Submerged skeleton suggests early humans only found the Americas once

Credit: Roberto Chaves Arce

Deep within a flooded cave in Mexico's Yucatan Peninsula, along with skeletons of saber-toothed tigers and giant sloths, scientists found the oldest complete human skeleton yet discovered in the Americas. The skeleton of a teenage girl, nicknamed Naia, was first found by a team of divers exploring the Hoyo Negro cave in 2007. The deep pit, part of a complex cave system, reaches more than 100 feet below sea level.

Besides being a completely awesome exercise in underwater archeology, the team of scientists studying the skeleton think that it provides critical information that will help us understand the human colonization of the Americas.

The first humans arrived in North America from Northeast Asia via a land bridge. After entering what is now Alaska about 20,000 years ago, they slowly spread into the continent. But archeologists studying the remains of paleoamericans from several thousand years ago have found that, morphologically, the skulls and teeth of early Americans were more similar to modern people in Africa or Australia than to modern Native Americans or Siberian people. These differences suggest that either the Americans were colonized more than once or that evolutionary changes after colonization were responsible for the mismatched traits.