[lumberjim]

The shape of the skulls changes between 9,000 and 7,000 years ago from being exclusively negroid to exclusively mongoloid. Combined with rock art evidence of increasing violence at this time, it appears that the mongoloid people from the north invaded and wiped out the original Americans.

The identity of the first Americans is an emotive and controversial question. But the evidence from Brazil, and a handful of people who still live at the very tip of South America, suggests that the Americas have been home to a greater diversity of humans than previously thought - and for much longer.