I’ve been looking at uniparental lineages recently. That is, direct maternal and paternal lineages. The mtDNA and Y chromosomal phylogenies. Between the late 1990s and 2000s phylogenetic reconstructions of these lineages dominated historical population genetic inference.
Today with ancient DNA and genomewide SNP analysis, and now even whole-genome analysis, there isn’t nearly as much focus on Y and mtDNA. But curiously in some ways, the scaffold of autosomal ancestry through ancient DNA allows for better leveraging of the insights of Y and mtDNA patterns.
We now know that the Austro-Asiatic Munda people of northeast India are about 30% East Asian in their ancestry. But their dominant haplogroup, which connects them to East Asia, is present at 60% frequency. In contrast, their mtDNA is totally indistinguishable from their Indian neighbors.
One sees a similar dynamic among the Finnic people. These populations have high frequencies of a Siberian Y chromosomal haplogroup (~60%), which seems to have arrived within the last 3,000 years. But the mitochondrial lineages are very similar to their neighbors (though there are a few stray East Eurasian mtDNA lineages). In fact, Finns and Sami are enriched for U5, which seems to be the dominant lineage of Mesolithic hunter-gatherers. Additionally, “non-European” (East Asian-like) ancestry in Finns is around in the 5-10% range and ~20% for the Sami. This seems quite lower than the frequency of N1c, the haplogroup in question, but a reasonable hypothesis is that the men who brought N1c were already quite mixed between eastern and western ancestry.
In any case, I want to close out this post with a quote which won’t surprise closer readers, Punctuated bursts in human male demography inferred from 1,244 worldwide Y-chromosome sequences:
Potential correspondences between genetics and archaeology in South and East Asia have received less investigation. In South Asia, we detect eight lineage expansions dating to ~4.0–7.3 kya and involving haplogroups H1-M52, L-M11, and R1a-Z93 (Supplementary Figs. 14b, 14d, and 14e). The most striking are expansions within R1a-Z93, ~4.0–4.5 kya. This time predates by a few centuries the collapse of the Indus Valley Civilization, associated by some with the historical migration of Indo-European speakers from the western steppes into the Indian sub-continent27. There is a notable parallel with events in Europe, and future aDNA evidence may prove to be as informative as it has been in Europe. Finally, East Asia stands out from the rest of the Old World for its paucity of sudden expansions, perhaps reflecting a larger starting population or the coexistence of multiple prehistoric cultures wherein one lineage could rarely dominate. We observed just one notable expansion within each of the O2b-M176 and O3-M122 clades.
In First Farmers: The Origins of Agricultural Societies Peter Bellwood argues that agricultural expansions explain most of the genetic variation in the world. In Europe and South Asia, this needs to be updated and modified. Late Neolithic and Bronze Age migrations clearly had a major impact. But what about East Asia?
Japan, for one, transformed in the recent past with the assimilation of post-Jomon people into the Yayoi 2,000 years ago. And the expansion of the Han entailed recent assimilations. But, perhaps there is no “star-shape” phylogeny because these expansions were fundamentally bottom-up demographic expansions as posited by Bellwood.