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, of the Americas and of 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. The date it gives is a floor. What sets the ceiling is a separate result: the ancestors of all non-Africans were still a single population between 49,000 and 45,000 years ago, so the split cannot be much older than that either.
Dating & uncertainty
Lipson and Reich date this bifurcation to at least 45,000 years ago, which is a lower bound and not a measurement. Reviews place the major divergences among non-Africans between 50,000 and 40,000 years ago. The window drawn here sits at the older edge of that range, because the branches descending from it must exist before the people they lead to.
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