PreNeolithicMalaria · Evolutionary history of the sickle cell trait among Central African hunter-gatherers and farmers
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2019-05-01 → 2021-10-17
- EU contribution
- €224,934
- Participants
- 1
- Scheme
- MSCA-IF-EF-CAR
Lines connect the coordinator with its partners.
Results in brief
Evolutionary history of the sickle cell trait among Central African hunter-gatherers and farmers
The 'PreNeolithic Malaria' project investigates the Paleolithic origin of human genetic traits that confer protections against deadly malarial infections. By applying cutting-edge methods, the project explored the genetics of Central African populations with different subsistence economies, either based prevalently on farming or hunting-gathering. Both groups of populations are known to be affected by genetically inherited blood disorders that confer them a variable level of protection from strong malarial infections, by allowing them to keep the infection at low levels. These blood disorders are caused by different kinds of genetic mutations, which are transmitted from one generation to the other as long as malaria is endemic in the environment where the populations live. Such evolutionary adaptation is linked to a double public health problem: the first is the need for people to survive malarial infections, not yet eradicated in many parts of the world with limited access to medical treatment; the second is caused by the mutations causing blood diseases that are protective from malaria but also can be damaging for the carrier. This scenario is considered as an evolutionary trade-off that allows populations living in malarial endemic areas to survive the infections at the cost of losing the lives of individuals who are affected by severe inherited blood conditions. As many of the populations living in malarial areas are very little studied from a medical genetic perspective, the genetic basis of their inherited blood conditions is also limitedly known. This project serves the double aim of studying in deep the genetic underlying blood disorders in these populations, both known and unknown, and, at the same time, understanding the ultimate evolutionary origin of human adaptation to a deadly parasite (the malarial causal parasite) which has affected our species for thousands of years. Conclusions of the action: The results so far obtained from the preliminary data analysis suggest a high variation of genetic variants protecting from malaria in hunter-gatherers, some of which are known to be mostly present in populations outside of Africa and differ from those carried by neighboring farmers. As such, my results point to an ancient adaptation to malarial parasites in hunter-gatherers
Data: CORDIS, © European Union
Project 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.
Original text from CORDIS.
Participants
- THE UNIVERSITY COURT OF THE UNIVERSITY OF ST ANDREWS · ST ANDREWSCoordinatorUnited Kingdom
Links
Data: CORDIS, © European Union