Would it be possible that hairlessness and skin color evolved to allow fathers to identify their direct biological offspring, so as not to have to support another male’s genes. In many other species, when a new male/group of males takes over they kill the existing pups, so there seems to be pretty good evidence for parents to prefer their direct offspring to the offspring of others. Now it’s difficult to say that this is natural selection as there’s no particular reason to think that the existing brood has “less fit” genes than the new brood would provide. It would also be interesting to see whether or not there is greater morphological variation in appearance in humans than in other great apes. This would seemingly bolster the argument that much of human culture evolved around allowing fathers to identify their specific offspring and prefer them over other male’s offspring. Men would tend to prefer women with greater morphological variation and hairlessness because these women’s children would tend to exhibit features that would allow the male to more readily identify parentage. I have done a fair amount of googling and have not been able to find anyone else making this hypothesis but I would be happy if someone could provide any insight into prior references to this sort of theory, namely that hairlessness was sexually selected so that fathers could identify their specific biological offspring.

The one hypothesis posited by Judith Rich Harris seems to assert post-modernist sounding psychological factors; her “us hairless/them hairy” sounds like something straight out of post-colonialist theory or the Frankfurt School. If we are going to seriously consider the role of genetics and evolutionary history in current human affairs we need to prefer strict genetic causes over psychological-ideal “causes”, which are really manifestations of the ghost-in-the-machine mentality.

My interest in genetics comes from my interest in ethical philosophy and economics, so I’ll admit up-front that I have no expertise here and I’ll ask for your indulgence. As I understand it sexual selection for dimorphism takes a long time. However, traits that are sexually monomorphic can manifest relatively quickly in a population. Significant selective pressure for less hairy females would result in offspring of both sexes exhibiting lower levels of fur over probably a relatively short period of time. I just wanted to add that last part because I want to state up-front that I have no specific expertise in this area.

If there is one thing that I believe that I cannot yet demonstrate it’s that much of varieties of human life and culture evolved to allow human beings to identify their kin and prefer those kin to non-kin.

A final note: most people agree that sexual selection takes place on the male which is why males in almost every attribute exhibit. This is true. But imagine a situation where a particular region has developed high rates of pair-bonding and males and females raise their offspring as a pair. Males might not be willing to care for a child that they could not specifically recognize as their own, therefore, the female would continue eliminating children until she produced an individual child for which a specific male would/could identify as his own and take responsibility. So, what I am doing is taking a cue from Harris and combining parental selection as a cognitively complex variation on sexual selection; this is kin selection plus sexual selection.

P.S. this is my first post so be gentle

From Different Matrilineal Contributions to Genetic Structure of Ethnic Groups in the Silk Road Region in China:

Although our samples were from the same geographic location, a decreasing tendency of the western Eurasian-specific haplogroup frequency was observed, with the highest frequency present in Uygur (42.6%) and Uzbek (41.4%) samples, followed by Kazak (30.2%), Mongolian (14.3%), and Hui (6.7%).

The paper supports the idea that Uyghurs are an admixed population from Western and Eastern sources. But is this just an ancient cline of allele frequencies? In other words, are Uyghur lineage frequencies simply a function of their geographical position between East and West?

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Jacques Barzun Turns 100.

I’m sure many of you will be busy getting to your “destinations” in the next day or two before Christmas. Hope all goes well. Also, my mother informed me it was Eid ul-Adha a few days ago, so best wishes to the Muslim readers (when I was a kid I didn’t know they were two Eid festivals, just assumed that the lunar calender was wack with frequency). Since I’m partial to Greeks, that’s all I’ll say for winter holidays this year. Below the fold, some Christmas music….

Are you getting enough vitamin D?:

The research, which is awaiting publication in a medical journal, found that 100 per cent of those of African origin were short of vitamin D, as were 93 per cent of South Asians (those of Indian or Pakistani origin), and 85 per cent of East Asians (those of Chinese, Indochinese or Filipino origin, among other countries).
…
Insufficient vitamin D amounts were also found among those of European ancestry, but were less widespread, at 34 per cent of those surveyed.

This is in Canada, very far north. That being said, if 93 percent of South Asians in Canada have Vitamin D deficiency I doubt it is that much lower in the United States, we aren’t that far south. Additionally, a greater proportion of Canadian South Asians are light skinned Punjabis, while more American South Asians are darker skinned Gujaratis. My doctor had me tested because she knew I didn’t drink milk, and her own olive skin had resulted in her having a deficiency. As for as other groups, blacks and East Asians are generally not lactose tolerant, so it is more likely that these groups won’t be drinking fortified milk. That’s a problem.
Why should you care? There are probably some long term consequences in terms of chronic diseases of old age, but the biggest issue is probably it makes you more susceptible to flu and other low grade ailments. It’s a quality of life issue.

The New York Times has a story, Where Boys Were Kings, a Shift Toward Baby Girls:

…South Korea is the first of several Asian countries with large sex imbalances at birth to reverse the trend, moving toward greater parity between the sexes. Last year, the ratio was 107.4 boys born for every 100 girls, still above what is considered normal, but down from a peak of 116.5 boys born for every 100 girls in 1990.

