Inde : des humains vivants malgrè les eruptions volcaniques massives de - 74 000 ans ? il manque les fossiles

5 July 2007; | doi:10.1038/news070702-15 / http://www.nature.com/news/2007/070702/full/070702-15.html

Super-eruption: no problem?

Tools found before and after a massive eruption hint at a hardy population.

Katharine Sanderson

Massive eruptions make it tough for life living under the ash cloud. Getty

A stash of ancient tools in India hints that life carried on as usual for humans living in the fall-out of a massive volcanic eruption 74,000 years ago.

Michael Petraglia, from the University of Cambridge, UK, and his colleagues found the stone tools at a site called Jwalapuram, in Andhra Pradesh, southern India, above and below a thick layer of ash from the eruption of the Toba volcano in Indonesia - an event known as the Youngest Toba Tuff eruption.

The tools from each layer were remarkably similar, and Petraglia says that this shows that the huge dust clouds from the eruption didn't wipe out the population of tool-using people. "Whoever was there seems to have persisted through the eruption," he says.

This is the first archaeological evidence associated with the Toba super eruption, says Petraglia, and it contradicts theories that the eruption had a catastrophic effect on the area that its ash blanketed.

Modern man?

Petraglia thinks that modern humans - rather than Neanderthals or other hominins - are the only species that would have been able to persist through an event as dramatic as the Toba eruption. This theory will spur much debate, he admits, because modern humans were not thought to have reached India, from Africa, so long ago. "It's controversial," says Petraglia, "but it makes a lot of sense."

Petraglia and his team compared the tools they found to others from Africa from different periods in this week's edition of Science. The Indian tools look a lot like those from the African Middle Stone Age about 100,000 years ago, when modern humans were thought to have lived, he says. "Whoever was living in India was doing things identical to modern humans living in Africa." Neanderthal toolkits found in Europe are very different, he says. This is more evidence, he says, that the plucky ash-covered inhabitants of Jwalapuram were modern humans.

Stanley Ambrose, from the University of Illinois at Urbana-Champaign, disagrees with Petraglia's conclusions. "It is highly speculative to say the eruption had no impact," he says. Ambrose argues that Petraglia's sample size is too small to make proper comparisons with other tools. And, he adds, "stone artifacts cannot be used to differentiate Neanderthals from African moderns."

Petraglia says he has plenty more stone tools to back up his suggestions, beyond the ones presented in Science. "We have reported only some of our assemblages," he says. He adds that much more work needs to be done on the Indian subcontinent, and much more needs to be learned from comparing archaeological evidence in Africa to that in India.

"The only way to definitively demonstrate the existence of modern humans before and after the eruption in India is by discovering human fossil skulls," says Ambrose. This is something that Petruglia will go some way to agreeing with: "It's true we have to look for fossils," he says. "The search is on."

Reference : Petraglia, M. et al. Science 317, 114-116 (2007).