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July 08, 2004

Lifestyle of myopia

Lifestyle causes myopia, not genes. Money shot:

...There, 80 per cent of 18-year-old male army recruits are myopic, up from 25 per cent just 30 years ago....

For instance, 70 per cent of 18-year-old men of Indian origin living in Singapore have myopia, while in India itself the rate is roughly 10 per cent.

Another study found myopia rates of 80 per cent in 14 to 18-year-old boys studying in schools in Israel that emphasise reading religious texts. The rate for boys in state schools was just 30 per cent.

This does not deny that genetics has some influence of course. Read the full article to get beyond the headline. Differences between groups (that is, religious students in Israel might be of a different ethnic mix) or selection bias (that is, immigrants to Singapore are not a proper sample of Indians) can explain some of the results, but the ones that look at the same population over a few generations are pretty hard to explain genetically (note that of course some people might be genetically predisposed to develop myopia in a given environment, while others might develop it no matter the environment, while some will never develop myopia and are insensitive to environmental inputs).

Godless comments:

NCBI summary article on genetics of myopia:

High-grade myopia is a refractive error greater than or equal to 6 diopters. Several loci for high-grade myopia have been mapped: MYP1 (310460) on Xq28, MYP2 on chromosome 18p, MYP3 (603221) on chromosome 12q, MYP4 (608367) on chromosome 7q, and MYP5 (608474) on chromosome 17q.

Myopia of severe degree was transmitted through 4 generations in the family reported by Francois (1961). Franceschetti (1953) observed a family with 10 cases in 4 generations. Four suffered detachment of the retina. Myopia is, in a sense, a metric character. Variation in many components of the eye contributes to its refractive capacity (Sorsby et al., 1962). Some myopia, perhaps most, is multifactorial in causation. Although autosomal recessive inheritance has been suggested (Macklin, 1927; Karlsson, 1975; Edwards and Lewis, 1991), autosomal dominant myopia has been reported by Flach (1942), Franceschetti (1953), and Francois (1961). DelBono et al. (1995) described 52 2- and 3-generation families with 2 or more individuals affected by juvenile-onset myopia, defined as refractive error of more than -0.75 diopters by age 15 years.

Karlsson (1975) concluded that the 'myopia gene' may influence brain development. Myopic high school students aged 17 or 18 years performed better on IQ tests than their nonmyopic classmates. Comparison with test results obtained 10 years earlier before development of myopia suggested that the influence of the gene on the brain was of fundamental importance. Cohn et al. (1988) investigated the association between myopia and superior intelligence in the general population in a group of intellectually gifted children and their less gifted full sibs. A highly significant gifted-nongifted sib difference in myopia was found consistent with the hypothesis that intelligence and myopia are related pleiotropically.

On the basis of studies in the Finnish Twin Cohort, Teikari et al. (1991) estimated that the heritability of myopia is 0.58 (0.74 for males and 0.61 for females) when myopia is considered a dichotomous variable.

Kolata (1985) summarized the work of Raviola and Wiesel (1985), which is relevant to the nature/nurture controversy in the area of myopia. Their work with an animal model suggested that myopia is caused by abnormal influences of the nervous system on the developing eye. In studying the effects of visual deprivation on the development of the visual system, they sutured shut the eyes of young monkeys. In the course of this they found that the eyeball grew abnormally long as in myopia. Monkeys with sutured eyes reared in the light became myopic whereas those reared in the dark did not. Distortion of the visual image by injecting small polystyrene beads into the corneal stroma likewise led to myopia. In humans it has been found that children with ptosis become myopic and children with unilateral hemangioma of the eyelid develop myopia in the closed eye. Children with corneal opacities tend to be myopic as do those with mild retrolental fibroplasia which distorts vision. In the rhesus macaque monkey, atropine did not prevent development of myopia; in the stumptailed macaque it did. Section of the optic nerve did not prevent development of myopia in the macaque but did in the stumptail. This was interpreted as indicating that growth factors produced by the retina are important in the former and brain impulses in the latter species; both factors may be operative in man.

We're going to be posting on the Karlsson psychosis-IQ connection in a few days. Also see demographics of myopia:

"Race exercises a considerable influence over myopia. High degrees with degenerative changes are very common in certain races, such as Chinese, Japanese, Arab, and Jewish persons. Myopia is uncommon in black, Nubian, and Sudanese persons. The variation probably is due more to heredity than habit. "

Remember, a high heritabilty figure means roughly that rank order is preserved though the mean can translate. In other words, it's a centered correlation. So the rise of myopia prevalence to 70% from 10% in one generation does not invalidate the role of genetics, especially when we have mapped loci already. Instead, what it (usually) means is that if A is more myopic than B, A's child will tend to be more myopic than B's child. In this case that interpretation is complicated because the heritability figure was estimated with a logit value for myopia (1 or 0) rather than a continuous value (i.e. the aforementioned refractive error, in diopters). But heritability alone does not allow you to compare A and A's child in *absolute* value. As an analogy, you could take population A to be Asians, B to be Europeans, and the variable to be height.

Also see Marginal Revolution.

Posted by razib at 09:18 PM | | TrackBack

Balancing selection in color blindness?

I've posted about differences between "traditional" (hunter-gatherer) and modern populations in terms of the frequency of color blindess before and its possible implications for the impact of selection against deleterious mutations in modern populations. As Greg Cochran noted, the colour blindness genes tend to mutate a lot. So in any case, I was listening to the radio when I heard about a paper to be published this September in The American Journal of Human Genetics on color blindness. You can find the archive of the show here tomorrow, about 50 minutes in. In any case, I found a press release on the research of Sarah Tishkoff and Brian Verrelli. The researchers seem to be suggesting that the high level of variation found at the red and green "opsin" genes is the result of natural selection, that is, balancing selection that favors polymorphisms, perhaps because certain combinations of alleles have a fitness advantages (this applies to women, who have two X chromosomes, and so two alleles of each gene). The authors suggest that women are more likely to be able to distinguish shades of color in comparison to the typical non-color-blind male, not a great surprise to men who have had to deal with the female penchant for color coordinating, and they suggest that it had fitness consequences in the past because of the female gathering niche. Verrelli notes in the radio interview that male and female chimps also tend to show a difference in their ability to discern various red and orange shades, with the females being far pickier about what sort of fruit they'll put in their mouths. Note that this a case where what was originally modelled as a simple recessive-dominant affect is actually more complex, with different "dominant" (that is, functioning) alleles combining to express somewhat different phenotypes.

Posted by razib at 08:13 PM | | TrackBack

When axioms attack!

