Human history is written in DNA. Where did our ancestors live and who they loved — the story is right there if we can see their genes. Trouble is that the ravages of climate and time degrade DNA, making its secrets increasingly difficult to uncover. Gradually, however, scientists began to go back in time by sequencing ancient DNA. In 2016, researchers at the Max Planck Institute for Evolutionary Anthropology splicing DNA together from a skeleton found in a cave in northern Spain. Human ancestors lived more than 430,000 years ago.
Other ancient DNA discoveries have added to our knowledge of humanity’s distant past. A cave in Siberia yields a bone that DNA analysis shows belonged to a woman from 90,000 years ago, half Neanderthals and half Denisovan. Another skeleton from the same cave gave us Neanderthal DNA from 120,000 years ago. But all of this DNA has one thing in common: Almost all of it comes from Europe and Asia. The oldest DNA from sub-Saharan Africa – where the story of the whole human race begins – dates back less than 10,000 years ago.
Now a new discoveries Africa’s oldest DNA is pushing back against this bias, and in the process revealing how our ancestors lived and moved on the continent tens of thousands of years ago. These findings add further evidence to the idea that, about 20,000 years ago, some people in Africa began to cluster together into larger, more settled populations. Evidence of particles and pigments from burial sites suggests that something changed in Africa 20,000 years ago that made these societies closely resemble today’s society. Now DNA evidence suggests that it may be involved in these ancient patterns of movement. “We’ve never had any actual genetic evidence for that up until this point,” said Jessica Thompson, an anthropologist at Yale University and co-author of the new study. We have never had any skeletons.
The big problem facing archaeologists is that ancient DNA did not last long in tropical environments. Heat and humidity decompose it, making it extremely difficult to extract from the bone. That’s one reason why the best preserved ancient genomes scientists have access to tend to come from cold and dry environments – often in caves sheltered from the weather. For this study, Thompson and her colleagues had to work with extremely small pieces of bone — in one case, the DNA came from a finger bone of an infant. The oldest DNA they managed to recover from African bones dates from 17,000 to 20,000 years ago, although in this case the bones available were so few that the researchers had to estimate the age of the bones. Ostrich egg artifacts found in the burial site.
Thompson and her colleagues analyzed the DNA of 34 individuals — six of them for the first time — who lived in Africa between 500 and 20,000 years ago. By analyzing specific regions within these genomes, they were able to model how ancient populations may have moved between 50,000 and 20,000 years ago. Maggie Katongo, assistant archeologist at the Livingstone Museum in Zambia, a PhD student at Rice University and one of the study’s co-authors, said the findings will help tell the history of the people in the area. south-central Africa. “This type of research provides us with information that can be used to tell the story of past communities that may have lived around different parts of Zambia,” she said.
The researchers compared the DNA of ancient Africans with samples of people living in Africa today to see how much genetic variation there was between people living in different places and times. Ancient DNA from central south and east Africa shows that these people had ancestors from three different regions of the continent: Central Africa, South Africa, and East Africa. “It shows there’s a lot of movement and the mix of long-distance and eastern Africa in particular is a really important hub,” Thompson said.
