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The major genetic divergences among non-Africans took place within a relatively short period of time, between 50 and 40 thousand years ago. These events shaped human diversity worldwide and set the basis for our current understanding of demographic history, patterns of adaptation and genetic burden across human populations. While the global picture appears already set, with the main human expansion Out of Africa inferred to have occurred between 60 and 70 thousand years ago and the main separation between contemporary East and West Eurasian to have taken place at around 40 thousand years ago, several finer details remain unresolved, including the whereabouts of such expansions and the dynamics of their interactions with archaic hominins and the interplay between environmental, cultural and demographic effectors. Here we review the major events that characterize human movements across and beyond Eurasia until the last glacial maximum and, at the end of each paragraph, spell out in italics the major questions that remain unsolved and that may provide major breakthroughs in the field in the upcoming years.

The population dynamics that followed the Out of Africa (OoA) expansion and the whereabouts of the early migrants before the differentiation that ultimately led to the formation of Oceanian, West and East Eurasian macropopulations have long been debated. Shedding light on these events may, in turn, provide clues to better understand the cultural evolution in Eurasia between 50 and 35 ka. Here, we analyze Eurasian Paleolithic DNA evidence to provide a comprehensive population model and validate it in light of available material culture. Leveraging on our integrated approach we propose the existence of a Eurasian population Hub, where Homo sapiens lived between the OoA and the broader colonization of Eurasia, which was characterized by multiple events of expansion and local extinction. A major population wave out of Hub, of which Ust'Ishim, Bacho Kiro, and Tianyuan are unadmixed representatives, is broadly associated with Initial Upper Paleolithic lithics and populated West and East Eurasia before or around 45 ka, before getting largely extinct in Europe. In this light, we suggest a parsimonious placement of Oase1 as an individual related to Bacho Kiro who experienced additional Neanderthal introgression. Another expansion, started before 38 ka, is broadly associated with Upper Paleolithic industries and repopulated Europe with sporadic admixtures with the previous wave (GoyetQ116-1) and more systematic ones, whereas moving through Siberia (Yana, Mal'ta). Before these events, we also confirm Zlatý Kůň as the most basal human lineage sequenced to date OoA, potentially representing an earlier wave of expansion out of the Hub., (© The Author(s) 2022. Published by Oxford University Press on behalf of Society for Molecular Biology and Evolution.)