Originally from Cape Verde, scientist reviews African past – 11/30/2023 – Darwin and God

Cesar Augusto Fortes-Lima is the name of the beast, ladies and gentlemen. It’s a name that could very well belong to a Brazilian, of course, and I came across it frequently when carrying out my usual follow-up of archaeological studies, especially those dealing with the genomics of ancient populations in Africa. I finally had the opportunity to interview him as one of the authors of a study on the great prehistoric expansion of the Bantu peoples on the African continent, reassembled thanks to the study of DNA.

And finally I clarified the mystery. Fortes-Lima’s family is from Cape Verde, which was part of the Portuguese colonial empire in Africa. But he grew up in Spain and is now a researcher at Uppsala University in Sweden. Below, I present the full interview I did with him for the report. I hope to have you here more often!

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Darwin and God – The samples of ancient human DNA used in his work are relatively recent. What is the chance of older individuals being included in the sample? From what I’ve seen, the hot climate is no longer a barrier to the study of ancient DNA, right?

Cesar Augusto Fortes-Lima – It is undoubtedly possible. Our study was able to obtain complete genomes from human remains from Africa dating back 97 to 688 years. Future studies could also obtain genomic data from older samples related to Bantu populations that were discovered in caves in Africa.

Even in hot regions, it is possible to find human remains in rocky caves that isolate samples from high temperatures or the acidic, humid soil conditions of tropical climates. More answers about the expansion of Bantu populations can be found in these caves.

In their advance across the continent, how did the Bantu interact with other peoples? Was there the asymmetry typical of other similar cases, in which men from expanded peoples generally incorporate women from dominated peoples into their group?

Our study clearly indicates the complexity of interbreeding between Bantu populations and local populations where they expanded. In West Africa, interbreeding occurred with hunter-gatherer populations, while in the east it occurred mainly with populations speaking Nilo-Saharan and Afro-Asiatic languages, and in the south with those speaking Khoisan.

Due to this complexity, in some regions of Africa the asymmetry is on the maternal or paternal side, or there is no asymmetry. This issue must be treated with care because in some groups the mixing pattern is different, as are the local populations with which they interact.

Does genomic data give clues as to why, such as agricultural, technical or military skills, that allowed the Bantu to spread over such a large area of ​​the African continent?

We were able to estimate how Bantu populations initially expanded from the region between Nigeria and Cameroon to the eastern and southern territories of the African continent. With data from hundreds of populations, we reconstructed the routes taken by the migratory waves that arrived in South Africa.

Since its initial expansion, its diversity patterns have progressively decreased to the extremes of expansion; these patterns also correlate with a decrease in the linguistic diversity of the more distant populations of west-central Africa.

The Bantu people initially used advanced livestock and agricultural techniques and, later, the use of ceramics and metals. We have been working together with archaeologists, linguists and geneticists to better understand the different stages and pathways of this important expansion. Our study shows how data and methods from different disciplines can complement each other to better understand the history of human populations.

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