These skulls and their analysis muddle the theory that the first settlers in the Americas were much more biologically similar. Scientists have long talked about the settlement of the Americas as if North and South shared a common narrative, but there stories are indeed very different.
They found them in submerged caves in Quintana Roo, Mexico. When the people the skulls belonged to were living the caves were above sea level.
The oldest of the skulls was very much akin to North American arctic people. The second oldest skull was more alike to European people. The third more alike to Asian or Native American peoples. The fourth sharing similarities with arctic peoples but having some South American features.
The skulls are very important because in North American fewer than 20 skeletons over eight thousand years old have been found, where as in South America between 300 to 400 have been found.