View Full Version : Deep relationships of modern human genetic lineages outside of Africa

12-01-17, 00:28
A new Reich, Lipson paper on the deep relationships of the OOA populations

working model of the deep relationships of diverse modern human genetic lineages outside of Africa

"A major topic of interest in human prehistory is how the large-scale genetic structure of modern populations outside of Africa was established. Demographic models have been developed that capture the relationships among small numbers of populations or within particular geographical regions, but constructing a phylogenetic tree with gene flow events for a wide diversity of non-Africans remains a difficult problem. Here, we report a model that provides a good statistical fit to allele-frequency correlation patterns among East Asians, Australasians, Native Americans, and ancient western and northern Eurasians, together with archaic human groups. The model features a primary eastern/western bifurcation dating to at least 45,000 years ago, with Australasians nested inside the eastern clade, and a parsimonious set of admixture events. While our results still represent a simplified picture, they provide a useful summary of deep Eurasian population history that can serve as a null model for future studies and a baseline for further discoveries."

12-01-17, 00:59
Interesting that they don't come to a conclusion on this:

"The earliest strong archaeological evidence of modern human occupation outside of Africa comes from the Levant, approximately 100 thousand years ago (kya), but these and other Middle Paleolithic remains from Southwest (Armitage et al., 2011) and South Asia (Blinkhorn et al., 2013) may or may not be from groups related to present-day Eurasians."

"modern humans in Eurasia can be divided into what we will refer to as eastern and western clades. The former includes present-day East Asians and had differentiated as early as the ∼40 kya Tianyuan individual (Fu et al., 2013), while early members of the latter include ancient European hunter-gatherers (Lazaridis et al., 2014; Seguin-Orlando et al., 2014; Fu et al., 2016) and the ancient northern Eurasian Mal’ta 1 (MA1, a ∼24 kya Upper Paleolithic individual from south-central Siberia)"

"Interestingly, two early modern Eurasians (Ust’-Ishim (Fu et al., 2014), from ∼45 kya in western Siberia, and Oase 1 (Fu et al., 2015), from ∼40 kya in Romania) have been found that share little or no ancestry with either clade, unlike any known present-day population. After the initial modern human colonization of Eurasia, later migrations led to the formation of major populations with mixed ancestry from both clades, notably including South Asians (Reich et al., 2009) and Native Americans (Raghavan et al., 2014). It has also been proposed that ancestors of Europeans and East Asians experienced continuing gene flow after the initial eastern/western separation."

"It has been argued by some authors that this model of a primary split between eastern and western Eurasians is incorrect for certain present-day populations from Oceania and Southeast Asia. Under the “southern route hypothesis,” Australians, New Guineans, and perhaps Southeast Asian “Negrito” populations are descended in part from an early out-of-Africa dispersal..., we proposed a historical model that fit better without any such deep-source ancestry than with it (Mallick et al., 2016)"

"Here, we study the deep relationships of most non-African continental groups by building a unified historical model based on patterns of allele frequency correlations due to genetic drift."

Figure 1 is on page 28. Interestingly, as I speculated long ago, the graph seems to indicate that Mal'ta does have East Asian admixture. I don't know what more detailed reading of the paper will show, however. It's 63 pages!

Click to enlarge...If someone can post a better image so people don't have to go to page 28 that would be great.