It’s been a long time since we had any romantic dealings with Neanderthals, but research suggests that our past inter-breeding with this extinct hominid may continue to influence our health today. According to a new study in the journal Genome Biology and Evolution, Neanderthal DNA within the modern human genome could determine the susceptibility of certain populations to prostate cancer, autoimmune diseases and diabetes.
When the first Homo sapiens migrated out of Africa and began spreading across the Eurasian landmass, they encountered some of our ancestral cousins, including Denisovans and Neanderthals. While the latter of these became extinct some 40,000 years ago, there was still plenty of time for hanky-panky, which is why many modern humans from outside of Africa carry small amounts of Neanderthal DNA.
For instance, previous research has indicated that certain Neanderthal genes influence the susceptibility of Europeans to conditions like cystic fibrosis and schizophrenia. However, the impact of these ancient genes on geographically diverse human populations has remained largely unstudied.
To address this, Michael Dannemann from the University of Tartu in Estonia analyzed data from the Biobank Japan Project, looking specifically at the genome-wide association maps for 40 different diseases. When comparing these to similar data relating to a British cohort, Dannemann noted a number of associations between Neanderthal DNA and health that are specific to Asians.
For example, three key ancient gene variants – otherwise known as archaic single nucleotide polymorphisms (aSNPs) – were found to directly impact dermatitis, Graves' disease and rheumatoid arthritis in the Japanese cohort. All these conditions have been linked to autoimmune processes and were found to be significantly more common in people carrying these particular aSNPs.
Interestingly, a completely different aSNP was found to contribute to the risk of dermatitis in the British cohort, suggesting that Neanderthal DNA affects the health of multiple human populations, but that the exact genes involved differ from group to group.
A single aSNP was also associated with a decreased risk of prostate cancer among the UK sample, while two separate aSNPs were found to work together to produce this effect in the Japanese population. This is particularly interesting as it suggests that Neanderthal DNA brings both advantages and disadvantages, by promoting susceptibility to certain conditions while protecting against others.
This conclusion is backed up by the fact that two aSNPs were identified as contributors to type 2 diabetes among Japanese people, one of which increases the risk of developing the condition while the other decreases this risk. Both of these ancient genes are extremely rare among Brits yet have a significant impact on diabetes rates in Japan.
"My findings show that while the Neandertal DNA in European and Asian populations differ they both contain variants that increase the risk of autoimmune diseases like dermatitis, Graves' disease and rheumatoid arthritis," explained Dannemann in a statement.
"This [highlights] the importance of studying a wider range of ancestries to help us to ascertain how the phenotypic legacy of Neandertals influences modern humans today."