That was a close one
According to a new article over at the Scientific American website, humans nearly became extinct a million years ago. They estimate that the breeding pool was down to just 18,500 individuals, a group smaller than many endangered species. That wasn't the last time we almost got wiped off the map, either - it's posited that the Toba super-volcano might have reduced the total breeding human population to 10,000 or less, a mere 70,000 years ago.