Korea is I suspect a case where these dynamics might become more important in the coming years because of its religious diversity. Additionally, religious tension is not a new feature of the culture. It isn't too hard to find instances of fundamentalist Christians attacking Buddhism. This is similar to cases in Brazil where evangelicals have destroyed statues of the Virgin Mary. There several recent incidents associated with the current head of state which precipitated the present crisis, but note this:

But tension has been building up since December, when newly elected president Lee began filling his first cabinet with Christians. At least a half of his new ministers were people professing to be Christians, with the prime minister, Han Seung Soo, said to be a Roman Catholic. Not a single cabinet minister professed to be Buddhist.

or

Of the 15 members of Lee's Cabinet, 12 are Christian and one is Buddhist while the affiliation of two others was not immediately available.

So obviously there's some disagreement, but one can assume here that though Christians are 1/3 of the population they are the substantial majority of the cabinet. Is this prejudice? Discrimination? Do Buddhists have grounds to be angry? As I have noted before in South Korea Christianity has a strong correlation with higher socioeconomic status. If one assumes that cabinet level positions sample from the social and educational elites, then they will naturally tend to preponderantly be Christians! Of course since the president is a zealous Christian one can always be suspicious of his motive and method, so as a precautionary principle one could argue that there should have been an affirmative action to reach out to Buddhists so that the cabinet "looked like the nation."

In the United States we're so hung up on racial and ethnic factions that we often don't notice that the disparate representations of different religious groups in government. Check the religious affiliations of Congress and Governors. Thank God we live well below the Malthusian limit!

Labels: culture, History, Religion

Having previously commented on R. A. Fisher's views on epistasis, I have noticed another relevant passage in The Genetical Theory of Natural Selection:

Each successful gene which spreads through the species, must in some measure alter the selective advantage or disadvantage of many other genes. It will thus affect the rates at which these other genes are increasing or decreasing, and so the rate of change of its own selective advantage. The general statistical consequence is that any gene which increases in numbers, whether this increase is due to a selective advantage , an increased mutation rate, or any other cause, such as a succession of favourable seasons, will so react upon the genetic constitution of the species, as to accelerate its increase of selective advantage if this is increasing, or to retard its decrease if it is decreasing. To put the matter in another way, each gene is constantly tending to create genetic situations favourable to its own survival, so that an increase in numbers due to any cause will in turn react favourably upon the selective advantage which it enjoys. The Genetical Theory of Natural Selection, Dover edn., pp.102-3

It would be hard to find a stronger statement of the pervasive role of epistatic fitness in evolution. But I dare say the myth that Fisher 'did not believe in epistasis' will persist.

Labels: Burbridge, Population genetics

As a special case of the downward trend in homicide and forcible rape beginning in the early 1990s, from 1990 to 2004, sexual abuse of minors steadily declined by 49%, reversing an upward trend from the 15 years before 1990; and from 1993 to 2004, sexual assaults against 12 to 17 year-olds steadily declined by 67%. See Finkelhor & Jones (2006) (free PDF here) for a review of the data, why they are real declines, and some proposed explanations. Also see Wolak et al. (2008) (free PDF here) for a review of the fact and fiction about internet sexual predators -- in particular, it appears that most sexual relationships involving teenage females that began with internet contact are voluntary (although still statutory rape if the female is under the age of consent), often repeated, and that the males rarely use deception. Unwholesome, but not what you see on To Catch a Predator.

Not to put too fine a point on it, but the recent panic that the mass media have been fueling about "sexual predators" is horseshit. For the same methodological reasons as in this post on the rape hysterias, I look at data on the popularity of the "sexual predator" theme in the New York Times. It is the opposite of the prediction from a "following the beat" view of journalistic practice, instead fitting a "spreading an unfounded rumor" view. I propose a simple model and estimate the annual growth rate of the rumor. First, let's see how many articles were written in the NYT in a given year that contained "sexual predator," "sex predator," or the plural forms of these two terms.

Here is a graph:



Right away we observe that the coverage is completely outta whack with the crime statistics on the ground: the phrases first appear in 1966, but there is essentially no coverage up through 1980, a moderate increase until 1990, and an explosion of articles starting around 1990. Because the increase in coverage cannot be explained by a rational response to easily discovered crime statistics, we conclude that it is an irrational "moral panic" -- if the sexual predator did not exist, it would be necessary to invent him.

Going further, let's look at the data from 1981 to 2007. I start with 1981 because that is the first year when at least 2 articles appear -- 1 article every 5 or 10 years you could write off as flukes -- and I drop 2008 since the year is not done yet:



Of the typical curves used to fit data, here the exponential does the best: r^2 = 0.8772, and there is a theoretical reason to expect exponential growth. Actually, a quadratic curve improves r^2 by 0.0037, but that's not very much, and it doesn't illuminate what's going on. By setting 1981 equal to t = 1, and calling the number of articles N, the curve above is:

N(t) = 0.8896*exp(0.1665*t) - 1

So, the estimated annual growth rate is 0.1665.

An exponential function solves a differential equation of the form:

dN/dt = r*N

In words, the rate of increase in the number of articles is directly proportional to the current number of articles, where r is the growth rate we just estimated above. This says that somehow each article begets more articles which beget more articles. This is how a rumor spreads, although "articles written" are technically not the same thing as "people who have heard the rumor." Perhaps in the future the number of articles will saturate at some level, and we will have to re-model it using logistic growth. Or the meme could become unfashionable and the number will plummet to 0, in which case we'd use a boom-and-bust model. These two more realistic models are variations on the S-I-R model of the spread of contagious diseases, the only difference being whether the "infected" people can lose their infectivity or stay infected forever.

