While reading through a Nature Genetics Review article, I came cross a link to this catalog of published genome-wide association studies. Pretty cool stuff.

Labels: Genetics

I have a piece up for The Guardian's new Comment is Free Belief site, The use and abuse of statistics - Prophecies of the extinction of religion, or its triumph, fall prey to the weaknesses of linear prediction. Implicit in my argument are these sorts of dynamics:

Bearman and Bruckner have also identified a peculiar dilemma: in some schools, if too many teens pledge, the effort basically collapses. Pledgers apparently gather strength from the sense that they are an embattled minority; once their numbers exceed thirty per cent, and proclaimed chastity becomes the norm, that special identity is lost....

This is in regards to virginity, but the insight is generalizable. You don't have to know anything about dynamics though, just read a cultural history of France since the Revolution and you'll see what I mean.

Condé Nast Cuts Focus on 2 Magazines:

Through the first nine months of the year, ad pages in all United States magazines were down 9.5 percent from the same period in 2007. Most magazines produced by Condé Nast - including Vogue, GQ, Architectural Digest and Wired - have had much smaller declines, but they are also among the most expensive magazines to produce.

Portfolio, started last year amid much fanfare, is Condé Nast's first business magazine and its most expensive new project in years. Executives said the company was willing to lose more than $100 million on it.

I immediately thought of this, Can Si Newhouse Keep Condé Nast's Gloss Going?:

Some extravagances have been curtailed, but no one in the business disputes that Condé still spends far more money than its competitors. Magazine publishers and editors in chief haul in $400,000 to $2 million in salary and bonuses, current and former executives say, and many executives have clothing allowances in the high five figures.

...

Last July, Vanity Fair printed 20 different versions of its cover, a daisy chain of celebrity pairs shot over many months and on multiple continents by Ms. Leibovitz, a project that cost millions. It paid for itself, says the magazine’s editor, Mr. Carter, in increased newsstand sales and buzz.

Mr. Phillips, the investment banker, observed, "I would say if you look across their whole portfolio, Condé Nast does a better job of producing high-quality magazines than anybody else in the industry." But, he adds, "you really could spend a lot less money on those magazines without affecting quality."

I remember thinking at the time that when the bubble bursts they'll regret not running a more efficient operation. To some extent it seems like Advance treats its glossies like performance art as opposed to a business operation. Of course, S. I. Newhouse is nearly a 10 billionaire so I guess he can afford to be less orthodox than the typical billion-pinching mogul. At least The Big Money isn't going anywhere.

H/T Tyler.

Evolution of trust and trustworthiness: social awareness favours personality differences (Open Access):

Interest in the evolution and maintenance of personality is burgeoning. Individuals of diverse animal species differ in their aggressiveness, fearfulness, sociability and activity. Strong trade-offs, mutation-selection balance, spatio-temporal fluctuations in selection, frequency dependence and good-genes mate choice are invoked to explain heritable personality variation, yet for continuous behavioural traits, it remains unclear which selective force is likely to maintain distinct polymorphisms. Using a model of trust and cooperation, we show how allowing individuals to monitor each other's cooperative tendencies, at a cost, can select for heritable polymorphisms in trustworthiness. This variation, in turn, favours costly 'social awareness' in some individuals. Feedback of this sort can explain the individual differences in trust and trustworthiness so often documented by economists in experimental public goods games across a range of cultures. Our work adds to growing evidence that evolutionary game theorists can no longer afford to ignore the importance of real world inter-individual variation in their models.

The fact that evolutionary psychology traditionally focuses on universal traits which are genetically fixed while behavior genetics is preconditioned on heritable variation of similar traitshas been a distinction which has been brought to light by skeptics of any biological component to human behavior. In The Undiscovered Mind John Horgan attempted to throw cold water on the rise of neuro and cognitive sciences precisely using this sort of tactic. Though I think many critics of evolutionary psychology argue in bad faith, at the end of the day some of their criticisms land on target because of the huge sample space of laugh-out-loud "theorizing" by scholars fixated on an outmoded paradigm.

Humans are not the same. We vary. And we vary in part because of heritable biological factors. Some evolutionary psychologists, Satoshi Kanazawa comes to mind, work under an old model where deviations from their expectation of human modal behavior is treated simply as trivial holdovers along the transient from the ancestral to the derived phenotype, or noise introduced by environmental factors. Because of he elegant simplicity of their model evolutionary psychologists of this school are expert verbal showmen.

Certainly there are plenty of human universals. But there are plenty of non-universals. We are familiar with the Red Queen hypothesis in relation to our immune systems. This model arose in large part because of the necessity for constant evolution in the forever war with parasites. If humans are a cultural animal par excellence for whom the flexibility of their behavioral toolkit is essential, should it surprise us if frequency dependent evolutionary dynamics result in a large number of morphs constantly cycling? Perhaps H. sapiens is the environment of evolutionary adaptedness of H. sapiens?

Related: Heritability of the Ultimatum Game, Altruism and Risk-Taking: Kinda Heritable and Variation as the ultimate.

Labels: Behavior Genetics, Evolutionary Psychology

I'll yank this up from the comments:

...Would it really be worse to have a future civilization full of ultra-intelligent robotic minds pushing science forward tirelessly than the Jerry Springer-esque Idiocracy that we are careening towards?

So did anyone root for the AIs in The Galactic Center Saga? In the Dune universe there was an explicit emphasis on keeping tech relatively low because of the fear of Thinking Machines (though the post-Frank Herbert sequels did have a "happy ending" in the man vs. machine conflict). In the Foundation universe (specifically the sequels not written by Asimov) one element of the back story which emerged was that benevolent robots actually created diseases which made the average human less intelligent than they would have otherwise been because that was the only way that social equilibrium could be maintained (Hari Seldon was brilliant in part because he was never infected).

