When a Ghost from the Past Paved the Way for a New World

Thousands of years ago, a small group of people undertook an incredible feat, crossing a land bridge to a continent no human had ever inhabited. They carried with them not only new technologies and cultures but also a hidden genetic advantage: a fragment of DNA inherited from a distant, extinct relative. A new study in the journal Science now suggests that this ancient biological inheritance may have been crucial for survival in the Americas, providing an exceptional example of how our evolutionary history is a complex tapestry of adaptation and deep genetic ties to other hominins.

The research revisits a species known as Denisovans, an ancient hominin whose existence was only confirmed about 15 years ago from a small fragment of bone found in a Siberian cave. While fossil evidence for Denisovans remains scarce, their genetic legacy is increasingly clear. They interbred with both Homo sapiens and Neanderthals, leaving a profound mark on the biology of many people alive today.

“In terms of evolution, this is an incredible leap,” said Fernando Villanea, an assistant professor at the University of Colorado Boulder and a lead author of the study. “It shows an amount of adaptation and resilience within a population that is simply amazing.”

In their investigation, Villanea and his colleagues, including co-lead author David Peede from Brown University, examined human genomes from around the world. Their focus was a gene called MUC19, which is part of a family of genes that produce mucins, the proteins that make up mucus. This vital substance can protect body tissues from pathogens. The researchers found that people with Indigenous American ancestry are significantly more likely to carry a variant of MUC19 that originated from Denisovans. This ancient genetic inheritance may have provided a biological tool to contend with the unique ecosystems, foods, and diseases of the Americas.