20 October 2011 Updated at 21:21 ET
Old American theory is 'speared'
Jonathan Amos
Science correspondent, BBC News
It would have taken a lot of force to drive the point into the mastodon bone
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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.
link-
http://www.bbc.co.uk/news/science-environment-15391388