This is the sort of post which brings out a lot of opinions because it is explicitly designed to smoke out norms and values. Frankly, I think most of the human race would prefer the Idiocracy. The minority who would be more ambivalent, or even prefer the idea of intelligence which is not tied to our particular human substrate, are likely to be non-modal in their psychology. Additionally, the non-modals are more likely be in research positions where they could forward the project of post-human sentience. To be explicit, I wonder if post-human sentience would simply be the apotheosis of the Nerd. Movies like Twelve Monkeys play on the idea of a Doomsday Cult which releases a deadly pathogen which kills most humans, but what about the possibility of a group of social outcasts intent on giving rise to a species which better encapsulates the set of values which reflect the priorities of nerds?

Labels: post-humanism

Gene Expression Profiles during In Vivo Human Rhinovirus Infection (also, ScienceDaily summary):

Rhinovirus infection significantly alters the expression of many genes associated with the immune response, including chemokines and antivirals. The data obtained provide insights into the host response to rhinovirus infection and identify potential novel targets for further evaluation.

.

About those viruses:

Epidemiologists have established minimal population size and density thresholds for particular diseases (such as measels, mumps, rubella, smallpox, influenza, rhinovirus) to survive and spread. In small hunter-gatherer groups or even small farming villages, such diseases would have been incapable of spreading very far and woul have disappeared (Black 1975). This implies that many diseases must be recent.

There's a reason that some of the cites for the adaptive acceleration theory use microbial models; here are lot's of them and they breed fast. Microbiologists are fond of reminding people that on the order of 90% of the cells in your body are bacteria resident in your gut; but I wonder if the last 10,000 years might not have been a boon for a whole host of virulent less friendly microbes which "tag along" with H. sapiens.

Related: Toxoplasma gondii & human culture, Obesity germs, thrifty genes, Another Nobel for the New Germ Theory of disease and Toxoplasma gondii's South American origins and its influence on culture.

Labels: Human Evolution, pathogens

Greg Cochran left the following comment in a Matt Yglesias blog entry:

What you need is a map of the world in which the sizes of the countries are adjusted to the number of column-inches they get in the New York Times and the Washington Post. I think it would be illuminating.

Well, I've done something close enough. I only looked at the NYT, and I made a bubble chart instead of one of those distorted cartograms. Also, I used number of articles rather than column inches -- but these must correlate highly. It's not as if Tonga gets a few 10,000-word articles, while Iraq gets many 50-word articles. At any rate, let's see what the results look like.


Here are the results for the 192 members of the United Nations. Move the mouse over an unlabeled blob to see who it is, or search for a specific country. The results cover 2000 to the present, and are standardized by dividing by the number of articles for the entire period. To ensure that the graphing algorithm would pick up order-of-magnitude differences, I multiplied the fractions -- which ranged in order from 10^(-5) to 0.1 -- by 10^5, so that they range in order from 1 to 10,000. Some countries I had to estimate rather than get the exact number, since their names are shared with other things, like Turkey (see Note).

The first thing you notice is a few big blobs and lots of tiny blobs, in accord with a Power Law. Rather than futz around with getting my pictures to post here, I'll simply list the frequency distribution, where the first column is the fraction of all NYT articles devoted to some country, binned by order of magnitude:

Order-----Frequency
0.00001--0.046875
0.0001---0.354167
0.001----0.5
0.01-----0.09375
0.1------0.005208

The one country in the 0.1 bin is the US. Everyone else is lucky to get something on the order of a percent in coverage. Still, the modal country gets mentioned on the order of once every thousand articles -- not too shabby if you're Qatar. Here is the full dataset, in case you want to download and play around with it yourself.

How do we infer the level of insanity in our foreign policy implied by these data? Looking at the countries from greatest to least emphasis, the low-ranking ones make sense -- they belong to the parts of the world you've never heard of, and will not have reason to hear about within your lifetime, such as Tuvalu and Bhutan.

But there are some funny ones at the top. For example, it takes the top 9 to discover all 5 permanent members of the UN Security Council. The remainder of the top 9 are Germany and Japan -- which at least are G8 countries -- but also Iraq and Israel. Speaking of the G8, it takes the top 12 to discover them, which adds another lesser country to this elite list -- Mexico (China is not G8 but is still important). Afghanistan, Iran, and Pakistan also rank pretty high.

This is a perfectly rational outcome -- our foreign policy may obsess over these places, but by placing criteria on them like "permanent member of UN Security Council" or "member of G8," we can see which ones don't deserve the attention. They represent the parts of the world, like Iraq, where we're wasting a bunch of money to squat over an over-glorified sandbox, hoping that our colonial piss will transform it into a lush oasis. Or they're the places, like Mexico, where we're importing a large illiterate peasant underclass from. This seems like a useful way to change our foreign policy: see who we're obsessed with, but who don't really matter, and cut them loose (relatively speaking).

By the way, the Many Eyes website has a global map feature, but it only allows an additive scale for bubble size, with the three smallest orders-of-magnitude collapsed into one bubble-size. So it didn't look very good. Maybe at some point I'll screen-capture the bubble chart, and cut and paste each bubble onto a picture of a world map, but that probably won't happen.

Note: I used the common English names for countries -- e.g., Syria rather than Syrian Arab Republic -- and made the following modifications to make sure I picked up the country rather than something else by that name:

Chad: added "Africa" to search
Georgia: added "Tbilisi" -- probably an undercount, but not my much
Guinea: subtracted "Equatorial Guinea," "Guinea-Bissau," and things like "guinea pig"
Jordan: added "Israel" -- again, an undercount, but not by much
Palau: subtracted "Barcelona" and "Catalonia" (it means "palace" in Catalan)
Turkey: subtracted "Thanksgiving" -- probably an overcount, but not by much
United States: searched "America," and subtracted "Latin America," "South America," and "Central America"

Labels: culture, politics

Well, I assume most people probably accept that some people are better than average at learning languages, while others are not as good. But the reasons for this aren't quite clear. PNAS has a paper out on this topic, Brain potentials to native phoneme discrimination reveal the origin of individual differences in learning the sounds of a second language. I find the ScienceDaily summary comprehensible, and one of the researchers says:

"Therefore, these results show that there is a positive correlation between specific speech discrimination abilities and the ability to learn a second language, which means that the individual ability to distinguish the specific phonemes of the language, both in the case of the mother tongue and in the case of other languages, is, without a doubt, a decisive factor in the learning process, and the ability to speak and master other languages," concludes Begona Diaz.

