[sradman]

The paper Neanderthal-Denisovan ancestors interbred with a distantly related hominin [1] suggests a simple model of hominid population movement

> ...which involves only three expansions of humans from Africa into Eurasia: an expansion of early Homo at about 1.9 Ma ago, an expansion of neandersovans at about 700 ka ago, and an expansion of modern humans at about 50 ka ago.

The “early Homo” or “superarchaics” are H. erectus and their DNA contribution is inferred since no sequences have yet been extracted. “Neandersovans” is the common ancestor of European Neanderthals and Asian Denisovans.

Interbreeding occurred in Eurasia after the second and third expansion.

[1] https://advances.sciencemag.org/content/6/8/eaay5483