Near Extinction for Humans

This National Geographic article describes a phenomenon that happened around 150,000 years ago before humans migrated out of Africa.  Because of drought conditions in Africa, the human population dropped to around 2,000 individuals.  These remaining individuals formed two population groups; one in south Africa and the other in east Africa.  These two populations lived in genetic isolation for nearly 100,000 years before recombining and moving out of africa around 40,000 years ago.