Labels: Cognitive Science

I recently attended a talk by Marshall Brain. He made the argument that the shift toward intelligent robots in the labor force will result in a much higher degree of structural unemployment in our economy. Brain presented some economic data which showed that gains in productivity over the past 10 years have not yield median wage gains or maintained a demand for labor. There were some details where I thought Brain undercut his plausibility (e.g., he didn't seem to be using the most wildly accepted definition of a recession, instead simply focusing on the metric of full employment as the only worthwhile economic indicator). An irritated audience member asked him if he had heard about a discipline called history which suggests that these sorts of predictions never pan out.

Brain's response was that the difference between labor saving technology in the past and the emergence of intelligent robots is that the latter are a new species. In other words, the demand for labor may increase with an expanding economy, but intelligent robots will have incredible comparative advantages compared to humans for the new occupational opportunities. Additionally, while technology expands and leverages human abilities, opening up opportunities, intelligent robots with agency would not need the complement of particular human cognitive skills.

The empirical argument is based on the peculiarities of the recent past, so the historical argument looking back to the "industrial revolution" and its effect on economic growth and long term demand for labor and the impact on wages is compelling. In Farewell to Alms Greg Clark points out that in fact since the Great Divergence the rise of the mass consumer society has been enabled by enormous comparative and absolute gains of wealth accrued toward unskilled labor. Only since 1970 has this dynamic been somewhat reversed. But I think that one point to remember is that the pattern of 1800-1970 itself is a relatively short time window. Obviously a future where intelligent robots substitute for human labor and management is not analogous to a pre-modern agrarian economy caught in the Malthusian trap, but I think it is important to remember that refuting Brain's argument by an appeal to history itself relies on fixing a particular set of background conditions which themselves are relatively new.

All that being said, I can imagine intelligent robots replacing humans in a wide range of service, manufacturing and even professional jobs. Imagine for example a robot doctor who has immediate access to the total body of the latest research, but can intelligently weight these results appropriately so the swell of most recent likely false positives don't hold so much sway. There would be no worries that a robot doctor would not be able to engage in Bayesian logic. But does that mean there won't be roles for humans? Perhaps there are niches for human art and cultural production where robots might crave organic authenticity? After all, why couldn't there be Bobo robots who are willing to shell out extra for human-made products which exhibit the imprecise, irrational and wild creativity characteristic of the organic substrate mind? Humans would have an enormous advantage over robots in Outsider Art. One could spin many scenarios of this sort, as Brain's model seems to be predicated on the standard opposition between man and machine which goes back to the Luddites.

Finally, I wonder if a nation like Japan might not be well positioned if the rise of the machines does result in reduced demand for human labor. Japan's native labor force is shrinking. This sort of thing is generally considered to be bad, but if robots entered the labor force and increased total productivity greatly then the problem of an imbalance between a large retired class and a smaller labor force goes away. The remaining younger humans in the labor force could focus on jobs where humans have a shot; e.g., instead of the Salaryman the Freeter might be the modal human Japanese.

Labels: post-humanism

In the book Red State, Blue State, Rich State, Poor State (see Razib's review here and the book's blog here), the authors note that the two major political parties have become more polarized in various ways since the 1990s, even though the average voter hasn't changed much. Also, the key message of the book is that the red state - blue state culture war is mostly restricted to high-income, and to a lesser extent middle-income voters.

They searched some mainstream media outlets for the words "polarizing / polarization," as well as buzzwords for the cultural split like "NASCAR dad" and "soccer mom," and found that they either show up for the first time or increase during the early/mid-1990s and remain as high today. I've searched the NYT for "partisan," as well as a variety of newspapers for the pejorative "partisan hack," and they show the same pattern.

Here are the graphs:




For the first graph, I took the number of articles with "partisan" and standardized this by dividing by the number of articles with "the" -- basically, all articles. (The 2008 point is an estimate based on the year so far.) Aside from 1984, when there was a huge divide between the two presidential candidates, there is nearly no change from 1981 to 1991. However, in 1992, when the culture war begins to take center stage, the frequency increases to about twice as high as during the 1980s.

For the second graph, I did a Lexis-Nexis search for "partisan hack," a common culture war swear-word for what the other guy is. I included the 12 newspapers with the highest counts, and that covered most of the major papers as well as some lesser known ones (see full list below). Not being able to search the database for "the," I couldn't standardize these data, but they show the same pattern as above, so I doubt the year-to-year variation in total output explains it. Here is the total output per year for the NYT, for comparison. Again, the 2008 point is for the year so far.

Aside from a few jabs from The Oregonian in the early 1990s, the first time this phrase shows up is in 1994, and it spreads to an order of magnitude larger by the 2000s. Outside of newspapers, Lexis-Nexis returns a result from 1984 where a politician is quoted as calling another a partisan hack. So the term must have been invented before the 1990s, but surged during the culture war.

These data agree with the larger picture in the book: the topic of partisanship has become much more talked about since the 1990s, and the specific slander "partisan hack" has increased noticeably during the same time.

List of newspapers included in the Lexis-Nexis results: New York Times, Washington Post, Washington Times, Boston Globe, Arkansas Democrat-Gazette, The Star-Ledger, Richmond Times, Palm Beach Post, St. Petersburg Times, Pittsburgh Post-Gazette, Atlanta Journal-Constitution, and The Oregonian.

