Lineage separation· Where Sapiens lives
The east-west split
49 ka
The deepest division among people living outside Africa: on one side the ancestors of West Eurasians, on the other those of East Asians and of everyone who later reaches the Americas and the Pacific. Everything the timeline shows east of the Levant descends from this side of it.
What the evidence shows
The model that carries this branching is a phylogeny fitted to allele-frequency patterns across East Asians, Australasians, Native Americans and ancient western and northern Eurasians, together with the archaic groups. It resolves into a primary eastern and western bifurcation with a small number of admixture events, and its authors present it as a null model rather than a conclusion. A supertree assembled from 257 genetic and linguistic trees recovers the same grouping, with Sahul-Oceanian, East Asian and Beringian-American peoples together on the eastern side. What the model does not give is an age: 45,000 years is the youngest the bifurcation can be, not the year it happened.
Dating & uncertainty
Reviews of the field place the major divergences among non-Africans between 50,000 and 40,000 years ago, younger than the window drawn here. The disagreement is not about whether the eastern and western lines parted, but about how much of the parting had already happened when people crossed into Sahul.
Sources
- Lipson, M., Reich, D. (2017), Molecular Biology and Evolution · A working model of the deep relationships of diverse modern human genetic lineages outside of Africa
- Vallini, L. et al. (2022), Journal of Anthropological Sciences · The future of the Eurasian past: highlighting plotholes and pillars of human population movements in the Late Pleistocene
- Sümer et al. (2024), Nature · Earliest modern human genomes constrain timing of Neanderthal admixture