Washington, Aug 23 : A recent study by a researcher from the University of Southern California has revealed that individuals of European descent could be up to five percent Neanderthal, while West Africans could be related to an archaic human population.
Professor Vincent Plagnol in the University’s Department of Molecular and Computational Biology has said that a study of genes of people from Yoruba and individuals living in Utah with ancestry from Northern and Western Europe revealed the existence of archaic DNA in the genes.
This countered the view that modern humans left Africa and replaced all other existing hominid populations, he said.
"Instead of a population that left Africa 100,000 years ago and replaced all other archaic human groups, we propose that this population interacted with another population that had been in Europe for much longer, maybe 400,000 years," Discovery News quoted Prof. Plagnol, co-author of the study as saying.
For their study, Prof. Plagnol and his colleague Prof. Jeffrey Wall analyzed patterns of ancestral linkage in 135 modern individuals.
Using statistics and computer modelling, they focused on linkage disequilibriums, or sections within genes that did not make sense if only modern human matings were considered.
According to the paper, which was published in PLoS Genetics, missing genetic links only fit if some other hominid population was introduced into the model.
"We considered the data from modern human DNA and fitted a model to explain what we see. We found that a simple model cannot explain the data if we do not add an ‘ancestral population.’ If this population did not cross with modern humans — or almost did not — the effect is too small to explain the data. We find that a rate of five percent is what is needed to explain what we see," said Prof. Plagnol.
They said that portions of the European genome, such as those associated with nuclear DNA might still harbour the Neanderthal imprint.
Prof. Plagnol said different parts of the genome hade different ancestry, so an individual could have a fraction of a certain chromosome that was inherited from a Neanderthal, but then possess "very typical homo sapiens mtDNA".
Alan Templeton, professor of Evolutionary and Population Programs at the University of Michigan, who also conducted DNA studies and came to similar conclusion said, that “humans who were in Africa and humans who were in Eurasia were regularly interchanging genes".
"There was interbreeding and when humans came out of Africa 100,000 years ago they did not replace these other human populations in Eurasia," he said.