Labels: culture, politics

Finally, Sewall Wright's Shifting Balance theory of evolution. This will positively, definitely, categorically be my last note on Sewall Wright. Unless I think of something else.

For convenience I will split the note into two parts, one dealing with the theory in its original form, and the second dealing with subsequent developments.

Two catch-phrases indissolubly linked with Sewall Wright are the adaptive landscape, and the shifting balance. In preparing my note on Wright's concept of the adaptive landscape I was surprised to discover that Wright himself seldom if ever used this expression. I could not find a single example. I was therefore half-expecting that I would not find any reference to the shifting balance either - and I would have been half-right. Wright did use that term, but not, as far as I can find, until surprisingly late in his long career....



All page references are to Evolution: Selected Papers unless otherwise stated. See the References for details.

The first mention of 'the shifting balance'

Wright refers extensively to the 'shifting balance theory' in Volume 3 of his treatise Evolution and the Genetics of Populations, published in 1977, but I have not found this term in the first two volumes (1968 and 1969), or in anything else published by Wright before 1970. Nor was it used by authors such as Dobzhansky, Mayr, and Simpson, when describing Wright's ideas. The earliest use of the term I have found is in Wright's article of 1970 on 'Random drift and the shifting balance theory of evolution'. Admittedly, I have not read all of his 200-odd papers published before that year, but unless anyone can unearth an earlier use I suggest that the term was in fact coined in this article of 1970, some 50 years into Wright's career. The terminology of a theory is less important than its substance, but the absence of the term 'shifting balance' before 1970 (if I am right about this) does have two implications: first, we should not expect other authors (such as Fisher and Haldane) to have commented on the 'shifting balance theory' as such, and second, in the absence of a single label, it may not have been perceived as a single unified theory at all.

Earlier terminology

The apparent absence of the phrase 'shifting balance' before 1970 does not mean that Wright had never previously used the terms 'balance' or 'shifting', sometimes in close proximity. Wright was fond of the term 'balance', and related terms such as 'equilibrium' or 'poise', and used them for a variety of purposes, sometimes with a precise mathematical meaning, and sometimes more loosely. Here are some examples, chronologically arranged:

1931: 'The conditions favorable to progressive evolution as a process of cumulative change are neither extreme mutation, extreme selection, extreme hybridization nor any other extreme, but rather a certain balance between conditions which make for genetic homogeneity and genetic heterogeneity' (96)

1931: 'Evolution as a process of cumulative change depends on a proper balance of the conditions which... make for genetic homogeneity and genetic heterogeneity of the species' (158)

1941: 'The most general conclusion that can be drawn from the attempt to develop a mathematical theory of the simultaneous effects of all statistical processes that affect the genetic composition of populations is that in general the most favorable conditions for evolutionary advance are found when these are balanced against each other in certain ways, rather than when any one completely dominates the situation' (488)

1951: 'The general qualitative conclusion would still seem to hold that this [the evolution of culture] or any other evolutionary process depends on a continuously shifting but never obliterated state of balance between factors of persistence and change, and that the most favourable condition for this occurs when there is a finely subdivided structure in which isolation and cross-communication are kept in proper balance' (596)

1959: 'It is concluded that the most favorable conditions are those of balance: a balance among the directed processes that insures the maintenance of a high degree of heterozygosis in minor factors and a balance between the directed processes as a group and various sorts of random ones that insures extensive random drift around the equilibrium positions of the gene frequencies. All these conditions are met in the highest degree where there is a certain balance between isolation and crossbreeding within each of a large number of local populations of the species' (Tax, 470-1)

1960: 'In developing the balance theory of evolution, I was trying to arrive at a judgement of the most favorable conditions for evolution under the Mendelian mechanism' (619)

It will be noted that in the last of these passages Wright refers to the 'balance theory of evolution', and in another the 'balance between factors of persistence and change' is said to be 'continuously shifting'. Wright therefore comes very close to using the phrase 'shifting balance theory', but the fact that even in these passages he does not actually use it strengthens the suspicion that he had not yet coined the term as such.

What balance? And what shifts?

Many other uses of the terms 'balance' and 'shift' by Wright could be cited. I have quoted only those which come closest to his explicit term 'the shifting balance'. But even these examples, on a careful reading, leave it unclear what is the 'balance' that is seen by Wright as essential to effective evolution. Many different things are said to be 'balanced'. What exactly is a 'balance between factors of persistence and change', and is it the same as 'balance between conditions which make for genetic homogeneity and genetic heterogeneity'? Migration, for example, is a factor usually making for genetic homogeneity, but it is also often a factor making for 'change'. So which side of the balance does it fall on?

It might be hoped that in Wright's 1970 article, or in Volume 3 of Evolution and the Genetics of Populations, where the 'shifting balance theory' is discussed at length, we would find a clear statement of the meaning of the term itself. What is the relevant balance, how does it shift, and how does Wright's theory of evolution depend on the shifting of the balance? It may be that the answers are there, but if so, I have not found them. While Wright discusses various component parts of his theory, the overarching term 'the shifting balance' is not itself defined or explained. Moreover, whatever interpretation we give to the term 'balance', it does not seem that the 'shifting' of the balance itself plays any essential part in Wright's conception of the evolutionary process. The balance between the various factors of evolution, including selection, mutation, migration, environment, genetic drift, and population structure - to list the obvious ones - might stay constant, yet the process of evolution as described by Wright could still work, if the balance of factors is right. It is not the shifting of the balance, but the existence of the right kind of balance, which according to Wright is favourable to evolutionary progress. I conclude that the 'shifting balance theory' is a convenient and memorable label, but one without a precise literal meaning in isolation.

When was the theory first published?

