With Ancient Human DNA, Africa's Deep History Is Coming to Light https://t.co/y1NRffhKiI
But around 70 percent of those sequences are from Eurasia, where cold temperatures favor DNA preservation and considerable archaeological research has occurred. For researchers interested in the genetic history of Europe and Asia, there are plenty of excavated skeletons, sitting in museums and other collections, and there’s a good chance those bones hold appreciable DNA.
The situation is different in Africa — the place where Homo sapiens originated some 300,000 years ago and has continued diversifying ever since. Despite Africa’s prominence in the human story, so far only 30 ancient genomes between 300 and 15,000 years old have been published from the continent.
Part of the reason is methodological and environmental: Hot, humid conditions destroy DNA in human remains, long before geneticists attempt to extract it. However, in 2015 scientists showed that aDNA preservation can be 100-fold higher in the petrous — dense bone surrounding the inner ear — than other skeletal parts. In 2018, researchers used this bone to recover the oldest African genomes yet, from 15,000-year-old skeletons excavated from a cave in Morocco.
It’s unlikely geneticists will capture much older African DNA than that. So, the petrous find is a “game changer,” not a miracle maker. But bones between 5,000 and 15,000 years old — surrounding the start of the Holocene, our current geologic epoch — can reveal much about the genetic history of Africa. That’s because they predate major events that upended African populations and territories. These include the slave trade and colonialism. Earlier still, there were major migrations within Africa linked to the spread of herders and farmers, starting around 5,000 years ago.