A new model for human evolution claims that the modern Wise man descended from multiple genetically distinct populations in Africa rather than from a single ancestral population. This conclusion was reached after the researchers analyzed genetic data from present-day African populations, including 44 newly sequenced genomes from the Nama group of South Africa. The research suggests that the earliest detectable split in early human populations occurred 120,000 to 135,000 years ago, after long periods of genetic mixing, and that subsequent migrations created a loosely structured genetic stock. Contrary to some previous models, this study suggests that the contribution of archaic hominins is unlikely to have significantly influenced wise man evolution.
A new model for human evolution suggests that Homo sapiens arose from multiple closely related populations.
A new study in Nature challenges prevailing theories, suggesting that Homo sapiens evolved from multiple distinct populations in Africa, with the earliest noticeable split occurring 120,000-135,000 years ago, after extended periods of genetic mixing.
In testing the genetic material of current populations in Africa and comparing it to existing fossil evidence from an early age Wise man populations there, researchers have discovered a new model of human evolution – overturning previous beliefs that a single African population gave rise to all humans. The new research was published May 17 in the journal Nature.
Although it is widely understood that Wise man originated in Africa, uncertainty surrounds how the branches of human evolution diverged and how people migrated across the continent, said Brenna Henn, professor of anthropology and the Genome Center at UC Davis, corresponding author of the study.
View of the village of Kuboes, on the border of South Africa and Namibia. DNA samples were collected from Nama individuals who historically lived in the region. Credit: Brenna Henn/UC Davis
“This uncertainty is due to limited fossil and ancient genomic data and the fact that fossils do not always match expectations from models built using modern DNA,” she said. “This new research changes the origins of kinds.”
Research co-led by Henn and Simon Gravel of McGill University tested a range of competing models of evolution and migration in Africa proposed in the paleoanthropological and genetic literature, involving population genome data from southern, eastern and western Africa.
A Nama woman standing on the doorstep of her home in Kuboes, South Africa, a UNESCO World Heritage Site. Credit: Justin Myrick-Tarrant/with permission
The authors included newly sequenced genomes from 44 modern Nama individuals from South Africa, an indigenous population known to carry exceptional levels of genetic diversity compared to other modern groups. The researchers generated genetic data by collecting saliva samples from modern humans going about their daily business in their villages between 2012 and 2015.
The model suggests that the earliest population split among early humans detectable in modern populations occurred 120,000 to 135,000 years ago, after two or more weakly genetically differentiated Homo populations have intermixed for hundreds of thousands of years. After the population split, individuals still migrated between stem populations, creating a loosely structured stem. This offers a better explanation of genetic variation among individuals and human groups than previous models, the authors suggest.
“We’re introducing something that people have never tested before,” Henn said of the research. “It moves anthropological science significantly forward.”
“Previous more complex models suggested a contribution from archaic hominins, but this model shows otherwise,” said co-author Tim Weaver, a professor of anthropology at UC Davis. He has expertise in what early human fossils looked like and provided comparative studies for the study.
The authors predict that, according to this model, 1–4% of the genetic differentiation among modern human populations can be attributed to variation in stem populations. This pattern may have important implications for fossil interpretation. Due to migration between branches, these multiple lineages were likely morphologically similar, meaning morphologically different hominid fossils (such as Homo star) are unlikely to represent branches that contributed to the evolution of Wise manthe authors said.
Reference: “A Loosely Structured Basis for Human Origins in Africa” by Aaron P. Ragsdale, Timothy D. Weaver, Elizabeth G. Atkinson, Eileen G. Hoall, Marlo Moeller, Brenna M. Henn, and Simon Gravel, 17 May 2023, Nature.
DOI: 10.1038/s41586-023-06055-y
Additional co-authors include Aaron Ragsdale, University of Wisconsin, Madison; Elizabeth Atkinson, Baylor College of Medicine; and Eileen Hoal and Marlo Möller, Stellenbosch University, South Africa.
Leave a Reply