When little differences matter a great deal

In the comment below Clark alludes to the fact that Jonathan Haidt kept reiterating that even if there were differences between populations due to recent evolution, if it was due to selection on standing variation upon quantitative traits then the between group variation would be dwarfed by within group variation. He didn’t quite say it like that, but I’m sure that’s what he meant. For example, there is now evidence that alleles which can explain the small height difference between Northern and Southern Europeans have been subject to natural selection. Most of the variation obviously remains within the groups; you can’t guess that someone is Italian or Dutch just based on their height. There are many tall Italians, and many short Dutch. But on average there are differences between the groups which can be attributed to genes, and those genes seem to have been targets of selection.

This is good as fair as it goes…but small average differences may not necessarily be marginal. That is because sometimes you select from the tails of a distribution. For example, if you want to ascertain which population will produce more N.B.A. players, it is less important that there is a small average differences, so the populations mostly overlap, than that that average difference can result in a large disproportion at the tails of the distributions.

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Jonah Lehrer, science fiction writer

He’s back, and he’s out with a new book, Imagine: How Creativity Works. I am talking of course about Jonah Lehrer, the enfant terrible of cognitive neuroscience. OK, perhaps more Wunderkind. In any case, I was struck by this post on his weblog, The Cost Of Creativity:

There is a serious complication to this triumphant narrative of cliff edges and innovation, however. Because our lifestyle has become so expensive to maintain, every new resource now becomes exhausted at a faster rate. This means that the cycle of innovations has to constantly accelerate, with each breakthrough providing a shorter reprieve. The end result is that our creativity isn’t just increasing the pace of life; it is also increasing the pace at which life changes. “It’s like being on a treadmill that keeps on getting faster,” West says. “We used to get a big revolution every few thousand years. And then it took us a century to go from the steam engine to the internal-­combustion engine. Now we’re down to about 15 years between big innovations. What this means is that, for the first time ever, people are living through multiple revolutions.”

Needless to say, such revolutions aren’t fun. They’re unsettling and disruptive. But they appear to be the inevitable downside of our ceaseless ingenuity, for creativity comes with a multiplier effect: new ideas beget more new ideas. The treadmill is going fast. And it’s getting faster.

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Jonathan Haidt & Robert Wright: crazy delicious

Last night I listened to a very long discussion between Robert Wright, author of The Moral Animal, and Jonathan Haidt, author of The Righteous Mind: Why Good People Are Divided by Politics and Religion. If you have been reading my weblog for years there may not be much new, but if you haven’t, then you’ll encounter a lot of novel information, in particular from Jonathan Haidt. I was intrigued by Haidt’s references to evolutionary and anthropology, and I immediately noticed on Twitter that of the 17 people he follows, two are John Hawks and Paul Bloom. John is a friend, and Paul Bloom has been highly influential in my own thinking about cognitive psychology (see Descarte’s Baby). Additionally, many of the other “shout outs” which Haidt makes are familiar to me as well (e.g., Scott Atran, the neo-functionalism of David Sloan Wilson, etc.).

In lieu of a conventional blog post here a list of comments, reacting mostly to Haidt’s various assertions.

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Post-Neolithic revenge of the foragers

If I have something to share, why not share it? Over the past few weeks I’ve been ruminating on some of the possible intersections between historical population genetics and anthropology, especially in light of the discussion that I’ve had in the past with Robin Hanson about ‘farmers vs. foragers’. Entering into the record that such a dichotomy is too stark, and only marginally useful (i.e., I think it is important to separate farmers and foragers in to their own sub-classes, as some farmer types may share more with some forager types, and so forth), it may be that after the first wave of the Neolithic expansion the descendants of the foragers “bounced back” in many regions of the world. It does seem that ancient European hunter-gatherers have left modern descendants. They were not totally swamped out. Using autosomal patterns some genome bloggers have inferred the same pattern, and perhaps even a counter-reaction by “Mesolithic” populations which adopted some aspects of the “Neolithic” cultural toolkit.

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Cultural Folkways in Flux

A fascinating post over at The Crux, Votes and Vowels: A Changing Accent Shows How Language Parallels Politics. Here’s the section which I might quibble with though:

Labov points out that the residents of the Inland North have long-standing differences with their neighbors to the south, who speak what’s known as the Midland dialect. The two groups originated from distinct groups of settlers; the Inland Northerners migrated west from New England, while the Midlanders originated in Pennsylvania via the Appalachian region. Historically, the two settlement streams typically found themselves with sharply diverging political views and voting habits, with the northerners aligning much more closely with agenerally being more liberal ideology.

