The Pygmy hunter–gatherers of central Africa are an amalgamation of various groups of people that are on average about 4 feet tall. Some genetic and linguistic evidence point to them being direct descendants of hunter-gatherers from the late Stone Age. But that’s about it, there’s not much archaeological evidence to corroborate with this observation.
Most modern day Pygmy populations live in the rain forest alongside Bantu-speaking farmers. It is one of the few places in the world were we see cohabitation of hunter-gatherers with farmers. These two groups have very different lifestyles and a new multidisciplinary study sought to determine to what extent social, cultural and demographic factors have influenced the genetic heritage of these two populations.
The open access paper, “Maternal traces of deep common ancestry and asymmetric gene flow between Pygmy hunter–gatherers and Bantu-speaking farmers,” is published in PNAS. The authors analyzed the variation in mtDNA of 1,404 individuals from 20 Bantu farming populations and 9 Pygmy populations. They were able to identify a sing ancestral and indigenous lineage of mtDNA that was formerly shared by Pygmies and Bantu people. The Pygmy lineage diverged from the ancestral population about 70,000 years ago, at which point they began to be isolated and when the short phenotype began to differentiate. Pygmy variability is much more weak compared to the variability observed in Bantu populations which tells us that modern Pygmies came from a small common ancestor population.
And since they were comparing mtDNA, starting 40,000 years ago, the researchers were able to identify that female Pygmies were reproducing with Bantu males. Subsequently, the mtDNA gene pool of the Pygmies was not enriched by external gene influxes. The Bantu farmer gene pool, however, was enriched during the so-called “Bantu expansions”, an event corresponding to technological, demographic and linguistic advances in the late Stone Age.
The authors write that they wanna expand their study to Y-chromosomal relationships between these two groups and also to study the relationships between the genome and the populations’ vulnerability or resistance to pathogens. Why do they wanna do this? Well, as Razib has written often, the transition into sedentary lifestyle is often accompanied with a shakeup on populations, pathogens, and selection.
- Quintana-Murci, L., Quach, H., Harmant, C., Luca, F., Massonnet, B., Patin, E., Sica, L., Mouguiama-Daouda, P., Comas, D., Tzur, S., Balanovsky, O., Kidd, K.K., Kidd, J.R., van der Veen, L., Hombert, J., Gessain, A., Verdu, P., Froment, A., Bahuchet, S., Heyer, E., Dausset, J., Salas, A., Behar, D.M. (2008). Maternal traces of deep common ancestry and asymmetric gene flow between Pygmy hunter-gatherers and Bantu-speaking farmers. Proceedings of the National Academy of Sciences, 105(5), 1596-1601. DOI: 10.1073/pnas.0711467105