Scientists have explained which people tolerate the cold better

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A gene variant that affects the function of skeletal muscles yams, could protect people from lower temperatures when they migrated from Africa to Europe more than 50,000 years ago. That's what the study suggests.

A loss-of-function (LOF) variant of the ACTN3 gene is known to cause the loss of a skeletal muscle protein called alpha-actinin-3, and is more common as modern humans are moving to colder environments. Now researchers show that alpha-actinin-3 deficiency improves cold tolerance in humans by increasing muscle tone.

“Our study shows improved cold tolerance in people lacking alpha-actinin-3. This would be an evolutionary advantage for survival when moving to a colder climate,” says study co-author Håkan Westerblad from the Karolinska Institute. “Our work also highlights the enormous importance of skeletal muscle as a heat generator for humans.”

As part of the study, scientists immersed 42 healthy adult men between the ages of 18 and 40 with the lof variant of the ACTN3 gene and a normally functioning gene in water with a temperature of 14 degrees Celsius for 20 minutes. They were interspersed with 10-minute breaks. In total, the effect lasted for two hours.

69% of participants with the LOF variant were able to maintain their body temperature above 35.5, while only 30% of people with working genes succeeded.