When the Toba volcano erupted 74,000 years ago, this had worldwide consequences. But they were obviously less catastrophic than they had been for a long time. Because new tool finds from the Son Valley in India not only suggest that the region was populated even before the Toba eruption. The populations living there also seem to have easily survived the subsequent volcanic winter. The results thus provide further evidence that the eruption of the super volcano may have brought only a mild cooling. They also provide new insights into the spread of our species from Africa to Asia and Australia, as the researchers report.
The eruption of the volcano Toba on Sumatra is one of the greatest volcanic events of the past two million years. The eruption 74,000 years ago had global effects: ash and dust led to a so-called volcanic winter that lasted for years and cooled the earth’s surface – with potentially catastrophic consequences. Even our ancestors could hardly have escaped extinction at the time. Some researchers suspect that early Homo sapiens populations shrank significantly and that our ancestors only survived in a few refuges in Africa. The cold phase therefore stood in the way of its further expansion to Asia and Australia. How much the Toba outbreak really affected people is controversial.
“Central to this debate is the question of whether representatives of Homo sapiens arrived in India before the Toba outbreak,” said Chris Clarkson of the University of Queensland in St. Lucia and his colleagues. The subcontinent is considered a key region for the colonization of Australasia by anatomically modern humans and could thus provide valuable information about the consequences of the eruption – but so far there has been a lack of meaningful archaeological finds. The discovery that the team around Clarkson is now reporting is all the more exciting: Stone tools at the Dhaba site in the Indian valley testify to the presence of human inhabitants. These artifacts are between 80,000 and 40,000 years old and thus date from before, during and after the Toba eruption.
Inhabited continuously
As the scientists report, there is a clear development in stone tools. While the people in Dhaba initially used roughly processed flints, they later produced ever smaller and more sophisticated tools that were only a few centimeters long. The bottom line: “The stone tools are similar to the tools that Homo sapiens used in Africa at the same time,” says Clarkson. In addition, some of them looked like the earliest known artifacts from Australia. “The Dhaba finds act as an important bridge between regions with similar archeology in the east and west,” explains the team. What does that mean specifically? Given the striking similarity, the researchers assume that Dhaba’s tools could be products of earlier representatives of our species.
This not only confirms genetic and fossil finds, according to which Homo sapiens had reached Asia at least 60,000 years ago. The complete archaeological tradition also indicates that the region was continuously inhabited. “The finds provide evidence of long-term human settlement,” Clarkson and his colleagues state. “The fact that the tools did not disappear at the time of the volcanic eruption or that the technology changed dramatically afterwards suggests that the local populations around Dhaba survived the so-called catastrophe,” Clarkson adds. Accordingly, the people in India seem to have easily survived ash rain and cooling – although the Toba eruption has also been shown to leave its mark there. Researchers in the Son Valley found ashes from this event as early as the 1980s.
Less disastrous than expected
All in all, the results suggest that the eruption of the volcano 74,000 years ago was less apocalyptic than we thought for our ancestors. According to the scientists, this also speaks for the adaptability of people. Apparently, the hunters and gatherers in the Son Valley could react flexibly to changes in their environment. “The archaeological finds testify to a remarkable resilience,” comments co-author Michael Petraglia from the Max Planck Institute for the History of Humanity in Jena. At the same time, it shows that the “volcanic winter” was probably not as violent as originally thought. In fact, previous studies suggested less drastic cooling.
Source: Chris Clarkson (University of Queensland, St. Lucia) et al., Nature Communications, doi: 10.1038 / s41467-020-14668-4