The loss of a single gene millions of years ago may have helped human ancestors make the change from a forest environment to life as hunter-gatherers on the African savannah, according to a new study.
And this, in turn, may have contributed to modern humans’ unmatched abilities as long-distance runners.
A mutation linked to the lack of a gene called CMAH lines up with the emergence of several key changes in early hominids’ bodies, such as long legs and more powerful gluteal muscles, all of which helped to drive our species’ physical endurance.
In the new study, researchers from the University of California, San Diego examined mice who were engineered to lack this gene.
The loss of CMAH has previously been tied to modern humans’ fertility rates and even cancer risk from red meat.
And, it sets humans apart from our closest living ancestors, who have this gene.
‘We discovered this first clear genetic difference between humans and our closest living evolutionary relatives, the chimpanzees, more than 20 years ago,’ said senior author Ajit Varki, MD.
In the study, the researchers constructed running wheels and a mouse treadmill, and investigated the differences between those with and without the gene.
According to the team, mice lacking the gene were more resistant to fatigue, had increase mitochondrial respiration and hind-limb muscle, and benefited from increased blood and oxygen supply.
‘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,’ said Okerblom, the study’s first author.
Similar improvements may have occurred in human ancestors, too, the researchers say.
‘And if the findings translate to humans, they may have provided early hominids with a selective advantage in their move from trees to becoming permanent hunter-gatherers on the open range,’ Varki said.
According to the researchers, the CMAH gene was lost about 2 to 3 million years ago in the Homo genus as a result of mutations.
This mutation changed the way we use sialic acids, or a family of sugar molecules that coat animal cells.
And, if affects nearly every cell type in our bodies.
The loss of the CMAH gene wasn’t all good, though. While it may have turned us into better runners and boosted immunity, this change may have increased the risk of certain types of cancer and diabetes.
‘They are a double-edged sword,’ Varki said.
‘The consequence of a single lost gene and a small molecular change that appears to have profoundly altered human biology and abilities going back to our origins.’