Please note that the “normal” sex ratio is usually skewed somewhat toward males, around 105 to 100 (the explanation I received about this is that sperm carrying the Y are faster because they are smaller, I appreciate anyone to falsifying this if they know the “true story”). But I also found it peculiar that the article did not note that another East Asian society has switched from son to daughter preference in the past few decades, Japan. The moral of this story is, I think, that economic and social development are more critical in shaping these trends than laws enacted from on high. Japan developed earlier than South Korea, and the change in societal attitudes on this issue occurred earlier.

As background to a couple previous posts where I made somewhat technical comments about simulations in population genetics, I was in the middle of writing a rather lengthy primer on coalescent theory. Then I saw that RPM has an old post pointing to some of the same material I was planning on hitting. So instead I’ll just say read his post and the links therein. I may get around to finishing what I was writing (there’s a bit of math that most people don’t care to see, so maybe not), but you can essentially boil it down to RPM’s last point:

Without a null model based on the coalescent, there is no way to statistically test hypotheses that are based on DNA data, regarding things like population structure.

Or natural selection.

Nature has a commentary on the use of “cognitive-enhancing drugs” in healthy and “diseased” individuals. They opine:

The debate over cognitive-enhancing drugs must also consider the expected magnitude of the benefits and weigh them against the risks and side effects of each drug. Most readers would not consider that having a double shot of espresso or a soft drink containing caffeine would confer an unfair advantage at work. The use of caffeine to enhance concentration is commonplace, despite having side effects in at least some individuals. Often overlooked in media reports on cognitive enhancers is the fact that many of the effects in healthy individuals are transient and small-to-moderate in size. Just as one would hardly propose that a strong cup of coffee could be the secret of academic achievement or faster career advancement, the use of such drugs does not necessarily entail cheating.

Cognitive enhancers with small or no side effects but with moderate enhancing effects that alleviate forgetfulness or enable one to focus better on the task at hand during a tiring day at work would be unlikely to meet much objection. And does it matter if it is delivered as a pill or a drink?

There seems to be some ingrained human reaction against what is considered “cheating” (which is one those things whose obvious definition to one person might be considered ridiculous by someone else); this would be the major barrier these drugs will have to overcome in order to being commonplace.

Shelly Batts at Retrospectacle asks the question I was thinking when I read this article:

A commentary today in Nature, by Sahakian and Morein-Zamir, poses the question: if you could take a pill which enhanced attention and cognition with few or no side effects, would you?

But I ask, why wouldn’t you?

Frankly, I do enjoy having my “attention enhancers” in the widely-used and socially acceptable beverage form, but I can imagine a world where it’s socially acceptable to pop an IQ pill, and it doesn’t seem that bad to me at all.

No, this should not be in the “Physical Science” category. By hypersphere I’m thinking of the model that R.A. Fisher popularized as opposed to Sewall Wright’s conception of the adaptive landscape, a multidimensional sphere within which was located a position which was the adaptive optimum. While Wright’s landscapes were rugged, and so opened up the possibility that gene-gene interactions and some level of stochasticity and meta-population dynamics were critical factors in evolution over the long term, Fisher’s more symmetrical model focuses on the power of selection operating on loci of independent effect in driving inevitable frequency changes. The image to the left is simply a 2-dimensional rendering of Fisher’s idea, as a population converges upon the adaptive peak the mutations should be of smaller and smaller effect so that they do not result in an “overshoot” and a decrease in fitness. The implication clear: initial mutations may be of large effect, but over time as selection for a trait affects change across the genome subsequent mutations should be of smaller fitness effect. Additionally, if the ecological pressures remain the same it seems plausible that the selection coefficient of the initial mutant which drives the population toward the optimal phenotype will be greater than the selection coefficients of subsequent mutations, which after all arise in a situation where other mutants already exist.
That’s the theory. Why do I bring this up? It’s about the evolution of skin color. I’ve posted quite a bit on this topic, and have read many of the recent papers coming out of genomics labs. In short over the past 5 years a lot has come into clearer focus and we seem to know the half a dozen or so genes of large effect which control most of the world wide variation in pigmentation. These genes and their allelic variants come in many flavors and combinations which result in the range of phenotypes we see around us, a continuous variable controlled by discrete genetic components. There are many of these genes. SLC24A5, SLC45A2/MAPT/AIM1 (yes, it has three names that I can tell), KITLG, OCA2, MC1R and ATRN, these are just some of the candidates which have been fingered so far. Note that some genes seem to be responsible for between population variation in some comparisons but not in others (e.g., SLC24A5 can account for about 1/3 of the difference between Europeans and Africans, it can account for none of the difference between East Asians and Africans). Additionally note that some of these genes are definitely responsible for other traits. OCA2 and KITLG seem to have associations with variation on eye color and hair color, while some MC1R alleles cause red hair.

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Specifically, as evolgen points out the acceleration paper was focused on adaptive evolution, the subset of allele frequency changes driven predominantly by the force of natural selection. What’s the rest? Read the post.
Why does this matter? Evolution is a science, and in science this sort of pedantic precision in definition, terminology and meaning matters a great deal because it is embedded in a contingent system. One of the most frustrating things about the necessity of the rearguard action against Creationists is that the “controversy” swamps this reality, that evolution is a science which is the process of refinement and change due to theoretical & empirical developments. Instead evolution is only discussed in the broadest generalities, which is an insight with might spark the imagination in the 19th century, but is now simply a background assumption which serves as the framework for the real action. Books such as this one are a necessary evil. Why evil? Because the time invested in the production of that prose could have been time devoted to research and (alas) grant writing.