I've been poo-pooing the importance of axioms, explicit principles, in shaping societies recently. But I think there are clear cases where principles have been important in differentiating societies. One of the crucial matters is about HIV-AIDS in Africa. Christian blogger Martin Roth points out that "in general the HIV/AIDS rate is highest in those countries where Protestants and other non-Catholic Christians predominate" (see his graphs). Why might this be? I think there are issues of correlation and conflation of various causes, but, here are two points that are axiomatic differences between Christianity and Islam:

1) Islam accepts polygamy, traditionally Christianity does not, or at least the European derived Christianity that was introduced into most of Africa.

2) Muslims generally circumcise, while Christians often do not.

There are issues with these "axioms," in that the Koran does not sanction circumcision, but rather, it is an Arab tradition that has become synomous with Islamicization. Similarly, from what I gather the monogamy of early Christianity was the reflection of its growth in a Greco-Roman mileu where monogamy was the norm among the gentile peoples (European Jews accepted polygamy until the 9th century and some non-European Jews still do). African Christians point out that issues like monogamy are not as cut & dried in their Biblical grounding as Europeans like to assert, but, operationally, these issues are closely tied with adherence to these faiths, that is, they are close to being axiomatic and entail a change of behavior or act upon conversion (nevertheless, many African Christians do practice polygamy).

How does this relate to AIDS? In the case of circumcision, Christian groups that practice it have lower rates of HIV infection than those who do not practice circumcision, while Muslim groups all practice it. There is some evidence that circumcision in certan contexts can reduce the spread of HIV.

On the issue of polygamy, the evidence is thinner and the speculation more extravagant. This article in The Economist paints the general thesis:

In many places men used to be polygamous but faithful, albeit to several wives. In northern Mozambique, which is much more Muslim than other parts of the country, this is still typical. It almost certainly contributes to the much lower prevalence of HIV in the north. In most places, however, monogamy now supposedly obtains, though men persist in having several sexual partners. Since they marry only one (at most), the other women they sleep with must make ends meet as best they can.

Here you have a case where axioms and traditions are in conflict, the solution is to have a public face that is possibly at odds with the private reality (which has to change in reaction to the new principles). Martin Roth notes the high rates of infection in countries with "evangelical Protestants," likely the group most stringent about "keeping up appearences" and least sensitive to cultural differences.

Posted by razib at 06:30 PM | | TrackBack

Tip of my tongue....

For those who think that the blog isn't concerned with emotions, beauty and all that jazz....

I'll be camping in the Bend area Friday to Sunday, and internet access will be spotty for those who might respond to some of my more recent tenditious posts and find that I don't meet the challenge with anything but silence. But, I will be reading the following:

Game Theory and Animal Behavior (half-way through, pretty good)
Basic Economics, by Thomas Sowell, so I have to read it....

On the picture above, like some, I prefer Maria Sharapova to Anna Kournikova, though I know this is a minority viewpoint. Re-reading The Red Queen, it was hilarious to watch Ridley stumble around and try to explain some of the weird beauty fads (tall and super-skinny vs. fatter, etc.). In Survival of the Prettiest, the author notes that in 1959 half of women surveyed wanted to be shorter and in the 1940s women were given hormone treatment to stunt their growth. Today, tall leggy women don't seem to have a problem getting looks.

Speaking of looks, I had the most intense aesthetic turn-around elicited by the female form recently. My girlfriend was going down the main drag of our town, and I was on the passenger side. There was a young woman running on the side-walk ahead of me. You know the general picture, silky blonde hair dancing around her delicate neck while her long muscular tanned legs pumped up and down. My girlfriend noted that she seemed to have a good figure, and gave me explicit instructions to rubber-neck.

The pock-marked face that I saw shocked me. It was as if the girl had had a bout of small-pox, and her proboscis-like nose didn't help. In 15 seconds I had run the gambit of emotion, from leering lust to revulsion. One thing for sure, that girl could stop traffic and cause psychological distress. The horror!

Finally, Michael Farris suggested that the tendency for Chinese and Indians to abort/kill females might be a tragedy of a commons issue. I thought that was kind of strange, since if women were communal property, free and open for use, we would be walking around with rather heavy balls. Let me elaborate: chimpanzee females are promiscuous, they are communal sperm receptacles when they are in estrous, so male chimps engage in "sperm competition", and so have to have large testicles to store their enormous loads. I know that's not what Michael was thinking of when he brought in the term "tragedy of the commons" in the context of male:female sex ratio....

Posted by razib at 05:26 PM | | TrackBack

Propositional civilizations II

Randall and I continue our discusssion on the differences between our civilizations below. I suggest readers who are interested check out the comments below. But, I would prefer to make some clarifications before I post on this topic in the future:

1) I do believe that the "character" of civilizations may differ.
2) On the other hand, I also assert there is a large amount of substructure along various axes.
3) This substructure may be constrainted by axiomatic factors (that is, a constitution or religious text).
4) But the constraints may be illusory, because human rationalization can often reformulate the axioms to justify any given contemporary zeitgeist.
5) The dynamic bidirectional interaction between axioms and behaviors supposedly dictated by those first principles makes the long term impact of initial axioms difficult to characterize, that is, they may play a role in determining the path of cultural evolution by shaping the character of the initial culture, which may then reformulate the axioms, and the process may cycle infinitely.
6) Historical scholarship is subject to a large amount of selection bias (ie; what we know about pagan Scandinavians is largely from accounts written by Christian missionaries or Christians who lived under their rule). Additionally, the generalizations do not give an accurate description of the statistical distribution of any assertion. That is, a generalization presumably describes the mean or median of a trait, the closest aproximation to "truth," but does not quantify variance, skew or other modes.

Let me illustrate. Take the following assertion:

Islam was generally spread by forced conversion.

Imagine a bar graph which is divided into various categories, with the height of the bars dependent on the ratio between the numbers of people who fell into each category of "converts." For example:

1) Forced conversion directly.
2) Forced conversion of elite, then forced to convert.
3) Conversion through indirect coercion (ie; threatened loss of elite status).
4) Conversion through self-interest (ie; possible acquisition of elite status).
5) Conversion through moral suasion.

(an aproximate axis of coercion)

Imagine the changes to the shape of the graph as a function of time.

1) In the first 30 years of Islam, conversion through moral suasion would be the mode.
2) For 10-20 years after that, there would be a spike in the other categories (Muhammed's conquest of Arabia).
3) With the expansion of the Arabs, 3 & 4 would rise as a proportion of conversions.

