A brand new mannequin for human evolution asserts that fashionable Homo sapiens stemmed from a number of genetically various populations throughout Africa relatively than a single ancestral inhabitants. This conclusion was reached after researchers analyzed genetic knowledge from present-day African populations, together with 44 newly sequenced genomes from the Nama group of southern Africa. The analysis means that the earliest detectable cut up in early human populations occurred between 120,000 to 135,000 years in the past, after lengthy intervals of genetic intermixing, and that subsequent migrations created a weakly structured genetic stem. Contrary to some earlier fashions, this analysis implies that contributions from archaic hominins have been unlikely to have considerably affected Homo sapiens’ evolution.
New mannequin for human evolution suggests Homo sapiens arose from a number of intently associated populations.
A brand new research in Nature challenges prevailing theories, suggesting that Homo sapiens advanced from a number of various populations throughout Africa, with the earliest detectable cut up occurring 120,000-135,000 years in the past, after extended intervals of genetic intermixing.
In testing the genetic materials of present populations in Africa and evaluating it towards current fossil proof of early Homo sapiens populations there, researchers have uncovered a brand new mannequin of human evolution — overturning earlier beliefs {that a} single African inhabitants gave rise to all people. The new analysis was printed on May 17, within the journal Nature.
Although it’s broadly understood that Homo sapiens originated in Africa, uncertainty surrounds how branches of human evolution diverged and the way individuals migrated throughout the continent, stated Brenna Henn, professor of anthropology and the Genome Center at UC Davis, corresponding creator of the analysis.
View of the village of Kuboes, on the border of South Africa and Namibia. DNA samples have been collected from Nama people who’ve traditionally lived within the area. Credit: Brenna Henn/UC Davis
“This uncertainty is because of restricted fossil and historic genomic knowledge, and to the truth that the fossil document doesn’t at all times align with expectations from fashions constructed utilizing fashionable DNA,” she said. “This new research changes the origin of species.”
Research co-led by Henn and Simon Gravel of McGill University tested a range of competing models of evolution and migration across Africa proposed in the paleoanthropological and genetics literature, incorporating population genome data from southern, eastern, and western Africa.
Nama woman standing in the doorway to 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 southern Africa, an Indigenous population known to carry exceptional levels of genetic diversity compared to other modern groups. Researchers generated genetic data by collecting saliva samples from modern individuals going about their everyday business in their villages between 2012 and 2015.
The model suggests the earliest population split among early humans that is detectable in contemporary populations occurred 120,000 to 135,000 years ago, after two or more weakly genetically differentiated Homo populations had been mixing for hundreds of thousands of years. After the population split, people still migrated between the stem populations, creating a weakly structured stem. This offers a better explanation of genetic variation among individual humans and human groups than do previous models, the authors suggest.
“We are presenting something that people had never even tested before,” Henn said of the research. “This moves anthropological science significantly forward.”
“Previous more complicated models proposed contributions from archaic hominins, but this model indicates otherwise,” said co-author Tim Weaver, UC Davis professor of anthropology. He has expertise in what early human fossils looked like and provided comparative research for the study.
The authors predict that, according to this model, 1-4% of genetic differentiation among contemporary human populations can be attributed to variation in the stem populations. This model may have important consequences for the interpretation of the fossil record. Owing to migration between the branches, these multiple lineages were probably morphologically similar, which means morphologically divergent hominid fossils (such as Homo naledi) are unlikely to represent branches that contributed to the evolution of Homo sapiens, the authors said.
Reference: “A weakly structured stem for human origins in Africa” by Aaron P. Ragsdale, Timothy D. Weaver, Elizabeth G. Atkinson, Eileen G. Hoal, Marlo Möller, 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.
