News / Science & Technology

    Study: Zebras' Stripes Not Camouflage

    Zebra couples  are seen hugging in Serengeti, Tanzania in this file photo.
    Zebra couples are seen hugging in Serengeti, Tanzania in this file photo.

    Related Articles

    ‘Elusive’ Bush Dog Caught on Camera

    Rarely seen dog may be more common than thought in Panama

    Facebook Tweak Could Evade Chinese, Iranian Censors

    An Android app will allow users to connect to Facebook using the Tor network

    Report: Any Extraterrestrial Life Likely Extinct

    Researchers say most fledgling life on another planet would likely go extinct rapidly
    VOA News

    It has long been thought a zebra’s distinctive black and white striping serves as camouflage from predators, but a new study finds that is not the case.

    Writing in the journal PLOS ONE, researchers from the University of California Davis and the University of Calgary say they calculated how a zebra’s stripes would appear to lions, spotted hyenas and other zebras when viewed in varying levels of light.

    "The most longstanding hypothesis for zebra striping is crypsis, or camouflaging, but until now the question has always been framed through human eyes," said the study's lead author Amanda Melin, an assistant professor of biological anthropology at the University of Calgary, Canada.

    They found that the stripes “cannot be involved in allowing the zebras to blend in with the background of their environment or in breaking up the outline of the zebra” because at the distance a predator would be able to see the stripes, they would likely already have heard or smelled the zebra.

    The researchers noted that at further than 50 meters in daylight or 30 meters at twilight, a zebra’s stripes are easily seen by humans, but not so for would-be predators. On a moonless night, the researchers said the stripes were hard to see by predators and humans, even from just 9 meters away.

    This, researchers said, means that the idea that a zebra’s stripes mimicked tree trunks and shafts of light, did not make sense.

    Furthermore, in the open, where zebras are most commonly found, the stripes do not “disrupt the outline” of the zebra. Lions, researchers said, could see the the outline of zebras just as they could a solid-colored animal.

    "The results from this new study provide no support at all for the idea that the zebra's stripes provide some type of anti-predator camouflaging effect,"said Tim Caro, a UC Davis professor of wildlife biology. "Instead, we reject this long-standing hypothesis that was debated by Charles Darwin and Alfred Russell Wallace."

    Another theory about the stripes, that they better allow zebra’s to see one another was also discredited by the research. While zebra’s can see the stripes over a further distance than its predators, other animals related to zebras can also see each other despite not being striped.

    While not conclusive, the researchers say one reason for the stripes might be to deter biting flies, a common zebra pest.

    You May Like

    Chechen Suspected in Istanbul Attack, but Questions Remain

    Turkish sources say North Caucasus militants involved in bombing at Ataturk airport, but name of at least one alleged attacker raises doubts

    With Johnson Out, Can a New ‘Margaret Thatcher’ Save Britain?

    Contest to replace David Cameron as Britain’s prime minister started in earnest Thursday with top candidates outlining strategy to deal with Brexit fallout

    US Finds Progress Slow Against Human Trafficking in Africa

    Africa continues to be a major source and destination for human trafficking of all kinds -- from forced labor to sexual slavery, says State Department report

    This forum has been closed.
    Comment Sorting
    Comments page of 2
    by: Jim
    January 27, 2016 12:27 PM
    If an animal "needs" a horn due to surviving its environment, evolution will create one? Right? Don't all animals that "need" horns have them? And animals that don't "need" them, don't have them? What if unique characteristics, such as a creature's "camouflage" is not a result of their environment? What if the animals that looks like beach sand, are decimated by predators in other environment except sandy beaches? Thus, through millennia, their "native" environment becomes sandy beaches because this is where they can thrive due to their sandy appearance?

    by: Jim Banville
    January 26, 2016 11:04 AM
    You guys are most likely wrong. Zebras are not the only animal to flee from predators while in herds. If the stripes "developed" as a result of their need to confuse the predator, why wouldn't all the other fleeing-while-in-herds animals develop stripes as well?
    In Response

    by: Brian
    January 26, 2016 2:34 PM
    B/c that isn't how evolution occurs. Animals will evolve whatever trait they happened to develop. That's like saying "If a rhino's horn is for protection, why don't all animals in the universe have a single-pronged horn jutting out of their skull?" You could replace "stripes" in your question with any other distinctive trait possessed by any of the multitudes of unique animals in the earth's biosphere (e.g. giraffes and their long necks, turtles and their shells, etc.)