One can imagine this process as a function of time, and the characterization of Islam would change with each decade. Additionally, there would be geographical substructure. For example, during the initial phase of the conversion of Indonesia, 3, 4, 5 would be dominant, as local elites would convert to Islam to join the transnational Muslim elite (conversion through self-interest). They would often force their subjects to convert (I don't really have this category above, voluntary conversion of elite, forced conversion of populace). Later on, as time passed, the critical mass of Muslim rulers began to wage jihad against Indonesia's Hindu & Buddhist rulers, so 1 & 2 would become more prominent.

I can do the same sort of thing to Christianity. The overall point is that I'm careful of generalizations that stretch across time and space, and crucially, neglect the huge variation between individuals and groups (so I put on qualifiers which don't really give a good characterization of the distribution). Perhaps history is just too complicated to ever really be a social science, and must remain ideology buttressed by facts. In any case, simplistic generalizations work in the context of talking to the "common man," but I shy away from that on this blog (or am attempting to), since I presume that the readers are intelligent and well-read. Additionally, I also think that the ingelligent are susceptible to an axiomatic conception of cultural change, direction and dictation, because they are more likely to look at things axiomatically. To some extent, the axiomatic viewpoint works because until recently, elites have dominated many elements of cultural change.

Posted by razib at 02:25 PM | | TrackBack

Defining Group Selection: Price's Equation

In an earlier discussion of group selection (here) I said that much of the argument about the importance of group selection was a disagreement over semantics rather than facts.

In re-reading the earlier post I think I could have usefully mentioned George Price’s covariance formula, as explained by W. D. Hamilton, Narrow Roads of Gene Land, vol. 1, p. 332....

The following, unless otherwise stated, deals only with the selection of genes, not of memes, cultural traits, etc.

Suppose we wish to consider the change of frequency of a gene in a population from one generation to the next. Suppose also that the population is divided into a number of groups, either in some natural way (e.g. as discrete geographical sub-populations), or by a decision of the investigator. Price’s equation provides a means of analysing any overall change of frequency of the gene into two components.

One component (the ’intragroup’ component) takes account of the change of frequency of the gene within each group, so that the total contribution of these changes is simply the average of the intragroup changes in frequency, weighted by the size of each group and its own fitness (rate of growth or decline).

The other component (‘intergroup’) is more subtle, and takes account of any covariance between the fitness of the groups and the initial frequency of the gene within them. Thus, if groups which have a high initial frequency of the gene tend to have higher (or lower) fitness than others, this will affect the frequency of the gene in the total population, but it is not taken into account in the intragroup component. (Incidentally, in Price’s formula the intergroup component comes first, but that is just a matter of presentation.)

The covariance (a statistical measure of the association of two variables) can also be expressed as the product of the regression of group fitness on gene frequency, times the variance in the initial gene frequency itself. An important consequence of this is that if there is no variance between groups in the initial gene frequency, then the intergroup component of the Price formula must be zero.

The beauty of Price’s formulation is that it provides a general, mathematically watertight, and relatively simple framework for identifying the contributions of different levels of selection. (In principle it can be extended to more than two levels, but I won’t consider that. For the formula itself, see the Technical Note below.)

It is naturally tempting to propose that the intragroup component should be identified with individual selection, while the intergroup component represents group selection. I think there are two problems with this suggestion. One is that some processes potentially affecting the intragroup component, such as reciprocal altruism and help given to relatives, are regarded by some biologists as group-selection phenomena, while some processes affecting the intergroup component, such as the geographical association of relatives, would be regarded by other biologists as contributing to kin selection rather than group selection. So the proposal is unlikely to be acceptable to either side in the debate. More seriously, whether a process falls within or between groups may depend on how the population is divided up. So it would be difficult to say categorically whether a process was ’individual’ or ’group’ selection without considering every possible way of dividing the population.

Nevertheless, even if the formula does not provide a knock-down solution to the group selection controversy, it does offer a means of clarifying the issues. For any process which is postulated as a form of group selection, it should be possible to specify whether it contributes to the intragroup or intergroup component of the Price formula.

If it contributes to the intergroup component (assuming that this is non-zero), it should be possible further to specify what gives rise to the covariance between gene frequency and group fitness. Crucially, there cannot be non-zero covariance unless there is also variance in each variable. An important part of the analysis is therefore to explain how the initial variance in gene frequency arises, i. e. how some groups come to have a higher frequency of the gene in question than others. So far as I am aware, there are five main ways in which such variance may arise:

a. Pure chance: the random assortment of individuals leading to differences in gene frequency between different groups. As Hamilton shows, the random assortment of individuals in a single generation does not create enough between-group variance for an ’altruistic’ gene to increase in frequency through the intergroup component of Price’s formula, if the fitness effects of the gene are simply additive. However, if the fitness effects are synergistic (i. e. increase disproportionately as the number of altruists increases) this objection does not necessarily apply.

b. Genetic drift over several generations in isolated groups could lead to a divergence of gene frequencies between the groups.

c. Individuals with relevant traits may associate together for behavioural reasons.

d. Individuals living close together geographically are also likely to be genetically related, and therefore to have a higher frequency of certain genes than the population average. This is especially true in small local populations with little migration. Such populations are also liable to inbreeding and genetic drift due to the chance loss of alleles from the local gene pool, so this source of variance tends to overlap with (b).

e. Different selection pressures may apply in different places, leading to geographical variation in gene frequencies and consequently to variance in gene frequency between groups living in different places. Since the variation in gene frequencies is a straightforward consequence of individual natural selection, this is seldom considered relevant in the context of group selection, though in principle it should be, since it might lead to a non-zero intergroup component in the Price formula. However, an intergroup component will not arise merely because each group is specially adapted to its local conditions. This will produce variance in gene frequency between groups, but in itself it will not produce covariance between gene frequency and group fitness.

Provided the investigator clearly specifies how the population is divided into groups, and how any covariance between group fitness and gene-frequency arises, it is a matter of linguistic convenience whether a process is described as group selection, individual selection, kin selection, or whatever. Hamilton’s own suggestions (op. cit., p. 337) seem quite balanced and sensible: “if we insist that group selection is different from kin selection the term should be restricted to situations definitely not involving kin. But it seems on the whole preferable to retain a more flexible use of terms; to use group selection where groups are clearly in evidence and to qualify with mention of ’kin’ (as in the ’kin-group’ selection referred to by Brown), ’relatedness’ or ’low migration’ (which is often the cause of relatedness in groups), or else ‘assortation’, as appropriate. The term ’kin selection’ appeals most where pedigrees tend to be unbounded and interwoven, as is so often the case with humans”.

