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1 .This is Scientific American 60-Second Science. I'm Cynthia Graber. This'll just take a minute.
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2 .Early modern humans didn't just chip away at stones to create their tools.
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3 .They treated stone with fire in a sophisticated fashion, according to research published August 14th in the journal Science.
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4 .About 72,000 years ago, our ancestors along coastal South Africa made tools from silcrete, a cement-like layer of soil.
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5 .The silcrete found at archaeological sites was glossy with a fine grain and a reddish color.
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6 .It didn't match stones in local outcroppings.
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7 .Researchers from the University of Cape Town couldn't find big enough pieces to learn more, until a couple of years ago.
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8 .Then a colleague from Arizona State University remarked that a piece of silcrete reminded him of heat-treated tools in the Southwest.
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9 .So the researchers set up a fire pit and buried a silcrete sample at high temperature.
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10 .The next day, the stone looked like ones used by early humans.
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11 .It flaked easily and provided the basic material for complex tools.
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12 .Until now, heat treatment was thought to have started in Europe 25,000 years ago.
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13 .This discovery pushes it back tens of thousands of years into Africa,
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14 .and suggests that the southern African coast may have been the site of a truly Promethean revolution.
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15 .Thanks for the minute, for Scientific American 60-Second Science. I'm Cynthia Graber.
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