Neanderthals, often identified as unsightly grunting cavemen with massive foreheads and nearly nonexistent necks, are believed to have died out 40,000 years ago. Yet through their genome, they still have a say in the status of modern humans.
U.S. researchers shed new light on how these ancient ones still influence genes in modern humans, likely contributing to traits including height and the likelihood of having diseases such as lupus and schizophrenia.
"Even 50,000 years after the last human-Neanderthal mating, we can still see measurable impacts on gene expression," said University of Washington geneticist and study co-author Joshua Akey in a statement.
Neanderthal genetic variants have been previously linked to vulnerability to certain conditions, but scientists had difficulty knowing which mechanisms cause the said effects. Genetic instructions can be obtained from fossils, but they can no longer recover the RNA helping transmit the genetic information.
The team mined data from the Genotype-Tissue Expression (GTEx) Project, which looked for people carrying both Neanderthal and modern human versions of a gene, a version from each parent.
Akey, helping identify 12 Neanderthal genes associated with increased disease risk last year, said their results showed that Neanderthal DNA sequences still had an impact on how genes were turned on or off in humans today.
Even 50,000 years after the last interbreeding, the genetic influence remains "pervasive and important," Akey said.
The Neanderthal version of a gene known as ADAMTSL3, for instance, is tied to height and schizophrenia. Causal mutation, according to the study, was inherited from the Neanderthals.
Akey added that hybridization between Neanderthals and modern man is still a valid source of worry, as those ancient relics still result in greater genomic complexity. As a next endeavor, the team also seeks to investigate whether another hominid species, called Denisovans, contribute to gene expression.
The findings were discussed in the journal Cell.
Other Studies On Neanderthal Influence
A separate study published November last year pointed to the waning presence of the Neanderthal genes in modern humans because of the removal of weak, deleterious genes from humans during natural selection. It noted that genetic content of Neanderthals has been reduced to less than 4 percent in the genomes of modern non-African people.
The research also rebutted the conventional “survival of the fittest” concept, showing there was hardly any reason to believe that Neanderthals were genetically inferior to modern humans and failed to make it. The authors pinpointed the slender population size of the Neanderthals mixing with a huge group of modern humans as the likely factor behind the gene erosion.
Interbreeding with Neanderthals and other groups like Denisovans, on the other hand, was shown by a different study — also authored by Akey — to have been gainful encounters, such as the emergence of strong immune systems (for surviving in hard environments) and skin pigmentation. It revealed that non-African people inherited almost 2 percent of Neanderthal genomes, while the Denisovan genome content in individuals of Melanesian ancestry is within 2 to 3 percent from ancestors.