BioEd Online

From the BA Festival of Science, Exeter, UK.

The first colonizers of the Americas came from Australia, according to archaeologists who have analysed skulls from 12,000-year-old skeletons found in California. The finding contradicts the traditional view that the first immigrants were the ancestors of modern Native Americans.

The skulls, taken from skeletal remains found in the desert of the Baja California peninsula in Mexico, are long and narrow. "This is completely different to the Native Americans' rounder skull shape," explains lead researcher Silvia Gonzalez from the Liverpool John Moores University, UK.

The skeletons are housed by the National Museum of Anthropology in Mexico City. They were embedded in volcanic deposits that deteriorated the structure of the bones and made them difficult to date accurately. But the skulls' intriguing form has driven researchers to work out how old they are.

Gonzalez and her team announced their first set of results on 6 September at the Exeter-based Festival of Science, run by the British Association for the Advancement of Science. They have managed to radiocarbon date 4 of the 27 skeletons. So far, the oldest, belonging to an individual called Peñon Woman III, is 12,700 years old.

Cue from the Pericues

Traditional colonization theories hold that the first wave of humans to migrate to the Americas came from Siberia at the end of the last ice age. Skeletons of these migrants are dated at about 9,000 years old. So Gonzalez says the new evidence means that the Siberians, who are related to modern day Native Americans, did not get there first after all.

She believes the lost tribe of immigrants, known as the Pericues, are related to modern Australian Aborigines, who have a similar skull shape, and that they became extinct between 200 and 300 years ago. "There are eighteenth century reports from missionaries in Baja California of thin, hunter-gatherer, shellfish-eating people," says Gonzalez. "These seafaring travellers would have followed a corridor around the Pacific coast from Australia, along the coast of Japan, to Baja."

"The theory that the first migrant population to the Americas is not connected to the current Native Americans has been debated for five to ten years," says Chris Stringer at the Natural History Museum in London. "If Dr Gonzalez has dated these skeletons accurately, then this is a very exciting result."

The researchers now hope to strengthen their theory of a link with aboriginal Australians by doing a DNA analysis of the Pericue skeletons' bones.