A recent study, co-led by UCL researchers and published in Communications Biology, has shed light on how interbreeding with Neanderthals has impacted modern human genetics. The research focused on the SCN9A gene, which plays a role in sensory neurons and pain sensitivity. Individuals carrying three specific Neanderthal gene variants within SCN9A, known as M932L, V991L, and D1908G, were found to be more sensitive to pain caused by skin pricking after exposure to mustard oil.
An international team of researchers conducted pain threshold tests on 1,963 people from Colombia, using various stimuli. The SCN9A gene encodes a sodium channel found in sensory neurons, responsible for detecting signals from damaged tissue. The study revealed that the presence of the D1908G variant was around 20% within the population, and about 30% of those with this variant also carried the M932L and V991L variants. These three Neanderthal variants were linked to lower pain thresholds for skin pricking, but not for heat or pressure. Moreover, individuals carrying all three variants exhibited greater pain sensitivity.
Analysis of genetic data from 5,971 individuals across several South American populations showed that these Neanderthal variants were more common in groups with higher Native American ancestry. The researchers hypothesize that these variants may make sensory neurons more sensitive by altering the nerve impulse generation threshold. It is suggested that their prevalence in populations with significant Native American ancestry might be due to historical population bottlenecks and chance.
The study raises questions about whether increased pain sensitivity conferred any evolutionary advantage. While pain sensitivity is crucial for avoiding harm, further research is required to determine the significance of these genetic variants in human evolution.
Co-corresponding author Dr. Kaustubh Adhikari, known for previous research on Neanderthal genetic influence on human nose shape, highlighted the ongoing exploration of what we inherited from Neanderthals due to ancient interbreeding. Dr. Adhikari stressed the importance of understanding the evolutionary implications of increased pain sensitivity. First author Dr. Pierre Faux acknowledged that genes are just one factor influencing pain perception, with environmental, experiential, and psychological factors playing significant roles.
Source: University College London