Old American theory is 'speared'

[Gerald]

An ancient bone with a projectile point lodged within it appears to up-end - once and for all - a long-held idea of how the Americas were first populated.The rib, from a tusked beast known as a mastodon, has been dated precisely to 13,800 years ago.This places it before the so-called Clovis hunters, who many academics had argued were the North American continent's original inhabitants.News of the dating results is reported in Science magazine.In truth, the "Clovis first" model, which holds to the idea that America's original human population swept across a land-bridge from Siberia some 13,000 years ago, has looked untenable for some time.A succession of archaeological finds right across the United States and northern Mexico have indicated there was human activity much earlier than this - perhaps as early as 15-16,000 years ago.The mastodon rib, however, really leaves the once cherished model with nowhere to go.The specimen has actually been known about for more than 30 years. It is plainly from an old male animal that had been attacked with some kind of weaponry.

http://www.bbc.co.uk/news/science-environment-15391388

Note: 21 October 2011 Last updated at 01:21 GMT