Even if the label 'shifting balance theory' was not adopted until 1970, the doctrines covered by that label may have been propounded earlier. Wright himself, in 1970, claimed to have first published the theory as long ago as 1929. It can be confirmed that some of the key elements of the theory were contained in Wright's great 1931 paper 'Evolution in Mendelian populations', and summarised in shorter related papers beginning in 1929. Notably, these contain several key propositions which Wright maintained consistently to the end of his life:

a) The most favourable circumstances for evolution are in large populations subdivided into many small partially isolated populations;

b) Large freely interbreeding populations are not favourable to continuing evolution;

c) Genetic drift is an important part of the evolutionary process; and

d) The differential success of subpopulations, which Wright describes as 'intergroup selection', is an important contributor to cumulative evolutionary change.

If we regard these four propositions as constituting the shifting balance theory, then it was indeed first published in 1929.

Changes to the theory

This does not mean that there were no important changes to the theory after 1929. I believe there were changes both of substance and of emphasis, which I would summarise as follows:

1. In 1932 Wright adopted the metaphor of a multidimensional field of gene combinations and fitness values, which was later described (though not by Wright) as the 'adaptive landscape'. In my view this was more than just an illustrative device. The concept of selective peaks as alternative states of stable equilibrium was a valuable addition of substance to the theory, not corresponding to anything clearly stated in the original version.

2. Whereas in 1929-31 Wright had denied that temporary changes in environmental conditions would have major evolutionary effects, in 1932 he changed his position and accepted that environmental fluctuations could 'shuffle' populations from one evolutionary position of equilibrium to another, usually higher, one.

3. As a consequence of change (2), Wright reduced his emphasis on the importance of genetic drift, which he had originally claimed as essential to long-term evolutionary progress. After 1932 genetic drift was in principle only one of several mechanisms for change. But Wright did not make it sufficiently clear that his position had changed, and did not follow through the implications of the change for his views on the importance of population structure.

4. Throughout his career Wright maintained that the evolutionary process was partly adaptive and partly non-adaptive or 'random', but the emphasis he put on these elements shifted from the non-adaptive aspect to a greater emphasis on adaptation.

5. In his later writings on the subject Wright identified three 'phases' in the shifting balance process, but these are much less clear in the earlier versions of the theory.

Some but not all of these changes have already been identified in William Provine's admirable biography of Wright. The remainder of this note will mainly be concerned with documenting the various changes.

The original version of the theory (1929-31)

The key propositions of the original version of the theory were conveniently summarised by Wright himself in a short paper of 1929, which I will quote in full:

The frequency of a given gene in the population is affected by mutation, selection, migration and chance variation. The pressure exerted by these factors (excluding chance) and the position of equilibrium between opposing pressures are easily found. Gene frequency fluctuates about this equilibrium in a distribution curve, determined by size of population and the various pressures. The mean and variability of characters, correlation between relatives and the evolution of the population, depend on these distributions. In too small a population, there is nearly complete random fixation, little variation, little effect of selection and thus a static condition, modified occasionally by chance fixation of a new mutation, leading to degeneration and extinction. In too large a freely interbreeding population, there is great variability, but such a close approach of all gene frequencies to equilibrium that there is no evolution under static conditions. Changed conditions cause a usually slight and reversible shift of the gene frequencies to new equilibrium points. With intermediate size of population, there is continual random shifting of gene frequencies and consequent alteration of all selection coefficients, leading to relatively rapid, indefinitely continuing, irreversible and large fortuitous but not degenerative changes even under static conditions. The absolute rate, however, is slow, being limited by mutation pressure. Finally, in a large but subdivided population, there is continually shifting differentiation among the local races, even under uniform static conditions, which through intergroup selection brings about indefinitely continuing, irreversible, adaptive and much more rapid evolution of the species as a whole. (78)

These propositions are all stated more fully and supported by arguments in the 1931 papers 'Statistical theory of evolution' and 'Evolution in Mendelian populations'. (Although 'Statistical theory of evolution' was published first, it seems that 'Evolution in Mendelian populations' was completed first and 'Statistical theory of evolution' written as a summary of it.) Some of them are also covered in Wright's 1930 review of Fisher's Genetical Theory of Natural Selection. Most of them are restated and defended throughout Wright's career. The arguments given by Wright to support the key propositions (quoted in italics from the 1929 article) can be summarised as follows:

In too small a population, there is nearly complete random fixation, little variation, little effect of selection and thus a static condition, modified occasionally by chance fixation of a new mutation, leading to degeneration and extinction.

For this purpose 'too small' a population is one in which 1/4N (where N is the effective population size) is much larger than selection and mutation rates. (148) In this case genetic drift will be the main factor in evolution. Most genes will soon be fixed, there will be little variation within each population, and random unadaptive changes will lead to extinction. (93, 142, 148)

In too large a freely interbreeding population, there is great variability, but such a close approach of all gene frequencies to equilibrium that there is no evolution under static conditions.

For this purpose 'too large' a population is one in which both selection and mutation rates are much larger than 1/4N. (148) In this case, genetic drift will have little effect, and gene frequencies will be determined by the balance of selection and mutation. If selection on a gene is much stronger than mutation pressure, there will be almost complete fixation at each locus and therefore no evolution under fixed conditions. (148-50) If selection is not much stronger than mutation pressure, there will be more genetic diversity, but all gene frequencies will be close to equilibrium and evolution will be very slow unless conditions change. (150) Note that these arguments tacitly assume that there are no new favourable mutations, or existing ones still under selection.

Changed conditions cause a usually slight and reversible shift of the gene frequencies to new equilibrium points.

