Friday, June 12, 2015

Paul Heggarty critiques the recent Allentoft et al. and Haak et al. papers: "Ancient DNA and the Indo-European Question"

Ancient DNA and the Indo-European Question
by Paul Heggarty, Max Planck Institute for Evolutionary Anthropology, Leipzig.

1. Towards the End-Game at Last?
An ‘ancient DNA revolution’ is now sweeping through genetics. Suddenly, ancient population migrations can be recovered far more clearly than before.  For linguists, this holds out the prospect of ‘closure’, at last, on the Indo-European question.  And that is quite some prospect, for agreement on the origins of Indo-European has eluded us ever since linguistic science began, when Sir William Jones first posed this very question in 1786.
Today’s issue of Nature (11th June 2015) publishes two major papers based on Bronze Age ancient DNA from the Eurasian Steppe — one of the two leading candidates for the original homeland of the Indo-European family.
  • Haak, W. et al. [David Reich’s group, Harvard] 2015. (online since 2015-03-01)
    Massive migration from the steppe was a source for Indo-European languages in Europe.
    Nature 522 (7555): p.207–211.
Both papers interpret their results as leaning towards the Steppe hypothesis, albeit rather tentatively and superficially in places. On closer inspection, indeed, all is by no means so clear cut. The new data actually turn out to be equally compatible, if not more so, with the Steppe as the immediate origin of just a few branches of Indo-European (notably Balto-Slavic and perhaps Tocharian). These Bronze Age movements would thus be only secondary to an original Neolithic expansion of the Indo-European family as a whole, with farming, out of the northern arc of the Fertile Crescent (i.e. the ‘Anatolian’ hypothesis). The ancient DNA data also reconfirm the spread of farming as the dominant shaper of the genetic make-up of Indo-European-speaking southern, Mediterranean Europe, with relatively little Steppe impact.
Now there is of course one big caveat to all of this:  languages do not always ‘go with genes’ in any case.  So at the end of this blog, Addendum 1 takes up just that issue.  Still, the claim in both Haak et al. (2015) and Allentoft et al. (2015) to support the Steppe hypothesis is indeed founded specifically on their new genetic data, so it is on that basis that this blog will assess them.

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