200,000 years ago, a new species appeared on the African landscape -- Homo sapiens. Scientists imagined eastern Africa was a real-life Garden of Eden, but the latest research suggests we evolved in many places across the continent at the same time. Diversity is etched into our biological blueprint. DNA from a 19th Century African-American slave is forcing geneticists to re-think the origins of our species. The idea is that our ancestors met, mated and hybridized with other types of human in Africa -- creating ever greater diversity within our species.