In 'Statistical theory of evolution' Wright says that 'Changes in conditions should be followed by systematic changes in gene frequencies until all have reached the new positions of equilibrium. Return to the old conditions should be followed by return to the old equilibria' (92). No specific reason is given for this conclusion. In 'Evolution in Mendelian populations' the explanation is slightly fuller. Following a strengthening of selection, gene frequencies will change, but 'The rapid advance has been at the expense of the store of variability of the species and ultimately puts the latter in a condition in which any further change must be exceedingly slow. Moreover, the advance is of an essentially reversible type. There has been a parallel movement of all the equilibria affected and on cessation of the drastic selection, mutation pressure should (with extreme slowness) carry all equilibria back to their original positions. Practically, complete reversibility is not to be expected, and especially under changes in selection which are more complicated than can be described as alternately severe and relaxed. Nevertheless, the situation is distinctly unfavorable for a continuing evolutionary process' (150). Note that Wright does not claim the changes are always reversible, only that this is 'essentially' or 'usually' the case. Bur he gives no clear reasons for this position, and only a year later (1932) he abandons it. As this is one of the major developments in the theory I consider it more fully in Part 2 of this note.

With intermediate size of population, there is continual random shifting of gene frequencies and consequent alteration of all selection coefficients, leading to relatively rapid, indefinitely continuing, irreversible and large fortuitous but not degenerative changes even under static conditions. The absolute rate, however, is slow, being limited by mutation pressure.

For this purpose an intermediate size of population is one where, for many genes, the selection pressure is not much stronger than the mutation rate, and neither selection pressure not mutation rate are much higher than 1/4N (150-1). (Since mutation rates were known by Wright not to be much higher than 1 in 100,000, this implies an effective population size of the order of 25,000.) In these circumstances genetic drift will be strong enough to cause considerable fluctuation in gene frequencies, but not to lead to rapid fixation of genes and loss of genetic diversity. Wright describes the result as 'a kaleidoscopic shifting of the average characters of the population through predominant types which practically are never repeated' (95, see also 151). But Wright emphasises that it would be a very slow process, as 'hundreds of thousands of generations are required for important evolutionary changes' (95). He mentions the effect of mutation rates as limiting the speed of change (78, 95, 151), presumably because with mutation rates not very different from the rate of genetic drift, mutation pressure tends to maintain genetic uniformity. But surely the main reason for slowness is that genetic drift itself is very slow in a population of many thousands.

Finally, in a large but subdivided population, there is continually shifting differentiation among the local races, even under uniform static conditions, which through intergroup selection brings about indefinitely continuing, irreversible, adaptive and much more rapid evolution of the species as a whole.

This is the most important proposition of the shifting balance theory in its original form. Wright never abandoned his view that a large subdivided population is most favourable to evolution. The subdivisions must be small enough, and isolated enough from each other, that the subpopulations can diverge in gene frequencies (151-2). Curiously, there is an important difference between Wright's accounts in his two 1931 presentations of the theory. In 'Statistical theory of evolution' Wright mentions only 'random drift' as causing the divergence between subpopulations, with the result that there is a 'geologically rapid drifting apart of the various sub-groups, even under uniform conditions. This is a non-adaptive radiation, but, on the average, not such as to lead to appreciable deterioration' (95). In 'Evolution in Mendelian populations', on the other hand, Wright mentions both genetic drift and local variation in selection pressures, so that the result is 'a partly nonadaptive, partly adaptive radiation among the subgroups' (151). There is of course no reason why both processes should not occur at once, perhaps in different subgroups or at different loci in the same subgroups at the same time. But the difference does have implications for the final phase of the process, which is 'intergroup selection'. On this, Wright says that 'Those [subgroups] in which the most successful types are reached presumably flourish and tend to overflow their boundaries while others decline, leading to changes in the mean gene frequencies of the population as a whole' (152). But if adaptive variation among subgroups is due only to local circumstances of selection (as seems to be suggested in 'Evolution in Mendelian populations'), those types which have highest fitness in their own locality cannot be expected to succeed elsewhere. If on the other hand the variation among subgroups is purely due to random drift (as seems to be suggested in 'Statistical theory of evolution'), it is not obvious that they will differ significantly in fitness for genetic reasons. 'Statistical theory of evolution' does however contain a very important development or clarification of the theory: 'Exceptionally favorable combinations of genes may come to predominate in some of the subgroups. These may be expected to expand their range while others dwindle. This process of intergroup selection may be very rapid as compared with mass selection of individuals, among whom favorable combinations are broken up by the reduction-fertilization mechanism in the next generation after formation' (95). The reference to 'favorable combinations' here is the first sign of the emphasis on epistatic fitness interactions which becomes increasingly important in the later development of the theory. But in the original statement, in 1931, it comes out of the blue and unsupported by any detailed analysis.

Likewise, the concept of 'intergroup selection' is not explored in any depth, and the claim that it would be more rapid than 'mass selection of individuals' is little more than a bare assertion. The suggested advantage that 'favorable combinations' are not immediately broken up by sexual reproduction seems to require not only a high degree of genetic unity within the subgroups, but the maintenance of that unity during the process of 'intergroup selection', despite the probable intermingling of different groups. The credibility of this process has been one of the main areas for recent controversy and research on the shifting balance theory. It should incidentally be stressed (see also Provine, p.288) that 'intergroup selection' as envisaged by Wright has little to do with 'group selection' as envisaged by most of its recent advocates. Wright does not suggest that successful groups have evolved adaptations for group living, or that their members behave 'altruistically' towards each other (though his theory does not exclude this either, and he later made some comments in this direction). His claim is rather that the subdivided population structure allows some groups, by chance, to form combinations of genes that are advantageous to individual fitness. The higher mean fitness of the groups is the resultant of these individual fitness advantages.

Wright also gives mixed messages about the adaptiveness of the process. While repeatedly claiming that in the long run the process is adaptive, Wright accepted the common view of many biologists at the time that the differences between subspecies and even between species of the same genera are usually non-adaptive (154, see also Provine p.288-99), a view which would seem to require the adaptive process of 'intergroup selection' to occur mainly between different genera or even higher taxa! But in this case 'intergroup selection' between small subgroups of the same species would be irrelevant to the process. Yet in 'Evolution in Mendelian populations' Wright also suggests that intergroup selection within the species may be responsible for 'peculiar adaptations' and 'extreme perfection' (154-5), a claim which is not, I think, repeated anywhere else. Overall, the emphasis in these early writings is more on the nonadaptive than the adaptive aspects of the process.

