Indigenous people that lived in southeastern Brazil in the late 1800s shared some genetic sequences with Polynesians, an analysis of their remains shows. The finding offers some support for the possibility that Pacific islanders traded with South America thousands of years ago, but researchers say that the distinctive DNA sequences, or haplogroups, may have entered the genomes of the native Brazilians through the slave trade during the nineteenth century.

Most scientists agree that humans arrived in the Americas between 15,000 and 20,000 years ago, probably via the Bering land bridge linking northeastern Asia with what is now Alaska. But the precise timing and the number of ‘migration waves’ is unclear, owing largely to variations in early Americans’ physical features, says Sérgio Pena, a molecular geneticist at the Federal University of Minas Gerais in Belo Horizonte, Brazil.

One broad group of these Palaeoamericans — the Botocudo people, who lived in inland regions of southeastern Brazil — stands out, having skull shapes that were intermediate between those of other Palaeoamericans and a presumed ancestral population in eastern Asia.