The eruption of a supervolcano is extremely powerful, but also a very rare event. The first happened 25 million years ago, long before humans ever evolved. However, the last happened just 71,000 years ago, when Toba, located on the island of Sumatra, blew up. The caldera of Toba, a hole visible even from space, formed when the volcano collapsed during the eruption. Estimated 1,700 cubic-miles of rock, a volume comparable to almost 3 million Empire State Buildings, were displaced by the eruption. 

Toba was at least one to two magnitudes larger (and 1o times more powerful) than Tambora, considered the most violent eruption witnessed by humans in modern history. The eruption of Tambora in 1815 was followed by years of unusual chaotic weather in Europe, Asia and America, as the volcanic ash disrupted Earth's atmospheric circulation. Toba sent even more ash into the atmosphere. Some authors have suggested that the Toba supervolcano eruption and resulting volcanic winter almost killed off our species. Genetic evidence suggests, that around 70,000 years ago the human population, widely distributed on the African continent, suddenly collapsed. Only a small group survived. The exact cause of this genetic bottleneck is unknown, but a volcanic winter, with widespread and severe droughts in Africa, could maybe explain the reduced genetic variability. Most early humans didn't make it, as the climate and environment suddenly changed everywhere, and only a small group, with limited genetic variability, survived by chance in Eastern Africa. Later this group left Africa, migrating north into Europe and east into Asia. We, as modern humans, descend from those survivors.

In this scenario, humans were severely affected by Toba, even if not directly witnessing the eruption. However, recent discoveries suggest otherwise. The recent discovery of 65,000-year-old stone tools in northern Australia was quite a sensation. Humankind must have left Africa much earlier than previously thought, migrating between 75,000 and 60,000 years ago into Asia. Two human teeth, discovered more than 100 years ago in the Lida Ajer archaeological site, a cave located in Sumatra, even suggest that humans lived on Sumatra when the Toba erupted. Using a modern dating technique, the researchers were able to date the human remains of unknown age to 63,000-73,000 years, just in time for the Toba eruption. However, it is not clear if the now dated human remains came from an established, local population, living permanently on the island, or just from a migrating group, heading towards Australia.

The new timeline also poses a problem to the "genetic bottleneck caused by the Toba aftermath" hypothesis. It suggests that humans were far more widespread and already leaving Africa long before Toba went off. So if, and how, the Toba eruption influenced human evolution remains unclear at this moment. Maybe future discoveries, for example of human remains embedded in the volcanic ash of Toba, will shed some light on this question.