What set these migrations in motion? Climate change – today’s big threat –
seems to have had a long history of tormenting our species. Around 70,000
years ago it was getting very nippy in the northern part of the globe, with ice
sheets bearing down on Seattle and New York; this was the last Ice Age. At
that time, though, our species, Homo sapiens, was still limited to Africa; we
were very much homebodies. But the encroaching Ice Age, perhaps coupled
with the eruption of a super-volcano named Toba, in Sumatra, dried out the
tropics and nearly decimated the early human population. While Homo
sapiens can be traced to around 200,000 years ago in the fossil record, it is
remarkably difficult to find an archaeological record of our species between
80,000 and 50,000 years ago, and genetic data suggest that the population
eventually dwindled to as few as 2,000 individuals. Yes, 2000 – fewer than fit
into many symphony halls. We were on the brink of extinction.