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Sunday, September 21, 2014

Corded Ware people: more versatile and healthier than Neolithic farmers


Over at West Hunter Greg Cochran argues that late Neolithic farmers in Northern Europe experienced nothing short of genocide at the hands of Corded Ware Culture (CWC) pastoralists, who pushed deep into the continent from somewhere east of present-day Germany around 4,800 years ago.

I think he's exaggerating. My view is that farming populations throughout much of Neolithic Europe began to crash well ahead of any invasions, perhaps as a result of climate change, overpopulation, environmental degradation and bad health. This, I'd say, created a vacuum that attracted groups from the peripheries of the Neolithic world, like the CWC nomads.

If so, it's likely that many of the surviving farmers were killed or marginalized in the process, although their women might have been incorporated on a large scale into the new post-Neolithic societies. This is perhaps why the most common Neolithic Y-chromosome haplogroup, G2a, is now so scarce in Europe, while a wide variety of mitochondrial (mtDNA) lineages frequently found among Neolithic skeletons are still carried by many Europeans today.

Nevertheless, I'm not aware of any evidence of a wholesale slaughter, or even any wars, going on in Europe during the early CWC period.

This new paper at Anthropologie seems to back up my case. The Corded Ware people were simply more versatile and healthier than the Neolithic farmers. No wonder then, that they eventually came out on top.

This study focuses on the changes in the human skeleton that are associated with the transition to agricultural subsistence. Two populations from the territory of contemporary Poland that differ in terms of their subsistence strategies are compared. An agricultural subsistence strategy is represented by a Lengyel Culture population from Oslonki (5690-4950 BP), whilst the Corded Ware populations from Zerniki Gorne and Zlota (c. 4160-3900 BP) represent mixed, agricultural-breeding-pastoral economies supplemented with hunting and gathering. The Corded Ware sample consisted of 62 individuals in total, and the Lengyel sample comprised 68 individuals. Health status was examined through skeletal stress indicators, cribra orbitalia, enamel hypoplasia and Harris lines. The analysis of enamel hypoplasia showed the effect of different adaptive strategies on buffering adverse nutritional factors and diseases. The prevalence and severity of the condition proved significantly higher in the Lengyel sample than in the Corded Ware population (64.7% vs. 43.5%, respectively). It is suggested that agricultural subsistence, associated with a less diversified diet, sedentism, exposure to pathogens, spread of infections and increased population density, caused more frequent and severe stress episodes than the mixed economy of the Corded Ware people. The inverse relationship between enamel hypoplasia and the mean age at death found in the agricultural population clearly shows an effect of adverse living conditions on the biological development of the individuals studied.

Citation...

Krenz-Niedbala M, A biocultural perspective on the transition to agriculture in Central Europe, Anthropologie, 2014/Volume 52/Issue 2/pp. 115-132, ISSN 0323-1119

See also...

Best of 2008: Corded Ware DNA from Germany

Corded Ware Culture linked to the spread of ANE across Europe

Thursday, September 4, 2014

Ancient North Eurasian (ANE) admixture across Europe & Asia


Another update: ANE is the primary cause of west to east genetic differentiation within West Eurasia

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This is an update of a supervised ADMIXTURE analysis that I ran earlier this year looking at ANE levels throughout Asia, the results of which I posted at my other blog (see here). Anyone wanna make a map?

ANE admixture across Europe & Asia spreadsheet

My claim is that these estimates are more accurate than those we've seen recently in scientific literature. Obviously I'm referring here to Lazaridis et al. 2013/14 (see here). That's not to say that the authors of this paper don't know what they're doing. Clearly they do, but at the fine-scale there's usually room for improvement no matter who you are.

For instance, in their paper in table S14.9 they list the Basques (in fact, French Basques) as 11.4% ANE, which sounds reasonable, although perhaps a little too high considering they admit that this population can be modeled as 0% ANE. On the other hand, they estimate the "North Spanish" to be 16.3% ANE.

Now, this reference set is actually from the 1000 Genomes project, where it's listed as Spaniards from Pais Vasco (ie. Basque Country). Essentially, what this means is that these are Basques from Spain. So why would Basques from France carry only 11.4% ANE, and Basques from Spain a whopping 16.3%? Not only that, but according to Lazaridis et al., these "North Spanish" also can be modeled as 0% ANE.

Obviously, something's not quite right there. Indeed, in my spreadsheet, the very same French Basques are listed as 7.4% ANE, while the Pais Vasco Spaniards as just over 8%. Call me crazy, and many do, but I think these results actually make good sense.

By the way, I made ten synthetic samples from the ANE allele frequencies from this test, and remarkably, in all of the analyses I've ran so far they behaved very much like MA-1 or Mal'ta boy, the main ANE proxy. Below, for example, is a Principal Component Analysis (PCA) of West Eurasia featuring these individuals. The result is very similar to that I obtained with Mal'ta boy (see here).




The synthetic ANE samples are available here. Feel free to play around with them, and if you do, please let me know what you discover.

As some regular visitors already know, I'm currently designing a new test for GEDmatch that will include various ancient components like ANE. Unfortunately, it might be a while before it's ready, simply because I want it to be as accurate as possible.

See also...

Eurogenes ANE K7

Corded Ware Culture linked to the spread of ANE across Europe