Evolution in Action: A Single Gene Mutation Let Humans Become Long-Distance Runners

Humans may be such great long-distance runners, compared to other members of the animal kingdom, thanks to a single gene mutation. That's according to new research.

The team at the University of California, San Diego, behind the study homed in on a gene called CMAH—or lack thereof. Around 2 million to 3 million years ago a genetic mutation triggered the functional loss of CMAH in our ancestors.

This coincided with early hominids adapting to life away from forests and moving to barren savannahs in Africa. The shift in our ancestors’ physiology and skeletons, which set us apart from primates, caused us to develop big feet, strong gluteal muscles, and long, springy legs. Our new sweat glands, meanwhile, helped our bodies cool down more efficiently. 

As a result, early hominids could run for longer distances and until the point of exhaustion—known as persistence hunting—all while coping with the sun's heat, while other animals snoozed.

Scientists believe humans lost the function of CMAH in response to an ancient disease, which changed how future generations processed the sugar molecules that coat animal cells. This single change is thought to have affected everything from raising our risk of cancer and type 2 diabetes, to boosting our immunity.

Running-stock Researchers investigated the role of the CMAH gene in long-distance running. Getty Images

Dr. Ajit Varki, author of the study and distinguished professor of medicine and cellular and molecular medicine at UC San Diego School of Medicine, said in a statement: "The consequence of a single lost gene and a small molecular change appears to have profoundly altered human biology and abilities going back to our origins."

In their paper published in the journal Proceedings of the Royal Society B, researchers showed how this mutation also turned us into champion runners.

The team engineered mice prone to muscle dystrophy to lack CMAH, and monitored the animals as they ran on treadmills and running wheels.

Researchers noted the mice without CMAH tired less quickly than the control mice, their mitochondria respired more efficiently and their hind-limb muscles were bigger.

monkey-human-hands-evolution-stock Researchers studied mice without the CMAH gene to investigate how the functional loss of this gene affected human evolution. Getty Images

Jon Okerblom, the study’s first author and a graduate student at UC San Diego, explained: "We evaluated the exercise capacity [of mice lacking the CMAH gene], and noted an increased performance during treadmill testing and after 15 days of voluntary wheel running.”

As the study was carried out on mice, scientists can’t be sure the results relate to humans. However, they believe their study gives a strong indication that the loss of CMAH could have given our ancestors a selective advantage as we became hunter-gatherers.

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Varki told Newsweek: “Doing the study was a long shot based on a hunch derived from multiple different clues from different sources.”

Delving into our genes in this way could help scientists develop new approaches to understanding what promotes cardiovascular fitness and running ability in humans, said Varki. 

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