Just a heads up, I’ve been posting now and then to the quasi-Twitteresque site Talk Islam run by my friend Aziz Poonawalla. I also have a sub-weblog where I’ll be posting some of my longer form ruminations…but it might be best to just sign up for the RSS so you’re notified when I start posting there regularly. I’ve been reading God’s Rule – Government and Islam: Six Centuries of Medieval Islamic Political Thought on & off for weeks now, and I think I’ll put up a review over there after I’m done….

If you read this weblog you are aware that I have a fascination with the intersection of human history and human evolutionary genetics. There are many questions I have about the finding from evolutionary genomic studies that light skin evolved at least twice independently in Eurasia within the last 20,000 years or so at the extremities. The selection coefficients are large, so I am confused as to why even minimal gene flow did not result in equilibration and homogenization of the allelic profiles of the populations. I have posited that the answer has to do with very low population densities verging upon nil in Central Asia. From The Horse, the Wheel, and Language: How Bronze-Age Riders from the Eurasian Steppes Shaped the Modern World (a book I can not recommend enough!):

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A few weeks ago Tyler Cowen mentioned he was reading David W. Anthony’s The Horse, the Wheel, and Language: How Bronze-Age Riders from the Eurasian Steppes Shaped the Modern World. I ordered it on Amazon, and it was hanging around the house so I decided to check it out early this evening…I read all 466 pages in one sitting. If you are a GNXP reader interested in archeology, prehistory and Central Asia you have to read this book! I’ve read In Search of the Indo-Europeans: Language, Archaeology and Myth, The Coming of the Greeks, and Archaeology and Language: The Puzzle of Indo-European Origins, but David W. Anthony really achieved something here which I wasn’t prepared for with all due respect to the scholars who authored the aforementioned works. Most readers are aware that I’ve complained about how happily pig-ignorant of other fields most archaeologists are. Frankly, when I see an academic book I’m curious about, but find out that the author is an archaeologist I get really suspicious. They’re good at collecting data, but once the stamps are arranged there seems an extreme reluctance to fire up a real analytic engine.

The author of The Horse, the Wheel, and Language is well aware of these prejudices and refers to them obliquely. He obviously doesn’t want to dismiss all of his colleagues as psuedo-scientific quacks, but he admits the general ignorance of archaeologists of fields such historical linguistics which you would think they’d check in on, and alludes to their nearly fanatical adherence to the “Pots not Peoples” paradigm (a reaction to their pre-World War II love affair with migrations). Anthony’s interdisciplinary scope is very impressive; he references ideas and conclusions from Albion’s Seed and Y: The Descent of Man. Cutting edge research on the evolution of lactose tolerance & the phylogenetics of domesticated cattle are intelligently integrated into the narrative. Nevertheless, the bulk of the text is an extremely dense exposition of archaeological discoveries from sites on the Pontic Steppe since the fall of the Soviet Union. The central argument is that Indo-Europeans emerged from this region between the Dnieper and Volga around 3500 BCE and over the next 1500 years spread in all directions. I won’t detail the how or the why, I just finished the book about 15 minutes ago and haven’t fully assimilated that much of it, but you can read chapter 1 online.

Note: I don’t want to make it seem like this is a breezy popular book, about 2/3 of the material consists of detailed reportage of various sites and analysis of data on pots, cemeteries and seed-husks. Anthony is clearly talking to his fellow scholars, but I think the prose is accessible enough for an interested lay reader as he avoids obscuring jargon. Rather, if you are scared by an endless parade of facts this might not be for you. On the other hand, if your data-gullet is endless, what are you waiting for?

Related: The Inner Asian gap: the Afanasievo breakthrough.

Picking Up Evolution’s Beat. Via Kambiz. A representative paper.

