Ancient Skeletons Reveal Secrets to Africa’s Unknown Past
Two years ago researchers discovered the first ancient human genome in Africa, but this week an international team of scientists have reported that they had recovered far older bone fragments.
The fragments found in Malawai date back 8,100 years. They also retrieved DNA from 15 other ancient people in eastern and southern Africa, and compared the genes to those of living Africans.
The analysis published in Cell, includes important clues to Africa’s unknown prehistory, including details of migrations that shaped the populations that have become today.
A geneticist at the University of Oxford, George Busby, explained, “There are some amazing insights that come from it.”
Scientists found it more difficult to use ancient DNA to irradiate the past in Africa than Europe. This is due to their being fewer skeletons in museums, and the fact that most searches for genetic material failed.
Jessica Thompson, an archaeologist at Emory University who does field work in Malawi, said, “It’s been mad, watching all the advances in what we understand about European prehistory.” More recently, she has worked with experts in ancient DNA and began searching for skeletons in Malawi. She and her colleagues analysed DNA from 16 of these fossils, along with the one previously found in Ethiopia, comparing the genetic material to that of living people throughout Africa as well as on other continents.
For the new study, David Reich, a geneticist at Harvard Medical School and co-author, alongside his colleagues analysed DNA from 16 fossils, along with one previously found in Ethiopia, comparing the genetic material to that of living people throughout Africa as well as on other continents.
As a result, they were able to determine how living Africans descended from ancient populations, which are older in Africa than anywhere else on Earth. “Africa is now going to be fully included in the ancient genomics revolution,” Dr Reich said. “We’re going to be able to do a lot of things in Africa that we’ve been able to do in Europe and elsewhere.”
Earlier studies concluded that the hunter gatherers who live today in the Kalahari Desert and other parts of Southern Africa descend from the branch believed to be the first to have divided from other Africans. However, the new study suggests that there may be even older branches in the tree. “Something more complicated is going on,” Dr Reich added.
The group discovered that some people in West Africa share a unique collection of genetic variants that suggest an even deeper ancestry, raising the possibility that an earlier population of humans in West Africa diverged from rest.
At present, only a single, small population of living Africans share the same genetic link, those being the Tanzanian hunter-gatherers called the Hadza. “They’re the group of living Africans most closely related to non-Africans,” he said.
Dr Thompson is now looking to the future, as she hopes to dig into archaeological sites for evidence of the Bantu arrival in Malawi, looking for tools, bones and perhaps even more DNA.
She added, “We want to see if we can catch the timing of that transition and see if there was trade between the groups, or if the whole area was taken over.”
Anicent DNA in skeletons from western Africa would be just as valuable; it may hold profound secrets about the early history of our species.
Nevertheless, this won’t be easy to find. The early archaeological record there is sparse, and there are few caves to search. Pontus Skoglund, a postdoctoral researcher and co-author of the new study, said, “It is the major gap in our ancient DNA coverage.”