Why Do Zebras Have Stripes?

For over 150 years, scientists debated zebra stripes: camouflage, thermoregulation, social signalling, or predator confusion? A 2014 study by Tim Caro at UC Davis found a strong geographic correlation between stripe intensity and tsetse fly/horsefly prevalence. In 2019, experiments with horses wearing striped coats confirmed that flies had difficulty landing on stripes, possibly because the alternating black-and-white pattern disrupts their visual approach. Stripe width roughly matches the wavelength of light that horsefly eyes resolve, creating a kind of optical "dazzle." Thermal imaging studies show only modest temperature differences between black and white stripes, weakening the thermoregulation hypothesis. Each zebra stripe pattern is unique, like a fingerprint, which may aid individual recognition within herds.