Did you read about the new hypothesis that the entire human species, about 70,000 years ago, declined to no more than 2000 people? Genetic studies suggest that severe climate conditions caused the near extinction of Stone Age humanity. At first I wondered whether this discovery meant only one small group of people survived. The researchers think, however, that “humans separated into small populations prior to the Stone Age” and later “came back together and began to increase in numbers and spread to other areas.” Depending on how many tens of thousands of years they were separated, though, I wondered why genetic drift didn’t make it impossible for them to produce fertile offspring when they reunited.
This theory brings to mind numerous SF and fantasy post-apocalyptic scenarios. (It also makes me think of Noah’s flood and the dispersion of the people who built the