Taking stock

Before exploring the subsequent development of the theory (in Part 2), I will try to take stock of the position reached by 1931.

Already in his summary note of 1929 Wright had stated some of the key propositions of the shifting balance theory. In the two articles of 1931 he began the task of justifying these propositions. The arguments he put forward were ingenious, stimulating, and not implausible, but far from conclusive. There were moreover a number of tensions, if not actual inconsistencies, within Wright's accounts. One of these concerned the extent to which the process was adaptive, as has been explored fully by Provine. Another is the respective roles of genetic drift and local selection, on which I have pointed out an apparent difference between the two articles of 1931. Another is the problem of migration between groups. As suggested in my earlier note on migration, Wright did not attempt to quantify the effects of migration until after he had committed himself to the importance of random drift within semi-isolated subgroups. Only then, in 1929, did he discover 'that isolation in districts must be much more nearly complete than I realized at first' for the process to work. 'Evolution in Mendelian populations' makes an attempt to remedy the deficiency (128), but further work was clearly needed.

Several important aspects of the theory in its mature form are also lacking from the original version. Notably, there is nothing clearly corresponding to Wright's later emphasis on alternative local optima - 'selective peaks' - available to populations or subpopulations. These local optima depend heavily on epistatic fitness interactions, which are hardly mentioned in the original version. In the mature theory, subpopulations 'explore' the field of possibilities under the influence of random factors (genetic drift, but also environmental fluctuations) until they wander into the zone of attraction of a new selective peak. The stage of 'exploration' is Phase 1 of the process, while the climbing of the population up a peak is Phase 2, and intergroup selection is Phase 3. In the original version of the theory there is no clear distinction between Phase 1 and Phase 2, because there is nothing to suggest that the process of 'exploration' ever stops, short of the exhaustion of genetic variation by random fixation of genes. The phrase 'continually shifting differentiation' seems inconsistent with any sharp distinction between two phases. The first signs of a new approach are to be found in 'Statistical theory of evolution', with its reference to some groups finding 'exceptionally favorable combinations of genes', implying epistatic peaks of fitness. Quite possibly this had been in Wright's mind all along, but I do not think it can be identified in anything written before 'Statistical theory', including the much more widely read 'Evolution in Mendelian populations'.

Another important omission is any serious discussion of the probability of favourable new mutations. Wright's negative assessment of the prospects for evolution in large freely interbreeding populations depends on the tacit assumption that new mutations can be neglected. Wright later developed arguments to support this position.

Overall, a careful reader of Wright's publications up to 1931, without knowledge of subsequent developments, might reasonably conclude that Wright had put forward a remarkably original, ingenious, and comprehensive theory of evolution, consistent with most of what was then believed about the observed pattern of evolution, and free of any obvious fatal defects. This is itself was a very major achievement. But the same reader might also think that the theory was sketchy and speculative, and in need of further elaboration, not to mention empirical tests. Wright himself was no doubt aware of this, and continued to develop the theory for another 50 years, as I will discuss in Part 2.


References
William B. Provine, Sewall Wright and Evolutionary Biology, 1986.
Sewall Wright: 'Physiological genetics, ecology of populations, and natural selection', in Evolution After Darwin, vol. 1, ed. Sol Tax, 1960 (Tax). (Article first published in 1959.)
Sewall Wright: Evolution: Selected Papers (ESP), ed. William B.Provine, 1986.
Sewall Wright: 'Random drift and the shifting balance theory of evolution', in Mathematical Topics in Population Genetics, ed. Kojima, 1970.

It's a big blogosphere. Aziz points me Islam in China. They have an interesting post up which reiterates much of what I said about the diversity of Chinese Muslims, along with obscure facts such as that the second ranking Vice Premier of China is Hui. Not that there's anything wrong it....

Labels: China

I've been somewhat out of the loop of hip hop music, though I'm catching up. A club that I go to regularly has been playing a song whose lyrics argue for the Father Absence theory of why some people grow up to be wilder than others. (See the video here.)

It used to be that art referred to theories that weren't even plausible on their face -- Freud's idea of the Oedipus Complex being one. Whether Teairra Mari's song "No Daddy" reflects a shift over time to more plausible ideas, or simply the contrast between moronic intellectuals and those who believe their lying eyes, I couldn't say. Also unknown is whether she's read Harpending & Draper (1982) or just figured it out on her own. If the latter, she must have been pretty perceptive, as the song was released when she was 17.

Andrew Sullivan points to a post by DJ Drummond which makes the claim that the polls are significantly biased towards the Democrats. This is a perfect example of partisanship taking precedence over facts, and it thus deserves a thorough fisking. Drummond begins:

it needs noting that all of the major polling organizations are based in locations where liberals are strongest and conservatives weakest, where 'democrat' and 'republican' take on meanings wildly different from the rest of the country. The people making the executive decisions at these polls, most likely including the wording and order of polling questions, whether to focus on urban or suburban areas, the weighting of political affiliation, and the definition of 'likely voter', are most likely in regular contact and association with the most liberal factions of politics. It does not mean that they have deliberately skewed their decisions to support Obama, but it is obvious that there is an apparent conflict of interest in their process modality.

