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Evolutionary history of the sickle cell trait among Central African hunter-gatherers and farmers

Project description

Human genomic evolution during the Neolithic transition

In sub-Saharan Africa, 400 000 people die every year from malaria. The prevailing view among scientists was that malaria was active since the Neolithic transition, a period marked by the diffusion of agriculture. It is believed that the genetic disease sickle cell anaemia developed as a survival mechanism against malaria. Recent comparative studies detected Pygmy populations with high incidence of sickle cell anaemia, suggesting that malaria has a pre-Neolithic origin. The EU-funded PreNeolithicMalaria project will use genetic data from Bantu and Pygmy populations to test the hypothesis that sickle cell developed in pre-Neolithic times. If proven, it will indicate that human genomic resistance to malaria could have facilitated the Neolithic transition.

Objective

Tertian malignant malaria (or malaria for short) currently kills more than 400k people per year in sub-Saharan Africa. Malaria probably became endemic in that region during the Neolithic transition, due to the spread of agriculture, thus imposing a strong selective pressure on the human genome. As a consequence, sickle cell anemia, a genetic disease that protects against malaria, is thought to have been selected and maintained at high frequencies among sub-Saharan farmers (Bantus) by balancing selection since the Neolithic. However, recent observations provide grounds for challenging this predominant view. Indeed, the high incidence of the sickle cell trait in sub-Saharan hunter-gatherers (Pygmies) and a pre-Neolithic origin of the human malaria parasite suggest that malaria infections affected humans much earlier than the Neolithic. Using genetic data from a cohort of Bantu and Pygmy populations, I will here test the alternative hypothesis that the sickle cell trait was selected and spread among African hunter-gatherers before the Neolithic. If proved correct, this hypothesis would indicate that human genomic resistance to parasitemias exacerbated by the spread of agriculture could have facilitated the Neolithic transition, rather than being its consequence. This new knowledge would allow us to re-evaluate the long-term role played by genetic adaptation to malaria in human evolution and to put into a new perspective a classical case study of gene-culture co-evolution.

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Coordinator

THE UNIVERSITY COURT OF THE UNIVERSITY OF ST ANDREWS
Net EU contribution
€ 224 933,76
Address
North street 66 college gate
KY16 9AJ St andrews
United Kingdom

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Region
Scotland Eastern Scotland Clackmannanshire and Fife
Activity type
Higher or Secondary Education Establishments
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Other funding
€ 0,00