Zebras are black and white because this high-contrast pattern is a highly effective defense against biting flies, which is a major evolutionary advantage.
While scientists have debated this for over a century, the most widely supported theory revolves around fending off these dangerous pests.
The Main Reason: Biting Fly Deterrence 🦟
The leading theory is that zebra stripes evolved to deter biting insects like tsetse flies and horseflies. These flies are common in the zebra’s African habitat and can transmit deadly diseases like trypanosomiasis (sleeping sickness).
- How it works: Studies show that flies have difficulty landing on a striped surface. The high-contrast black and white pattern appears to confuse their visual systems, possibly by disrupting their ability to judge speed and distance as they approach.
- Why black and white: This specific combination creates the strongest possible visual contrast, maximizing the confusing effect. A pattern with less contrast (like brown and tan) would not be as effective at scrambling the flies’ vision.
Other Theories
While fly deterrence has the most scientific support, other theories may also play a secondary role:
- Predator Confusion (Dazzle Camouflage): When zebras are in a herd, their moving stripes can create an optical illusion known as “dazzle camouflage.” This can make it difficult for a predator, like a lion, to single out one individual from the confusing mass of moving lines.
- Thermoregulation (Cooling): The stripes might help zebras stay cool. The black stripes absorb heat, and the white stripes reflect it. This difference in temperature could create tiny convection currents (mini-breezes) over the zebra’s skin, aiding in cooling.
- Social Signaling: Just like a human fingerprint, every zebra has a unique stripe pattern. This may help zebras recognize each other within the herd, particularly between a mother and her foal.
Are They Black with White Stripes or White with Black Stripes?
Genetics provides a clear answer: zebras are black with white stripes.
Embryological evidence shows that the underlying color of the zebra’s skin and fur is black. The white stripes are areas where the production of the melanin pigment (which creates the black color) has been inhibited during development.