A common gene variant associated with migraines may have helped early humans adapt to cold weather as they moved to northern climates, according to new research.
Migraine headaches are more common among people of European descent than those of African descent. Although it was not understood why, scientists have believed it to be related to both the environment and genetics.
In a new study, researchers focused on a gene called TRPM8, which has been linked to both vulnerability to migraines and the ability to detect cold. TRPM8 is “the only known receptor for the sensation of moderate cold temperature,” according to the study’s authors.
Led by Felix Key at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and supervised by Aida Andrés at University College London in the UK, the team published their results in the journal PLoS Genetics on Thursday.
After analysing genetic data from people around the world, researchers found that a newer “upstream variant” that could regulate the TRPM8 gene was more common among people living in colder climates, especially in Europe, while an older variant of the gene was more common among people living in Africa.
“We found a correlation between frequency [of the gene] and latitude,” Key told New Scientist. The correlation was “beyond what can be explained by shared ancestry and population substructure,” according to the study.
“Most genetic variants have very similar frequencies across human populations,” Andres told Reuters. “So it was surprising that this (variant) is at very low frequency in some populations, say Yoruba, Nigeria, and very high frequency in others, for example Finnish in northern Europe.” The team’s analysis showed that around 88% of Finnish people carry the newer variant, compared to only 5% of Nigerians.
Researchers speculated that the newer variant, which they say became more common in populations living in colder, northern climates over the past 25,000 years, could be partially explained by early humans’ adaptation to cold temperatures.
Scientists do not yet understand how cold sensation and migraines are directly connected. Key told Reuters: “Both are related to pain which provides a possible, but speculative, link.”
Greg Dussor, a researcher at the University of Texas at Dallas, told Reuters that cold can trigger migraines. “The migraine might be a warning sign that the stressor, in this case cold, could be dangerous and the person should protect themself from the temperature,” explained Dussor, who was not involved in the study.
Mark Shriver, a Professor of Anthropology at Penn State University in the United States who was also not involved in the study, told New Scientist that the increased risk of migraines associated with the gene variant was likely an unlucky side effect rather than an advantageous trait for early humans.