Oddly, Price’s equation has been taken by enthusiasts as somehow vindicating the importance of group selection. But quite apart from the point that Price’s formula does not automatically resolve the semantic dispute, it remains entirely a matter of fact whether or not the intergroup component of the formula is important in nature. I am not aware of much evidence that it is - if there were, enthusiasts for group selection would presumably bring it forward.

To mention briefly the group selection of memes, cultural traits, etc., in principle the Price-Hamilton approach could be applied, but we have a much less clear idea of what the units of replication are, and how to measure their frequency and fitness, than in the case of genes. At present I don’t think there is any alternative to giving a detailed ad hoc explanation of what is meant by ‘group selection’ in any particular case of cultural evolution.

Technical Note (for masochists only)

Price’s equation applies to selection within a population of ‘particles‘. It may help to imagine these as genes at a single locus in a haploid population, so that the number of particles equals the number of individual organisms. (This is my suggestion, just to help the interpretation. I have also modified the notation to avoid using subscripts and Greek letters.) If the number of the total population in the first generation is N, suppose that this is divided in some way into groups. We denote the number in each group by lower-case n (not necessarily the same for each group). We use the letter S to denote summation over all groups, so Sn = N, as the total population number must be the sum of the group numbers. We are interested in genes of a particular type, A. We designate the frequency of A within the population as Q, and within each group as q (not necessarily the same for each group). QN is the total number of A genes in the population, and qn is the number in each group, therefore Sqn = QN, since the total population is just the sum of its groups. (NB: when the product of two variables appears within the scope of a summation, as in Sqn, this indicates that the value of one variable is to be multiplied by the corresponding value of the other variable before summing.)

So far we have been dealing only with the first generation. We assume that there are discrete generations. For each value in the first generation, the corresponding value in the second generation may be designated by an asterisk. Thus the total population in the second generation is N*, the population of a group is n*, the frequency of A in the second generation is Q* for the whole population and q* for each group. The total number of A genes in the second generation is Q*N* for the whole population and q*n* for a group.

We can now define a concept of fitness, denoted by W = N*/N for the whole population and w = n*/n for a group. W (or w) therefore measures the rate of growth or decline of a population from one generation to the next. Note that NW = N* and nw = n*, so Snw = Sn* = N* = NW.

Finally, we may denote the change in frequency of A as dQ = (Q* - Q) for the whole population and dq = (q* - q) for a group.

With this notation Price’s equation may be expressed as follows (adapted from Hamilton‘s version):

WdQ = Snw(q - Q)/N + Snwdq/N.

Hamilton remarks that with such notation the equation is ‘easy to derive’, and leaves it for his readers to do so for themselves. Well, I found it bloody difficult, so for the benefit of others I will give my own working:

WdQ = (N*/N)dQ = (N*/N)(Q* - Q) = Snw(Q* - Q)/N = SnwQ*/N - SnwQ/N .

So far, fairly mechanical. The non-mechanical part now is to recognise that SnwQ* = Snwq*. To me, at least, this is not obvious. But reflect that the total number of A genes in the second generation can be arrived at in two ways: either by taking the total of the second generation population and then multiplying it by Q*, or by calculating the number for each group in turn, and then summing the numbers. The first way gives N*Q* = SnwQ*, while the second gives n*q* = nwq* for each group, which is summed to get Snwq*. Since the total must be the same, whichever way we reach it, we have SnwQ* = Snwq*. (For the same basic reason, Snq = SnQ, and Snw = SnW.) We may therefore substitute Snwq* for SnwQ* in the expression SnwQ*/N - SnwQ/N, giving Snwq*/N - SnwQ/N.

Since q* = q + dq, we can rewrite this as Snw(q + dq)/N - SnwQ/N.

This may be rearranged as Snw(q - Q)/N + Snwdq/N, which is the right hand side of the desired equation WdQ = Snw(q - Q)/N + Snwdq/N. QED.

The first term on the right hand side is usually described as the ’covariance’ term. It measures the association between the fitness of the group and the extent to which the frequency q in the group diverges from the frequency Q in the whole population. But as a covariance it has several puzzling features, which took me quite a while to fathom. If it were a covariance between properties of groups, we might expect it to take the form S(w - Mw)(q - Mq)/G, where G is the number of groups, Mw is the mean of the w’s for the groups (i.e. the sum of the w’s divided by G) and Mq is the mean of the q’s for the groups (the sum of the q’s divided by G) So why is the denominator N and not G, why does the term n appear in the numerator, why is the mean of the q terms Q and not Mq (which is not necessarily the same as Q unless the size of each group is equal), and what has happened to the mean of the w’s?

The answer to the first three questions is essentially the same: the covariance is not a covariance between properties of groups as such but between certain properties of individuals defined by reference to their groups. The product sum consists of the sum of N terms, one for each individual, arrived at by multiplying the w and q of that individual’s group. The total number of ‘observations’ is therefore the total number of individuals, N, and not the number of groups, which explains why N is the denominator. It also explains why the term n enters into the numerator, so that each w and q is multiplied by the appropriate number of individuals, and why the mean of the q‘s is Q (the mean for all individuals) and not Mq. As to the absence of any term for the mean of the w’s, it would be legitimate to express the numerator in the form Sn(w -W)(q - Q), but it will be found that the terms involving W cancel out, as SnqW = SnQW, so that the expression may be reduced to Snw(q - Q). (Alternatively, one could cancel out the terms in Q, since SnwQ = SnWQ, and reduce the expression to Snq(w - W). I have not seen it in this form. The fuller form Sn(w -W)(q - Q) is perhaps preferable, as it makes it clear that variation in both w and q is needed before there can be an ‘intergroup’ component.)

Despite its odd appearance, Snw(q - Q)/N is therefore an ordinary covariance, provided it is understood not as a covariance between properties of groups but between properties of individuals defined by reference to their groups. It may be described in words as the covariance between the property of being a member of a group with fitness w and the property of being a member of a group with frequency q. The difference is subtle but important, because Price’s equation is only valid if the number of individuals in each group is taken into account. Similarly, in expressing the covariance as Variance x Regression, it is strictly the variance and regression of properties of individuals that needs to be measured, even though the properties inescapably involve their groups. This is a somewhat peculiar situation, and it is not very clearly explained by Hamilton, so it is perhaps not surprising that the formula has taken a long time to catch on.

Posted by David B at 06:15 AM | | TrackBack

July 07, 2004

Human evolution

A report in today's Science Daily Magazine previews a forthcoming article by Caspari and Lee in Proceedings of the National Academy of Sciences. C & L have analysed over 750 paleolithic human remains to determine their age at the time of death. The analysis shows a large increase in the proportion of relatively mature individuals (over about 30) in the Upper Paleolithic, around 30,000 years BC.

