Shannon Hall writes:

The Toba supereruption [about 74,000 years ago] expelled roughly 10,000 times more rock and ash than the 1980 Mount St. Helens eruption. So much ejecta would have darkened skies worldwide, causing scientists to speculate that it might have plunged the Earth into a volcanic winter whose chill could be felt far from Indonesia. Climate models suggest that temperatures may have plummeted by as much as 30 degrees Fahrenheit. And in such a cold world, plants may have ceased growing, glaciers may have advanced, sea-levels may have dropped and rainfall may have slowed.

Then in 1998, Stanley Ambrose, an anthropologist, linked the proposed disaster to genetic evidence that suggested a population bottleneck had occurred around the same time. He was certain that the Toba supereruption had caused the human population to decline to some 10,000 people — a close call for our ancestors.

“These were dramatic theories,” said Michael Petraglia, an archaeologist at the Max Planck Institute for the Science of Human History who was not involved in the study. “They were very popular — both in the scientific world, but also in the public imagination.”

The latest study, however, suggests that those theories are incorrect, Dr. Petraglia said. “We’re not seeing all the drama.” [Continue reading…]

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