Evolution and humans: Neanderthal contributions (Evolution)

by David Turell , Tuesday, December 31, 2019, 15:33 (1787 days ago) @ David Turell

Another new article makes the same points:

https://www.the-scientist.com/features/neanderthal-dna-in-modern-human-genomes-is-not-s...

"With the issue of Neanderthal/modern human mating settled, scientists could focus on a new goal, says Akey, now at Princeton University. Namely, what was the consequence of this interbreeding? “Was it just this curious feature of human history that didn’t have an impact, or did it alter the trajectory of human evolution?”

"In the past five years, a flurry of research has sought to answer that question. Genomic analyses have associated Neanderthal variants with differences in the expression levels of diverse genes and of phenotypes ranging from skin and hair color to immune function and neuropsychiatric disease. But researchers cannot yet say how these archaic sequences affect people today, much less the humans who acquired them some 50,000–55,000 years ago.

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"In collaboration with Akey and Vernot, who helped identify Neanderthal variants in the genetic data included in the database, Capra’s group looked for links between the archaic DNA and more than 1,000 phenotypes across some 28,000 people of European ancestry. They reported in 2016 that Neanderthal DNA at various sites in the genome influences a range of immune and autoimmune traits, and there was some association with obesity and malnutrition, pointing to potential metabolic effects. The researchers also saw an association between Neanderthal ancestry and two types of noncancerous skin growths associated with dysfunctional keratinocyte biology—supporting the idea that the Neanderthal DNA was at one point selected for its effects on skin.

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"People who carried Neanderthal DNA there tended to have pale skin that burned instead of tanned, Kelso says. And the stretch that included BNC2 was just one of many, she adds: around 50 percent of Neanderthal variants linked with phenotype in her study have something to do with skin or hair color.

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"In their 2017 analysis, for example, Kelso and Dannemann found that Neanderthal variants were associated with chronotype—whether people identify as early birds or night owls—as well as links with susceptibility to feelings of loneliness or isolation and low enthusiasm or interest. The associations with mood-related phenotypes jibe with what Capra’s group had found the year before in its dataset of medical information, which linked Neanderthal variants to risks for depression and addiction. “These were associations that were quite strong,” says Capra.

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"Akey has come upon another interesting twist: Africans do have Neanderthal ancestry. Unpublished work from his group points to the possibility that some of the ancient modern humans that bred with Neanderthals migrated back to Africa, where they mixed with the modern humans there, sharing bits of Neanderthal DNA. If true, that would mean that Africa is not devoid of Neanderthals’ genetic influence, Akey notes. “There’s Neanderthal basically all over the world.'”

Comment: my view is still the same. God used evolution and the development of different Homo species in different environments to provide more advantageous adaptations which would then be combined beneficently into H. sapiens by interbreeding.