This could be very significant in explaining the 'explosion' of cultural development around that time. Of course, there is a chicken-and-egg problem: which came first, the improvement in life expectancy, or the cultural development?

One would also want such a dramatic finding to be independently verified, preferably on separate material, before getting too gung-ho about its importance.

Posted by David B at 12:39 PM | | TrackBack

What's in a byproduct, everything?

Just found online archives of Scott Atran and Dan Sperber. Both are cognitive scientists who have been really changing how I view "human nature" and "culture." Basically, Atran & Sperber would probably characterize much of anthropology as pure description and typology, with little predictive power. They tend to use a reductionistic ground-up methodology, that is, a "mind's-eye" angle that explains culture as an emergent property of the interplay play between mental modules. Roughly speaking, they oppose simple memetic & functionalist arguments, and they seem quite often similar in tone to "blank slaters" who argue for an almost random and profusion of cultural "spandrels," but Atran & Sperber work within the field of evolutionary psychology, and so are critically aware of the constraints placed upon cultural evolution by our mental hardware.

I especially recommend Dan Sperber's An objection to the memetic approach to culture. It is ironic in light of Dawkins' role in the "sociobiology controversy" that from where Sperber stands Dawkinsian memetics neglects essential innate features in the human mind and overplays the card of conscious cognition.

Related note: Recently, I have come to thinking about societies in a way influenced by the modular mind thesis. It seems that the conventional "blank slate" paradigm implies the possibility of a level of free-form social diversity congenial to those who place a primacy on a particular set of norms, usually espoused by "progressives" of any given age. Roughly speaking, they would not put much stock in the idea of a finite number of social equilibria, rather, all social configurations are at the same "energetic state," so only considerations of norms and values come into play. In contrast, another view of human nature is, roughly speaking, "deterministic," and only considers one social configuration as the ideal equilibrium, that is, at a "low energetic state." In relation to that social configuration all other configurations are uphill, and therefore unstable. Because there is only one stable equilibrium, which is maintained by a fixed set of social norms, those must be the norms that any society must uphold to stave off collapse. This deterministic view is often aligned with a "conservative" position, which holds that the "traditional" customs & beliefs of the recent past reflect the only equilibrium. But, there is also a third way, one which denies the rejection of any constraints of the "blank slaters," or the restrictive conception of only one-true-equilibrium of traditionalists. When anthropologists survey and classify cultures, I do not believe that they see a flat distrubtion of populations along most of the significant axes of classification. That is, populations are not equitably distributed along a spectrum, for example, an equal number of highly polygynous cultures, moderately polygynous cultures, monogamous cultures, moderately polyandrous cultures and highly polygamous cultures. Rather, there is a strong skew toward polygyny as the idealized norm in many cultures, though the majority are functionally monogamous. A small group of cultures are polyandrous, but they are often characterized by the marriage of brothers to one woman in environmental contexts where scarcity of resources dictates that the burden of raising a family must be shared. In other words, there does exist a small coterie of peoples who exist at a different stable equilibrium than is the norm. This equilibrium is stable and at a low energetic state only under particular constraints. Neverthless, it illustrates the point that adherence to the infinite possibility of cultures is non-empirical (human cultures tend to cluster around certain social configurations), while the conception of only one way-of-life is probably shaped by the reality of the environmental and social context that a particular culture exists within. After all, a world where slavery was abolished would have been unimaginable 300 years ago! And yet 99% of the world's cultures now get along fine without an institution that was once omnipresent in various forms.

Basically, this is just a recasting of the idea of an adaptive landscape.

Posted by razib at 12:22 AM | | TrackBack

July 06, 2004

Propositional civilizations?

From my post precision vs. accuracy, Randall asks:

Razib, Why do you argue that it doesn't matter what the common canon is for the elites? Surely different canons promote different sets of values and those different sets of values produce different kinds of civilization.

I don't buy the idea that the various canons all express the same set of human universals. I think you would like that to be the case but that you really do not believe it either.

Samuel P. Huntington is right. The different civilizations have different rankings of values. Value surveys done across societies find this result.

This is an interesting question, as I've been addressing topics such as "memes," "human universals," and so forth, a great deal recently. Do the central documents of the literate class influence the character of a civilization? I suspect to some extent, but I can't frankly quantify in my own head with high certainty whether that amount is trivial or non-trivial.

For example, the Bible was the primary source document for Christian civilization from about the 6th century A.D. to the 13th century A.D.. Even after the 13th century, literacy for the vast majority of individuals within Christendom basically meant being able to read the Bible (in particular after Protestant translations into the vernacular). So, can we predict the nature of Biblo-centric cultures? To some extent, but...as I note in a comment below, the Bible has been used to justify just about every political and social system under heaven (I hyperbolize for effect, but those who have studied the literature of Christian libertarians and the Christian Reconstructionists might wonder if they are reading from the same book!). The Bible has within it enough contradictions that one can select whatever passage suits an individual. The Hebrew Bible has enough ethnic cleansing to satisfy the warrior while the parables of Jesus can be rendered in a pacifist fashion. Christian civilization itself is cleaved and subdivided, as Samuel Huntington acknowledges in The Clash of Civilizations, even splitting the "Orthodox" from the Western Christian tradition.

I have of course covered many of my sketchy and qualified opinions before, I do think explicit textual precedents can serve as constraints (perhaps the messy nature of the Christian Bible allows Western civilizations a flexibility that the more integrated Koran and Hadiths do not?). But, I would argue that the organic development of a civilization simply channels the interpretation of a text into whatever form it wishes. Look at how the modern Bible is seen in a universalist and anti-racial light by most Christians, while 200 years ago it seemed to justify segregation and slavery. The text did not change, the civilization did.

Moving on, I am curious why Randall believes I would like it to be the case that texts express a universal set of values? I will be frank and admit that I tire of the narrowness of scholars within any particular tradition when they express the sentiment that their particular text was "revolutionary" because it introduced certain principles to humanity (see my post that discusses "ethno-autism"). A quick reading of alternative religious & philosphical traditions would, in my opinion, show that ethics did not arise in the mind of Yawheh, Brahma or Confucius. Even the oppositional Hellenistic ethical philosophies of Epicureanism & Stoicism in practice sanctioned a similar life of moderation for most adherents.

