razib | December 20, 2007In response to my post Mixed-race but homogeneous appearance? several individuals mooted the possibility that admixture may result in the vanishing of race as a social construct. Actually, I don't think this is the true. To the left is a photo from my post Can you tell if you're black or white? where I explored the genetics of a case where two black-white biracial parents produced fraternal twin daughters of disparate appearance. While one sister seemed to favor her African ancestors in look, another sister seemed to resemble her European forebears. Across the full sample space of their…
razib | December 19, 2007Ross Douthat introduces The Table: Atlantic Voices in Conversation. I dig the head bob! Very professional.
razib | December 19, 2007Ed, Greg & PZ have commented on the strange reaction of the president of the Southern Baptist Theological Seminary toward Richard Dawkins' enthusiasm for Christmas traditions. So "why would an atheist want to sing Christmas carols?"
The same reason that the study and reading of literature has not been reduced to physics. We humans appreciate great stories, and we can conceive in our mind's eye ideas which may not be true, but we enjoy the play of those ideas nonetheless. One does not have to be a Greek pagan to appreciate the beauty and power of the Iliad, and in fact for centuries…
razib | December 19, 2007EVOLUTIONARY ADAPTATIONS: THE IMPACT OF LIGHTER SKIN:
It would take someone with dark skin of African or South Asian ancestry about 60 minutes at the same time of day to make the amount of vitamin D that a person of European ancestry would make in about 10 minutes, estimates Reinhold Vieth, one of Canada's top vitamin D experts and a professor in the department of nutritional sciences at the University of Toronto.
You probably know of Vitamin D deficiency for rickets, but I think more common ailments might have a major fitness impact:
VDR ligands have also been shown to increase the activity…
razib | December 19, 2007So The Superficial is reporting that Jamie Lynn Spears is pregnant by her boyfriend Casey Aldridge. Jamie Lynn is Britney Spears' younger sister, and at 16 she will be a "teen mother," but not a stereotypical one. Jamie Lynn Spears has her own television show and seems to have her shit "together." The stereotype is that the poor and those of lower SES are more likely to get pregnant as teens. That is statistically true:
Compared to teens from higher income families, poor and low-income teens are somewhat more likely to be sexually active and somewhat less likely to use contraceptives or to…
razib | December 18, 2007Family Ties That Bind: Maternal Grandparents Are More Involved In The Lives Of Their Grandchildren:
For grandparents living within 19.5 miles (30 km) of their grandchildren, over 30% of the maternal grandmothers had contact daily or a few times a week. Around 25% of the maternal grandfathers had contact daily or a few times a week. In contrast, only around 15 % of the paternal grandmothers and little more than 15% of the paternal grandfathers would have contact daily or a few times a week.
The sample was Dutch, and the authors hypothesize that the reason that maternal, as opposed to paternal…
razib | December 17, 2007The acceleration story has finally cooled down a bit judging by my google news feed. That being said, I suggest you check out the comments threads on p-ter's two posts, here & here. John Hawks and some of the other authors of the paper have been participating in the back and forth. The paper is finally on PNAS's site (Open Access), with the supplementary information. It is also important that you read this paper in concert with Global landscape of recent inferred Darwinian selection for Homo sapiens, which has a detailed explication of the methods and more specific data.
razib | December 16, 2007Greg Laden has a pretty thorough critique of Life history trade-offs explain the evolution of human pygmies.
razib | December 15, 2007I received this email today:
Hi, I have a younger cousin who ran with a protestant fundamentalist crowd early in high school and as result started turning her nose at the notion of evolution, I thought she was a lost cause but now in her senior year she as mellowed (probably due to the mellowing of her crush on the fundie boy that drew her to this crowd in the first place) and I'd like to give her a book for Christmas that would relax whatever reflexive hang-ups she has acquired to studying evolution and biology. Since she's planning on going into engineering and has a real interest in the…
razib | December 15, 2007Here is an article suggesting that Creationists should be scared of the accelerated human adaptation paper. At first, I would be skeptical, after all, this is microevolution, which Creationists ostensibly accept.1 But the reality is that anti-evolutionary thinking is pretty shallow, most Creationists barely know what they believe aside from the fact that they aren't "descended from monkeys," let alone the details of evolution (aside from canned talking points which they parrot with absolutely no understanding, e.g., "The second law of thermodynamics...."). I bring this up because a friend…
razib | December 13, 2007I've blogged about The Grandmother Hypothesis. Roughly, the question is why do women go through a "change" which rapidly shifts them from being able to become pregnant, though at sharply reduced rates by the time that menopause occurs, to a state of infertility where they may survive for up to three decades? Some argue that this is a peculiar human adaptation and that our social structures, where grandmothers may gain more in investing in their grandchildren than continuing to produce offspring in terms of long term reproductive fitness, are the cause. In contrast to women for males the…
razib | December 13, 2007A few years ago, a new paper, SLC24A5, a putative cation exchanger, affects pigmentation in zebrafish and humans, made some waves. It used zebrafish to elucidate the genetics of a locus, SLC24A5, which is responsible for 1/3 of the between population difference between Europeans and Africans in skin color. In short, Europeans are fixed for a derived variant, and Africans and East Asians for an ancestral one. Additionally, SLC24A5 shows up in tests for very recent (last 10,000 years) selection, and is implicated in 1/3 of the skin color variation in South Asians. Today, a similar paper which…
razib | December 12, 2007Two articles in PNAS caught my attention, Rapid dental development in a Middle Paleolithic Belgian Neanderthal & Life history trade-offs explain the evolution of human pygmies. Here are the abstracts:
Recent evidence for developmental differences between modern humans and Neanderthals remains ambiguous. By measuring tooth formation in the entire dentition of a juvenile Neanderthal from Scladina, Belgium, we show that most teeth formed over a shorter time than in modern humans and that dental initiation and eruption were relatively advanced. By registering manifestations of stress…
razib | December 11, 2007In Britain there's a story circulating about a young woman of Pakistani ethnicity who converted to Christianity and was persecuted by her family. Specifically:
Last week, it was reported that the daughter of a British imam was living under police protection, after receiving death threats from her family for having left Islam.
There's more. Note that this is about converts to Christianity. This is a particular problem, secularism or private atheism are less likely to be the target of violence because it is not a defection to an alternative and vigorous rival faith. There have been other…
razib | December 11, 2007In light of the recent work on the acceleration of human evolution due to increased population size, this paper in Genetics, Inferring Human Population Sizes, Divergence Times and Rates of Gene Flow From Mitochondrial, X and Y Chromosome Resequencing Data:
We estimate parameters of a general isolation-with-migration model using resequence data from mitochondrial DNA (mtDNA), the Y chromosome, and two loci on the X chromosome in samples of 25-50 individuals from each of 10 human populations. Application of a coalescent-based Markov chain Monte Carlo technique allows simultaneous inference of…