Not to be mean or sarcastic, but, we have all seen someone one time or another with heavy brow ridges, stocky builds and other physical traits that look as though they had ancestors who might have been Neanderthals, although scientists have always claimed that that cross mating between them and modern humans never happened.
Now suddenly, those same scientists are saying that Jean Auel may have gotten it right when she wrote about such occurrences in her “Clan of Cave Bear” books. In fact, last year, they finally admitted that the two species had interbred, but that the few Neanderthal genes that survived in modern human DNA were not functional. This change of heart is a direct result of the first sequencing of the Neanderthal genome by a team of biologists led by Svante Paabo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, using DNA extracted from ancient bones. From this, they estimated that “1% – 4% of modern Eurasian genomes came from our close hominid relatives.”
Now, many even believe that key versions of immune system genes in modern humans appear to have been passed down by “archaic relatives,” including Neanderthals, after all. They have also learned that “ DNA inherited from Neanderthals and newly discovered hominids dubbed the Denisovans has contributed to key types of immune genes still present among populations in Europe, Asia and Oceania,” leading them to surmise that these variations in genes “must have been highly beneficial to modern humans, helping them thrive as they migrated throughout the world.”
This DNA has had a very profound functional impact in the immune systems of modern humans,” stated study first author Laurent Abi-Rached, a postdoctoral researcher in the lab of senior author Peter Parham of the Stanford University School of Medicine.
While no one knows what Denisovans looked like (the sole confirmed evidence of the group, which is thought to have split from the Neanderthals about 350,000 years ago and migrated east, being a tooth and a pinkie finger bone found in a Siberian cave in 2008), Paabo and his colleagues were able to calculated that “4% to 6% of modern Melanesian genomes came from Denisovans.”
In addition, by concentrating their studies on a small set of genes on chromosome 6 known as the human leukocyte antigen (HLA) class I genes. Abi-Rached’s study has concluded that
“more than half of the genetic variants in one HLA gene in Europeans could be traced to Neanderthal or Denisovan DNA. For Asians, that proportion was more than 70%; in people from Papua New Guinea, it was as much as 95%.
HLA (human leukocyte antigen) is a protein that aids the immune system detect problems in cells such as infection as well as cancer, so that it can fight off disease.
“The genes come in many forms that vary in frequency around the world, probably because our genomes have been tailored by evolution to fight specific disease threats that exist in particular places. We expected we’d see some, but the extent that these contributed to the modern [genomes] is stunning,” Abi-Rached said of the findings, released Thursday by the journal Science.
“Our ancestors’ HLA systems may have been perfectly tailored for Africa but naive to bacteria, viruses and parasites that existed in Europe or Asia, rendering them susceptible to disease.Mating and mixing their genomes with those of their Neanderthal and Denisovan relatives could have been a speedy way to set up their immune systems to combat new, unencountered threats. ”
Readers can learn more about our ancient ancestors by visiting the Yale Peabody Museum of Natural History, 170 Whitney Ave., New Haven, CT 203 432-5050.
For realted articles check out http://joltleft.com/wellness-in-hartford/who-s-your-daddy-dna-evidence-points-to-new-branch-the-human-family-tree and http://joltleft.com/wellness-in-hartford/our-ancient-ancestors-may-have-left-africa-earlier-than-thought