Washington, Aug 14 - New evidence has surfaced which reveals how early humans used fire in southern Africa to improve the quality and efficiency of stone tools. The evidence has also changed scientific perceptions of how human brain power evolved.

Curtis Marean, a paleo-anthropologist with the Institute of Human Origins at Arizona State University (ASU), and an international team of researchers with members from South Africa, England, Australia and France found 72,000-year-old, silcrete rocks that had been fired and flaked to make stone tools in a cave along the coast of the southern tip of Africa in Mossel Bay.

The finding indicates that humans' ability to solve complex problems may have occurred at the same time their modern genetic lineage appeared, rather than developing later as has been widely speculated.

These findings were published in Science.