We almost went the way of the dinosaur. Humans came close to extinction 70,000 years ago, when genetic research shows that there were only about 2,000 of us alive. Just one major disease or environmental disaster (like the meteor that wiped out the dinosaurs), and we wouldn’t be here today. Unlike chimps, who are our closest relatives, all human DNA is almost identical. We split off the family tree 5 or 6 million years ago, which is plenty of time for lots of genetic differences to turn up. The fact that we’re all so alike means that in the recent past, there weren’t many of us around. Everyone on Earth today came from that tiny, struggling population.
But once we got on our feet again, we traveled extensively.