Why do zebras have stripes? Do zebras’ stripes really keep them cool in blaring sunlight?
Researchers at Lund University (Sweden) believe they have disproved the widely-believed theory that zebras have their stripes in order to stay cool in the blaring sun.
The widely-believed theory is that zebras’ black stripes get warmer than the white ones, creating small vortexes that act as a fan when the hot air above the black stripes meets the cool air above the white stripes.
In order to disprove this theory, the team covered water-filled barrels with different colors and patterns; including black, white and striped versions. After then placing the barrels in the sun and measuring the temperature of water inside each barrel, they discovered that whilst the back barrels were hottest and white barrels were coolest, stripes made no difference.
“The stripes didn’t lower the temperature. It turns out stripes don’t actually cool zebras”, commented Susanne Åkesson, a professor in evolutionary ecology at Lund University and co-author of the study.
Åkesson and colleagues won the Ig Nobel prize in 2016 for their work on why horseflies aren’t as attracted to white horses as black horses. They believe that this could also be the underlying reason for why zebras have stripes.
They claim that horseflies are attracted to the polarized light that results from reflection of sunlight off dark fur. When sunlight is reflected off white fur, there is no polarized light. Hence, horses with lighter fur are more protected against horseflies than those with darker fur. This research has also resulted in the production of zebra striped coats for horses to protect them from horseflies.
Written ByAbigail Sawyer
Updated 6 August, 2019
SourceHorvath G, Pereszlenyi A, Szaz D et al. Experimental evidence that stripes do not cool zebras. Sci. Rep. 8:9351 (2018)https://www.nature.com/articles/s41598-018-27637-1 https://www.lunduniversity.lu.se/article/stripes-may-be-cool-but-they-dont-cool-zebras-down