It’s an age old question: Why do zebras have stripes? 
 
 There have been many theories -- four of them, to be exact -- according to researchers of a new study. 
 
 The issue isn’t so black and white, it appears. 
 
 The four theories include confusing predators, regulating temperature, helping zebras recognize each other and avoiding biting flies. However, temperature has the highest correlation to the number of stripes on a zebra, the researchers reported in the journal Royal Society Open Science. 
 
 They also found that the warmer it is, the more stripes a zebra has. 
 
 Brenda Larison, co-author of the study, told ABC News that there are two ways temperature could affect striping. 
 
 One is called the “cooling eddy” theory that suggests there are opposing airflows on a zebra’s black and white stripes because of the different speeds heat rises on black and white fur. At the intersections of these currents, there are whirlpools of air that cool their skin. 
 
 These cooling swirls of air could also repel biting insects that prefer the heat, such as tsetse flies. 
 
 The researchers of the study came to this conclusion by checking the relationship between stripes and 29 different environmental factors at 16 different wildlife sites within Central and Southern Africa. They also chose to study zebras that live on plains because they are the most common. 
 
 Larison said the study is the first to look at the correlation between all the theories, which had only been tested one at a time until now. 
 
 “What we really feel is important about our study is that most studies so far have only taken one hypothesis and studied it by itself,” said Larison, “but that doesn’t help disprove or help prove the others. We made an effort to throw some of these ideas against each other.” 
 
 Larison adds that they think there are still more complex and multiple factors that influence striping, so for now, the issue still isn’t so black and white. ||||| Plains zebras living in central Africa, like this one in Uganda, tend to have more defined stripes than plains zebras living in more Southern, cooler regions of Africa. 
 
 Zebras' thick, black stripes may have evolved to help these iconic creatures stay cool in the midday African heat, a new study suggests. 
 
 Many African animals sport some stripes on their bodies, but none of these patterns contrast as starkly as the zebra's. Researchers have long struggled to explain the purpose of the zebra's unique black-and-white coat. Some have suggested that the stripes may help zebras camouflage themselves and escape from lions and other predators; avoid nasty bites from disease-carrying flies; or control body heat by generating small-scale breezes over the zebra's body when light and dark stripes heat up at different rates. 
 
 Still, few scientists have tested these explanations, and many argue that the stripes serve a complex mix of purposes. [See images of plains zebras across southern Africa] 
 
 Now, researchers based at the University of California, Los Angeles (UCLA) have produced one of the most comprehensive zebra stripe studies yet by examining how 29 different environmental variables influence the stripe styles of plains zebras at 16 different sites from south to central Africa. 
 
 The scientists found that the definition of stripes along a zebra's back most closely correlated with temperature and precipitation in a zebra's environment, and did not correlate with the prevalence of lions or tsetse flies in the region. These findings suggest that torso stripes may do more to help zebras regulate their body temperature than to avoid predators and tsetse flies, the team reported Tuesday (Jan. 13) in the journal Royal Society Open Science. 
 
 "This wall we kept hitting up against was, 'Well, why do zebra have to have stripes for predation? Other animals have predators, and they don't have stripes,'" said study co-author Ren Larison, a researcher in the Department of Ecology and Evolutionary Biology at UCLA. "And other animals get bitten by flies, and they don't have stripes, either." 
 
 Other animals also need to regulate body temperature, or thermoregulate, Larison pointed out, but zebras may especially benefit from an extra cooling system because they digest food much less efficiently than other grazers in Africa. As such, zebras need to spend longer periods of time out in the heat of the midday sun, eating more food. 
 
 "Zebra have a need to keep foraging throughout the day, which keeps them out in the open more of the time than other animals," Larison told Live Science. "An additional cooling mechanism could be very useful under these circumstances." 
 
 The team found that the plains zebras with the most-defined torso stripes generally lived in the Northern, equatorial region of their range, whereas those with less-defined torso stripes were more common in the Southern, cooler regions of the range — a finding that supports the thermoregulation explanation. 
 
 Still, the researchers have not experimentally tested the theory that black and white stripes may generate small-scale breezes over a zebra's body, and some researchers don't think stripes can actually create this effect. 
 
 "I don't think that you would want to have a lot of black hairs along the top of your back if you wanted to try to keep cool," said Tim Caro, a professor of wildlife biology at the University of California, Davis, who studies zebra stripes but was not involved in the new study. "It's kind of the last color that you would want." 
 
 Caro said regions with warmer, wetter climates are particularly susceptible to several species of disease-carrying flies other than the tsetse fliesthat the team considered in their study, and that the relationship the researchers found may actually be a function of fly avoidance, not thermoregulation. Flies seem to struggle to recognize striped surfaces, but scientists have not quite figured out why this is, Caro told Live Science. 
 
 The study co-authors emphasized that their findings require follow-up research, and that a zebra's stripes likely serve multiple purposes. For example, stripes on a zebra's back may help thermoregulate, whereas stripes on the animal's legs — where zebras are more likely to get bitten by flies — may help them avoid disease-carrying flies other than tsetses, Larison said. 
 
 "Really, the striping is kind of extraordinary, so you need something extraordinary to explain it," Larison said. 
 
 The researchers plan to test their thermoregulation hypothesis, either by studying the behavior of air currents over zebra pelts, or by implanting wild zebras with temperature sensors, if they are granted permission to do so, Larison said. 
 
 Follow Laura Poppick on Twitter. Follow us @livescience, Facebook & Google+. Original article on Live Science.
– There are all kinds of explanations out there for why zebras have stripes, ranging from tricking lions to putting off bugs. A new study helps clarify the situation: Zebras' stripes appear to be linked to temperature, National Geographic reports. Zebras living in warmer temperatures have more stripes than their cousins in colder weather, and researchers wanted to find out why. Investigating 16 different zebra populations, they looked at 29 features of their various environments, from soil to disease prevalence. Seeking a link between these features and the zebras' various stripe patterns, they found the strongest connection involved temperature. The link was so strong that scientists, armed with temperature data, were able to predict stripe patterns among other zebra populations. One reason for the connection might be that the way air interacts with the different colors could help keep zebras cool. Because they're not so efficient at digesting food, zebras have to keep eating—under a hot sun—more often than other animals, making cooling important, LiveScience reports. The stripes may also keep away disease-carrying bugs, who like hot areas and don't like stripes. The specifics remain unclear, but the study sheds some light on the subject. "What we really feel is important about our study is that most studies so far have only taken one hypothesis and studied it by itself," a researcher tells ABC News. "We made an effort to throw some of these ideas against each other.” One thing that seems clear: Stripe patterns aren't connected to the local lion population. (Here's more evidence the stripes are there to deter biting flies.)