Scientists estimate that zebra stripes are useless as a disguise
North American zoologists from the University of Calgary and the University of California at Davis in their new work refute the widespread hypothesis about the purpose of stripes on the skin of zebras. The calculations of scientists are contrary to the popular opinion that strips are primarily used for camouflage, i.e. visual protection against predators. In addition, the social hypothesis of the presence of bands is called into question.
Scientists have so far agreed on one issue regarding the color of the skin of zebras - these herbivores are uniquely black in white stripes. It used to be that they were white with black stripes, due to the white color of the abdomen. But then studies at the embryonic level confirmed that these animals were originally black.
But there are several hypotheses about the purpose of the stripes on the skin of a zebra - and scientists have not yet come to a unified and universally accepted opinion on this subject. The most popular hypothesis is camouflage, which allows them to hide in the grass and confuses the vision of predators by flickering stripes.
Other hypotheses suggest that a unique pattern of stripes can serve social purposes - to identify individuals within the herd. It is also believed that striped animals are more difficult to recognize for various parasitic insects, in particular tsetse flies. There is a physical explanation for the stripes - the alternation of white and black colors leads to the appearance of regions of different temperatures on the skin, because of which there are convection air currents that effectively cool the animal on a hot day.
Zoologists realized that the judgments about the stripes in the role of camouflage were made on the basis of human vision. But how do predators see and perceive zebras? According to scientists, it turned out that the strips are unlikely to be able to fulfill this role. From the distance from which they become visually distinguishable, zebra predators will probably be able to hear or smell their prey.
Taking photos of a zebra using a color palette to calibrate color balance
“Research doesn’t confirm that stripes can be camouflage that protects zebras from predators,” said Tim Caro, a wildlife biologist at the University of California. “We refute this old hypothesis, which was still being discussed by Charles Darwin and Alfred Wallace .”
By passing digital photographs through specially created software filters, taking into account the difference in the brightness of the bands and using confirmed scientific data on the mechanisms of vision of lions and hyenas, the main predators that hunt zebras, the scientists came to the following conclusions. The stripes become indistinguishable already at distances of more than 50 m during the day and 30 m at dusk. On moonless nights, this distance generally drops to 9 m.
Scientists refute the social hypothesis of the stripes - in the herds of other herbivores, close relatives of zebras, but without stripes, individuals perfectly cope with the task of distinguishing different relatives without any stripes.