An Unexpected Connection in the Amazon
For decades, the leading theory held that the first Americans arrived in a single migratory wave from Eurasia across the Bering land bridge over 15,000 years ago.
But recent genetic research has uncovered something unexpected: certain Indigenous groups in the Amazon share genetic markers not with Siberians, but with people from Australasia—regions like New Guinea, Australia, and the Andaman Islands.
DNA From a Disconnected Past
The finding emerged when researchers at Harvard University, led by David Reich and Pontus Skoglund, analyzed the genomes of 30 Native American populations across Central and South America.
Three Amazonian groups—the Suruí, Karitiana, and Xavante—showed a persistent genetic affinity to Australasians. The research team dubbed the unknown source of this signal “Population Y,” from the Tupi word ypykuéra, meaning “ancestor.”
A Parallel Migration or Ancient Mixture?
The data suggest that Population Y branched off from a common ancestor tens of thousands of years ago—one group moving south to Australasia, and another northward, eventually crossing into the Americas.
Whether Population Y arrived before, after, or alongside the main wave from Eurasia remains unknown. But unlike other Native American groups, Amazonian tribes have remained genetically isolated, preserving the signal.
Debate Over Origins Continues
Not everyone is convinced. Some researchers argue that the findings could result from genetic drift, especially given the low genetic diversity of Amazonian populations. Others suggest any Australasian link may have come much later through indirect contact.
Yet, the presence of similar features in ancient South American skulls, combined with the genetic data, continues to challenge long-standing assumptions. The story of the Americas’ first settlers, it seems, is still unfolding.
For years, scientists believed all Native Americans descended from a single group that crossed into Alaska over 15,000 years ago.
But DNA from Amazonian tribes now hints at something unexpected—a genetic connection to Indigenous Australians and New Guineans…🧵👇 pic.twitter.com/CaYrdv1CdY
— Detective Tiger's Stories (@TigerDetective) June 16, 2025