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Scientists Solve the Mystery of Why Zebras Have Stripes 190

Posted by samzenpus
from the leopards-took-the-spots dept.
Hugh Pickens DOT Com (2995471) writes "There have been many explanations for the zebra's impressive stripes including Darwin who thought that the stripes help males and females make sensible choices about whom they mate with. Now Henry Nicholls reports at The Guardian that Tim Caro at the University of California, Davis, has taken a completely original approach, stepping back from one species of zebra and attempting to account for the differences in patterning across different species and subspecies of zebras, horses and asses to see if there is anything about the habitat or ecology of these different equids that hints at the function of stripes. To answer that question, Caro and his colleagues created a detailed map charting the ranges of striped vs. non-striped species and subspecies. Then they worked on a map for the bloodsuckers that targeted those species — specifically, abanid biting flies (horse flies) and tsetse flies.

'I was amazed by our results,' says Caro. 'Again and again, there was greater striping on areas of the body in those parts of the world where there was more annoyance from biting flies.' Where there are tsetse flies, for instance, the equids tend to come in stripes. Where there aren't, they don't. Biologists who buy into the bug-repellent hypothesis say that, all other things being equal, striped animals would have an evolutionary advantage because they wouldn't suffer from the loss of blood, reduced weight gain and lowered milk production that's associated with bug bites. Tsetse flies are also associated with the transmission of diseases. 'There are a lot of them, such as sleeping sickness, equine anemia and equine influenza,' Caro says. Why would zebras evolve to have stripes whereas other hooved mammals did not? The study found that, unlike other African hooved mammals living in the same areas as zebras, zebra hair is shorter than the mouthpart length of biting flies, so zebras may be particularly susceptible to annoyance by biting flies. 'It's clear that the flies can get through that hair and get to the skin.'"
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Scientists Solve the Mystery of Why Zebras Have Stripes

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  • by Mr D from 63 (3395377) on Thursday April 03, 2014 @08:05AM (#46647741)
    So, this is why very few referees suffer from fly bites? I always wondered.
  • Terrible summary (Score:5, Insightful)

    by timholman (71886) on Thursday April 03, 2014 @08:09AM (#46647767)

    You know, if you're going to just copy and paste part of the article as your summary, you might as well post the last paragraph, and get to the actual explanation:

    Zebras have stripes because biting flies have an aversion to landing on striped surfaces.

    • Re: (Score:3, Insightful)

      by Joce640k (829181)

      biting flies have an aversion to landing on striped surfaces.

      Biting flies can't evolve?

      I found the whole thing very unconvincing.

      • Re:Terrible summary (Score:5, Interesting)

        by Thanshin (1188877) on Thursday April 03, 2014 @08:42AM (#46647973)

        biting flies have an aversion to landing on striped surfaces.

        Biting flies can't evolve?

        I found the whole thing very unconvincing.

        If it's proven that biting flies have aversion to landing on striped surfaces, it makes no sense to say it can't be true because flies would evolve. One should rather ask "Why didn't flies evolve past this limitation?"

        One could start with various hypotheses like:
        - It's a behavior that protects them from something. Maybe the advantage of biting zebras has a lesser weight than the disadvantage of losing that protection.
        - It's a behavior that's consequence of something they can't evolve past without not being flies anymore. Maybe their eyes are not able to know the distance of a striped surface with the required precision, for whatever physical reasons, and better eyes would be too expensive.

        • by davewoods (2450314) on Thursday April 03, 2014 @09:06AM (#46648181)

          better eyes would be too expensive.

          They simply ran out of evolution points when they were rolling their species.

        • by Joce640k (829181) on Thursday April 03, 2014 @09:13AM (#46648239) Homepage

          Biting flies can't evolve?

          I found the whole thing very unconvincing.

          If it's proven that biting flies have aversion to landing on striped surfaces, it makes no sense to say it can't be true because flies would evolve.

          Correlation != causation.

          To me it makes much more sense that biting flies have evolved to avoid landing on Zebras (eg. because Zebras have a secret anti-fly weapon we don't know about yet).

          How do they know to avoid Zebras? Because of the stripes.

          Carts and horses. Make sure you know which is which...