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Genetic variation in human NPY expression affects stress response and emotion:

Understanding inter-individual differences in stress response requires the explanation of genetic influences at multiple phenotypic levels, including complex behaviours and the metabolic responses of brain regions to emotional stimuli. Neuropeptide Y (NPY) is anxiolytic…and its release is induced by stress…NPY is abundantly expressed in regions of the limbic system that are implicated in arousal and in the assignment of emotional valences to stimuli and memories…Here we show that haplotype-driven NPY expression predicts brain responses to emotional and stress challenges and also inversely correlates with trait anxiety. NPY haplotypes predicted levels of NPY messenger RNA in post-mortem brain and lymphoblasts, and levels of plasma NPY. Lower haplotype-driven NPY expression predicted higher emotion-induced activation of the amygdala, as well as diminished resiliency as assessed by pain/stress-induced activations of endogenous opioid neurotransmission in various brain regions. A single nucleotide polymorphism (SNP rs16147) located in the promoter region alters NPY expression in vitro and seems to account for more than half of the variation in expression in vivo. These convergent findings are consistent with the function of NPY as an anxiolytic peptide and help to explain inter-individual variation in resiliency to stress, a risk factor for many diseases.

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A new paper, The Dawn of Human Matrilineal Diversity, is out in AJHG. I read too much John Hawks to really be all that excited about mtDNA based studies, and this paper is Mitochondrial Eve to the nth power. But…I do think it is indicative of a trend which suggests a rollback from the most extreme Out of Africa scenarios; i.e., that one band somewhere in Eastern Africa arose ~100,000 years ago and expanded demographically so that they were the exclusive ancestors of all human beings.1 The introgression story is one angle; but the likelihood of preexistent population substructure within Africa itself is another. If you don’t read the paper (which is Open Access), just check out Figure 1 and the map. Breathless description of the study over at ScienceDaily of course….

Related: Kambiz comments in more detail.

1 – Some of this was more about public perception than reality; just like the one mtDNA ancestor was conflated with one female ancestor (the same trick of course applied to the NRY).

One of the “debates” currently occupying evolutionary biology is whether evolution occurs primarily via changes in protein-coding sequence or via changes in gene regulation (apparently it’s become so heated that battles between the two camps are now fought through t-shirts).

As understanding of the genetics of adaptation advances, this debate will likely fade away–a priori, it’s easy to make the case for either, and well-studied individual examples are showing that, as one might expect, evolution isn’t particularly dogmatic about the sources of variation it works with.

It’s these case studies that are most interesting–take, for example, a recent study on the adaptation of Arabidopsis halleri to the heavy-metal-polluted soils it now occupies. This is quite a nice example of evolution via gene regulation–the authors map the ability to tolerate heavy metals to a particular candidate gene, then identify both a change in copy number as well as changes in the promoter region of the gene that lead to high levels of expression. To complete the story, they then pop this highly expressing version of the gene back into A. thaliana (the model organism) and show they’re able to recreate the crucial aspects of the adaptation in that species.

Is it necessary to assume an apartheid-like social structure in Early Anglo-Saxon England? :

It has recently been argued that there was an apartheid-like social structure operating in Early Anglo-Saxon England. This was proposed in order to explain the relatively high degree of similarity between Germanic-speaking areas of northwest Europe and England. Opinions vary as to whether there was a substantial Germanic invasion or only a relatively small number arrived in Britain during this period. Contrary to the assumption of limited intermarriage made in the apartheid simulation, there is evidence that significant mixing of the British and Germanic peoples occurred, and that the early law codes, such as that of King Ine of Wessex, could have deliberately encouraged such mixing. More importantly, the simulation did not take into account any northwest European immigration that arrived both before and after the Early Anglo-Saxon period. In view of the uncertainty of the places of origin of the various Germanic peoples, and their numbers and dates of arrival, the present study adopts an alternative approach to estimate the percentage of indigenous Britons in the current British population. It was found unnecessary to introduce any special social structure among the diverse Anglo-Saxon people in order to account for the estimates of northwest European intrusion into the British population.

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Mother’s Diet Influences Infant Sex: High Energy Intake Linked To Conception Of Sons:

…The study shows a clear link between higher energy intake around the time of conception and the birth of sons. The findings may help explain the falling birth-rate of boys in industrialised countries, including the UK and US.
The study focused on 740 first-time pregnant mothers in the UK, who did not know the sex of their fetus. They were asked to provide records of their eating habits before and during the early stages of pregnancy. They were then split into three groups according to the number of calories consumed per day around the time they conceived. 56% of the women in the group with the highest energy intake at conception had sons, compared with 45% in the lowest group. As well as consuming more calories, women who had sons were more likely to have eaten a higher quantity and wider range of nutrients, including potassium, calcium and vitamins C, E and B12. There was also a strong correlation between women eating breakfast cereals and producing sons.

What’s going on? Probably the Trivers-Willard Hypothesis:

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