Zebras in motion
Text size
Daniel Bar-On
Zebras: Confusing, isn't it. Photo by Daniel Bar-On

Evolution is supposed to ensure the survival of the fittest, which translates into the optimal survival of the species. If a characteristic is preserved over the eons, and in more than one subspecies, the suspicion is that it does something pretty important.
In the case of zebras, all species are striped. It seems the stripes do play some role, hence the survival of the feature in the different species of zebra.

So how do they make these horses – which is what they are - better at surviving?

Now, one researcher believes he has the answer and he isn't even a zoologist. Johannes Zanker, a computational neuroscientist at Royal Holloway University, says it's all about the way we perceive movement.

Or rather, the way lions and other predators perceive it. They get confused.

When you look at a zebra moving – and let's face it, they're pretty much always bopping about – your brain generates "very peculiar" motion illusions, he explains.

"Their stripe patterns confuse the visual system of a potential predator, or, let's say, equally, of insects, which are not just a nuisance to these animals, but also could be carrying diseases," he postulates.

By the way, keeping watch on a herd of zebras can be quite an exercise in frustration due to so-called "motion dazzle," which reinforces Zankner's theory.
Don't believe it? The motion illusion to which Zanker refers is also evident in rotating barber shop poles and wagon wheels. The way these objects are actually moving, and the way we see them moving, are completely different.

Moving beyond the African plains, Zanker feels the findings could have wider significance - especially for road safety. If zebra crossing lines were painted horizontally to approaching cars, drivers would be more inclined to notice them earlier, he points out.

Where the research goes next remains to be seen, but Zanker says he's certain the zebra's stripes could be far more useful than nature ever intended.

Even the quagga, an extinct form of zebra, had the stripes on its rear parts.

Don't believe it? If you're in Israel you can observe the zebras at the Ramat Gan Safari Park, for instance, where they run free - within the confines of a large park.

As for the age-old question of whether zebras are white with black stripes or black with white stripes, embryological research indicates they're underlying color is black and the white stripes and bellies develop later.

Another example of an important but mysterious characteristic preserved throughout evolution is the cat's purr. Almost all species of cat, including the big ones, purr in some fashion, which is indicative that the characteristic does something important. Nobody knows what that might be, but the latest thinking is that the vibration of the purr has a healing aspect. A broken bone heals better when subjected to that sort of gentle vibration, and if it comes with fur, well.