Israeli researchers have concluded that approximately 70,000 years ago humans may have narrowly dodged extinction as drought killed off all but an estimated 2,000 people (according to researchers at Stanford) scattered about sub-Saharan Africa in the pre-Stone Age.

The new study looks at the mitochondrial DNA of the Khoi and San people in South Africa which appear to have diverged from other people between 90,000 and 150,000 years ago.

The researchers led by Doron Behar of Rambam Medical Center in Haifa, Israel and Saharon Rosset of IBM T.J. Watson Research Center in Yorktown Heights, N.Y., and Tel Aviv University concluded that humans separated into small populations prior to the Stone Age, when they came back together and began to increase in numbers and spread to other areas.

Eastern Africa experienced a series of severe droughts between 135,000 and 90,000 years ago and the researchers said this climatological shift may have contributed to the population changes, dividing into small, isolated groups which developed independently.

Climatological shift. Bringing about widespread regional drought. As a point of comparison, there are estimated to be over ten times as many polar bears in existence now as there were humans 70,000 years ago – and global warming may drive polar bears to extinction within the next hundred years. We were awfully close to extinction. A hair’s breadth.

Obviously, with 6.6 billion of us now, and vastly improved technology, global warming won’t drive us to extinction. But it could kill a lot of people, and almost certainly will wipe many species off the face of the planet. If human activity is having an effect – and the data strongly suggests that it does – then we need to do something about that. Before it’s too late, and many other species are submitted to the fate we oh-so-narrowly avoided.