We can put a man on the moon, but we don't know why zebras have stripes.
While you'd think science would have sorted this particular mystery out by now, there isn't a conclusive answer to explain zebras' stripes. But a new study suggests that one explanation is stronger than the others: temperature. The researchers with the University of California at Los Angeles published their findings Tuesday in the journal Royal Society Open Science.
For this study, researchers looked at 16 sites where you can find plains zebras, the common species of zebra that are found from eastern Africa to South Africa. The stripes that plains zebras sport vary by region; some have strong black and white striping all over their bodies, while others have thinner stripes or not as many.
After examining 29 different environmental factors, including prevalence of biting flies, heat and predators, the researchers found that temperature had the strongest correlation with stripe patterns. And while they can't say for sure why temperature differences account for the patterns, they suggest it may be related to body temperature regulation, with black stripes absorbing heat while the white stripes reflect it.
The researchers also said they found no evidence to support the theory that avoiding predators plays a role in stripping patterns.
Earlier this year, a group of University of California atDavis researchers said a different explanation accounted for the stripes: that disease-carrying biting flies drove zebras to evolve stripes. They published their findings in the journal Nature Communications. Those researchers mapped out zebras' geographic ranges and overlaid them with the ranges of large predators and two types of flies: tsetse flies and horseflies. They also looked at temperature.
Although the UCLA researchers behind this most recent study write they didn't find "clear support" for the theory of avoiding biting flies or predators, they acknowledge that zebra striping is likely the result of complex factors.
And they write that more research is needed to into whether zebra stripes function as an optical illusion for potential predators or biting insects.
"While stripes clearly create confusion in the constrained environment of a computer screen, this same phenomenon may not occur on a larger scale under normal conditions," they write. "Larger scale experiments using live animals or a virtual system are clearly warranted."