          • by JMJimmy (2036122)

            Very interesting idea... it could also be that they also evolved them together, each re-enforcing the other. I wonder if the idea about keeping cool...

            Of course the savannah is a very got place and keeping cool is very important. Another theory has to do with the way light is reflects from the pattern of stripes. The black and white stripes reflect the sun in different ways, the white reflects the sun and causes an upward movement of air. The black absorbs the sun, which causes a downward movement of air. This is said to create a circular air movement around the zebra, which is thought to help keep the zebra cool.

            If this causes turbulence which makes it difficult for the flies to land and take off?

          • by xevioso (598654)

            I don't understand why this would make sense. Flies like the taste of Zebra, lets assume. The fly would not have likely evolved to not like the taste of zebra, unless something about the taste of zebra made it disadvantageous to want to taste zebra. What is more likely is that the zebra evolved stripes first, and the evolution of the eyesight of flies hasn't evolved to keep up with it.

            This is curious because perhaps evolutionary changes in eyesight take much longer to happen than changes in things like sk

        • by ZahrGnosis (66741)

          I half agree and half don't. Asking why the flies did not evolve to adjust is a good question; most animals do evolve to exploit readily available food sources, not to have seemingly random phobias of them, so there seems to be a large unanswered question. My problem with any evolutionary theory, though, that uses the word "why" is that it's implying causality from correlation, which is a science no-no.

          It could be, for example, that flies have some other aversion to zebras -- for example they may have a m

          • by Joce640k (829181)

            I also tend to believe that the result is correct

            Why?

            All we have at the moment is a correlation.

            that the zebra evolved stripes because those with particularly dominant stripes were less prone to disease and problems brought on by fly bites

            Maybe the stripes just help zebras distinguish other zebras clearly in a world full of hoofed animals.

            • by ZahrGnosis (66741)

              Well, "why" I believe it is because I feel like it. :-) Not to be TOO snarky -- that's just the sort of line I draw between "belief" and scientific-fact. This is the strongest correlation I've seen, and to me it's convincing enough until something stronger comes along. I wouldn't call it a strong belief (I mean I just posted paragraphs on how it could be wrong, and it's not really a topic that I have any stake in whatsoever), but if some undead omniscient egyptian deity threatens to kill me unless I answ

            • I also tend to believe that the result is correct

              Why?

              All we have at the moment is a correlation.

              ...

              Au contraire, if you read TFA you will find we have this correlation across multiple equid species (not just zebras) and we have experimental evidence that biting flies do indeed dislike striped surfaces.

        • by GodfatherofSoul (174979) on Thursday April 03, 2014 @11:36AM (#46649753)

          Or, the flies just move on to the millions of other herd animals around without stripes.

        • My guess: Flying towards a striped surface, when you are dependent on multi-faceted bug eyes, looks like flashes of light. Flying insects have evolved instincts to avoid flashes of light, because that is your only tell tale sign that you are about to get caught in a spider web.

          So it is not that they have an "aversion" to striped surfaces exactly. But when approaching a striped surface they will tend to suddenly turn 90 degrees away, which comes out to the same effect.

          • by xevioso (598654)

            Well that assumes that the evolution to avoid light flashes is primarily to avoid becoming dinner of a spider. Perhaps it's because it screws with their ability to see so much that they can't even see what surface they are about to land on. Maybe it hinders their ability to detect their own "altitude" and rather than crash into a surface they will move away.

            • There is a degree of guesswork I was making. It could be spiders, or it could be that these shifts look like movement, which might be a bird.

              I was just watching a mockingbird in my yard the other day. They hunt for bugs by standing still on ground under bushes, then opening their wings. The underside of their wings has a strong white & dark pattern. Apparently that can trigger an insect flight instinct of some kind, causing the insects to move, revealing their location to the sharp eyes of a very st

          • If the field of view of a single facet of the common biting bugs eyes is correlated to the width of the corresponding horse's stripes there would be actual evidence for some sort of bug vision artifact being exploited by evolution.

            It could be tough for a bug brain to evolve out of such an exploit.

