eLife digest | Admixture into and within sub-Saharan Africa

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Admixture into and within sub-Saharan Africa

eLife digest

Affiliation details

Wellcome Trust Centre for Human Genetics, United Kingdom; Wellcome Trust Sanger Institute, United Kingdom; Medical Research Council Unit, The Gambia; Royal Victoria Teaching Hospital, The Gambia; Centre National de Recherche et de Formation sur le Paludisme, Burkina Faso; University of Rome La Sapienza, Italy; Navrongo Health Research Centre, Ghana; Komfo Anokye Teaching Hospital, Ghana; University of Buea, Cameroon; KEMRI-Wellcome Trust Research Programme, Kenya; Kilimanjaro Christian Medical College, Tanzania; London School of Hygiene and Tropical Medicine, United Kingdom; College of Medicine, University of Malawi, Malawi; University of Bamako, Mali

Our genomes contain a record of historical events. This is because when groups of people are separated for generations, the DNA sequence in the two groups’ genomes will change in different ways. Looking at the differences in the genomes of people from the same population can help researchers to understand and reconstruct the historical interactions that brought their ancestors together. The mixing of two populations that were previously separate is known as admixture.

Africa as a continent has few written records of its history. This means that it is somewhat unknown which important movements of people in the past generated the populations found in modern-day Africa. Busby et al. have now attempted to use DNA to look into this and reconstruct the last 4000 years of genetic history in African populations.

As has been shown in other regions of the world, the new analysis showed that all African populations are the result of historical admixture events. However, Busby et al. could characterize these events to unprecedented level of detail. For example, multiple ethnic groups from The Gambia and Mali all show signs of sharing the same set of ancestors from West Africa, Europe and Asia who mixed around 2000 years ago. Evidence of a migration of people from Central West Africa, known as the Bantu expansion, could also be detected, and was shown to carry genes to the south and east. An important next step will be to now look at the consequences of the observed gene-flow, and ask if it has contributed to spreading beneficial, or detrimental, mutations around Africa.

DOI: http://dx.doi.org/10.7554/eLife.15266.002