The effect that agriculturalists, and the farming that they introduced, has had on rainforest hunter-gatherers in Africa is explored in a paper in Nature Communications. The study sheds light on the social impact that farming has had on these populations and highlights the recent genetic exchange that occurred between the two groups.
The emergence of farming in West-Central Africa approximately 5,000 years ago initiated the spread of an agricultural and sedentary lifestyle throughout sub-Saharan Africa. However, some rainforest hunter-gatherer populations continued to live as mobile bands and the full extent of the effect that the dispersion of agricultural culture and technology has had on the demographic history of rainforest hunter-gatherers remains largely unknown.
Lluis Quintana-Murci and colleagues generated genome-wide single nucleotide polymorphisms data from present day rainforest hunter-gathers and agriculturalists across sub-Saharan Africa to study the genetic diversity and evolutionary relationship between these populations. They find that the gene flow between the two groups occurred only in the last 1,000 years, suggesting that initial interactions between the populations were limited to the exchange of socio-economic ideas, such as tools and plant cultivation techniques. The genomic signatures further suggest that the expansion of African farming populations occurred before, and therefore cannot be attributed to, the emergence of agriculture.