            • It is a little more complicated than that because perception within field of view changes with distance. But your idea does suggest some interesting experiments: how/whether variations in stripe width and distance to striped object can affect insect flight patterns.
              • Sure; but all things being equal, a wider field of view/cell would imply a wider stripe to trigger a similar artifact. Biting flies being fairly similar in size/flight speed/wing loading, I'd assume their landing patterns are also similar. You could adjust data to the degree that's not true. Not sure there's enough striped animals, biting flies and variation in eye physiology in the world to get a statistically significant answer.

                Your experiment would be tricky to carry out. The 'will they prefer to land

        • by mikael (484)

          If a bug lands or even flies past an area of white hair, it becomes immediately noticeable to fast-moving predators like birds.

      • by kruach aum (1934852) on Thursday April 03, 2014 @08:46AM (#46648003)

        They can evolve, but they have evolved to a local maximum where they can't determine whether visual information received indicates a zebra, mud, or water. As they seem to be thriving at this level, there is no pressure for them to evolve the required discriminatory abilities.

        • replace "mud or water" with "things they don't want to land on." I made a thinko.

        • by asylumx (881307)
          Also, just because they haven't evolved to do this yet doesn't mean that they won't ever evolve to do that. People seem to think as "today" as if it's the pinnacle of evolution, but it's not. Who knows what kinds of species the Earth will be home to in 100,000 yrs? 1 million years?
      • by rmdingler (1955220) on Thursday April 03, 2014 @08:48AM (#46648019)
        Biting flies, like the zebra, certainly do evolve... typically at a much faster rate than large mammals.

        That would make the idea of evolving insect repellent coloring even more amazing.

        For proof like in the pudding, the biting flies would have to be shown to exert selection pressure on zebras that is not present where equines without stripes flourish.

        It could be the striped coat offers an amalgam of advantages. Hindering attacks from predators trying to pick out a single quarry in a sea of seizure-inducing undulating stripes should not be considered mutually exclusive from hindering insect bites.

        • by Joce640k (829181)

          Biting flies evolve... typically at a much faster rate than large mammals.

          ...which makes it even less likely that strips would work to keep them away. They'd out-evolve the stripes before the stripes ever developed fully.

          • by BasilBrush (643681) on Thursday April 03, 2014 @10:47AM (#46649235)

            Don't forget complexity of the change required.

            Flies eyes are segmented and see completely different to us. It could be that there's some sort of visual effect of stripes and segmented eyes.

            Evolving stripes is much easier than evolving a different kind of eye or vision system.

        • by jeffmeden (135043)

          Biting flies, like the zebra, certainly do evolve... typically at a much faster rate than large mammals.

          That would make the idea of evolving insect repellent coloring even more amazing.

          For proof like in the pudding, the biting flies would have to be shown to exert selection pressure on zebras that is not present where equines without stripes flourish.

          It could be the striped coat offers an amalgam of advantages. Hindering attacks from predators trying to pick out a single quarry in a sea of seizure-inducing undulating stripes should not be considered mutually exclusive from hindering insect bites.

          Predator logic...
          A few stripes: bite like hell until my mouth has food in it
          A shit-ton of stripes: bite like hell until my mouth has food in it

          • by Joce640k (829181)

            Hindering attacks from predators trying to pick out a single quarry in a sea of seizure-inducing undulating stripes should not be considered mutually exclusive from hindering insect bites.

            Predator logic...
            A few stripes: bite like hell until my mouth has food in it
            A shit-ton of stripes: bite like hell until my mouth has food in it

            Yep. If that's their strategy, it doesn't seem to be working: https://www.google.es/search?q... [google.es]

            The 'camouflage' explanation doesn't hold up under scrutiny. eg. I don't recall seeing human soldiers wearing black/white stripy uniforms in Africa...

            Me? I think other zebras just find stripes irresistible, ie. Zebra eyes have evolved to enjoy being surrounded by other zebras

      • biting flies have an aversion to landing on striped surfaces.

        Biting flies can't evolve?

        I found the whole thing very unconvincing.

        Not only that, but wouldn't it be easier to just grow longer hair?

      • by geekmux (1040042) on Thursday April 03, 2014 @09:34AM (#46648463)

        biting flies have an aversion to landing on striped surfaces.

        Biting flies can't evolve?

        I found the whole thing very unconvincing.

        For biting flies to evolve, there would likely have to be a considerable reason to, such as zebras being their only source to lay eggs. Chances are their ecosystem was hardly impacted at all by zebra evolution due to diversity.

