The Mal’ta genome, in other words, was a key not just to the prehistory of the Americas but to the prehistory of Eurasia as a whole.

The child who died near Lake Baikal 24,000 years ago, wrapped in his beads and his ivory ornaments, carried a genome that turned out to be relevant to the ancestral histories of populations on multiple continents.

This is one of the recurring themes of ancient genomics: that the deep past of human populations was more connected, more mobile, and more complex than the geographic and cultural boundaries of the historical period would suggest.

People moved.