The largest known volcanic eruption in human history, 74,000 years ago, was at Mount Toba in northern Sumatra. Researchers believed this cloud of millions of metric tons of volcanic ash and sulfur set off a volcanic winter which included a thousand years of cold climate and perhaps a human genetic 'bottleneck' which may have reduced our species to just a few thousand mating pairs.
Other hypotheses have believed it may have been other volcanoes and they were even responsible for the demise of neanderthals.
Climate modeler Claudia Timmreck of the Max-Planck Institute for Meteorology created a numerical model and says it was nothing so extreme. Temperatures dropped less than half previous estimates and the effects of sulfur in the stratosphere would have settled out and been diminished within 2 or 3 years rather than a thousand.
Stanley Ambrose, anthropologist at University of Illinois Urbana-Champaign and original proponent of the huma evolutionary 'bottleneck' has noted in the past similar models have flaws, namely an inability to correctly know how much sulfur was released in a large eruption like Mount Toba.
