Novi model ljudske evolucije tvrdi da je moderan Mudar čovek proizilazi iz više genetski raznolikih populacija širom Afrike, a ne iz jedne populacije predaka. Do ovog zaključka je došlo nakon što su istraživači analizirali genetske podatke iz današnje afričke populacije, uključujući 44 novo sekvencionirana genoma iz grupe Nama iz južne Afrike. Istraživanje sugerira da se najraniji rascjep koji se može otkriti u ranim ljudskim populacijama dogodio prije između 120.000 i 135.000 godina, nakon dugih perioda genetskog miješanja, i da su naknadne migracije stvorile slabo strukturirano genetsko stablo. Suprotno nekim prethodnim modelima, ovo istraživanje implicira da je malo vjerovatno da će doprinosi arhaičnih hominina značajno utjecati na mudar čovjek evolucija.
Novi model ljudske evolucije sugerira da je Homo sapiens nastao iz više blisko povezanih populacija.
Nova studija u Nature-u osporava preovlađujuće teorije, sugerirajući da je Homo sapiens evoluirao iz više različitih populacija širom Afrike, pri čemu se najraniji uočljivi podjel dogodio prije 120.000-135.000 godina, nakon dugih perioda genetskog miješanja.
U testiranju genetskog materijala trenutnih populacija u Africi i upoređivanju sa postojećim fosilnim dokazima ranih Mudar čovek tamošnje populacije, istraživači su otkrili novi model ljudske evolucije – poništivši prethodna vjerovanja da je jedna afrička populacija stvorila sve ljude. Novo istraživanje objavljeno je 17. maja u časopisu Priroda.
Iako je to široko prihvaćeno Mudar čovek nastao u Africi, neizvjesnost okružuje kako su se grane ljudske evolucije razišle i kako su ljudi migrirali širom kontinenta, rekla je Brenna Henn, profesorica antropologije i Genom centra pri UC Davisu, dopisna autorica istraživanja.
Pogled na selo Kuboes, na granici Južne Afrike i Namibije. Uzorci DNK su prikupljeni od Nama pojedinaca koji su istorijski živjeli u regiji. Zasluge: Brenna Henn/UC Davis
“Ova nesigurnost je posljedica ograničenih fosilnih i drevnih genomskih podataka, te činjenice da fosilni zapisi nisu uvijek u skladu s očekivanjima od modela napravljenih korištenjem modernih[{” attribute=””>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.
Izvor: scitechdaily.com
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