Cold Resilience and Human Evolution

Now that springtime and warmer days are around the corner, it’s time to put the coats and gloves away! But have you ever seen someone during those cold and windy winter days, wearing nothing but a hoodie and shorts? New research published in the American Journal of Human Genetics showed that a specific genetic mutation makes people more resilient to cold temperatures! This mutation is defined as the loss of a muscle protein called alpha-actinin-3 (α-actinin-3) within the skeletal muscle gene, ACTN3.

The loss of protein, expressed in fast-twitch skeletal muscle fibers, allows 1.5 billion people worldwide (1 in 5) to have weaker muscles but recover faster, conserve energy more efficiently, and maintain a higher core temperature. “Thus, this study provides a mechanism for the positive selection of the ACTN3 X-allele in cold climates and supports a key thermogenic role of skeletal muscle during cold exposure in humans,” state the researchers in the study.

The research sought out to find whether people with α-actinin-3-deficient (XX) or a fully functioning ACTN3, would better prevail during an acute cold challenge. 42 men between the ages of 18 to 40 years of age, were recruited to sit in a tub filled with 14-degree Celsius water for up to 2 hours (20 minutes at a time with a 10-minute break). The genetic mutation allowed those lacking the protein to succeed in the experiment, as they were better braced for the cold; a follow-up experiment was also conducted using mice! However, some side effects of this missing protein may include obesity and Type 2 Diabetes, if there’s ever any inactivity.

This genetic change most definitely became beneficial to us as time passed. It not only allows us to adapt and reduce shivering when found in colder climates, but it also allows those deficient in it, to conserve energy at a time where it’s most needed! However, it would be interesting to see whether results would vary in women.

Links:

Your genetics influence how resilient you are to cold temperatures – new research

Don't Suffer in The Cold? Turns Out There's a Genetic Mutation For That

Loss of α-actinin-3 during human evolution provides superior cold resilience and muscle heat generation