If you could put a wild cheetah up against a greyhound in a race, the cheetah would win, no problem. After all, the cheetah’s top recorded speed is 65 mph, and the cats are thought to be capable of much more. Greyhounds top out around 40 mph, fast enough to provide a show for bettors at the racetrack, but no match for the cats.
But why should that be? Cheetahs and greyhounds are about the same size, and they’ve got similar body shapes. In a new study in the Journal of Experimental Biology, biologists from the University of London made a series of measurements of cheetahs from a zoo in England and a cheetah center in South Africa and greyhounds that had retired from their racing careers in England to figure out why the cats are faster. The animals were filmed with high-speed cameras as they raced along a 100-yard track chasing a mechanical lure. Some of them were also trained to run across a force plate.
The cats and dogs had several differences in how they ran–at any given speed, the cheetahs used longer strides and fewer of them than the greyhounds. The cats also supported their weight differently, putting more of it on their hindlimbs, which may enhance their grip and allow for better acceleration and maneuvering while leaving their forelimbs free to capture prey.
But the scientists can’t say definitively that they’ve found out why cheetahs are faster because these cheetahs weren’t. They topped out at 39.8 mph, never reaching anywhere close to 65 mph and not even running faster than the greyhounds in the study. “They have lived in a zoo for several generations and have never had to run to catch food. They have probably never learned to run particularly,” says Alan Wilson, one of the project scientists. The greyhounds, meanwhile, were trained for races, encouraged to develop to run at the fastest speeds possible.
Io9 called this a failed experiment, since the captive cheetahs were so slow. But I would argue otherwise–the researchers identified plenty of differences between the two animals that may explain the cheetah’s edge, which was the point of the study. That said, it would be nice if they could try this with with wild cheetahs, which Wilson says they will try. Though I suspect that wrangling one of those speedy cats will provide new challenges to the researchers.