This guest post is by Brenna Henn, a doctoral student in Stanford University’s Department of Anthropology and a 23andMe consultant. Brenna studies human evolution using genetic information. Her interests include the origin of modern humans, migration patterns among African groups, and genetic models of demography.Proceedings of the National Academy of Sciences, scientists from Stanford University (several of whom are also associated with 23andMe, including myself) have used the principle of genetic and cultural exchange to find the first genetic evidence of a prehistoric migration of people from Tanzania to southern Africa. We discovered a mutation (aka ‘SNP’) on the Y-chromosome that originated about 10,000 years ago in eastern Africa and is now most common among people from two regions: Tanzania and southern Africa.Pastoralists (people who rely heavily on animal husbandry for food) such as the Datog and Burunge of northern Tanzania carry the newly discovered SNP. In fact, it is present among 30-40% of men from these populations. Unexpectedly, the click-speaking Kxoe of southern Africa carry the same SNP at similar levels to the Tanzanian populations, indicating that these people are closely related to the Tanzanian pastoralists. The evidence indicates that men from southern and eastern Africa shared very recent common ancestors between about 1,200 and 2,700 years ago.With this genetic evidence in hand, we then turned to archaeologists to see if the fossil record indicated an ancient migration around this time. Nama of Namibia began practicing pastoralism not long after its arrival in southern Africa and continue to do so today.The question of whether the shift from hunting and gathering to agriculture was the result of cultural exchange or actual migrations between groups is one of the most important debates among archaeologists and geneticists. With this new genetic evidence, we think we have answered this question, at least in southern Africa. Future studies will further examine the relationhip between genes and culture, and how this relationship has influenced the genetic and cultural makeup of modern African populations.
The Origins of Pastoralism in Africa: What do the Genes Say
August 4, 2008