Clearly the unlimited exponential growth model is inadequate because the total number of articles in all of the NYT is bounded, so the articles written on "sexual predators" cannot increase without bound. But since their number has not saturated yet (logistic model) or crashed downward (boom-and-bust model), we can't decide between the two more plausible models, let alone estimate the related parameters (like the steady-state number of articles in the logistic model). What is important here is that we have shown that the popularity of the "sexual predator" idea behaves like a rumor and takes on a life of its own or fuels its own growth.

To wrap up, the panic over "sexual predators" is a lot like the Early Modern witch-hunts, which could not have succeeded without mass communication to spread the rumors of well-to-do worry-warts. Because it's easier to swallow rumors than to investigate them, there's a clear incentive for most reporters to do just that. And most of the blogosphere too, for that matter. The desire to know is just not uniformly distributed among the population, even among the affluent sectors. That's something to consider any time you find yourself parroting the hype -- if it were based on good work, then it would pay to buy into it. But most journalists are too stupid, lazy, credulous, or moralistic to figure out what's going on. And most of the blogosphere too, for that matter.

Labels: crime, culture, mathematics

If you aren't subscribed to the DNA Network RSS you might not know that Genetic Future has moved to ScienceBlogs.

Aside from grunge music, what made the late '80s and early '90s culture so gay was a Third Wave of feminist panic, this time without a threat on the ground to respond to. A full employment plan for professional feminists thus required cooking up a boogeyman, and because they prey mostly on impressionable undergrad and grad students, they found it useful to invent the threat of "campus rape" and "date rape." There was a real rape problem in the general population leading up to 1992, though, so Third Wavers were simply parasitizing the popularity of a campaign aimed at helping real rape victims. Let's have a look at whether the various rape hysterias, measured by coverage in the NYT, responded to a real or manufactured threat.

To begin with the facts on the real threat, the Bureau of Justice Statistics, part of the US Department of Justice, has data available on forcible rape from 1960 to 2006...

Here is a graph:



There is a fairly steady increase from 1964 to 1992, and a pretty steady decrease from then to 2006. To measure the national hysteria, we will count how many articles appeared in the opinion-leading NYT in a given year that contain some relevant phrase, which tells us how "in the air" the idea is. [1] Here is the graph for "rape crisis," almost always in the context of rape crisis centers, their organizers, and so on:



Overall it looks like it's tracking something real, namely the forcible rape rate: the phrase first appears soon after rape crisis centers were founded in the early '70s, and the graph steadily rises until 1993 and steadily falls afterward. A separate question is whether the level of panic in a given year is "appropriate" to the threat -- is there too much or too little coverage? That's a value judgment, or perhaps a tough empirical matter, so I won't explore that. What is clear is that the trend in coverage of rape crisis centers tracks the trend in forcible rape rate pretty well, so these articles are reporting on something real.

Rape crisis centers were not confined to colleges -- they were part of community outreach programs, so it makes sense that they would have been more in touch with reality. What happens if we look just at the hysteria about rape on college campuses? Heather Mac Donald wrote a good overview of the subject, called "The Campus Rape Myth". Here is the graph for "campus rape," "rape on campus," or the plural forms of these two phrases, which supports her use of the term "myth":



The graph is very different from before: there is almost no coverage until the late '80s, there is an abrupt spike lasting through the early '90s, and a sudden return to a lower level. The increase-then-decrease pattern is correct, and the peak is roughly where it should be, but the rest of the shape is all wrong. There should be a steady increase up to and away from the peak, not a sudden spike.

What the "campus rape" meme resembles is a bit of gossip that flares up and burns out quickly. The rise and fall of real rape happens on the time scale of decades, while the rise and fall of the "campus rape" myth unfolds on the scale of years. That's what we expect from a gossip model, since gossip spreads very quickly -- by word-of-mouth -- while the social forces that cause the rape rate to change cannot produce such fast changes, judging by how "slowly" social change in related areas proceeds (such as the rates for homicide, illegitimacy, divorce, etc., which also rise and fall on the order of decades). The fact that the two peaks are very close suggests that this myth "piggy-backed" on the popularity of a real threat; otherwise it wouldn't have been taken seriously. [2]

Lastly, let's look at the popularity of the more nebulous concept called "date rape." Here's a graph for articles containing "date rape," "date rapes," or "date raped":



As with "campus rape," the coverage is mostly divorced from reality: there is almost no coverage until the late '80s, an abrupt spike, a sudden downturn, and a steady but still high level afterward. So, unlike "campus rape," the "date rape" myth remains popular. Now, "date rape" is a great myth because it is too vague to easily measure, and therefore difficult to show it's not a grave threat. We know that this coverage cannot reflect forcible rape in general, since that has been declining since 1992, not stabilizing after 1995. One useful definition of "date rape" is rape by an acquaintance, as opposed to those dark-alley events. Here is a relevant fact from a journal article on the decline in many forms of abuse against minors since the early 1990s (another story you haven't heard anything about in the gossip-driven media):

Sexual assaults of teenagers have dropped, according to the National Crime Victimization Survey (NCVS). From 1993 through 2004, overall sexual assaults decreased 67% (Figure 2). The subgroup of sexual assaults by known persons was down even more.

