How the Zebra Got Its Stripes

How did the zebra get its stripes? The first thing that would come to mind would be an amusing and entertaining camouflage explanation. This would make sense if we lived in a black and white world in which zebras would basically fuse with their surroundings. But that is not the case. The reality of the situation is that the black and white stripes of the zebra are not the only important part of their skin coat, but also the arrangement and angles of the stripes.

In MANY places of the world, especially in Africa and Budapest, there is a big concentration of insects called Horseflies or Tabanids. These deliver nasty bites, carry countless diseases and (most annoying) distract gazing animals from feeding. "According to 'Horvath' the Tabanids are attracted to horizontally polarized light because reflections from water are horizontally polarized and aquatic insects use this phenomenon to identify stretches of water where they can mate and lay eggs. However, blood-sucking female Tabanids are also guided to victims by linearly polarized light reflected from their hides". Basically it means that these insects are attracted not only to horizontally arranged "lights", but they are also attracted to darker colors.

After several experiments with different kinds of horses to prove this, it has been concluded that the "flies" were not attracted to white horses; however, the brown and black horses were completely covered with bites.

Zebras have an arrangement of mostly vertically aligned stripes and those have a variety of black and white patterns in them. The flies are DEFINETELY not attracted to the color white. You might ask “but what about the black stripes?”. That’s when the arrangement of the stripes comes in. The stripes are arranged in a non-vertical position so that the flies are actually repelled by the positioning of the lines.

This is a hypothesis based discovery because the scientists involved in this experiment knew that the stripes had some sort of function (in the zebra), but they did not have clear what it was. They experimented on several horses and zebras, and concluded what they started their research for; the purpose of the stripes.

This discovery does not really have a direct importance for humans, but it is valuable knowledge and it could be helpful in future situations.

Science Daily (Feb. 9, 2012)

Kathryn Knight.