DNA from child burials reveals ‘profoundly different' human landscape in ancient Africa
Central Africa is too hot and humid for ancient DNA to survive—or so researchers thought. But now the bones of four children buried thousands of years ago in a rock shelter in the grasslands of Cameroon have yielded enough DNA for scientists to analyze. It's the first ancient DNA from humans in the region, and as the team reports today in Nature, it holds multiple surprises. For one, the area today is the homeland of Bantu speakers, the majority group in western and Central Africa. But the children turned out to be most closely related to hunter-gatherers such as the Baka and Aka—groups traditionally known as "pygmies"—who today live at least 500 kilometers away in the rainforests of western Central Africa.
"In the supposed cradle of Bantu languages and, therefore, Bantu people, these people are basically ‘pygmy' hunter-gatherers," says Lluís Quintana-Murci, a population geneticist at the Pasteur Institute and CNRS, the French national research agency, who was not part of the new study. He and others have long suspected that these groups had a larger range before the Bantu population exploded 3000 years ago. The second big surprise came when the team compared the children's DNA to other genetic data from Africa and found hints that the Baka, Aka, and other Central African hunter-gatherers belong to one of the most ancient lineages of modern humans, with roots going back 250,000 years.
In the new study, geneticists and archaeologists took samples from the DNA-rich inner ear bones of the four children, who were buried 3000 and 8000 years ago at the famous archaeological site of Shum Laka. The researchers were able to sequence high-quality full genomes from two of the children and partial genomes from the other two. Comparing the sequences to those of living Africans, they found that the four children were distant cousins, and that all had inherited about one-third of their DNA from ancestors most closely related to the hunter-gatherers of western Central Africa. Another two-thirds of children's DNA came from an ancient "basal" source in West Africa, including some from a "long lost ghost population of modern humans that we didn't know about before," says population geneticist David Reich of Harvard University, leader of the study.
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