Evidence that human ancestors used stone-tipped weapons 200,000 years earlier than once thought has been found, changing notions about the smarts and capabilities of prehistoric people.

Spears topped with stone points were probably used for hunting large game and for self-defense and were an important advance in weaponry, said Jayne Wilkins, lead author of a paper yesterday in the journal Science. The points came from a Stone Age site in South Africa.

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Researchers first thought the early humans were using sharpened wood spears or stone hand axes, Wilkins said. The steps required to put a sharp-tipped stone at the end of a wood spear, called hafting, means these ancestors had to engage in planning and other goal-driven thought processes long before a hunt took place, she said.

"This expands the range of behavioral complexity known in human ancestors living 500,000 years ago," said Wilkins, a PhD candidate in anthropology at the University of Toronto. -- Bloomberg News