Stone tools found in central India suggest that ancient South Asians stayed the course after a massive explosion of Indonesia’s Toba volcano around 74,000 years ago, researchers say. While the volcanic eruption was Earth’s largest in the last 2 million years, scientists have disagreed about how much it affected human populations as well as the global climate.

Studying the tools, excavated at the Dhaba site in India’s Middle Son River Valley, the researchers found that the style of toolmaking stayed largely unchanged from roughly 80,000 to 48,000 years ago. That means toolmakers were striking sharp-edged flakes from prepared chunks of rock both before and after Toba erupted, report archaeologist Chris Clarkson of the University of Queensland in Brisbane, Australia, and his colleagues.

Excavations at India’s Dhaba site (shown) have uncovered stone tools suggesting that people who reached South Asia by around 80,000 years ago withstood the effects of a massive volcanic explosion in Indonesia. Christina Nuedorf

The finding, published February 25 in Nature Communications, adds to skepticism about claims that Toba’s ashy outburst triggered a planetary chill that nearly wiped out humankind (SN: 5/13/13).

Instead, the researchers say, people must have maintained their way of life in the area, despite the likelihood that ash from the volcanic blast temporarily blocked out the sun. Ash layers from the Toba eruption have been unearthed about 700 meters east of Dhaba.

In dating the tools, the researchers estimated when sediment layers containing the objects had last been exposed to sunlight. The oldest stone tools at Dhaba resemble artifacts that originated in Africa as early as 400,000 years ago (SN: 1/31/18) as well as stone tools found in Australia (SN: 7/19/17) that date to about 65,000 years ago.

To explain those similarities, the investigators suggest that some Homo sapiens left Africa by 100,000 years ago and moved eastward through South Asia and on to Australia, bringing with them an ancient toolmaking tradition. No fossils of H. sapiens or any other hominid have been found at Dhaba.