The people who eventually crossed into Beringia and then into the Americas were themselves the products of a long and complex ancestral history — a history that included the people who lived at Mal’ta, who made their ivory figurines and buried their dead with elaborately crafted grave goods, who looked up at the same stars that we look at from a world transformed beyond anything they could have imagined.

The child buried with the mammoth-ivory tiara and the 120 bone beads contributed his genome to this history.

Not by crossing any ocean or walking through any ice-free corridor, but simply by existing — by being born and living and dying and being buried with care by people who loved him, and by leaving behind, in the bones that the cold Siberian earth preserved, a molecular record that would eventually be read by scientists who had not yet been born.

That record helped reveal the hidden source of an ancestry that stretches from a grave near Lake Baikal to every corner of the Western Hemisphere.