This is scientific American 60 second science.

I'm Christopher Intagiyata.

Homosapians are nowhere near the fastest runners in the animal kingdom,

but what we lack in speed we make up for in endurance. And we're especially equipped to go the distance.

We've got bigger butt muscles than other primates. We lost most of our fur too, and sprouted lots of sweat glands to help us cool off.

Scientists believe our endurance-running abilities began to appear 2 to 3 million years ago,

around the time the genus Homo came about.

And a new study suggests that a mutation in one

key gene had something to do with it. The mutation in what's called the

CMAH gene altered the types of sugar molecules that decorate the surfaces of every cell in our bodies,

which in turn may have made our muscles less prone to fatigue.

Researchers have now found that mice spread with that same mutation can run longer without

tiring compared to regular mice.

The mice with a gene alteration also logged more miles running on their wheels, apparently

for fun, and they had more capillaries in their back leg muscles which

would increase the delivery of nutrients and oxygen during endurance exercise.

The complete stats are in the proceedings of the Royal Society B.

It's unclear if this small genetic tweak endows humans with the same benefits as the mice,

but if it does, it could help explain how early humans got a leg up on their competitors, or really two legs.

Thanks for listening. For Scientific American 60 Second Science, I'm Christopher

in Deliata.