    by: pocono from: the hills of Pennsylvania
    January 26, 2016 10:19 AM
    And to think, all commentators didn't spend thousands of dollars to know exactly why zebra have stripes. Talk about a waste of time and money that the university's involved spent.
    In Response

    by: Bill from: Oklahoma
    January 26, 2016 11:25 AM
    Since when is an attempt at understanding a waste of money?

    by: Andy
    January 26, 2016 10:09 AM
    It actually is camouflage! But not for there surroundings! When they are running from a predator, they blend in with each other! makes it hard to pick one out.
    In Response

    by: Brian
    January 26, 2016 2:35 PM
    True, that's what I learned too. I'm shocked that neither the article writer nor (evidently) the authors of this paper failed to mention that, as I believe that's the leading hypothesis. The fact that they don't makes me doubt all credibility contained therein.

    by: lydia from: midwest
    January 26, 2016 1:29 AM
    I just recently watched a program on public television stating that the reason they have stripes is to confuse the predators in the way of not being able to focus on their target. They used the example of a bike rim. When it's moving forward quickly it looks like it's moving the other way. They can't lock on the prey as easily in a short time frame.
    In Response

    by: Brian
    January 26, 2016 2:42 PM
    That's the leading hypothesis. The fact that this article (and perhaps the published authors as well) failed to address this makes the entire claim dubious.

    It also fails to mention that the stripes could have evolved by all of these things, depending on how much survival advantage each conferred. In other words, the stripes could have helped with insects, weather, and predators, but if the insects were a minimal threat historically to zebras compared with the threat of, say, hot weather, then their evolution was reinforced more by the weather than insects. Or predators if you like. All played a role in preserving/reinforcing/evolving the stripes but to varying degrees depending on the degree of threat imposed on the zebra populations.

    by: Anybody
    January 26, 2016 1:21 AM
    The stripes make it difficult for a predator to focus on a single zebra while running in a pack.

    by: Bread Ramp Jr. from: Minnesota
    January 26, 2016 1:17 AM
    Checkmate Atheists.

    by: Anonymous
    January 26, 2016 12:46 AM
    Jeeezusgawd! How many years now has it been understood that zebras' stripes create an optical movement camouflage? When they are running in a herd, the stripes play out like a psychadelic fractal image and confuse they eye of the predator, creating a larger margin of error in singling out one prey animal in the bunch....I see the people doing the research travelled back in time to regain ignorance....idiots......

    by: MSJ from: toledo, OH
    January 25, 2016 11:35 PM
    Question.. Could the stripes exist to confuse the attacking predator while the zebra herd scatters? It seems to me that the stripes of several zebra moving in different directions would have that affect.

    by: SamIAm
    January 25, 2016 11:34 PM
    Stripes camouflage the individual within the heard.
    Comments page of 2

    Featured Videos

    Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
    Clinton Leads Trump, But Many Voters Don't Like Eitheri
    Jim Malone
    June 29, 2016 6:16 PM
    In the U.S. presidential race, most recent polls show Democrat Hillary Clinton with a steady lead over Republican Donald Trump as both presumptive party nominees prepare for their party conventions next month. Trump’s disapproval ratings have risen in some recent surveys, but Clinton also suffers from high negative ratings, suggesting both candidates have a lot of work to do to improve their images before the November election. VOA National correspondent Jim Malone has more from Washington.

    Video Clinton Leads Trump, But Many Voters Don't Like Either

    In the U.S. presidential race, most recent polls show Democrat Hillary Clinton with a steady lead over Republican Donald Trump as both presumptive party nominees prepare for their party conventions next month. Trump’s disapproval ratings have risen in some recent surveys, but Clinton also suffers from high negative ratings, suggesting both candidates have a lot of work to do to improve their images before the November election. VOA National correspondent Jim Malone has more from Washington.

    Video Slow Rebuilding Amid Boko Haram Destruction in Nigeria’s Northeast

    Military operations have chased Boko Haram out of towns and cities in Nigeria’s northeast since early last year. But it is only recently that people have begun returning to their homes in Adamawa state, near the border with Cameroon, to try to rebuild their lives. For VOA, Chris Stein traveled to the area and has this report.

