Study Supported by Alfred P. Sloan Foundation Finds Genetic Link to Extinct Relative of Humans in Four Modern West African Populations
UCLA computational biologists have discovered that four populations in West Africa can trace about 8% of their genetic ancestry to an archaic hominin, an extinct relative of humans that branched off from the hominid evolutionary tree more than 600,000 years ago — about 100,000 years earlier than Neanderthals did. The study is published in Science Advances.
Over the past decade, advances in computing, statistical analysis, molecular biology and genetics have revealed a richer picture of humans and their interactions with ancient relatives, such as Neanderthals. But research on the genetic ancestry of African populations has lagged behind discoveries about people with ancestral roots in Europe.
The researchers, from the UCLA Samueli School of Engineering, analyzed modern DNA obtained from an international repository of genomic data. In the past, researchers would have needed to compare the modern DNA to so-called “reference DNA” from ancient fossils to draw such conclusions. But the improved statistical techniques available today enabled them to look backward in time hundreds of thousands of years without fossil DNA.
“This opens a new path in understanding the complexity of human evolutionary history in Africa, where the picture hasn’t been as clear,” said Sriram Sankararaman, the study’s principal investigator, a UCLA assistant professor with appointments in computer science, human genetics and computational medicine.
The archaic hominin identified in the UCLA research is a close evolutionary relative of humans.
“There is not a lot known about these archaic hominins, which makes finding out how this ‘ghost population’ fits into human evolutionary history challenging. But our findings are very exciting,” said Sankararaman, who also is a member of UCLA’s Bioinformatics Interdepartmental Program.
Previous genomic studies have presented evidence that modern populations in Africa have complex genetic lineages, in which humans and close evolutionary relatives intermixed as recently as just a few thousand years ago. But this study may provide the strongest evidence yet that this intermixture took place.
The UCLA research reveals much more of that story for the four modern groups of people, the Yoruba of Nigeria, the Mende of Sierra Leone, the Esan of Nigeria and the Gambian in Western Divisions of Gambia...