But first, here is a map of the dialects in question:


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Revenge of the herders

Let me make something explicit: I believe that the model outlined in First Farmers is too simple, and that extant patters of linguistic and genetic variation need to accept the likelihood of multiple population reorganizations across vast swaths of Eurasia within the last 10,000 years. The classic case in point are the Turks. Because of their exotic character vis-a-vis the populations which they displaced and assimilated we can peg rather easily their expansion. Between 0 and 1000 AD they began to make themselves felt across a broad expanse of Eurasia from the eastern fringes of Europe to the western fringes of China, and south toward the world of Islam. Between 1000 and 1800 the Turkic peoples took over much of Eurasia for various periods of time (e.g., the Ottomans, Safavids, and Mughals, were Turkic, while the Golden Horde which imposed the Tatar Yoke were mostly Turkic, not Mongol). It is notable to me that Turkic peoples contributed ~10 percent to the genetic ancestry of modern Anatolians. This is a significant achievement, because Anatolia has been a densely populated seat of agricultural civilization for almost the whole history of agriculture! In Central Asia Turks genetically admixed significantly, to the point of preponderance, with the Iranian substrate.

Why does this matter? Because if it hadn’t happened, and it hadn’t happened in the light of history, I doubt we’d believe it! The Turks were obscure tribes in Central Eurasia 2,000 years ago. There was no anticipating that somehow they would overturn what had been the Iranian world of western Inner Asia, and, that they would break through into the civilized societies of the periphery, to the point of taking them over from above, and assimilating them from below. I do not think the Turks are exceptional in this. It must have happened many times in the past. We just need to open our minds to the possibilities.

The real secret history of the Mongols?

Thank god for steppe hyper-patriarchy; it’s a model which we can test. Dienekes points me to a paper, The Y-chromosome C3* star-cluster attributed to Genghis Khan’s descendants is present at high frequency in the Kerey clan from Kazakhstan, which is notable for increasing sample coverage of the distribution of “Genghis Khan haplotype.” As you might recall in 2003 a paper reported that a particular Y-chromosomal phylogeny was extremely common in Central Eurasia, and, that it had expanded rather rapidly starting approximately ~1,000 years ago. The natural supposition was that this was connected to the rise of Genghis Khan, from whom male-line descent in particular has become a matter of pride and prestige across the former domains under his rule. Subsequent researchers have supported this finding insofar as the distribution of the haplotype does tend to drop off among the “Western Mongols,” who were for various reasons marginal during the time of Genghis Khan, and whose ruling class were subsequently diminished in part due to their lack of a Genghiside pedigree.


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Nature Precedings closes up shop

Here’s the announcement:

As of April 3rd 2012, we will cease to accept submissions to Nature Precedings. Nature Precedings will then be archived, and the archive will be maintained by NPG, while all hosted content will remain freely accessible to all.

Looking forward, NPG remains committed to exploring ways to help researchers, funders, and institutions manage data and best practices in data management, and we plan to introduce new services in this area.

We have truly valued your contributions as authors and users to Nature Precedings and hope that you will actively participate in this research and development with us.”

This comes on the heels of Dr. Joseph Pickrell’s first author submission of a preprint. Correlation? Yes. Coincidence? I’ll let you decide.

In other news the existence and flourishing of arXiv puts a whole different spin on “physics envy.” And, just to reiterate, if I post about a paper, and you don’t have access email me and I will send you the paper.

How culture crashes clines

The USA has been in Afghanistan for over 10 years now. Like many Americans my own personal preference is that we get out as soon as possible. Because of American involvement we see terms like “Pashtun” bandied about in the media, but there is little further exploration. But politics and international relations are the not focus of this post, at least not politics and international relations in our time. A new paper in PLoS ONE examines the Y-chromosomal patterns as they partition across ethnic groups in Afghanistan. By this, we mean the direct paternal lineage of Afghan men. Additionally, the authors place the results in a broader Eurasian context. The results are not surprising, though they add greater precision and power to our picture because of their sample size. The main downside is that they did not include mtDNA (maternal lineage) or autosomal analysis (the total ancestry, not just the paternal or maternal line).


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