Granted this is for victims aged 12 to 17, but the pattern among 18 to 24 year-olds must surely mirror this. Women far north of this are less likely to be raped at all, and in any event they are not the ones who the media portray as victims of date rape -- it's usually a naive college freshman, as in that dopey movie Higher Learning (a wonderful reflection of the zeitgeist). So, as with "campus rape," most of what you hear about "date rape" is folk mythology.

To close, how did the rape panics affect the average person? It likely gave well-to-do women an exaggerated view of the dangers of male sexuality, and likely left their male counterparts' heads spinning, with lasting effects. Let's take 1991 to be the peak year of these hysterias, and include the two years on either side, when the irrational ones were in their spike phase. Then let's consider people who were 15 to 24 years old -- those still forming their identities, growing into adulthood, figuring out how the social world works, who are open to new views, etc.

This creates a cohort born from roughly 1965 to 1978 that would most strongly bear the imprint of this hysteria, and especially those born around 1971 -- basically, Generation X, with Roissy's and Udolpho's cohorts being near ground zero, Half Sigma being one of the elder members, and Thursday being a younger member. Because the hysteria was so abrupt, there is a strong contrast right outside of this cohort -- for example, Steve Sailer and Alias Clio are not very far outside, but the tone of voice they use when talking about the battle of the sexes is very different, regardless of who turns out to be more accurate in a particular case. The same holds for most Baby Boomers.

The young people I'm friends with or have tutored, who were still in diapers in 1991, don't seem to bear the imprint of the hysteria -- you had to be a struggling adolescent or young adult at the time for it to really fuck with your mind. Children were too blissfully ignorant, while full adults' outlook on the world had already comfortably congealed, more or less. It is no accident that this cohort produced the pickup artists like Mystery -- the women in this group are more psycho than in other cohorts, and the men still have a bad taste in their mouths from being on the receiving end of a national witch hunt. (Full disclosure: I was born in 1980.)

Why didn't the nutty Second Wave of feminism leave a similar imprint on those born before 1965? All of that Andrea Dworkin stuff couldn't have been easy to stomach. I think because, as exaggerated as the Second Wave ideology was, there was a real and steady increase in violence against women at the time, not to mention the parallel increase in homicide, drug use, race riots, and all other kinds of sick shit. You may not have agreed with their assessment of how bad things were, or what caused them, but you could still tell that things seemed to be getting worse -- at least they weren't making everything up.

However, the '90s reversed just about every awful social trend of the previous 30-odd years. Surrounded by evidence of things not being so bad, you could only react with total bewilderment when a group of average women -- not just the bulldog lesbians -- got in your face about how awful men are for date raping their friends and turning college campuses into rape zones, so that women needed to Take Back the Night. The appropriate response to this is, of course, "Are you all fucking crazy?" But that would have only strengthened the witch-hunters' suspicion that you were a closet-rapist. It's a hardening experience to be told that you and the other guys in the room are potential rapists of the girl sitting the next row over.

Tomorrow I'll look at a closely related myth, though this time one that is still increasing in popularity, and I'll propose a model for it and estimate parameters.

[1] I eliminated any "duplicate" results, such as a "summary of the Metro section" that only mentions that there's an article on rape inside (I only counted the real article), or in some cases if what should have been a single long article was salami sliced into 6 or so short pieces -- for example, if a single day's feature on "campus rape" had 6 vignettes focusing on 6 campuses, I counted only one of them. Overall these were rare, though. The 2008 data-points are up through September 1, but I included them just to get a hint of where things are now.

[2] In terms of differential equation modeling, the growth rate of the parasitic response would be an increasing function of the current level of the real threat, and perhaps of the rational response too.

Labels: crime, culture, feminism, the early 90s were gay

My series of posts on the work of Sewall Wright is now approaching its (anti?)climax. The next post, on the shifting balance theory, should be the last. The present note deals with a closely related subject. Wright introduced the concept of the 'adaptive landscape' largely in order to illustrate the shifting balance theory. It does however have great interest in its own right, and there is a substantial literature on the concept of adaptive landscapes. [Note 1]

Wright's own treatment of the subject has attracted some controversy following the biography of Wright by William B. Provine. Provine pointed out that Wright used two different interpretations of the 'landscape', which in Provine's view were inconsistent with each other: 'One of Wright's two versions of the fitness surface is unintelligible, and even if one were to escape this problem and put the gene combinations on continuous axes, the two versions would be mathematically wholly incompatible and incommensurable, and there would be no way to transform one into the other' (Provine, p.313). I believe that Provine's criticisms are overstated, but he was right to point out that Wright's concept of the landscape is problematic. This note examines the issues. It is long.



Overview

The general concept of the adaptive landscape is that the genetic constitution of an individual or a population can be represented by a point in a space of many dimensions. The biological fitness associated with that genetic constitution can then be represented by a measurement along a further dimension. The fitness 'heights' of different genetic constitutions form a quasi-surface. Points or areas of high fitness can be described as 'peaks', points of low fitness as 'pits', 'troughs', etc, and more complex configurations as 'ridges', 'valleys', 'passes', etc. The genetic evolution of a population can be represented by the movement of points around the 'landscape'. Subject to certain provisos, under the influence of natural selection a population will move up the steepest available slope towards areas of higher fitness. If the population reaches a local peak - a point surrounded in all directions by lower ground - evolution will stop until circumstances change in some significant way.

