Neanderthal Gene Variants Increase Pain Sensitivity in Modern Humans

A study led by University College London researchers has revealed that individuals carrying three specific gene variants inherited from Neanderthals tend to be more sensitive to certain types of pain. The findings, published in Communications Biology, underscore how past interbreeding with Neanderthals has left a genetic imprint on modern humans, influencing various aspects of their biology.

The study's focus was on three Neanderthal variants found within the SCN9A gene, associated with sensory neurons. These gene variants, known as M932L, V991L, and D1908G, were previously identified in sequenced Neanderthal genomes and correlated with greater pain sensitivity among humans who carried all three variants. The specific sensory responses influenced by these variants remained unclear until now.

For this study, the team measured pain thresholds in 1,963 people from Colombia in response to various stimuli.

The SCN9A gene encodes a sodium channel that is highly expressed in sensory neurons responsible for detecting signals from damaged tissues. The D1908G variant of this gene was found in around 20% of chromosomes within the Colombian population, with about 30% of these chromosomes also carrying the M932L and V991L variants.

The study demonstrated that these three variants were linked to a lower pain threshold when subjected to skin pricking after prior exposure to mustard oil but did not affect sensitivity to heat or pressure. Carrying all three variants was associated with greater pain sensitivity compared to having only one.

Analyzing genetic data from 5,971 people in Brazil, Chile, Colombia, Mexico, and Peru, the researchers discovered that these Neanderthal variants were more prevalent in populations with higher proportions of Native American ancestry, such as the Peruvian population.

The study's authors suggest that these Neanderthal variants may make sensory neurons more sensitive by altering the nerve impulse generation threshold. They speculate that these variants might be more common in populations with higher proportions of Native American ancestry due to random chance and population bottlenecks during the initial colonization of the Americas.

Although the researchers acknowledge the significance of acute pain in moderating behavior and preventing further injury, they emphasize that additional research is needed to determine whether carrying these variants and experiencing increased pain sensitivity could have been evolutionarily advantageous.