Researchers have identified three genetic mutations that appear to have helped humans survive in the frigid climate of Siberia over the last 25,000 years. One helps the body's fat stores directly produce heat rather than producing chemical energy for muscle movements or brain functions, a process called 'nonshivering thermogenesis.' Another is involved in the contraction of smooth muscle, key to shivering and the constriction of blood vessels to avoid heat loss. And the third is implicated in the metabolism of fats, especially those in meat and dairy products—a staple of the fat-laden diets of Arctic peoples.

Previous research on cold adaptation included two Siberian populations and implicated a couple of related genes. For example, genes called UCP1 and UCP3 tend to be found in more active forms in populations that live in colder climes, according to work published in 2010 by University of Chicago geneticist Anna Di Rienzo and her colleagues. These genes help the body's fat stores directly produce heat rather than producing chemical energy for muscle movements or brain functions, a process called "nonshivering thermogenesis."

The new study sampled Siberians much more intensely, including 10 groups that represent nearly all of the region's native populations. Graduate student Alexia Cardona, a member of Toomas Kivisild's genetics group at the University of Cambridge, and her colleagues analyzed 200 DNA samples collected by researchers at the Institute of Biological Problems of the North in Magadan, Russia, seeking genes that help humans adapt to the cold. Cardona used several techniques that detect signs of natural selection in the human genome—that is, genes that have been favored by evolution because they helped humans to survive and reproduce. She found three genes. One was UCP1, confirming previous studies. Variants of two new genes, called ENPP7 and PRKG1, also appeared to have undergone positive selection.