Human near-extinction event discovered?

Lake bed sediments signal epic drought drove Eve out of Africa. Timing 70,000 years ago agrees with mitochondrial DNA evidence of ancient genetic bottleneck and peopling of the world by 10,000 early Africans.

-- from annual meeting of the American Geophysical Union via the BBC

P.S. Note this was a climate change? Shall we try not to let this happen again?