The Toba Catastrophe

The largest well-documented supereruption of the recent past struck at Toba, in Sumatra, Indonesia, about 74,000 years ago. It ejected an estimated 2,800 cubic kilometers of material — roughly the volume of a small mountain range turned to dust.

The ash and gas it threw into the sky likely triggered a volcanic winter, dropping global temperatures by several degrees for years.

Some scientists link Toba to a population bottleneck — a moment when the global human population may have crashed to only a few thousand people. This idea, the Toba catastrophe theory, is genuinely debated, and many researchers think the timing does not line up.

What is not disputed is that humans today carry surprisingly little genetic variation for a species spread across the planet. Something narrowed our ancestry — whether Toba or not.