Archaeologists: Mega-Eruption Didn't Change Human History

An ancient volcanic super-eruption, one of the largest known in Earth's history, may not have devastated the world and humanity as much as once thought.

The eruption at what is now Lake Toba in northwestern Sumatra roughly 75,000 years ago was the largest of the last 2 million years.

The gigantic blast released at least 7.7 trillion tons, or 670 cubic miles, of magma, equivalent in mass to more than 19 million Empire State Buildings.

• Click here for a satellite image of Lake Toba, the oval-shaped caldera of the dormant volcano.

Vast plumes of ash, carried by the summer monsoon winds, stretched from the South China Sea to the Arabian Sea and likely blotted out the sun and drastically cooled the Earth for years — a "volcanic winter."

Some scientists, supported by DNA evidence, think an environmental catastrophe resulted and influenced the course of human history, with the few thousand survivors becoming the ancestors of all almost people alive today.

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But newly unearthed prehistoric artifacts now suggest the blast might not have been "as catastrophic as before thought," said Cambridge University archaeologist Michael Petraglia.

Indirect clues

Petraglia and his colleagues investigated deposits of Toba ash more than 8 feet thick near the southern Indian village of Jwalapuram.

They found hundreds of stone blades and other tools below and above this ash layer — effectively immediately before and after the eruption — that are fairly similar to each other.

They also found pieces of red ochre, a mineral used for body art and cave drawings and for sticking tools together.

These 75,000-year-old artifacts appeared to be similar to others dating to around the same time period in Africa. These findings suggest humans continued to live in the area after the blast.

"We would have had very mobile populations of hunter-gatherers here, able to cope with all sorts of disasters," Petraglia told LiveScience. "If we [had been] talking about settled people with agriculture, the Toba super-eruption would have been a cataclysm."

Fortunately for humans living at the time of the Toba eruption, agriculture would not be developed for another 65,000 years.

The research was detailed in the July 6 issue of the journal Science.

More evidence needed

Not everyone thinks the new evidence is convincing.

Anthropological archaeologist Stanley Ambrose at the University of Illinois at Urbana-Champaign, who proposed that the Toba catastrophe influenced human evolution, found the published data inadequate.

"The only way to prove their assertions is to find human skeletons below the ash that look like Africans," Ambrose said.

Petraglia said they had "thousands more artifacts than we presented in the paper" to support the new claim, but did agree that fossils would be definitive proof.

"We don't have human fossils, we don't have Neanderthal fossils, we don't have any fossils. We'd love to find fossils," Petraglia said.

An exciting but controversial aspect of the new findings is the proposition that modern humans got out of Africa far earlier than had been thought.

"For the last 150 years, archaeologists have concentrated on when modern humans got out of Africa into Europe, but our findings suggest they might have gotten to India 30,000 years before they got to Europe," Petraglia said.

"There's a lot of really remarkable archaeology that can be done in India that we're excited about exploring," he said.

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