    Video New US Ambassador to Somalia Faces Heavy Challenges

    The new U.S. envoy to Somalia, who was sworn into office Monday, will be the first American ambassador to that nation in 25 years. He will take up his post as Somalia faces a number of crucial issues, including insecurity, an upcoming election, and the potential closure of the Dadaab refugee camp in Kenya. VOA’s Jill Craig asked Somalis living in Kenya’s capital city Nairobi how they feel about the U.S. finally installing a new ambassador.

    Video At National Zoo, Captivating Animal Sculptures Illustrate Tragedy of Ocean Pollution

    The National Zoo in Washington, D.C., is home to about 1,800 animals, representing 300 species. But throughout the summer, visitors can also see other kinds of creatures there. They are larger-than-life animal sculptures that speak volumes about a global issue — the massive plastic pollution in our oceans. VOA's June Soh takes us to the zoo's special exhibit, called Washed Ashore: Art to Save the Sea.

    Video Baghdad Bikers Defy War with a Roar

    Baghdad is a city of contradictions. War is a constant. Explosions and kidnappings are part of daily life. But the Iraqi capital remains a thriving city, even if a little beat up. VOA's Sharon Behn reports on how some in Baghdad are defying the stereotype of a nation at war by pursuing a lifestyle known for its iconic symbols of rebellion: motorbikes, leather jackets and roaring engines.

    Video Melting Pot of Immigrants Working to Restore US Capitol Dome

    The American Iron Works company is one of the firms working to renovate the iconic U.S. Capitol Dome. The company employs immigrants of many different cultural and national backgrounds. VOA’s Arman Tarjimanyan has more.

    Video Testing Bamboo as Building Material

    For thousands of years various species of bamboo - one of the world's most versatile plants - have been used for diverse purposes ranging from food and medicine to textiles and construction. But its use on a large scale is hampered because it's not manufactured to specific standards but grown in the ground. A University of Pittsburgh professor is on track to changing that. VOA’s George Putic reports.

    Video Orphanage in Iraqi City Houses Kids Who Lost their Parents to Attacks by IS

    An orphanage in Iraqi Kurdistan has become home to scores of Yazidi children who lost their parents after Islamic State militants took over Sinjar in Iraq’s Nineveh Province in 2014. Iraqi Kurdish forces backed by the U.S. airstrikes have since recaptured Sinjar but the need for the care provided by the orphanage continues. VOA’s Kawa Omar filed this report narrated by Rob Raffaele.

    Video Re-Opening Old Wounds in a Bullet-Riddled Cultural Landmark

    A cultural landmark before Lebanon’s civil war transformed it into a nest of snipers, Beirut’s ‘Yellow House’ is once again set to play a crucial role in the city.  Built in a neo-Ottoman style in the 1920s, in September it is set to be re-opened as a ‘memory museum’ - its bullet-riddled walls and bunkered positions overlooking the city’s notorious ‘Green Line’ maintained for posterity. John Owens reports from Beirut.

    Video Brexit Resounds in US Presidential Contest

    Britain’s decision to leave the European Union is resounding in America’s presidential race. As VOA’s Michael Bowman reports, Republican presumptive nominee Donald Trump sees Britain’s move as an affirmation of his campaign’s core messages, while Democrat Hillary Clinton sees the episode as further evidence that Trump is unfit to be president.

    Video NASA Juno Spacecraft, Nearing Jupiter, to Shed Light on Gas Giant

    After a five-year journey, the spacecraft Juno is nearing its destination, the giant planet Jupiter, where it will enter orbit and start sending data back July 4th. As Mike O'Sullivan reports from Pasadena, California, the craft will pierce the veil of Jupiter's dense cloud cover to reveal its mysteries.

    Video Orlando Shooting Changes Debate on Gun Control

    It’s been nearly two weeks since the largest mass shooting ever in the United States. Despite public calls for tighter gun control laws, Congress is at an impasse. Democratic lawmakers resorted to a 1960s civil rights tactic to portray their frustration. VOA’s Carolyn Presutti explains how the Orlando, Florida shooting is changing the debate.

    Special Report

    Adrift The Invisible African Diaspora