A great African gene migration

Exploring a huge number of genes has helped uncover migration of early humans and the evolution of disease-resistant genes in Africa.

In a paper published in the journal Nature, researchers discovered three million new genetic variants across 50 ethnic groups, making this one of the widest data sets of sequenced genes in African populations to date.

This huge data set helped the team, led by Zané Lombard from South Africa’s University of the Witwatersrand, identify populations with genes that helped combat certain diseases, such as malaria and sleeping sickness.

The flow of these genes through populations showed how humans diversified into different populations across Africa, the cradle of modern humans.

For example, it was previously thought that some populations had disease resistant genes because they were from places where the disease was common, and that their geographic location drove the evolution of these genes. 

However, they found that multiple disease-resistant genes were present in other ethnic groups, or absent from another ethnic group in the same geographic location, which suggests that disease resistance was actually spread due to some populations mixing briefly during migration.  

“Despite their shared geography, the two groups varied significantly in the frequencies of three of the four medically relevant variants surveyed,” the authors write, which means groups that shared a geographic location gained resistant genes from elsewhere.

By tracking genes that were shared through different populations, the team fine-tuned our historical understanding of the origin of genes and language groups in Africa due to the Bantu Expansion, a large migration of sub-Saharan people that began more than 2000 years ago.

Previously, this migration was studied using archaeological evidence and linguistic analysis, but this new genetic data adds extra insight into this movement.

“Our results reveal a genetic continuum of Niger–Congo speaker populations across the continent and extend our current understanding of the routes, timing and extent of the Bantu migration – the defining demographic event of African genetic diversity,” they write.

Related reading: The genes that shape your face

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