Sunday, June 14, 2015

Pre-History In A Nutshell

Razib has a lengthy synopsis of the recent history of archeogenetics (most of which has happened in my adult lifetime) at Gene Expression to put into context two major new ancient DNA studies in the Journal Nature published this month.

The big headline from these studies is that they provide new ancient DNA confirmation for the increasingly well supported hypothesis that there was an episode of dramatic population genetic change between the first farmer populations of the Neolithic era and modern Europeans, driven by mass migration from the Eurasian steppe, around the time of the early Bronze Age in Europe and almost surely coinciding with a major expansion of the Indo-European languages.

One important emphasis of Razib's account is that the phenotype of the modern European's appearance which we think of when we say that someone is racially "white", like the modern European gene pool more generally, did not really stabilize in Europe until the Bronze Age. Northern Europeans prior to Indo-European migration into Europe, for example, may have been blue eyed but dark skinned, while the invaders from the steppe may have had lighter skin and dark eyes.  The light skinned phenotype we associate with Europeans today didn't reach fixation until the Bronze Age. People who look like typical Northern Europeans today didn't exist when the Egyptians were building their pyramids.

Critics of some of the recent analysis of these studies suggest that important details of the narrative may be inaccurate, because Y-DNA haplogroup subtypes and evidence of ancient Northern European ancestry in some putative parent populations to European populations that were transformed demographically at this time don't track properly to the simplest of narratives advanced to explain the new ancient DNA result.

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