How horses lost their toes | Science News


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How horses lost their toes

Ancient equines had up to four toes, which they shed as their body size grew

9:00am, August 28, 2017
Hyracotherium illustration

TOES TO SPARE  The ancestral horse Hyracotherium (illustrated) roamed North America about 55 million years ago. It had four toes on its front feet and three on its back feet.

Horses can leap over high hurdles, gallop at speeds of up to 70 kilometers per hour and haul around up to nearly 1,000 kilograms of body weight — and all with just one big toe on each foot. Now, a new study published August 23 in Proceedings of the Royal Society B helps explain why: Streamlined digits improved horses’ strength and speed.

Along with zebras and donkeys, horses are among the few single-toed creatures in the animal kingdom. Scientists have long suspected that horses’ single, hoofed toes helped them run farther and faster over grasslands, letting them flee predators and find fresh forage. But the hypothesis that having one big toe is better than having several, biomechanically speaking, has never been directly tested.

“This study takes an important step” toward resolving why horses shed digits during their early evolution, says Karen Sears, an evolutionary biologist at

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