Toba catastrophe theory

The Toba catastrophe theory is a theory of how modern humans evolution has been affected by a recent supervolcanic event. It was proposed by Stanley H. Ambrose, of the University of Illinois at Urbana[?]. Knowledge of pre-human history is largely theoretical, but based in fossil, archeological, and genetic evidence.

Within the last three to five million years humans are believed to have diverged from apes, and were successful in producing a variety of human species. According to the Toba catastrophe theory a massive volcanic eruption changed the course of human history by severely reducing the human populations (called a bottleneck'): Around 75,000 years ago the Toba supervolcano in Indonesia errupted with a force three thousand times more powerful than Mount Saint Helens.

According to Ambrose, this led to a decrease in the average global temperatures by as much as 15°C. This massive environmental change is believed to have created population bottlenecks in the various human species that existed at the time; this in turn accelerated differentiation of the isolated human populations, eventually leading to the end of all the other human species except for the branch that became modern humans.

Some Geological evidence and computed models supports the plausibility of the Toba catastrophe theory, and genetic evidence shows that humans, despite their apparent variety all are related to a very small population. Using the average rates of genetic mutation, some geneticists have clocked this rated of change back to a time coinciding with the Toba event.

After Toba, and when the climate and other factors permitted, humans once again fanned out from Africa migrating first to Indochina, and Australia. The fertile crescent and the Middle East, being the cradle of civilization, migration routes to Asia created population centers in Uzbekistan, Afghanistan, and India. Divergences in skin color appeared - varied melanin levels to appropriate UV absorption rates for necessary vitamin D production. Europe became populated by migrants from the Uzbekistan region when the last ice age ended and Europe began to be more hospitable.