Despite a life of particularly harsh conditions, Neanderthals were carriers of genetic mutations that gave them an increased sensitivity to pain. But even more surprisingly, these mutations would have reached us and concern 0.4% of current Britons.
Neanderthals would have had an increased sensitivity to pain due to mutations in one of their genes.
Do you feel particularly sensitive to pain? Maybe it's because of your Neanderthal roots! In any case, this is what the study by the Karolinska Institute in Stockholm (Sweden) and the Max-Planck Institute for Evolutionary Anthropology in Leipzig (Germany) suggests, published in the journalCurrent Biology July 23, 2020.
Three mutations make the protein more effective
Svante Pääbo and Hugo Zeberg, lead authors of the study, discovered that Neanderthals carried three mutations in one of their genes. The latter, called SCN9A, codes for a protein whose role is to transmit painful sensations to the spinal cord and the brain. The three mutations detected during the study have the effect of modifying the conformation of the protein, which then becomes more efficient in transmitting pain.
These mutations have been found in several Neanderthal genomes in Croatia and Russia. "We were fortunate to find specimens that allowed us to determine whole genome sequences of good quality" explains to Sciences et Avenir Svante Pääbo, author of the study. The same version of the gene found repeatedly in these sequences led researchers to believe that it was common and common to all Neanderthal populations.
At least 0.4% of Britons carry these mutations
To determine the role of these three mutations, the researchers expressed the Neanderthal version of the protein in frog eggs and human kidney cells - useful model organisms for studying effects on the nervous system. Result:the protein was more active in cells that had undergone the three mutations than in cells that had not undergone these changes.
The scientists then looked for modern humans with the Neanderthal version of the protein. In total, around 0.4% of participants in Britain's Biobank - a database that stores the genomes of half a million Britons - had a copy of the mutated gene.
Study participants then reported their pain symptoms:carriers of the mutated gene reported on average more pain in their lives than people who did not. In other words, people who have inherited mutations from ancient hominins tend to experience more pain than others.
"This is an early example, in my opinion, of how we are beginning to get a potential idea of Neanderthal physiology using present-day people as transgenic models" , adds Svante Pääbo.
"Pain is adaptive"
However, the researchers call for caution regarding the interpretation of their results:according to them, their conclusions do not necessarily mean that Neanderthals would have felt more pain than modern humans. The sensations transmitted by the protein are in fact processed and modified in the spinal cord and the brain, which also contributes to the subjective experience of pain. "Pain is adaptive" , underlines Mr. Zeberg. "It's not specifically bad to feel it" .
At present, there is no data to confirm whether the mutations have persisted thanks to their beneficial aspect. Indeed, Neanderthal populations were small, and their low genetic diversity could favor the maintenance of harmful mutations for the species. In the next few years, Pääbo plans to sequence the genomes of around 100 Neanderthals to provide more answers to this question.