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Shedding Light on Human Genetic Diversity in Africa

Scientists reported on Wednesday that they had discovered evidence of an extinct branch of humans whose ancestors split from our own a million years ago. The evidence of these humans was not a fossil. Instead, the researchers found pieces of their DNA in the genomes of living people from West Africa. The researchers tracked how new variants of genes arose in each branch of humans. For the most part, the data fit the current thinking about human evolution. But in a few populations in West Africa, such as the Yoruba of Nigeria and the Mende of Sierra Leone, some of the DNA contained variants not found in other living humans, or even in Neanderthals or Denisovans. The scientists could not say what species of human the ghost archaic population belonged to. The fossil record in Africa offers only a few hints. A million years ago, Africa was home to a species known as Homo erectus. The oldest fossils of Homo sapiens date back 300,000 years, in Morocco. But researchers have also found a remarkable range of other fossils from our genus in Africa during that period of time.