As for Randall's last point, I agree, though I tend to view it as a complex process that evolved organically from within, rather than through textual influence. I suspect for example that if a complex society is open to the concept of individual liberty, it will manufacture justification for this principle in whatever texts are on hand. Scandinavia and Southwestern Europe both draw from the same Western Christian tradition, and yet their values differ a great deal. You see a form of this in the appeal of various contemporary camps to figures that have attained sainthood in American culture, for example, the Right and the Left now appeal to the words of Martin Luther King Jr. as if they were sacred text, each putting their own spin on King's message to forward their own political ends (personally, I suspect that the later King would sympathize with the modern Left's vision, but dead men don't dispute their legacy, and I think that the Rightist reading of King's message is perfectly sound if you selectively extract meaning from the text).

I know many readers disagree, but, here are two points:

1) Would an alien be able to predict the non-cosmetic differences between various cultures based on their texts? (that Scottish culture emphasizes individual liberty & autonomy more than Muslim cultures, though their central religious thinkers both tend toward predestinationism!)

2) One might be able to peruse a list of "top texts" selected by the intellectuals of a particular culture, and predict traits of the society from these, but of course, if a variety of texts are on hand, they will select those which are a reflection of the culture at the time (or more narrowly, emphasize certain books and chapters in texts and ignore others). It might not signal that those texts had any independent causative impact on the society in question, but only became prominent after-the-fact (or consider the decline of the model of the Roman Republic and the emphasis on Athenian Democracy with the transition of our republic from an elite to mass form).

Additionally, the example of Confucianism is cautionary, in the late 19th century, Confucianism was fingered as the reason that the inflexible Far Eastern cultures were in economic and cultural decline. Today, it is the one "reason" that the Asian economies have done so well, fostering a strong work ethic and social cohesion.

Addendum: Newer readers might be interested in similar posts:

Related note: One can agree on point Z, but it is important to delineate how one arrives at Z from point A. So, in the above context, I agree that there are:

1) distinct civilizational clusters
2) conflict/clash/tension between these clusters

But why do they cluster, and why do they conflict, are different questions with a variety of possible answers. And crucially, the string of propositions between A & Z that characterize one's opinion on a particular issue dictate what sort of "solutions" one proposes if Z is problematic. So, Victor Davis Hanson, from all I can see, has a highly propositional conception of the world. From where he stands based on his assumptions his solution might be:

A) Conquer them
B) Give them Western learning

Ergo, conflict resolved. There are other opinions about what the problem is, and how to solve it. Hanson fixates on the miraculous efflourescence of rational thought in Classical Greece, and imagines it as the universal model to emulate, exportable and translatable with the ease with which Prometheus gave man fire. But though man mastered fire, Prometheus was the one who paid the price....

Posted by razib at 11:40 PM | | TrackBack

Behavioral genetics keeps on a truckin'....

An Association Between a Functional Polymorphism in the Monoamine Oxidase A Gene Promoter, Impulsive Traits and Early Abuse Experiences:

Monoamine oxidase A (MAOA) activity is altered in mood disorders and lower activity associated with aggressive behavior. The gene has a functional polymorphism with a variable number tandem repeat (VNTR) in the upstream regulatory region (MAOA-uVNTR). In this study, we examined possible associations between the MAOA-uVNTR polymorphism and mood disorders, suicidal behavior, aggression/impulsivity, and effects of reported childhood abuse. In total, 663 unrelated subjects with a psychiatric disorder and 104 healthy volunteers were genotyped for the 30 base pair functional VNTR. A novel repeat variation was identified. No statistically significant associations were found between this functional MAOA-uVNTR polymorphism and mood disorders or suicide attempts. However, the lower expression allele was associated with a history of abuse before 15 years of age in male subjects and with higher impulsivity in males but not females. Our results suggest that the lower expression of the MAOA-uVNTR polymorphism is related to a history of early abuse and may sensitize males, but not females, to the effects of early abuse experiences on impulsive traits in adulthood. The polymorphism may be a marker for impulsivity that in turn may contribute to the risk for abuse. This trait could then be further aggravated by abuse.

Posted by razib at 08:43 PM | | TrackBack

Horny single man

I am now hearing about a new book titled Bare Branches: The Security Implications of Asia's Surplus Male Population. Here is an article in The Washington Post by the authors, and a more critical piece in The New York Times. Here is a quote from one of the critics:

"I don't believe that anyone has tested this in a systematic, worldwide comparative study," said Ms. Ember, a social anthropologist. She said the predictions of violence based simply on the number of bare branches discounts the theory that men are often socialized to be aggressive, rather than being inherently more violent than women.

The level of socially acceptable violence varies from society to society (though I know none where women are typically the more violent sex), and one might point to the Tibetans as an example where altered socialization has been crucial to constraining the violent impulses of Tibetan males. After all, this is the nation that brought the Chinese Empire to their knees and were the terror of Central Asia, but after the conversion to Buddhism they shifted away from being a martial people. Interestingly, a similar process can be gleaned among the Mongols, who after their conversion to the Buddhist faith no longer ventured like human scythes over the steppe [1]. An observation could be made that the diversion of as many as one out of three men into a system of monastaries might have sapped the martial vigor of both peoples, while the rise of more polities on the Eurasian rim who were no longer militarily inferior to the nomads sealed off the more conventional avenues of social releaes in rapine and pillage.

In any case, societies are complex, and I believe there are myriad stable startegies, that is equilibriums, to maintain a social system. One of the critics in The New York Times article points out that the kingdom of Dahomey was highly warlike, and there was male-female equality in that society (and female warriors even from what I recall!). Similarly, I could note that ancient Sparta was known for the liberty that it gave to its women, especially in comparison to sexist Athens. From this, I could perhaps generalize that female liberty leads to a warlike society that devalues art and intellect, but of course, I know not to use this example to prove my point when there are counter-examples, and similarly, I would also be cautious of falsifying statistically couched generalizations with only a few counter-examples (that is, look at the trend line).

Instead of looking at the broad-context, it might be instructive view the issue from the individual perspective. I think most readers would agree that the pursuit of sex is a primary activity of young males. Additionally, many of the other activities seemingly unrelated to sex, acquisition of money or social prestige through professional success, are likely proximate behaviors serving to enhance status, and so lead to sex. Sans sex, it seems likely male energies must be channeled into other pursuits. A surplus of males, or scarcity of resources that results in the inability to support a family, may result in social adaptations that do not involve violence. Tibetans offloaded many young men into monastaries, and practiced polyandry. This does not mean that there aren't other stable equilibriums, which is where the thesis above comes in.

Though I think societies with equalized sex ratios and a high status for women might be warlike (Sparta, Rome and to some extent Egypt would be examples from ancient history), societies that are highly polygynous, have skewed sex ratios and a low status for women are more likely to be warlike at a given time. Any particular social stress can be mitigated or released, but that does not falsify the reality of the stress.

