Mind & Body

Migraines May Be a Side Effect of a Helpful Genetic Adaptation

If there's one thing most misunderstand about evolution, it's the idea of continuous improvement. Evolution doesn't care about improving on or advancing its last model — it just cares whether or not an organism survives long enough to pass on its DNA, and sometimes that survival comes with unpleasant side effects. When our ancestors began walking on two legs instead of four, for example, it saved precious energy but it also led to a spate of back problems. New research adds one more genetic accident to the list: When humans left Africa, the genetic adaptation that helped them survive the cold may have also led to migraine headaches.

Out of Africa

Around 60,000 years ago, the first humans began venturing beyond our species' birthplace in Africa and settling in different regions of the world. Those different regions came with different environments, which required a lot of different adaptations in order to keep our species safe and fed and comfortable.

Felix Key of the Max Planck Institute for Evolutionary Anthropology and his team wanted to find evidence of these adaptations in human DNA. Because early humans would have definitely felt the shock of winter temperatures as they left sunbaked Africa, the team honed in on the gene responsible for the ability to detect and respond to cold, called TRPM8. Sure enough, they found that a particular genetic variant that may regulate TRPM8, called rs10166942, became more and more common in humans living in the colder latitudes of the world during the last 25,000 years. While only five percent of people with Nigerian ancestry carry this particular DNA quirk, a whopping 88 percent of people with Finnish ancestry do.

But this genetic variant was nothing new to science. We already knew about it — not because it helps carriers survive the cold, but because it's strongly associated with migraine headaches.

Cold Headache

One in seven people worldwide suffers from migraine headaches, making them the third-most prevalent medical condition worldwide (right behind dental cavities and tension headaches). This little-understood neurological disorder can lead to often debilitating headaches that last anywhere from four to 72 hours. Of course, no one gene is responsible for migraines — recent research has found that a number of genes can contribute to the disorder. But it's believed that the older variant of this cold-regulating gene protects against migraines, and the newer variant increases your risk of getting them.

Why would cold temperatures be linked to migraines? That's yet to have an answer. We've all experienced "brain freeze" triggered by eating or drinking something cold, but it's not clear whether that's related.

But what is clear from the new discovery is that humans have been evolving and adapting to new environments for at least the last 100,000 years. "This study nicely shows how past evolutionary pressures can influence present-day phenotypes," Felix Key said in a press release. Your ancestors programmed their adaptations into your DNA — for better or for worse.

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For a deeper dive into genetics, check out "She Has Her Mother's Laugh: The Powers, Perversions, and Potential of Heredity" by Carl Zimmer, named Science Book of the Year in 2018 by The Guardian. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Ashley Hamer June 1, 2018

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