Sunday, December 21, 2014
Gokhem2 + Motala12 =/= present-day Swedes
I've seen quite a few comments on this blog suggesting that most of the Ancient North Eurasian (ANE) admixture found in Northern Europe today might come from Scandinavian hunter-gatherers like Motala12 and Ajvide58. It's probably obvious to most that this is not realistic, because the Scandinavian forager genomes sequenced to date have very high ratios of Western European Hunter-Gatherer (WHG) ancestry (>80%), so basically the math doesn't add up.
Nevertheless, I thought it might be useful to drive the point home using this Principal Component Analysis (PCA) based on my new West Eurasia K8 test. The datasheet is available here. You can view a spreadsheet of the results with extra samples here.
Please note that neither Motala12 nor Gokhem2, a late Neolithic farmer from south Sweden belonging to the Funnelbeaker culture, can pass for present-day Swedes. Moreover, mixing Gokhem2 with Motala12, in any proportions, will not produce a result even vaguely similar to present-day Swedes (ie. the outcome will fall somewhere along the dotted line).
I'd say one of the most obvious ways to get the right result would be to blend the Scandinavian forager and farmer with at least one other sample from somewhere below (ie. geographically speaking, east or southeast) of the Swedish cluster.
It might be possible to come up with a more precise plot location, and thus perhaps geographic origin, for this putative third source of Swedish ancestry by running some complex tests with the PCA datasheet. If anyone wants to have a go at that, and you actually manage to come up with a coherent outcome, then feel free to post your findings in the comments below.
I've decided not to bother, because as far as I can see, the options are infinite. What we really need are more genomes from the Swedish late Neolithic/early Bronze Age (LN/EBA), preferably belonging to one of the local spin-offs of the Corded Ware culture, which is thought to have originated in Eastern Europe, to provide more datapoints and help narrow down the options.
On a related note, I'm catching up on some reading this holiday season, and currently going through this book chapter which discusses the upheavals during the LN/EBA in south Scandinavia as seen through its archeology.
Rune Iversen, Beyond the Neolithic transition - the "de-Neolithisation" of south Scandinavia
Bell Beaker, Corded Ware, EHG and Yamnaya genomes in the fateful triangle