Tuesday, November 18, 2014
Review paper: Human paleogenetics of Europe - The known knowns and the known unknowns
Many of us are waiting impatiently for the new manuscript from the Reich Lab on the genetic shifts in Central and Eastern Europe during the late Neolithic/early Bronze Age, which will apparently include genome-wide data from Bell Beaker, Corded Ware and Yamnaya remains (see here). Rumor has it that it'll appear at bioRxiv within a few weeks.
Meantime, it might be useful to check out this review paper by Guido Brandt et al. on the present state of play in European paleogenetics.
Human paleogenetics of Europe - The known knowns and the known unknowns
It's a thorough summary of almost all ancient DNA results to date from Europe, and includes some very nice maps and other figures that look like updates on the stuff from Brandt et al. 2013 (see here). However, there are a couple of major problems with this paper that drag it down a few notches in my estimation.
Firstly, the authors leave open the possibility that Indo-European languages were introduced into Europe by early Neolithic farmers from Anatolia. Maybe they're trying to be diplomatic and humor those that won't let this failed hypothesis finally die, because otherwise I have no idea why they even considered it?
There are some very good reasons now why this is indeed a failed hypothesis. For one, linguistic evidence shows that all Indo-European languages in Europe include similar loans of non-Indo-European origin associated with farming, like the words for bean, carrot, hemp, oats and pea (for instance, see here).
These words were in all likelihood borrowed by the early Indo-Europeans from someone else as they spread out across Europe well after agriculture had been established throughout much of the continent. So who was this someone else? Probably the non-Indo-European descendants of the non-Indo-European early farmers from Anatolia.
Ancient DNA shows something similar. All ancient European genomes in a farming context sequenced to date from the Neolithic to the Copper Age are clearly distinct from present-day Indo-European speaking Europeans. But they resemble very closely present-day Sardinians, whose ancestors only became Indo-European speakers during the late Iron Age.
The other serious problem with this paper is the suggestion that present-day Northeast Europeans show the highest genome-wide affinity to Pitted Ware hunter-gatherers because the eastern Baltic acted as a refugium during the Last Glacial Maximum (LGM). It's on page 10 of the PDF.
This must be some sort of oversight, because I refuse to believe that the authors aren't aware of the fact that the eastern Baltic was covered in a big fuck off ice sheet during the LGM. Here's a map from Mangerud et al 2004.
A much more plausible explanation why present-day Northeast Europeans show the highest genome-wide affinity to Pitted Ware hunter-gatherers, and indeed all European hunter-gatherers for whom we have data, is that their ancestors were amongst the last people in Europe to take up farming and Christianity.
Brandt, G., et al., Human paleogenetics of Europe - The known knowns and the known unknowns, Journal of Human Evolution (2014), http://dx.doi.org/10.1016/j.jhevol.2014.06.017