A recent study explained how neanderthal genes were able to have entered the DNA of humans years ago. Experts have found that it could be through interbreeding that took place some 47,000 years ago.
(Photo : Getty Images/JUSTIN TALLIS/AFP )
Interbreeding Process
Scientists were able to discover that the Neanderthals interbred with the ancestors of modern humans who migrated out of the African continent.
At present, the genomes of the modern human populations outside Africa were found to have contained about 1% to 2% of Neanderthal DNA.
In the study, experts said that the gene flow from Neandertals has shaped the landscape of genetic and phenotypic variation when it comes to modern human beings.
Researchers have identified the location and size of introgressed Neandertal ancestry segments across more than 300 genomes covering the last 50,000 years.
They studied and examined how this Neandertal ancestry has been shared among human beings to infer the time and duration of the Neandertal gene flow.
Scientists were able to find out that the correlation of Neandertal segment locations across individuals and their divergence to sequenced Neandertals both support a model of single major Neandertal gene flow.
The catalog of introgressed segments through time was able to confirm that most natural selection-positive and negative-on Neandertal ancestry variants occurred immediately after the gene flow,
The study has provided new insights for other experts and even the general public to learn how the contact with Neandertals were able to shape human origins and adaptation.
They pointed out that the sharing of Neandertal segments mirrors the population structure among non-Africans.
Further, this supports a single major Neandertal gene flow event into the common ancestors of all surviving lineages of non-Africans that occurred some 47,000 years ago, with a duration of 6,800 years.
To some extent, this gene flow continued as early modern humans spread throughout Eurasia. However, this did not leave detectable traces when it comes to the later populations.
Meanwhile, experts also underscored that neandertal ancestry plays a major role in human adaptation and even acquiring disease.
However, only a few studies have tracked how the frequency of Neandertal variants was able to alter through time.
Using Neandertal segments in ancient and present-day individuals, they were able to recover Neandertal ancestry in 61.7% (1,551 Mb) of the autosomal callable genome.
They explained that on the X-chromosome, they were able to discover Neandertal ancestry only in 18.7% (29 Mb / 154.84 Mb) of the genome.
The distribution of Neandertal ancestry segments on X chromosome was found to be non-uniformed and non-random distribution, with large regions devoid of any Neandertal segments.
Neanderthals are defined as species of the human genus (Homo) that inhabited much of Europe, the Mediterranean lands, and Central Asia some 200,000 to 24,000 years ago.
Neanderthals were found to be short, stout, and powerful. Their braincases were long, low, and wide, and their cranial capacity equaled or surpassed that of modern humans, scientists said.
The name was derived from the discovery in 1856 due to remains found in a cave above Germany's Neander Valley.
