Analyses of the genomes of ancient and modern individuals from Siberia and North America, published in two papers in this week’s Nature, reveal insights about major migration events and the population history of these regions.

Palaeo-Eskimos were the first people to settle in vast regions of the American Arctic around 5,000 years ago, and around 1,000 years ago they were joined and largely displaced by ancestors of the present-day Inuit and Yup’ik. The genetic relationships between Palaeo-Eskimos and Native American, Inuit, Yup’ik and Aleut populations remain uncertain.

Stephan Schiffels and colleagues present data from the genomes of 48 ancient individuals from the American Arctic and Siberia, including Chukotka, East Siberia, the Aleutian Islands, Alaska, and the Canadian Arctic, as well as from modern Alaskan Inupiat and West Siberian populations. The authors’ analyses suggest that the population history of North America was shaped by gene-flow between Palaeo-Eskimos and the First Americans, which gave rise to both the Eskimo-Aleut and Na-Dene-speaking populations.

In a separate paper, Eske Willerslev and colleagues report 34 ancient genomes (dated from 31,000-600 years ago) from northeastern Siberia, the location of the modern Russian Far East. This region has been inhabited by humans for more than 40,000 years, yet its deep population history remains poorly understood. The authors document complex population dynamics during this period, including at least three major migration events: an initial arrival of a previously unknown Palaeolithic population of Ancient North Siberians, distantly related to early West Eurasian hunter-gatherers; the arrival of East Asian peoples giving rise to Ancient Palaeo-Siberians and Native Americans; and a Holocene migration of East Asian peoples named Neo-Siberians, from whom many contemporary Siberians descend.