ENVIRONMENT

Surviving the Great Eruption

~74,000 years ago

Palaeolithic · Middle Stone Age · Last glacial

Around 74,000 years ago the Toba caldera in Sumatra produced the largest known eruption of the last two and a half million years, scattering ash across half the planet. For decades it was blamed for a global volcanic winter that supposedly drove humanity to the edge of extinction. The evidence now points the other way: lake records near the ash show no such winter, and at two South African sites the same microscopic glass lies within layers of unbroken, thriving human occupation.

Why it matters

A good story met the stratigraphy and lost. The Toba catastrophe once explained our species' low genetic diversity in one dramatic stroke; finer records dissolved the catastrophe while the diversity found other explanations. People fished a shrinking Ethiopian river through the ash years and kept living on the South African coast. The eruption remains a superb time marker, one glass layer tying sites across the world to a single year.

Dating & uncertainty

The eruption itself is well dated to about 74,000 years ago, and its microscopic glass is found from Sumatra to South Africa. What remains debated is its bite: high-resolution climate archives and archaeological continuity have dismantled the once-popular idea that Toba caused a global volcanic winter and a human near-extinction.

Sources

1. Smith et al. (2018), Nature · Humans thrived in South Africa through the Toba eruption about 74,000 years agodoi:10.1038/nature25967
2. Yost et al. (2018), Journal of Human Evolution · Subdecadal phytolith and charcoal records from Lake Malawi, East Africa imply minimal effects on human evolution from the ~74 ka Toba supereruptiondoi:10.1016/j.jhevol.2017.11.005
3. Kappelman et al. (2024), Nature · Adaptive foraging behaviours in the Horn of Africa during Toba supereruptiondoi:10.1038/s41586-024-07208-3

Our species’ history as one day

18:21:425 h 38 min before midnight

if the 315,000 years of Homo sapiens were compressed into a single day