In the beginning of the last ice age a supervolcano erupted in Indonesia. Theory states the effects of the eruption caused global climatic changes for many years, effectively obliterating most of the earlier cultures. Y-chromosomal Adam (90000 - 60000 BP, dated data) was initially dated here. Neanderthals survived this abrupt change in the environment, so it's possible for other human groups too. According to the theory humans survived in Africa, and began to resettle areas north, as the effects of the eruption slowly vanished. Upper Paleolithic revolution began after this extreme event, the earliest finds are dated c.50000 BCE.