There's an interesting article at New Scientist about what is possibly the most crucial issue of human prehistory: the Toba supervolcano explosion, which happened some 74,000 years ago.
There are two parallel debates: how catastrophic was Toba and were humans (H. sapiens) already in southern Asia then. They converge at the point on how could they survive the consequences of the supervolcano.
The debate seems to be quite hot and multifaceted: for some the catastrophe was really bad while for others only half that bad, for some humans were already in South Asia as evidenced by the toolkits so similar to African ones while others guided by the dubious molecular clock approaches prefer to consider a post-Toba out of Africa migration and yet others would push the dates of the migration back to c. 125,000 years ago, right at the Abbassia Pluvial, when there's abundant evidence also of H. sapiens in North Africa and Palestine.
A lot of information and synthesis of the various viewpoints can be found in the abstracts of the Oxford conference titled "The Toba Super-Eruption: A critical moment in human evolution?", which are freely downloadable as PDF.