Roughly 74,000 years ago, a super volcano erupted in Sumatra. This super volcano is known as Mount Toba. The eruption was on a scale that modern man can scarcely imagine. Volcanic ash was spread all over southern Asia. The ash and gasses that were expelled theoretically wreaked havoc on the planet. This theoretical havoc is known as the Toba Event.
The eruption that, in theory, caused the Toba Event was actually the largest of four eruptions from Mount Toba during the Quaternary Period. More specifically, it was the “Youngest Toba Tuff” eruption. It left a 60.1 by 18.6 mile caldera that is now a caldera lake known as Lake Toba. Such an explosive eruption would certainly have the ability to affect many things on the planet. The Toba Event is a theory that suggests that the Toba eruption did affect many things on the planet, specifically humans.
The study of human genetics has shown us that something called a bottleneck has happened at least once, probably more, in human history. A population bottleneck occurs when the numbers of a species’ population are reduced so dramatically that the genetic diversity of the species becomes limited. In other words, every individual that comes after the bottleneck has occurred is a descendant of the small group of individuals who were left after the population decline. A bottleneck can occur for many reasons, disease, famine, climate change or say a volcanic winter, like the Toba Event theory suggests.
Another interesting thing that may have happened around the time the YTT eruption took place is the start of a global cooling trend and a glacial period. It is known that a large volcanic eruption can cause a volcanic winter, as evidenced by the modern Tambora eruption that resulted in the “year without a summer.” The Tambora eruption was not nearly as powerful as the Youngest Toba Tuff eruption. Therefore, it is quite possible that the Youngest Toba Tuff eruption played a role in this global cooling.
It has been theorized that this global cooling was caused by the Youngest Toba Tuff eruption. It has even been suggested that this cooling, caused or exacerbated by the Toba eruption, caused a decline in the Earth’s human population, thus creating a population bottleneck. This is, in essence, the Toba Event. We know that something like the Toba Event can occur in the future and is likely to have occurred in the past.
Unfortunately, it is currently impossible to tell when this decrease in the diversity of human genetics occurred. It is also impossible to know what the Earth’s hominid population was at the time of the Toba Event, how many hominids died as a result and how many were left to repopulate (and then some) the planet. Interestingly, it is believed that roughly 3,000 to 10,000 individuals were left to breed. That’s one-sixth or less of the people needed to fill the Roman Coliseum.
Toba Volcano, Through the Bottleneck, retrieved 8/25/10, andaman.org/BOOK/originals/Weber-Toba/ch5_bottleneck/textr5.htm#5-2
Jones, Sacha, The Toba Supervolcanic Eruption, retrieved 8/25/10, cambridge.academia.edu/documents/0072/8443/Jones_in_Petraglia_Allchin__2007.pdf