Toba catastrophe theory Totally Explained

Everything about Toba Catastrophe Theory totally explained

According to the Toba catastrophe theory, 70,000 to 75,000 years ago a supervolcanic event at Lake Toba, on Sumatra, reduced the world's human population to 10,000 or even a mere 1,000 breeding pairs, creating a bottleneck in human evolution. The theory was proposed in 1998 by Stanley H. Ambrose of the University of Illinois at Urbana-Champaign.

History

Within the last three to five million years, after human and other ape lineages diverged from the hominid stem-line, the human line produced a variety of species, including H. ergaster, H. erectus, H. neanderthalensis and possibly H. floresiensis.
According to the Toba catastrophe theory, the consequences of a massive volcanic eruption severely reduced the human population. This may have occurred around 70,000–75,000 years ago when the Toba caldera in Indonesia underwent an eruption of category 8 (or "mega-colossal") on the Volcanic Explosivity Index. This released energy equivalent to about, three thousand times greater than the 1980 eruption of Mount St. Helens. According to Ambrose, this reduced the average global temperature by 5 degrees Celsius (9 degrees Fahrenheit) for several years and may have triggered an ice age.
Ambrose postulates that this massive environmental change created population bottlenecks in the various species that existed at the time; this in turn accelerated differentiation of the isolated human populations, eventually leading to the extinction of all the other human species except for the two branches that became Neanderthals (H. neanderthalensis) and modern humans (H. sapiens).

Evidence

Some geological evidence and computed models support the plausibility of the Toba catastrophe theory. The Greenland ice core data displays an abrupt change around this time, but in the corresponding Antarctic data the change isn't easily discernible. Ashes from this eruption of Lake Toba, located near the equator, should have spread all over the world.
Genetic evidence suggests that all humans alive today, despite their apparent variety, are descended from a very small population, perhaps between 1,000 and 10,000 breeding pairs.
Recent work by archaeologist Michael Petraglia suggests that in fact modern humans survived relatively unscathed in at least one settlement in India.

Analysis of lice genes

Alan Rogers, a co-author of this study and professor of anthropology at the University of Utah, says: “The record of our past is written in our parasites.” Rogers and others have proposed the bottleneck may have occurred because of a mass die-off of early humans due to a globally catastrophic volcanic eruption. The analysis of lice genes confirmed that the population of Homo sapiens mushroomed after a small band of early humans left Africa sometime between 150,000 and 50,000 years ago.

Migration

According to this theory, humans once again fanned out from Africa after Toba when the climate and other factors permitted. They migrated first to Arabia and India and onwards to Indochina and Australia (Ambrose, 1998, p. 631), and later to the Middle East and what would become the Fertile Crescent following the end of the Würm glaciation period (110,000–10,000 years ago).

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