A massive eruption 74,000 years ago affected the whole planet – archaeologists use volcanic glass to figure out how people survived
Mount Toba in the lake formed in the volcanic caldera
But that is where the similarity ends. There was no global flood a few thousand years ago, no ark, no family of eight repopulating the world, and no magic reset of human history in the Bronze Age Middle East. One of the real events sometimes discussed in this context occurred about 74,000 years ago, when the Toba volcano, in what is now Sumatra, Indonesia, produced one of the largest eruptions of the last 2.5 million years. The eruption ejected an estimated 672 cubic miles, or about 2,800 cubic kilometres, of volcanic material into the atmosphere, with the potential to darken skies, cool the climate and devastate ecosystems close to the volcano. [1]
For some years, this gave rise to the Toba catastrophe hypothesis: the idea that the eruption caused a volcanic winter and drove the human population down to fewer than 10,000 individuals. That would have been a dramatic genetic bottleneck, and it is easy to see why it attracted attention. However, the link between Toba and a species-wide human near-extinction is still debated, and recent archaeological and environmental evidence has increasingly complicated, and in some cases weakened, the original claim. Human groups close to the eruption may well have been wiped out, but evidence from other regions suggests continuity, survival and adaptation rather than global extinction followed by repopulation from a tiny remnant. [2]
The more interesting scientific question, therefore, is not simply whether humanity was almost wiped out, but how different human populations coped with a major environmental shock. Like many catastrophic events, the Toba eruption would have imposed severe local and regional pressures. Those who survived would not have done so because they were specially created or divinely protected, but because some populations had the behavioural flexibility, social cooperation, tool use and ecological knowledge needed to adapt to rapidly changing conditions.
The evidence for the eruption and its possible effects on human evolution is discussed in an article in The Conversation by Jayde N. Hirniak, Ph.D. Candidate in Anthropology at the Institute of Human Origins, Arizona State University, USA. Her article is reproduced here under a Creative Commons licence:


































