Native Americans living in the Amazon bear an unexpected genetic connection to indigenous people in Australasia, suggesting a previously unknown wave of migration to the Americas thousands of years ago, a new study has found.
“It’s incredibly surprising,” said David Reich, Harvard Medical School professor of genetics and senior author of the study. “There’s a strong working model in archaeology and genetics, of which I have been a proponent, that most Native Americans today extend from a single pulse of expansion south of the ice sheets—and that’s wrong. We missed something very important in the original data.”
Previous research had shown that Native Americans from the Arctic to the southern tip of South America can trace their ancestry to a single “founding population” called the First Americans, who came across the Bering land bridge about 15,000 years ago. In 2012, Reich and colleagues enriched this history by showing that certain indigenous groups in northern Canada inherited DNA from at least two subsequent waves of migration.