If you have noticed there is a paucity of ancient DNA studies from Africa. I’m not entirly sure why. Part of it can because there simply are not as many samples from the African fossil record as ancient DNA decays rapidly in warm, moist climates. Europe samples are sometimes found in cold, dry caves. And another part can because the infrastructure is not as robust as it is in Eurasia. That all may change soon as at this week’s annual meeting of the Society for Molecular Biology & Evolution one group said they have partially sequenced 15 ancient African genomes and another group sequenced seven more ancient humans from South Africa.
The first group was lead by Pontus Skoglund, an evolutionary geneticist from Harvard. where he and colleagues obtained DNA from 15 ancient Africans from between 500 and 6000 years ago, and compared the data to 19 modern populations across Africa including from Bantu as well as the Khoe-San and the Hadza. For the most part the ancient DNA was comparable to that of people currently living in the same places where the samples were found, but some interesting exceptions showed introgression and migration patterns and among various groups, such as the following key points.
- Southern Africans diverged Western Africans several thousand years ago. They evolved key adaptations which altered their taste buds and protected them from the sun.
- Again, several thousand years ago, likely Tanzanian herders migrated far and wide, reaching Southern Africa centuries before the first farmers. But curiously modern Malawians, who live just south of Tanzania, are likely descendants of West African farmers rather than local hunter-gatherers
- West Africans were likely early contributors to the gene pool of sub-Saharan Africans, but the donors were a hodgepodge of what are now two modern groups—the Mende and the Yoruba.
- Curiously, one ancient African herder showed influence from even farther abroad, with 38% of their DNA coming from outside Africa.
The second group was lead by Carina Schlebusch from Uppsala University in Sweden. She and her colleagues partially sequenced seven ancient genomes. Three of which are 2000-year-old hunter-gatherers and four from 300- to 500-year-old farmers and compared them to modern day populations. Like the first group, there are some fascinating findings and some right in line with Skoglund’s group.
- More modern farmers, the ones as old as 500 years old, did have Bantu DNA in their genomes, but the ancient hunter-gatherers predated the spread of the Bantu.
- 9-22% of the DNA of these modern farmers, including the southern Khoe-San—comes from East Africans and Eurasian herders, a curious finding resonating with Skoglund!
- The ancient hunter-gatherers she studied split off from other groups approximately 260,000 years ago, about the age of the oldest H. sapiens fossil, that we know of.
These two groups will likely come out with their in depth analysis soon. These two studies resonate the importance of investing into ancient DNA studies in Africa, both in looking hard and setting up systems to study the genomes of ancient African human genetics. Based off 22 individuals we already are already finding out how Africans divided into groups and when and how they moved around.