Neanderthal DNA influences our height, schizophrenia risk

Toby Manning
February 26, 2017

Having a Neanderthal allele of the gene, which causes cells' machinery to remove a segment of messenger-RNA that is expressed in the modern human version, seems to reduce the risk of schizophrenia and increase height. The Neanderthal DNA influence has declined fastest in parts of the body (especially the brain) that evolved most rapidly around that time. Scientists found that Neanderthal DNA comprises about 2 percent of the genomes of today's humans who are of European and Asian heritage, but now scientists have found that Neanderthal DNA still influences how our very genes work. Most recently, researchers being led by the University of Washington's Joshua Akey used that DNA and compared it to DNA taken from more than 200 volunteers located in the United States.

Neanderthals, often identified as unsightly grunting cavemen with massive foreheads and almost nonexistent necks, are believed to have died out 40,000 years ago. "Hybridization wasn't just something that happened 50,000 years ago that we don't have to worry about anymore".

According to New Scientist, around 50,000 years ago, the extinct Homo sapien subspecies of non-African descent mated with cousins of modern humans.

The big question is, what are those Neanderthal genes doing?

In some cases, carrying the Neanderthal version of a gene has been linked to changes in fat metabolism, depression and lupus risk.

Those are just correlations.

The US 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.

"This begins to help us connect the dots", McCoy said. However, working out the mechanism behind the correlations has proved challenging. DNA can be extracted from fossils and sequenced, but RNA cannot.

In this study, researchers from the University of Washington looked at the RNA read-outs of Neanderthal gene variants in modern humans.

"Those variations in gene expression contribute to human phenotypic variation and disease susceptibility", Akey said. For each such gene, the investigators then compared expression of the two alleles head-to-head in 52 different tissues. Racimo says he would like to see research into other cases of human hybridization, specifically ancient Denovisans and Australian aboriginals, whose genes live on in the inhabitants of Australia's Melanesian islands.

One example uncovered by this study is a Neanderthal allele of a gene called ADAMTSL3 that decreases risk of schizophrenia, while also influencing height.

This study found that the Neanderthal version is less-expressed. It's not clear, however, how that modified protein is connected to schizophrenia or height, the researchers said. "We can infer that maybe the greatest differences in gene regulation exist in the brain and testes between modern humans and Neanderthals", says Akey. But one theory is that genes in those tissues have evolved at a more rapid pace.

Professor Svante Paabo, a Swedish biologist specializing in evolutionary genetics, said, "Neanderthals are not totally extinct". The Neanderthal DNA can also make a person taller than they'd otherwise be.

Similarly, the effects of Neanderthal genes on the immune system and skin were probably a boon back in the day, Capra said.

Other reports by VgToday

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