Wright believed that in general there will be many local peaks of fitness in the landscape, often differing in height from each other. It is therefore likely that under the influence of natural selection alone, and under constant environmental conditions, a population will get 'stuck' on a peak which is not the highest in the landscape. Evolution would be quicker, and more beneficial to the species, if there were some means of shifting populations away from these suboptimal local peaks. According to the shifting balance theory in its original form, the only way of moving a population from a peak, other than a large and permanent change in environmental conditions, is by genetic drift, which enables a population to cross 'valleys' of relatively low fitness. This is most likely to occur if the species is divided into a large number of small, partially isolated, subpopulations. Some subpopulations will then by chance find themselves on higher peaks of fitness, and their greater reproductive success will result in a net gene flow into other subpopulations, raising the general fitness of the species and enabling evolution to continue. Wright later abandoned his original exclusive emphasis on genetic drift, but this has not always been sufficiently emphasised. I will deal with this more fully in the final post.

To consider the 'landscape' in more detail:

Sources

Wright's first known use of the landscape concept is in a letter of February 3 1931 to R. A. Fisher, quoted in Provine's biography (p.272). Wright's first published account came in a short paper in 1932. Thereafter he discussed the concept in most of his general surveys of population genetics and evolutionary theory. I cannot claim to have read all of Wright's scattered papers, and I have relied heavily on the collection 'Evolution: Selected Papers', (ESP) edited by Provine with Wright's co-operation. Unfortunately, by the operation of Sod's Law, probably the best account of the 'landscape' is not included in ESP (it is in a 1960 Darwin symposium volume edited by Sol Tax). Surprisingly, Wright's huge 4-volume treatise on Evolution and the Genetics of Populations has no systematic treatment of the landscape concept, though various of its component parts are discussed. Finally, a special interest attaches to a paper of 1988, since this came after the publication of Provine's biography. For details see the references.

Terminology

Wright himself seldom if ever uses the term 'landscape'. In fact, I have not found a single example of it. He does on one occasion (ESP p.625) use the similar term 'topography', but in general he uses two other terms: the field of gene combinations, and the surface of selective values. For convenience I will continue to use the term 'landscape', but anyone searching in Wright's own works should look for 'fields' and 'surfaces', not 'landscapes'. The popularity of the term 'landscape' probably stems from its use in George Gaylord Simpson's Tempo and Mode in Evolution (p.89) and The Major Features of Evolution (p.155), which were more widely read by biologists than Wright's own works. For the same reason, the landscape concept is often given interpretations which derive from Simpson rather than Wright, in which the 'peaks' of the landscape represent either locally optimal phenotypes, or ecological niches. These interpretations are compatible with those of Wright, but not the same as Wright's own landscape, in which the dimensions other than fitness always represent genetic rather than phenotypic variables.

The Number of Dimensions

Wright's landscape has one dimension for fitness, and others representing the genetic constitution of an individual or a population, which I will call the genetic dimensions. At least one genetic dimension is required for each distinct locus at which more than one allele is present in the population. A position along a genetic dimension represents either the number of copies of an allele (in the case of an individual) or the frequency (proportion) of that allele in the population. Since the number of genes at a locus in an individual must add up to the relevant ploidy (one for a haploid, two for a diploid, etc), and the frequencies of different alleles at a locus in a population must add up to 100%, it is only necessary to specify the number or frequencies of (n - 1) alleles at each locus, since the number or frequency of the n'th allele will then be determined as a residual. It is therefore sufficient to have (n - 1) dimensions for each locus, where n is the number of alleles in the population at that locus. The total number of genetic dimensions is the sum of the (n - 1)'s for all loci. The gene pool of any species probably has at least 1,000 loci at which there are two or more alleles present in the population. The number of genetic dimensions is therefore at least 1,000, and usually much larger.

The Axes

It might be supposed that the genetic dimensions would be represented diagrammatically by Cartesian axes at right angles to each other (orthogonal axes). For loci with more than two alleles this would however have the disadvantage that the alleles would not be treated symmetrically. For example, with 3 alleles (A, B and C) represented on two orthogonal axes, if one axis represented the balance between A and B, and the other axis the balance between A and C, the balance between B and C could be inferred but would not be directly shown in the diagram. Wright therefore suggests in several places (e.g. Tax p.431-2) that the axes need not be orthogonal, so that for example in the case just mentioned the pairs A-B, A-C, and B-C could be represented by the sides of an equilateral triangle. In practice, Wright usually illustrates his concept with diagrams showing two orthogonal axes for genetic dimensions and one axis (height) for fitness, which on a flat page can be indicated either by perspective or by contours on a map.

The Number of Genotypes

The number of possible genotypes is vast. With at least 1,000 loci, even if only two positions were possible at each locus, the total number of genotypes representable in the system would be at least 2^1000. Wright himself gives a more generous estimate of 10^1000. Either way, the number is super-astronomical. As Wright points out, it is larger than the number of elementary particles in the universe. It is certainly far greater than the number of individuals in any species. It follows that most of the positions in the genetic 'space' of any actual species will be empty. Even if for most loci a single allele has a high frequency in the population, the genotypes of individuals will be very sparsely scattered over the space. Apart from clones, it is unlikely that two individuals will ever have exactly the same genotype.

Genotypes or Frequencies?

As Provine showed clearly in his biography (pp.307-17), Wright used two different interpretations of his genetic dimensions. In one interpretation, which I will call the genotype version, a position along a genetic dimension represents the number of alleles of a certain type in an individual genotype. For example, if the dimension represents the allele pair A-a at a diploid locus, a position at one end of the axis would represent the homozygote AA, a position at the other end would represent the homozygote aa, and a position in the middle would represent the heterozygote Aa. [Note 2] The whole genotype of an individual would be represented by a single point in the many-dimensional genotype space, and the allele composition of the individual at a given locus could be 'read off' from the projection of that point onto the relevant axis. The genetic composition of a population could then be represented by a number of points, one for each member of the population, at appropriate positions in the 'space'.