To begin with, most major *conservative* media outlets (e.g Fox News, the National Review) are located in these regions. Drummond suggests that through some kind of opinion osmosis, pollsters in urban areas tilt their polls towards liberals. The evidence suggests this contention is wrong:

1. Fox News and Rasmussen (both Republican-owned) are going in the same direction as the average of all the other polls (including those funded by liberal/democrat organizations). The latest Fox Poll shows Obama leading by 9. Contrast this with the current pollster average difference of 8.
2. Pollsters polled the Bush-Kerry election correctly, accurately predicting a close victory by Bush. Also, they under-polled Gore by 3 points.
3. John McCain is campaigning most heavily in the swing states identified by the supposedly liberal-biased polls. His campaign, like all presidential campaigns, has its own internal polling. Apparently it matches up with Gallup et. al to a great degree.

Drummond goes on to make some specific arguments for his point of view:

most people do not have the interest to stop and take an 8-to-10 minute interview, especially from someone they do not know calling them up when they are likely to be busy doing something else. It's been established as well, that democrats in recent years are more willing to take part in polls than republicans, possibly due to perceived bias on the part of the media. But it is quite important to know if the pollsters were getting one person in ten to take the poll, or only one person in fifty, because the people not interviewed matter just as much as those who do participate. Yet I have never yet seen a poll this year that publishes response rates.

Although this has nothing to do with the claimed liberal bias of polling organizations, it is a generic methodological issue worth discussing. Response rates are typically in the 10 to 25% range (PDF link). In general, the candidate who excites their base more (regardless of party) will have a higher response rate from telephone polls. The argument is that this inflates estimates of their support. However, the evidence suggests the opposite; the candidate with more enthusiasm behind him/her inspires people not only to pickup the phone but also go to the voting booth.

It's also worth noting that Drummond ignores any methodological biases which would inflate McCain's estimated share of the vote. For example, people who either have no home phone or use cell phones are typically not being sampled. These people are disproportionately young and/or poor (both demographics favor Obama).

This is a big one that a lot of folks miss. I have noticed in the details, that all of the polls are asking about the public's opinion of the economy, and of their opinion of President Bush, even though he is not running this time.

These questions have been asked for decades, under both Republican and Democratic presidents. That Drummond is unaware of this shows that he doesn't know enough about polling to criticize it.

many polls ask a question about John McCain just after asking about the voter's opinion of President Bush, subtly linking the two men.

Polls that ask about the election first match the current polling trend. See, for example, that recent Fox News Poll where Obama leads by 9 (PDF link). This poll is in following with the majority of them in asking about Bush *after* they ask about the election.

no questions have been asked about approval of the specific performance of either Majority Leader Reid or Speaker Pelosi, and no other politician is linked to Barack Obama in the same way that polls link President Bush to John McCain.

First off, it's a rarity to poll about the performance of the Speaker or Majority Leader, regardless of whether they're Republican or Democrat. Second, it's not true that there haven't been polls dealing with Obama's connections. There have been several polls asking about voters' opinions on Obama's connections to Ayers and Wright.

Polls taken since Labor day have not mentioned foreign policy at all. There are no questions regarding Russia's invasion of Georgia, nor of Iran's nuclear weapons programs, nor about China's intentions viz a viz Taiwan, even though these are current events which have great significance in a presidential race, yet all of the polls are ignoring them. Again, the economy-only focus betrays a bias which violates the principles of the NCPP.

There have been polls on foreign policy since labor day, and it takes only a simple Google search to know this. See for example this one by the New York Times. The focus on the economy (both by the polls and by the candidates themselves) has not come about because of liberal bias, but because voters indicate that this is what matters to them.

The thing most folks forget about polls which get published in the media, is that the polls' first need is not to accurately reflect the election progress and report on actual support levels; it's about business.

This is a false dichotomy. These needs overlap to a great deal. SurveyUSA went from a no-name to the most respected pollster among bloggers (and, eventually the press) during the dem primaries simply because it more accurately predicted outcomes in the Democratic primary than anyone else. (They were frequently the outlier from the pack, by the way, and we'll get to that in a second). As a result they got more web traffic and citations. So there's definitely an economic and social incentive to give accurate polls. For a "conservative", this guy sure has a great disrespect for market efficiency.

you really think republicans or independents got more excited about Obama because of his convention, or that democrats and independents were more likely to vote for McCain because of the GOP convention? When you think about it, it should be obvious that these bumps are artificial unless there is a clear cause to show a change in support.

A simpler hypothesis is that the polling companies are accurately registering a slight increase in support for a given candidate in response to their increased positive media attention.

There has been unprecedented manipulation of demographics, corrupting even the raw data to the point where effective resolution of public opinion is doubtful. This might be described as an honest mistake, if one is willing to accept greed as an honest motive. Gallup, for example, who has more experience than any other polling group and who therefore should have known better more than anyone else to fiddle with the weights.

Where is the data? Where is the evidence that Gallup is not weighting demographics accurately? Drummond says he has written on it previously, but a search of his site for "gallup census" shows no posts which actually show the gallup weighting to be at odds with the US census. Demographics weighting varies as a function of the pollster. It's worth noting that despite their different weightings, the major pollsters agree that Obama is leading by at least 5 points right now.

So OK, Gallup is having a bad year, but what about the rest? Well, there the phrase to consider is follow the leader.

I've been following the polls since the primaries, and I can safely say: that hasn't been very true for this election or the dem primaries. There have been spreads as great as 15 points (see for example New Hampshire in the Democratic Primary) between various pollsters at several points in this year and last. The models, and occasionally the outcomes, have been significantly different from one pollster to the next. This guy needs to compare SurveyUSA to Gallup to Public Policy Polling before he writes another post accusing them of following one another.

So, could I be wrong? I have to be honest and admit that I could.

That's good to hear, because he actually is wrong. Here's why:

That McCain is more experienced with the key issues than Obama was ignored, that the historical significance of the debates shows that the effects appear several weeks later was also ignored. That the economy could be as reasonably blamed on the democrat-controlled Congress as on the republican President was never considered. That character would be a salient factor in the decisions of voters was rejected out of hand.

Wishful partisan thinking. Drummond wishes that people supported his president and candidate and issues, but because they don't he criti