View Full Version : Ancient Admixture in Human History (Patterson et al 2012)

Jean M
09-07-2012, 10:13 PM
Nick Patterson, Priya Moorjani, Yontao Luo, Swapan Mallick, Nadin Rohland, Yiping Zhan, Teri Genschoreck, Teresa Webster, and David Reich, Ancient admixture in human history (http://dx.doi.org/10.1534/genetics.112.145037), Genetics, Published ahead of print, September 7, 2012

Population mixture is an important process in biology. We present a suite of methods for learning about population mixtures, implemented in a software package called ADMIXTOOLS, that support formal tests for whether mixture occurred, and make it possible to infer proportions and dates of mixture. We also describe the development of a new single nucleotide polymorphism (SNP) array consisting of 629,433 sites with clearly documented ascertainment that was specifically designed for population genetic analyses, and that we genotyped in 934 individuals from 53 diverse populations. To illustrate the methods, we give a number of examples where they provide new insights about the history of human admixture. The most striking finding is a clear signal of admixture into northern Europe, with one ancestral population related to present day Basques and Sardinians, and the other related to present day populations of northeast Asia and the Americas. This likely reflects a history of admixture between Neolithic migrants and the indigenous Mesolithic population of Europe, consistent with recent analyses of ancient bones from Sweden and the sequencing of the genome of the Tyrolean ‘Iceman’.

Commentary by Dienekes (http://dienekes.blogspot.co.uk/2012/09/estimating-admixture-proportions-and.html) and Razib Khan (http://blogs.discovermagazine.com/gnxp/2012/09/across-the-sea-of-grass-how-northern-europeans-got-to-be-10-northeast-asian/).

Jean M
09-07-2012, 10:45 PM
They sum up:

Summary of inferences about European history from our methods

Our methods for analyzing genetic data have led to several novel inferences about history, showing the power of the approaches. In particular, we have presented evidence suggesting that the genetic history of Europe from around 5000 B.C. includes:

The arrival of Neolithic farmers probably from the Middle East.
Nearly complete replacement of the indigenous Mesolithic southern European populations by Neolithic migrants, and admixture between the Neolithic farmers and the indigenous Europeans in the north.
Substantial population movement into Spain occurring around the same time as the archaeologically attested Bell-Beaker phenomenon (HARRISON, 1980).
Subsequent mating between peoples of neighboring regions, resulting in isolation-by-distance (LAO et al., 2008; NOVEMBRE et al., 2008). This tended to smooth out population structure that existed 4,000 years ago.

Further, the populations of Sardinia and the Basque country today have been substantially less influenced by these events.