In the alternative interpretation, which I will call the frequency version, a position along a genetic dimension represents the proportion of alleles of a certain type in a population. For example, if the dimension represents the allele pair A-a at a diploid locus, a position at one end of the axis would represent fixation (100% frequency) for the allele A, a position at the other end would represent fixation for the allele a, and a position in between would represent an intermediate frequency, e.g. 60% A and 40% a. The entire genetic composition of a population could be represented by a single point at an appropriate position in the 'space'. It must not be inferred that all members of the population would have the genotype represented by this point under the genotype version. In fact, unless most loci are fixed for a single allele, it is extremely unlikely that any individual in the history of the species would have exactly that genotype.

There is no doubt that Wright uses both of these interpretations. In his first known account (in the 1931 letter to Fisher) he uses only the frequency version, but in the first published account (1932) he uses only the genotype version. From 1935 onwards his publications most often use the frequency version, but the genotype version is never entirely lost, and the two interpretations may even appear in the same work. (See Note 3 for my own attempt at a chronological listing.)

But is there really any inconsistency in the two different interpretations? It is evidently quite possible for a position along an axis to represent either an allele number or an allele frequency, and there is no fundamental reason why the two interpretations should not be used at different times, or even at the same time, provided the differences between the two interpretations are properly noted. There is of course a danger that the use of two different interpretations will lead to confusion, or even to actual error if theorems or generalisations which are valid only for one interpretation are applied to the other one. I am not aware that Wright himself ever falls into definite error, but his explanations are often unclear. According to Provine (p.311) , when he first pointed out the different interpretations to Wright, the latter was somewhat taken aback, and did not realise that he had been switching between them. Wright's 1988 paper, which includes a response to Provine's critique, is surprisingly insouciant about the issue, effectively taking the line: 'Why worry, it's only a diagram.'

Provine does have other criticisms, but before discussing these it will be useful to look at the remaining dimension of the landscape, that of fitness.

The Dimension of Fitness

In view of its importance Wright says surprisingly little about the nature or definition of fitness. In his first presentation of the landscape concept he says only that the entire field of gene combinations can be 'graded with respect to adaptive value under a particular set of conditions' (ESP p.162) . The word 'graded' seems to imply a relative measure of fitness, which is consistent with Wright's general approach and that of many other population geneticists, including Haldane. For most purposes a relative measure is sufficient. Wright does however recognise that an absolute measure, such as Fisher's Malthusian parameter, may be useful or necessary for some purposes, for example in dealing with overlapping generations (Tax, p.433).

A more important issue is the question of the relevant 'set of conditions', on which Wright is again disappointingly vague. Clearly the fitness of a given genotype will depend in part on the environment. It appears that Wright intends fitness to be averaged over the usual range of environments in which a species finds itself. But it would be reasonable to object that conditions will be constantly changing, so that there is no such thing as an 'average' environment except at a moment in time. Even at a moment in time the environment will vary in different parts of a species' geographical range. The most important aspect of a species' environment is often not the inorganic factors (climate, etc) but the organic or biotic environment of competitors, food, predators, parasites, and pathogens. These differ fundamentally from the inorganic environment because they are themselves evolving by natural selection, sometimes in response to the species of interest. For example, a new mutation occurring among any of the pathogens affecting a species may dramatically change the fitness of all the genotypes of that species. Wright does in various places recognise that the organic and inorganic environment are liable to change, but he tends to present this as a factor leading to movement of the species around the 'landscape', when it could arguably be seen as invalidating the concept of the landscape altogether. One of the essential features of a landscape, in the ordinary sense, is that it has at least a modicum of persistence through time.

For an individual member of a species, the other members of the same species are an important part of its biotic environment. This raises the possibility that the absolute or relative fitness of different genotypes may vary according to the genetic composition of the species population. Notably, this would be the case with various forms of frequency-dependent selection, for example, if pathogens or predators attack the most common variants. I cannot find any discussion of the issue in Wright's early papers. Under the first published (1932) account, which presents only the genotype version, it seems to be assumed that each genotype can be assigned a fitness regardless of gene frequencies. In the first published account of the frequency version (1935), Wright deals mainly with certain special cases, which again seem to be independent of frequency. In two more general presentations (1939 and 1940), I still find no clear statement. Finally, in 1942 (in an article based on a lecture given in September 1941) we find an explicit assumption that 'the relative selective values of these genotypes are independent of their frequencies' (ESP p.472). It may be relevant that in 1941, in a paper referenced in Wright's 1942 article, R. A. Fisher had sharply criticised Wright's 1940 presentation. Whatever the reasons, in later discussions, notably Tax and EGP, Wright gave more attention to the issue of frequency-dependence (see especially Tax pp.443-49). Generally speaking, frequency-dependence can involve either positive or negative feedback, in the first case driving alleles to fixation, and in the second often leading to a balanced polymorphism. If the latter case is common in nature, it would tend to make the landscape concept more difficult to interpret (see further below).

Is there a fitness surface?

On many occasions Wright refers to the values of the fitness dimension as forming a 'surface'. This would normally imply at least an approximate continuity of values for fitness with respect to changes along the other dimensions. Provine has pointed out that under the genotype version, the fitness values cannot be continuous. The genotype values themselves form a lattice of discrete points, not a surface, so the associated fitness values must likewise be discontinuous.