1 - The Mongol tribes who were the last to be fully converted to Lamaistic Buddhism, the Oyrats folk, were the last great tribal confederation that fought the gunpower empires of Asia, and lost.

Update: Article below from The Economist on India's sex imbalance....

Addendum: Randall has a related post.


Missing sisters
Apr 17th 2003 | ROHTAK
From The Economist print edition

A shortage of girls will haunt India for decades

Will there be wives for them?

IN THE district of Rohtak, a fairly well-off town in northern India's farm belt, it is estimated that one in every six girls conceived is aborted. Modern ultrasound technology, coupled with a traditional preference for boys, has led to mass female foeticide. Progress does not help: rising prosperity, public-education campaigns and strict-looking laws have all failed to curb the practice. But the resulting dearth of females is already wreaking social damage, which can only worsen.

Demographers have long puzzled over India's skewed sex ratio. Throughout the 20th century, it grew ever more unbalanced, from 972 women for every 1,000 men in 1901, to 927 in 1991. Encouragingly, it then climbed to 933 in 2001. This, however, masked a sharp imbalance among children under the age of seven: from 945 girls per 1,000 boys in 1991, to 927 in 2001. Data on the sex ratio at birth are scanty, because many births are not registered. Figures must be gleaned from the ten-yearly censuses, and from local surveys.

These show wide regional disparities. In the south, especially in the state of Kerala, there are many more girls. But in 48 of India's 577 districts, the sex ratio among children is below 850. Of these, 34 are, like Rohtak, in Haryana or its neighbouring state, Punjab. In Rohtak there are 847 females for every 1,000 males, and just 796 girls for every 1,000 boys.

A strong preference for boys is common in agricultural societies. Boys inherit the family name and land, and provide an old-age insurance policy. Girls join their husbands' families, and need dowries. When mobile ultrasound units started touring rural Haryana in the late 1980s, their advertising pitch was, appallingly, “Pay 500 rupees now and save 50,000 later.”

Pramod Gouri, director of Search, a government-financed civic-education outfit in Rohtak, offers two explanations as to why Punjab and Haryana should be so egregiously prone to female foeticide: the region's social norms have proved remarkably immune to “modernity”; and the agricultural “green revolution” put enough money in local pockets to make sex-selection affordable. Abortion is far more prevalent among better-off, town-dwelling, higher-caste and literate women. Smaller families have, as in China, also further encouraged female abortion.

In 1994, sex tests were made illegal. But in Haryana only three cases have been filed: the law is hard to enforce, since ultrasound scans are now widespread. For doctors, there is good money—3,000-5,000 rupees ($60-100) a time—to be made from (illegal) abortions.

Already, the female shortage is making itself felt. Urmila, a district councillor in the countryside near Rohtak, says unmarried young men are turning to crime, and violence against women has increased. Some men in Haryana are buying “brides” (for between 10,000 and 20,000 rupees) from other parts of India, or Bangladesh. There are an estimated 15,000 such women. Many, though, are treated as slaves. Even their children are shunned.

Despite the shortage of brides, Urmila says that dowries have risen, not fallen. In Rohtak, a middle-class family will typically spend 600,000-800,000 rupees—several years' earnings. Touring her district, she finds people anxiously asking her if she knows of any marriageable girls. This, she hopes, may be the first sign of a change in attitudes. But it may be too late to avoid serious social trauma.

Posted by razib at 07:38 PM | | TrackBack

Plasticity as g?

Since today's topic seems to center on the vertical aspects of g, I thought I would link to Garlick's article in Psychological Review a few years ago.1 I apologize if this was posted here before my "arrival" at GNXP, but I searched the archives and could find no mention of it.

In sum, he postulates that individual differences in g arise because of different, innate, capabilities for neural plasticity coupled with specific environmental interactions, which, of course, are non-independent.

However, it is then observed that if people differed in neural plasticity, or the ability to adapt their connections to the environment, then those highly developed in one intellectual ability would be highly developed in other intellectual abilities as well.

1. Please note the acknowledgement section of the paper. I cannot tell you how many articles I have read where Arthur Jensen has been acknowledged for his help with the paper. This on top of the 400+ articles of his own that he has published. One would be hard pressed to find a more devoted scientist to his/her field.

Posted by A. Beaujean at 03:47 PM | | TrackBack

Alfred Russel Wallace

For those interested in the life and work of Alfred Russel Wallace, often described as the 'co-discoverer' of natural selection, there is a great website here. This gives access to many of Wallace's rare short papers and reviews.

Posted by David B at 04:35 AM | | TrackBack

July 05, 2004

Spousal rage & all that

Below, I posted on the supposed increase in female infidelity (Steve Sailer expresses skepticism, which I share, though I think some of the difference might be less social stigma resulting in more open reporting from females). Here is a website I found that might shed light on the Newsweek article:

Buss & Shackelford (1997) investigated a number of mate retention tactics used by married couples. They found that for men, the number of acts of mate retention was positively correlated with their partner’s youth and physical attractiveness. In fact, the peak levels of mate retention also correlated to the peak reproductive years for women in general.

Here is fertility as a function of age:

Finally, readers might find this long piece about male responses to the possibility of infidelity interesting (it takes a cross-cultural anthroplogical view seasoned with evolutionary psychology).

Posted by razib at 01:31 PM | | TrackBack

Precision vs. accuracy

One thing that young people who are trained in the scientific disciplines learn early on is the distinction between precision and accuracy. I think that the distinction is something that might be important to introduce more widely into non-scientific discourse, especially when it comes to verbal communication.

From where I stand, our society tends to give an appropriate focus on accuracy, that is, whether the person who is trying to communicate facts & concepts is actually transmitting facts & concepts that are in line with the "truth." This is important in debates that revolve around topics that are heavily grounded in empiricism. On the other hand, I do not believe that people give great attention to precision. When the topic is less empirical, and more based on idealistic conceptions of ends and norms, this is an enormous problem, as, roughly speaking, "people often talk past one another" because of the lack of precision in terminology (how many arguments end in, "oh, that's what you meant!").

This is why a "canon" is important. Canons of texts, especially in areas like literature, express rather fuzzy "truths" that are not easy to establish empirically (let me be frank and say that I don't understand deep down what "insights on human nature" literature can give that biology, psychology and economics can't). Nevertheless, a common lexicon of references and values can evolve that allow the formation of a class of individuals that communicate with each other at a high level of precision.

