A new study published in Nature by an international team of researchers suggests that humans were living in different regions of Africa, migrating from one region of the continent to the other and mixing with each other over thousands of years. This is based on contemporary genomic evidence from across the continent that was analyzed in the study.
It is generally agreed that Homo sapiens, humans, us originated in Africa but we have not been able to confirm where this happened, when and how. There are many theories about this.
Competing theories about human origins in Africa
According to one theory there was a single ancestral population in Africa from which other populations diverged around 150,000 years ago.
A different theory suggests that this ancestral population was due to the mixing of modern humans with Neanderthal-like hominins.
“At different times, people who embraced the classic model of a single origin for Homo sapiens suggested that humans first emerged in either East or Southern Africa,” says Brenna Henn, a population geneticist in the Department of Anthropology and in the Genome Center at the University of California, Davis and co-lead author of the research. “But it has been difficult to reconcile these theories with the limited fossil and archaeological records of human occupation from sites as far afield as Morocco, Ethiopia, and South Africa which show that Homo sapiens were to be found living across the continent as far back as at least 300,000 years ago.”
The research team for this study took an alternate approach using contemporary genomic evidence.
Contemporary genomic evidence tells a different story
According to a statement: “In the first systematic test of these competing anthropological models against genetic data, the team worked backwards from contemporary genomic material of 290 individuals from four geographically and genetically diverse African groups to trace the similarities and differences between the populations over the past million years and gain insight into the genetic interconnections and human evolution across the continent. The groups were the Nama (Khoe-San from South Africa); the Mende (from Sierra Leone); the Gumuz (recent descendants of a hunter-gatherer group from Ethiopia); and the Amhara and Oromo (agriculturalists from eastern Africa). The researchers also included some Eurasian genetic material to include the traces of colonial incursions and mixing in Africa.”
“We used a new algorithm to rapidly test hundreds of possible scenarios. Those with gene flow back and forth between populations in various parts of the continent over the course of hundreds of thousands of years provided a much better explanation of the genetic variation we see today,” adds Simon Gravel, Associate Professor in the Department of Human Genetics at McGill University, and co-senior author on the paper. “We wrote this algorithm to understand how genetic disease risk varies across populations, and it led us to this deep dive into human origins. It’s been really fun to tie applied and fundamental research together in this way.”
Study: “A weakly structured stem for human origins in Africa” by Aaron Ragsdale et al was published in Nature.
Saima Baig
I am a Chartered Environmentalist from the Royal Society for the Environment, UK and co-owner of DoLocal Digital Marketing Agency Ltd, with a Master of Environmental Management from Yale University, an MBA in Finance, and a Bachelor of Science in Physics and Mathematics. I am passionate about science, history and environment and love to create content on these topics.
