This eruption was almost as disastrous as the meteorite impact that wiped out the dinosaurs. 74,000 years ago, the Sumatran Toba (western Indonesia) volcano threw the world in a volcanic winter followed by a severe ice age after expelling 720 cubic miles (3,000 cubic kilometers) of magma and huge amounts of sulfuric acid that reached even Greenland. Ice cores clime records showed that the world was colder by 5.4 - 9° F (3 - 5° C) for hundreds of years following the event. This is the largest volcanic eruption in the last two million years and covered all of India with about 6 inches (15 cm) of volcanic ash.
Now a team led by anthropologist Michael Petraglia found
not only that modern humans could have reached India at least two millenia before the super-eruption, but they survived its devastating effects. The researchers encountered stone tool assemblages from above and below the Toba ash layer in India's Jwalapuram Valley.
"We saw some stone tools above the ash, but we decided to test below the ash. It was a lucky strike," said Petraglia, of the University of Cambridge, England.
"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. 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. But they would have had a very, very difficult time." added Petraglia.
"My point is that humans were complex enough at this point to have dealt with that. In Africa at this time, humans were exhibiting early symbolism, complex toolmaking behavior, and sophisticated social behavior," said Will Harcourt-Smith, a paleontologist at the American Museum of Natural History in New York, not involved in the study.
Some scientists warn that it is hard to tell the difference between human-made stone tools and those made by Neanderthals, an extinct human species.
"South African and Neanderthal European [stone tool] assemblages are technologically and typologically indistinguishable. [The study authors] have a bagful of artifacts on which they're drawing conclusions that can only be confirmed by fossil evidence, and they don't have any fossils." said Stanley Ambrose, an archaeologist at the University of Illinois at Urbana-Champaign in Urbana, not involved in this research.
"A large piece of ground ochre was found below the ash with the stone tools. Ochre was used by early humans for art, symbols, curing hides, or helping to attach stone tools to build a wooden shaft. All of these potential uses hint at more complex behaviors than are usually attributed to earlier extinct hominin species, although we know European Neanderthals also used ochre a lot. More excavation will help us resolve whether this assemblage belongs to modern humans or not." said co-author Chris Clarkson, an archaeologist at Australia's University of Queensland.
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