I believe that our own culture is moving away from this precision, and this is partly due to the "opening of the canon." With gays studying gay literature, women studying feminist authors, minorities studying their own ethnic literature, cross-communication becomes labored because of a lack of common references to establish precise communication of intent and context. As something of a literary philistine I don't particularly care much what books we read, as long as the educated classes digest a common core of texts that can form the basis of a common world view of values and references.

The European elites had the classical authors and the Bible, the Chinese had the texts of the Spring & Autumn periods (and later commentaries), the Muslims had the Koran and Hadiths while Hindus had the Ramayana, Mahabharata and the Upanishads. Ultimately, I think the differences between these texts in detail is less salient than the human universals they express, and the common lexicon that they fostered among the elites of these societies.

Posted by razib at 01:02 PM | | TrackBack

Great Men

For those who haven't already done so, check out the Great Men section of links on the right hand side of the page.

Razib has just added a link for Francis Galton. The link is to Gavan Tredoux's remarkable Galton website. Among other goodies, this includes free downloadable PDF files of virtually all Galton's books and hundreds of papers, many of which are extremely rare and inaccessible. (Galton's works were never published in a collected edition.)

I also checked out the link for R. A. Fisher, which links to the University of Adelaide Library, which has the world's greatest archive of Fisher material. I was delighted to see that they are providing PDFs of Fisher's major papers in genetics and statistics. (Unlike Galton's papers, Fisher's have been published in a collected edition, but you will only find it in good academic libraries.)

Some day I hope to understand what, if anything, Fisher meant by fiducial inference, but it's a bit like learning German: every time I think I'm getting it, it slips away again.

Posted by David B at 02:38 AM | | TrackBack

July 04, 2004

The cheating lives of ladies

Newsweek has a showcase article titled "The Secret Lives of Wives" that chronicles the increasing in cheating among women. This is the sort of complex topic that needs to address hard-wired parameters, cultural constraints and individual motivations. It seems improbable to me that the two co-authors of this article read books like The Red Queen or The Blank Slate since their explanatory models tend to focus on the cultural and the individual, but it is I think a fragmentary picture to leave out the biological, as all three form a seamless whole that might explain social trends more realistically to readers, who after all often have an intuitive understanding of evolutionary factors.

The fact is, all cultures have equal, or more likely, harsher strictures against female infidelity than male "straying". The evolutionary reason seems obvious in the context of an EEA where there is scarcity of resources, men raising children who are not theirs genetically suffer a bigger hit than women who have to deal with less attention from their husbands, though he might still give most of his resources to one particular wife & their common children.

Interestingly, the article mentions women leaving for "wealthy" and "exciting" men, or fixating on personal trainers. This seems like a classic cads vs. dads issue. Certainly on a proximate level of the individual, one could hypothesize all sorts of "reasons" that a woman might make the decision that she does, but it is often instructive to take a step back and look at the overall pattern.

One thing that the article focuses on is the tendency for these affairs to happen in women as they age. As I've noted before, on the physiological level, there are various types of love, and the ardor of each might have different levels of waning and waxing intensity as a function of time. That is, a 45 year old woman that was married at 20 finding an affair "exciting" should be no surprise on the physiological level. On the evolutionary level, it is highly possible that pair-bonds on the order of 20+ years were not selected for, that is, mortality and the fact that the children had already reached maturity might have resulted in far less of a fitness cost if there was a dissolution of a relationship. The sexual dimoprhism (differences in morphology between males and females) in humans suggests that pure monogamy and fidelity is not the norm, rather, a mixed strategy, along with some expectation of infidelity might be the norm (human testicles are equidistant in size between those of chimps and gorillas, among the latter there is a lot of "sperm competition," while among gorillas the males tend to keep a close eye on their harems).

Of course, contexts change, some of the male "release mechanisms" toward female infidelity have been enshrined in cultural norms, in law and custom. Laws codified by a literate class and inserted in religious dogma can be difficult to modify later on. With the rise in life expectancy, and the affluence of American females (1/4 earn more than their husbands), innate release mechanisms within the cognitive substrate, and the cultural universals that they have spawned, have to face an environment far different than the EEA. The result is the confusion that you see on display in American culture today. The interplay between various forces might result in a new equilibrium.

To some extent in the EEA, and as the laws imply, "paternity was probability, not surety" [1]. The rage and violent reactions of males toward female infidelity was likely an adaptation to this reality. But today, with paternity tests, this is to some extent a superflous adaptation. The British push to roll-back secret paternity tests is wrong-headed. Surely it will cause a short-term disruption as re-equilibriation of social norms will not occur overnight [2]. But in the long term, full confidence of paternity might allow more acceptance of female infidelity in a fashion similar to the more open attitude that is found among male homosexuals. This sort of proposition won't make cultural conservatives happy, but the reality is that this sort of technology will automatically cause changes in human societies, and we need to figure out ways to deal with them, no matter if they cause us discomfort. There are, as noted in the piece above, more prosaic changes pushed upon us by the modern world, the fact that women encounter many more strange males in their lifetime in the workplace, and the proliferation of information technology that amplifies female social intelligence and reach.

Finally, I won't discount the impact of random-walk cultural changes and fads. On the simplest level, theorists have already shown that baby name popularity fluctuations can be modelled as genetic drift. Cultural fads, within the constraints and parameters above, require a level of flexibility in our conception of a normal society, as the mob tends to move in various directions. I'm wouldn't assert that all social changes must have a "reason" behind them. But something like female infidelity doesn't seem like a fad to me, rather, it seems to satisfy deep-seated psychological cravings, which can be explained by physiological changes in the life cycle of relationship shaped by evolutionary forces, as well as the relaxation of cultural and social constrains that emerged out of the interplay of more biologically hard-wired compulsions with the realities of the EEA, and especially post-EEA pre-industrial societies. If this is the "information age," we should take all the information come out of various disciplines to heart, and use it to analyse trends and patterns.

[1] American males who wish to naturalize children they had abroad with non-Americans who for some reason were separated from those children have to jump through more hoops that women. Why? The reason is the assumption that paternity is not as easy to establish, which of course is ridiculous.

[2] There is a common legal argument that one must act in "the best interests of the child." So, if a man agrees to be the father on a birth-certificate, he takes upon his shoulders life-long duties. There are many contexts where this happens, from casual flings that never crystallize into relationships all the way to men who have been unknowingly cuckolded and find out the true paternity after a divorce. I think it should change to "the best interests of children" rather than "the best interests of the child." The acknowledgment of new technological and social realities into the law will foster long term social satisfaction, as opposed to the short term familiar compromises made now.

Posted by razib at 08:39 PM | | TrackBack