Paris - High-tech dating of mastodon remains found in southern California has shattered the timeline of human migration to America, pushing the presence of hominins back to 130 000 years ago rather than just 15 000 years, researchers say.
Teeth and bones of the elephant-like creature unmistakably modified by human hands, along with stone hammers and anvils, leave no doubt that some species of early human feasted on its carcass, they reported in the journal Nature.
Discovered in 1992 during construction work to expand an expressway, the bone fragments "show clear signs of having been deliberately broken by humans with manual dexterity," said lead author Steve Holen, director of research at the Centre for American Paleolithic Research.
Up to now, the earliest confirmed passage of our ancestors into North America took place about 15 000 years ago. These were modern humans - Homo sapiens - that probably crossed from Siberia into what is today Alaska, by land or along the coast.
Homo sapiens
There have been several other claims of an even earlier bipedal footprint on the continent, but none would take that timeline back further than 50 000 years and all remain sharply contested.
The absence of human remains at the California site throws wide open the question of who these mysterious hunters were, as well as when - and how - they arrived on American shores.
One possibility that can be excluded with confidence is that they were like us. Homo sapiens, experts say, did not exit Africa until about 80 000 to about 100 000 years ago.
But that still leaves a wide range of candidates, including several other hominin species that roamed Eurasia 130 000 years ago, the authors said.
