And when the ice finally gave up what it had been keeping — when the sequencing machine read the fragmented code inside those small hard objects, and when the computational analysis mapped that code onto the tree of human population history — it turned out that two children who had once been very young and very cold above the Arctic Circle had helped illuminate one of the biggest questions in the story of humanity.

How did the Americas come to be populated?

Part of the answer, it turns out, had been waiting in the frozen ground above the Yana River for thirty-one thousand years.

The teeth knew.

They just needed us to learn how to listen.

The River Still Flows

The Yana River still runs north through Siberia, toward the Arctic Ocean.

The alluvial terrace where the Rhinoceros Horn Site sits is still there — still eroding, still yielding material from the permafrost as the climate changes and the frozen ground shifts.