Friday, February 14, 2014
Mapping the history of human admixture (paper + website)
Update 19/09/2015: Recent admixture in West Eurasia (including Europe)
Hellenthal et al. is a valiant attempt to map out the history of human admixture using modern DNA. Hopefully it's the last.
I don't want to sound too harsh, because it's a fascinating read, and the companion website a lot of fun, but studies like this really need ancient genomes nowadays to look convincing. Let's hope these guys can find the resources to repeat this effort using a wide range of carefully chosen ancient remains.
Indeed, here are a couple of examples of the sort of stuff that makes me skeptical about the accuracy of the methods employed by the authors. First of all, unless I'm reading this map wrong, then what I'm seeing here is a 23% contribution from the Hadza of East Africa to the Lithuanians. Apparently, this supposed admixture event happened during the early middle ages. Is this a typo or what?
Secondly, what's with the difference between the Orcadians and Norwegians? How can the Orcadians be unmixed if a large part of their recent ancestry derives from Norse settlers (which it certainly does)? So, did all of this admixture in Norway take place after the pure Norwegians settled the Orkneys? It's possible, but hardly plausible.
Hellenthal et al., A Genetic Atlas of Human Admixture History, Science 343, 747 (2014), DOI: 10.1126/science.1243518