Deep genetic affinities between Amazonian populations in South America, and Australasians; warmer colors indicate the strongest affinities.
Credit: Pontus Skoglund, Harvard Medical School

Who were the first Americans? Two research papers this week have arrived at contrasting interpretations.

One study, published Tuesday in the journal Science, proposes that the earliest Americans had singularly Siberian origins, crossing into the continent via the Bering land bridge in a single wave. Another, published Tuesday in Nature, suggests that some early Native Americans may have had genetic roots in Australia and its neighboring islands, a region known collectively as Australasia.

The peopling of the Americas is a matter of great anthropological and archaeological interest. We see evidence of unique culture on the continent over 10,000 years ago, but exactly how these populations arrived on the continent, and from where, has been debated for decades. Scientists generally agree that the first Americans crossed […]