It is well known that scientists believe we all came out of Africa some 200,000 years ago. But some of these first ancestors of ours also returned before Europeans even got there. The migration path went both ways. This is a resounding discovery. Erika Chek Hayden in her recent Nature article, “African Genes Tracked Back” says this “reverse” or two-step migration meant that these ancestors carried “…genes from the rest of the world [which] were carried back to southern Africa, long before European colonizers arrived.” The findings are from “a flurry of research enabled by better tools to survey African genomes” (Hayden).
But what does this finding mean? It means that we have not well understood until now the rich diversity of African genetics until superior DNA ancestry testing was used. Hayden quotes Luca Pagani, a geneticist at the Wellcome trust Saenger Institute near Cambridge, U.K who says, “Until now, we have been applying tools designed specifically for non-African people to African people.” Hayden also quotes Carina Schelbusch a geneticist at Uppsala University in Sweden, as saying, “It’s a really exciting time for African genetics.”
It also explains a mystery. It means that some African groups that were previously thought to be genetically isolated actually “…carry 1-5% of non- African DNA” according to population geneticists at Harvard Medical School in Boston, Mass., who examined the individual genetic variations of some 1,000 individuals (Hayden). And their DNA testing results? This admixture explains why some Africans carry non- African genes. In fact, some carry a lot of them. For instance, the male Y-DNA haplotype R1 b1 which is the most common haplotype among Western Europeans is also found among some Africans. Miguel Gonzalez et al in their 2012 article, “The Genetic Landscape of Equatorial Guinea,” in the European Journal of Human Genetics says that the human Y- DNA chromosomes R1b1 though “very common in Europe are usually a rare occurrence in Africa,” but there have been some “…recently published studies that have reported high frequencies of this haplogroup” in parts of Africa. One wondered why until now.
Hayden isn’t the first to propose the idea of an ancient trip from Africa and then back again. There have been genetic clues before this (Hayden). Gonzalez extrapolates from his R1b1 data “that this represents a ‘back-to-Africa’ migration during prehistoric times.” And Hammer et al in the article, “Out of Africa and Back In,” in the Oxford Journal of Evolution postulates that there was more than one African ancestral migration path.
Now that we have determined from these DNA testing results that this migratory path is more multifaceted than previously thought, how are we to think about it? What else can we extrapolate from this? Are we to really think people walked from Africa to other lands and then back again? How did this admixture occur? Might these people really had rafts after all as Thor Heyerdahl suggested ancient peoples did in his book Kon Tiki?
So where do you think is your ancestor from?