Modern Humans Migrated to Asia After Catastrophic Mount Toba Volcano Eruption

Modern humans have been migrating across the globe since they first emerged from Africa. Yet researchers have often wondered when they settled in Asia and what route they took from Africa. Now, scientists have made some new discoveries that may reveal the answer to this question.

Scientists have gone back and forth when it comes to the time period when modern humans arrived in Asia. Although the team previously showed that humans arrived in Asia after the catastrophic eruption of the Mount Toba volcano in Sumatra that occurred about 74,000 years ago, another group of researchers found evidence of stone tools that seemed to suggest that people were in Asia far before this eruption--possibly as early as 120,000 years ago.

In this latest study, though, the researchers decided to use material that wasn't available previously: a large body of DNA evidence. By using the mitochondrial DNA of today's populations and working backwards, and by drawing on a wide variety of other research, the scientists were able to make much more precise estimates for the arrival of modern humans in India.

It turns out that humans probably dispersed from Africa and settled in India no earlier than 60,000 years ago. This means that humans began migrating after the massive eruption in Sumatra, a time when the climate was shifting.

The researchers didn't just find out when humans moved out of Africa, though. They also discovered a possible reason for the earlier findings of stone tools in India.

"There were people in India before the Toba eruption, because there are stone tools there, but they could have been Neanderthal-s-or some other pre-modern population," said Martin Richards, one of the co-authors, in a news release. "The replacement of the presumably archaic humans living previously in South Asia by modern people with these new technologies appears analogous to the replacement of Neanderthals by modern humans in Europe and western Asian 50-40,000 years ago,"

The findings are published in the Proceedings of the National Academy of Sciences.