In a study published last week in the journal PLOS ONE, new research suggests that the age old theory that the stripes protected the zebra from predators has essentially been debunked.
Despite Charles Darwin’s argument about stripes on Zebras
The new research effectively proves that zebras’ stripes don’t help with camouflage and don’t break up the creatures outline enough to to confuse predators. When the stripes become visible to the Zebra’s natural predators, those same animals would have already seen or smelled the animal coming.
“The results from this new study provide no support at all for the idea that the zebra’s stripes provide some type of anti-predator camouflaging effect,” said co-author Tim Caro, UC Davis wildlife biology professor.
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“Instead, we reject this long-standing hypothesis that was debated by Charles Darwin and Alfred Russell Wallace.”
The researchers took digital images in Tanzania and they put them through spacial and color filters that would essentially show the scientists what lions and hyenas would see as well as other zebras.
Also, by knowing the visual capacities of these animals and measuring the contrast and width of the zebra’s stripes helped them form their hypothesis.
“The most longstanding hypothesis for zebra striping is crypsis, or camouflaging, but until now the question has always been framed through human eyes,” said lead author Amanda Melin, assistant professor of biological anthropology at the University of Calgary, Canada.
“We, instead, carried out a series of calculations through which we were able to estimate the distances at which lions and spotted hyenas, as well as zebras, can see zebra stripes under daylight, twilight, or during a moonless night.”
Using these lion and hyena eyes they created they determined that beyond 50 meters in the day or 30 meters at night, predators don’t see the stripes but can see the animal.
If not for camouflage, what do the stripes do?
One idea that was posited in a 2015 study published in the journal Royal Society Open Science, researchers believed that the stripes helped zebras cool off in the midday sun. Zebras do not digest food as well as other grazers but with a cooling system would be able to speed up digestion.
“Zebra have a need to keep foraging throughout the day, which keeps them out in the open more of the time than other animals,” said lead author Biologist Brenda Larison. “An additional cooling mechanism could be very useful under these circumstances.”
“Zebra have a need to keep foraging throughout the day, which keeps them out in the open more of the time than other animals,” said Larison. “An additional cooling mechanism could be very useful under these circumstances.”
In other study by Tim Caro, this one in 2014, Caro wrote of his belief that the stripes helped the zebra repel biting insects.
“Again and again, there was greater striping on areas of the body in those parts of the world where there was more annoyance from biting flies,” said Caro.