I think this objection is somewhat overstated. First, as a matter of textual detail, Wright seldom uses the term 'surface' when he is referring to the genotype version; in particular, he does not use the term in his first (1932) published account. But on at least one occasion (in 1939, ESP p.318), he does unambiguously refer to a fitness surface with respect to genotypes; also, as Provine points out, even in the 1932 account Wright uses a diagram which seems to imply a continuous surface. Provine's criticism therefore needs to be met, but I think it is not as serious as Provine suggests. It is true that the genotype values form a lattice of points rather than a surface, but it is possible to define a 'distance' between these points by the number of gene substitutions needed to go from one point to another. We can reasonably describe some points as being closer than others. It would then also be reasonable, if not mathematically exact, to say that the associated fitness values approximate to a surface, provided that small differences in distance correspond to small differences in fitness. The real objection, it seems to me, is not that the surface is not strictly continuous, but that the necessary correspondence between fitness and distance does not exist. Genotypes which differ only in a single allele may differ widely in fitness, for example if the heterozygote at a given locus has above-average fitness, whereas the recessive homozygote is lethal. I do not see any basis for an assumption that differences in fitness correspond, even loosely, to the number of genetic differences between two genotypes.

I suggest that the following picture is more plausible. A very large part of the 'genotype space' must correspond to zero fitness, since it would involve combinations of rare disadvantageous alleles which are unlikely ever to be combined in reality. Only a small 'corner' of the space is inhabited by actual genotypes. Most of these will have rather similar average fitness, equivalent to producing around two surviving offspring (by sexual reproduction), since, on average, this is what most genotypes actually achieve under their normal circumstances. (If they did not, the population would soon die out.) Among these mediocre genotypes there will be a scattering of super-fit types, and a larger scattering of low-fitness types. The geometrical picture is that most of the landscape would be flat, with uniformly zero fitness, rising gently up to a small inhabited plateau of mediocre fitness, in which there are numerous 'holes' corresponding to genotypes with low fitness (e.g. lethal recessives) compared to their immediate neighbours. [Note 4] There will also be scattered pimples or wrinkles of modest height representing clusters of genotypes containing advantageous genes that are still in the process of selection, and shallow depressions representing mildly disadvantageous genes. But because it contains numerous 'holes' - isolated genotypes or groups of genotypes with fitness much lower than their neighbours - the landscape is not even approximately a continuous surface.

If now we turn to the frequency version, there are better grounds for regarding the fitness surface as continuous. In the frequency version each point in the genetic space corresponds to a certain set of allele frequencies at each locus. Provided we make certain assumptions about the mating system and linkage (usually random mating and zero linkage), each array of allele frequencies will be associated with an array of all possible genotypes, each with a definite probability of occurrence. The mean fitness associated with a given point in the frequency space will therefore also be defined. As the point moves around the space, the genotype probabilities will vary continuously, and so will the average fitness, since the value of ab + cd varies continuously if a and c vary continuously, for any fixed values of b and d. It is true that in a finite population the allele frequencies cannot vary with strict mathematical continuity, since they are ultimately fractions with the population size as a denominator, but unless the population size is very small, the fitness surface will approximate to continuity.

What is a fitness peak?

The idea of a fitness 'peak' is central to Wright's use of the 'landscape' concept. So what exactly is a fitness peak? Characteristically, in introducing the term (in 1932) Wright does not formally define it, and his meaning has to be inferred from what he says about it.

This is one issue where it is important to distinguish between the genotype and frequency versions of the landscape. With the genotype version, the definition of a fitness peak is relatively straightforward. If a genotype has higher fitness than any genotype which can be derived from it by substituting another allele at a single site (including e.g. substituting a homozygote for a heterozygote at a given locus), then it may be described as a local fitness peak. So far as I am aware, this is how Wright always uses the term 'peak' under the genotype version.

Under the frequency version matters are less clear. We could, of course, stipulate that a set of frequencies is a local peak if any small frequency change at a single locus would reduce the mean fitness of the population. But this would exclude the reasonable possibility that frequencies may change slightly but simultaneously at more than one locus, which might increase mean fitness even though no single-locus change would do so. The natural definition of local fitness peak implied by these considerations is that a set of frequencies is a local fitness peak if no combination of small simultaneous frequency changes, at any number of loci, would increase mean fitness. Geometrically, this is equivalent to stipulating that a local fitness peak is immediately surrounded by downward slopes of fitness in all 'directions' in the genetic space. Probably this intuitive concept could be defined more precisely in terms of the 'principal directions' of differential geometry, but I am not aware that Wright himself ever took this approach. [Note 5] In practice, Wright deals mainly with specific cases where the intuitive meaning of a fitness peak is sufficiently clear.

How many peaks?

One of Wright's fundamental claims about the landscape is that it has numerous local peaks. Moreover, many of these have a different fitness 'height'. To give some examples (all page references to ESP), he claims that the number of peaks is 'many' (9, 483), 'enormous' (163, 370), 'large' (226), 'inconceivably great' (230), 'multiple' (318), 'innumerable' (348, 554), and even 'virtually infinite' (535). He also insists that many of these peaks will have a different selective value (see the cited or nearby pages for examples). Without these claims, the landscape concept has little interest. The basis of the claims therefore needs to be examined.

In his original 1932 presentation Wright used a simple probabilistic argument for the existence of numerous peaks. The number of possible genotypes is vast, so even if only a tiny proportion of them are local optima, the number of local optima would still be very large: 'With something like 10^1000 possibilities it may be taken as certain that there will be an enormous number of widely separated harmonious combinations. The chance that a random combination is as adaptive as those characteristic of the species may be as low as 10^-100 and still leave room for 10^800 separate peaks....(ESP p.163)'.

