for National Geographic News
A group of rocks that could easily be mistaken for gravel suggests that modern humans were in India spearing dinner and filleting meat 76,000 years ago, according to an international team of scientists.
The stone tools were found both above and below a layer of ash left behind by a volcanic "supereruption" 74,000 years ago. The discovery hints that humans in the region survived the blast's devastating effects.
The eruption of Toba, in what is now Indonesia, was the largest volcanic event of the last two million years (see map of Asia).
Toba spewed as much as 720 cubic miles (3,000 cubic kilometers) of magma, rained sulfuric acid down as far away as Greenland, and sent the world into a volcanic winter followed by a severe ice age.
It showered all of India with nearly 6 inches (15 centimeters) of volcanic ash, which acts as a marker of age in Earth's strata today (see a map of the eruption's effects).
Anthropologist Michael Petraglia and his colleagues unearthed stone tool assemblages from above and below the Toba ash deposit in India's Jwalapuram Valley.
"We saw some stone tools above the ash, but we decided to test below the ash," said Petraglia, of the University of Cambridge, England, and primary author of the study.
"It was a lucky strike."
The tools the team found resemble those made by modern humans in Africa, suggesting that the Indian ones could have been made by humans, too, Petraglia said.
"The fact that we have this ash is just icing on the cake, because it tells us that if it's modern humans, then they were able to persist through a major eruptive event," he said. "But they would have had a very, very difficult time."
The study appears in the latest issue of the journal Science.
Volcanic Winter 74,000 years Ago
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