The first Americans had Denisovan DNA. And it may have helped them survive.

Black-and-white image of a person handling a human jaw carefully while gloved.

The first people to step foot in the Americas were harboring a sliver of DNA from two extinct Eurasian human groups: the Neanderthals and the Denisovans, a new study finds. This genetic relic could have helped the earliest Americans fight diseases they encountered in their new environment, the researchers proposed.

Everyone alive today is "a result of like three different species coming together," study co-author Fernando Villanea, a population geneticist at the University of Colorado Boulder, told Live Science.