This is a dubious argument. It may be compared to a common argument for the existence of intelligent life elsewhere in the universe. There are around 10,000 billion billion stars in the universe, so even if the proportion of stars with planets supporting intelligent life is tiny - say, 1 in 10,000 billion - there would still be an enormous number of such stars. But consider the following counter-argument. It is plausible that the emergence and survival of intelligent life requires a moderately large number of conditions - say, at least 100 - to be met. It is also plausible that these conditions are largely independent, and individually quite improbable - say, with a probability of only 1 in 100. But with these assumptions, the probability that all of the necessary conditions are met in any given case is less than 1 in 1/100^100. This is vastly less than 1 in 10,000 billion billion, so rather than expecting there to be a large number of stars with planets supporting intelligent life, it would be a miracle if there are any at all. In reality, neither argument goes much further than establishing the bare possibility of the conclusion. Similarly, in the case of selective peaks, the sheer number of possible genotypes is in itself not a strong argument for the existence, rather than the bare possibility, of numerous different peaks.

Wright does later present better arguments for the existence of multiple peaks. By far his most common example is that of a quantitative trait controlled by several loci where the selective optimum for the trait is at an intermediate value, i.e. neither the highest nor the lowest that can be produced by the various possible combinations of alleles. In this situation it is likely that the optimum intermediate value of the trait can be produced by different allele combinations. The effect of an allele on fitness (not necessarily on the quantitative trait itself) is epistatic, i.e. dependent on the combination of other genes in the genotype. Which of the relevant alleles are favoured by selection may then depend on the accident of which allele at a locus happens to be most frequent when selection begins, with all other alleles at the locus being driven to extinction. This example is used repeatedly: ESP pp.247, 310, 319, 370, 477, 626, Tax p. 450, EGP vol. 1 pp.59-60.

The theoretical possibility of multiple selective peaks in this situation has been generally recognised. As I pointed out in a post on R. A. Fisher and epistasis, it was recognised by Fisher in 1930. It was also noted by J. B. S. Haldane, who is sometimes mentioned by Wright in this context. Indeed, a diagram used repeatedly by Wright to illustrate the point (e.g. ESP pp. 310, 371) looks suspiciously like an adaptation of one used by Haldane (Causes of Evolution, p.107).

It should be noted that the example of an intermediate optimal phenotype applies to both the genotype and frequency versions of the landscape concept. Provine has claimed that the two versions are 'mathematically wholly incompatible and incommensurable, and there would be no way to transform one into the other' (Provine, p.313). Like his other criticisms, I think this one is overstated. In at least one important class of cases a local peak under the genotype version will be a local peak under the frequency version as well. This is where the local optimum genotype is homozygous at all loci (or where the organism is haploid). In this case, if all the alleles of the optimum genotype are fixed (i.e. have a frequency of 100%) in the gene pool, all genotypes produced from the gene pool will be identical, and will have the local optimum value. Any change in frequencies (including simultaneous changes in several frequencies) can then only occur by mutations, producing a small proportion of alternative alleles. Assuming random mating and zero linkage, the genotypes produced from the new gene pool will usually differ from the local optimum genotype at no more than a single locus. But by definition these are all less fit than the local optimum, so the change in frequencies will be selected against. Genotypes which differ from the local optimum at more than one locus are indeed possible, and may be fitter than the local optimum, but they will occur so rarely that they can usually be neglected. The frequency array in which all the alleles of a local optimum genotype are fixed in the population will therefore usually be a local peak under the frequency version.

If the optimum genotype is not homozygous at all loci, I think Provine is right that there is no easy transition from the genotype version to the frequency version. For any locus that is heterozygous in the local optimum genotype, the heterozygote is most likely to be produced by a 50:50 ratio of the relevant alleles in the population. Let us suppose that the population is fixed for all the homozygous alleles in the optimum genotype, and has a 50:50 ratio for all the heterozygous alleles. Unlike the case where all loci are fixed, this frequency set will produce a multiplicity of genotypes. If there are more than a few heterozygous loci in the optimum genotype, only a small proportion of the genotypes produced from the frequency set will actually have the optimum genotype. (At any heterozygous locus a 50:50 frequency will produce 50% heterozygotes, so if there are n independent heterozygous loci the proportion of genotypes that are heterozygous at all the relevant loci will be (1/2)^n, which rapidly becomes negligible as n increases.) There is no guarantee that this frequency set will be a local fitness optimum (as defined under the frequency version), since this will depend on the fitness of numerous different genotypes, whose mean fitness may well be higher at some other nearby point in the frequency space. It all gets very complicated. If we also take account of frequency-dependent fitness, it is even messier, since there may be no such thing as a local optimum genotype that remains optimal under all frequency arrays.

