Recent research presents that a common genetic variant in the ACTN3 skeletal muscle gene makes some humans more resilient to colder temperatures. Due to an individual genetic change in the ACTN3 gene, approximately 1 out of 5 people lack a muscle protein named alpha-actinin-3. Researchers from Lithuania, Sweden, and Australia, have recently discovered that those who are alpha-actinin-3 deficient can maintain a higher core temperature in their body and will shiver less when exposed to the cold. The deficiency of alpha-actinin-3 became more frequent amongst modern humans as they migrated out of Africa and into cooler climates such as Europe and Asia. Alpha-actinin-3 muscles tend to be weaker and recover more quickly from fatigue, making it beneficial to have during endurance events. The enhanced endurance muscle capacity could affect a human's response to the cold. Studies show that the loss of ACTN3 increases the muscle's ability to generate heat, resulting in less shivering when exposed to colder temperatures. Moreover, the energy being saved from not shivering would be conserved, resulting in a higher rate of survival in colder temperatures. Humans having a higher survival rate in cooler climates is why this gene mutation is so common in humans today, as humans who migrated out of Africa and into cooler climates with this mutation had higher survival rates and were able to produce offspring with the gene variant that also could survive the cooler temperatures and pass down their genotype.
Loss of alpha-actinin-3 during human evolution provides superior cold resilience and muscle heat generation
By Katherine Morone