Volcanic eruptions can be disastrous to every organism living in its shadows. However, some volcanoes are so large that they are referred to as supervolcanoes. When supervolcanoes erupt, it can have world-wide catastrophic effects. In 1816, Mount Tambora erupted in Indonesia, and the emitted ash blocked out the sun in areas as far away as Vermont. This time is now referred to the “year without a summer”. Additionally, supereruptions can also decrease global temperatures much like what happened when Krakatoa erupted in 1883. However, these effects are minute in comparison to the Toba supereruption around 74,000 years ago. It is the largest documented volcanic eruption and scientists hypothesized that caused mass extinction events around the world.
Toba Catastrophe Theory
The Toba Catastrophe Theory is based on the belief that when Toba erupted, it effected modern human evolution. Toba eruption is thought to be the largest volcanic eruption the Earth has ever witnessed. Scientists postulate that it was a category 8 eruption on the Volcanic Explosivity Index. Toba spewed 2,800 cubic kilometers of magma and thousands of tons of ashes, which caused the average global temperatures to decrease by a little over 3 degrees Celsius (37.4 degrees Fahrenheit). A decrease in temperature of that magnitude could trigger an ice age. Massive environmental changes effect biodiversity, to include the humans that lived during that time. The theory states that there were multiple human species, but the Toba eruption caused most of the population to go extinct. Therefore, the species left evolved to become modern day humans. Additionally, the eruption caused many plant and animal species to go extinct as well.
Further proof that the eruption occurred can be seen in the geography surrounding the volcano. The supereruption caused a massive indentation in the ground which later filled with water to great Lake Toba.
Recently, new evidence surfaced that makes scientists question if a volcanic eruption really brought the human species to the verge of extinction. In a study published in the Journal of Human Evolution, scientists examined sediment cores from Lake Malawi located in Aftrica. In these cores, the time that Toba erupted is marked by crystals and glass, called cryptotephra. Based on traces of microscopic plant matter, they did not find evidence that there was a mass extinction event. Additionally, they didn’t find any changes in the microscopic composition that indicated a change in climate to support the theorized ice age.
In another study in Mossel Bay, South Africa, scientists analyzed cryptotephra layers in comparison to sediment layers that include tools, bones, and other indicators of human occupation. They found that prehistoric artifacts exist in approximately equal amounts above and below the layers containing cryptotephra. This means that the human populations likely did not change after the eruption, which does not support the theory of a mass extinction.
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Resources: https://www.sciencedaily.com/terms/toba_catastrophe_theory.htm, https://www.sciencedirect.com/science/article/pii/S0047248417302750?via%3Dihub, https://www.smithsonianmag.com/smart-news/ancient-humans-weathered-toba-supervolcano-just-fine-180968479/, https://www.theatlantic.com/science/archive/2018/03/supervolcano-goes-boom-humans-go-meh/555356/
Picture Resources: Featured Image: https://pixabay.com/en/volcanic-eruption-eruption-volcano-67668/, https://www.mediawiki.org/wiki/File:Tobaeruption.png, https://en.wikipedia.org/wiki/File:Toba_zoom.jpg