The case of optimum fitness of a trait with an intermediate value does however go some way towards vindicating Wright's confidence in the existence of numerous local peaks. Assuming that there are several such traits which are genetically independent of each other, and of other loci, this may lead to a very large number of local optimum genotypes. With at least two independent optima for each trait, the total number of local optimal genotypes will be at least 2^n, where n is the number of traits. This quickly leads to large numbers: over a thousand for n = 10, over a million for n = 20, over a billion for n = 30, and so on. But there is a snag. Selection for an intermediate value of a trait will, if it is successful, always produce much the same phenotype. For example, if the optimum length of a canine tooth is 1 inch, selection will tend to produce that length of tooth even if different combinations of alleles are involved. In this case there will be multiple peaks in the genetic landscape, but they will all be of much the same 'height' in the fitness dimension. This would take much of the interest out of the concept. Wright recognised this snag at least from 1935 onwards. His answer to the problem was to emphasise that most genes have multiple (pleiotropic) effects, and that the system of peaks relative to one character is therefore not independent of that relative to another (ESP p.230, 320, etc.) In some places Wright seems to imply that the allele frequencies may be fixed at an arbitrary peak by selection for the optimal value of one trait, leaving the effects on some other trait varying and often suboptimal (e.g. ESP p.595, but he is not explicit). But this is doubtful. Suppose for example that an allele combination which determines the length of the canine teeth also affects the incisors. If two such combinations produce the same optimum length of canines, but different lengths of incisors, there will be selective pressure to bring the latter towards its own optimum. In this situation there may well be genes at other loci that are capable of modifying the trait. If necessary, new mutations could be selected (not necessarily absolutely new, but newly advantageous.) It is not clear that significantly different (in fitness) multiple peaks will persist for any trait. In at least one place (Tax p.450) Wright himself may recognise this possibility, but it does not seem to have dented his confidence in the existence of multiple peaks with different fitness.

Although the case of intermediate optimum traits is by far the most common reason given by Wright for the existence of multiple peaks, it is not quite the only one. He does occasionally mention the possibility of multiple peaks at a single locus with two or more alleles, if the homozygotes are fitter than the heterozygotes. He also recognises the value of Simpson's concept of phenotypic and ecological peaks, distinguishing two cases: those where different phenotypes give alternative ways of adapting to the same selective conditions, and those where they give ways of adapting to different ecological niches within the same environment (ESP p.555).

Conclusions

Overall, it seems to me that Wright makes out a plausible case that there are likely to be multiple peaks of fitness, but the arguments are not conclusive. If the environment is changing, as it always is, the landscape itself becomes fluid. And if there is widespread genetic polymorphism and/or frequency-dependence in a population, much of Wright's original formulation is (by his own admission) not directly applicable. Provine's criticisms of the two different versions of the landscape concept seem to me overstated, but he is right to question its usefulness as a heuristic device. If several generations of biologists failed even to notice the existence of the two versions, the metaphor of the landscape can hardly be said to have encouraged clarity of thought.

The discussion so far has left some important issues untouched. What are the reasons for expecting a population to 'climb' up a fitness slope? Even if there are many fitness peaks in the landscape, are they all accessible to the population? Will a population get 'stuck' on a peak for any length of time? If so, what circumstances may shift it away from that peak? These questions all go to the heart of the shifting balance theory, so rather than discuss them now I will leave them for my intended note on the shifting balance theory. But before I get there I think it will be useful to cover two supplementary issues which are less directly concerned with Wright's own views. First, what did R. A. Fisher think about all this? And second, apart from Wright's own arguments, what other theoretical or empirical reasons are there for believing in multiple fitness peaks?

Note 1: I do not claim to be very familiar with this literature, which is often highly technical and has little to do with Wright's own formulation. See for example the book by Gavrilets and its extensive bibliography.

Note 2: Wright himself sometimes uses a notation in which only one of the two alleles at a locus is indicated, so that for example if there are three loci with alleles Aa, Bb, and Cc, the genotype AabbCc could be represented by small letters as abbc, and AABbcc as bcc, and so on. The single genotype in which there are no small letters at all is represented by +. Some of Wright's examples are very difficult to follow if these conventions are not understood.

Note 3: 1931 (letter to Fisher): frequency; 1932 (ESP p.163): genotype; 1935 (ESP p.226): frequency; 1937 (ESP p.248): frequency; 1939 (ESP pp.310, 318): both; 1940 (ESP p.347): genotype; 1940 (ESP p.370): frequency; 1941 (ESP p.472): frequency; 1948 (ESP p.535): genotype; 1948 (ESP p543): frequency; 1949 (ESP p. 552): frequency; 1960 (Tax): both; 1977 (ESP p.9): frequency; 1980 (ESP p.626): genotype.

Note 4: Terms like 'hole' and 'wrinkle' must be understood as the n-dimensional analogues of these terms in three dimensions. A 'hole' may itself be a figure with many dimensions.

Note 5: Even in 3 dimensions, containing 2-dimensional surfaces, differential geometry is a tough subject. For an introduction see Aleksandrov, ed, chapter 7.

References

Works by Sewall Wright

Evolution: Selected Papers (ESP), ed. William B.Provine, 1986
Evolution and the Genetics of Populations (EGP), 4 vols., 1968-1978
'Physiological genetics, ecology of populations, and natural selection', in Evolution After Darwin, vol. 1, ed. Sol Tax, 1960 (Tax)
'Surfaces of selective value revisited', American Naturalist, 131, 1988, 115-23.

Other works

A. Aleksandrov et al., eds., Mathematics: its content, methods, and meaning, vol. 2, 1963
R. A. Fisher, 'Average excess and average effect of a gene substitution', Annals of Eugenics, 11, 1941, 53-63.
Sergey Gavrilets, Fitness Landscapes and the Origin of Species, 2004
J. B. S. Haldane, The Causes of Evolution, 1932 (reprint ed. E. Leigh, 1990)
William B. Provine, Sewall Wright and Evolutionary Biology, 1986
G. G. Simpson: Tempo and Mode in Evolution, 1944 (reprint 1984)
The Major Features of Evolution, 1953

Labels: Burbridge, Population genetics