"Humans may have come close to extinction about 70,000 years ago, according to the latest genetic research.

The study suggests that at one point there may have been only 2,000 individuals alive as our species teetered on the brink.

This means that, for a while, humanity was in a perilous state, vulnerable to disease, environmental disasters and conflict. If any of these factors had turned against us, we would not be here."

Of course there is no suggestion that a global cataclysm could have caused not only the reduction in numbers, but also the reason for venturing out of Africa.

So, what happened 70,000 years ago?