        As evidenced, zebras did evolve due to considerable reasons, as their short hair made them rather specific targets for the flies above many other animals.

        Thankfully, evolution does require considerable justification. Questionable mutations would evolve otherwise, and we should be thankful it's not a knee-jerk reaction in nature, no matter how much we would like to prove it actually exists to those who refuse to acknowledge it on every level.

        • by Joce640k (829181)

          For biting flies to evolve, there would likely have to be a considerable reason to

          The same argument applies to stripes. Maybe more so - stripes aren't food, they have a much more subtle evolutionary pressure (assuming they're the repel flies).

          Longer, swishier tails to swat flies with seem much easier to evolve than stripes - there's already some genetic variation in tails.

        • As evidenced, zebras did evolve due to considerable reasons, as their short hair made them rather specific targets for the flies above many other animals.

          A person would think it would be "cheaper" in an evolutionary sense to evolve slightly longer hair instead of stripes. But meh, I am not an evolutionary biologist.

      • Biting flies can't evolve

        Like most science this brings up more questions. Additionally why didn't Zebras evolve longer hair if the flies can't get through that as well, apparently other animals did evolve long hair and not stripes. Maybe for different reasons, maybe none of the explanations are any good. Isn't science fun!

        • by Urkki (668283)

          Like most science this brings up more questions. Additionally why didn't Zebras evolve longer hair if the flies can't get through that as well, apparently other animals did evolve long hair and not stripes. Maybe for different reasons, maybe none of the explanations are any good. Isn't science fun!

          Well, I'd think longer hair also has some disadvantages. It's maybe more of a case of zebras evolving shorter hair after stripes made that possible.

      • Just playing devils advocate (I am sure there is a joke in there somewhere)...

        Anyway, as I understand it, evolution is about the selection of traits for survival, This usually involves environment, eating/not getting eaten, and procreation.

        It very well could be that Zebra's with their short hair, developed stripes to hide from biting insects, as their survival was significantly impacted enough to warrant the change. While on the insect side of things, perhaps they have enough of a food source that missing o

      • very unconvincing... wouldnt it be easier to grow your hair a few mm longer?
        • by JesseMcDonald (536341) on Thursday April 03, 2014 @11:19AM (#46649555) Homepage

          very unconvincing... wouldnt it be easier to grow your hair a few mm longer?

          What's to say that didn't happen? We just don't call the ones with longer hair instead of stripes "zebras".

          Evolution doesn't involve a species voting on how it would prefer to evolve. If there are multiple possible adaptations then it's entirely possible that different subgroups will evolve in different directions in response to the same environmental factors. This is one path to speciation, if the change are significant enough.

      • Isn't it obvious? This is why Elephants, Rhinos, Spring bucks, Antelopes, Giraffes, and Buffalo all have stripes too.

        And their stripe pattern has nothing to do with large, sight base feline predators like lions and tigers in Africa, or jaguars in South America. The selective pressure from being bitten by flies is way stronger than being eaten, especially since equines don't have to rely on camoflauge because they have armored skin, horns, and blazing speed like other potential prey species.
        • by xevioso (598654)

          Elephants and Rhinos have tougher skin. There are multiple species of antelope that have stripes or patterns that may accomplish the same thing. Same with a giraffe. Buffalo have longer hair, so they maybe don't need stripes.

      • Assuming the statistical analysis is correct, I will give the answer:

        As the fly flies by, the alternate dark and light banding confuses the fly into thinking it is the moving shadows of some threat from overhead, like a hungry bird.

        Go write a paper and list me as lead.

      • Biting flies can and do evolve, but they can't say to themselves, "I'd like to bite more zebras, so I'm going to evolve better ways to decide what to land on."

        If the flies who could and did land on zebras reproduced at a rate significantly higher than those who didn't land on zebras, then they would evolve. As that hasn't happened (turns out landing on a zebra isn't such a great thing for a fly to do anyway), there has been no evolutionary pressure and the flies haven't changed.

      • They could... However just as long as they can find alternate food in enough quantity to pass on to the next generation, why risk it.

        Normally stripped animals usually poisonous. Its aversion to stripes means to avoid from biting anything poisonous.

        Now if the fly didn't have other food sources, I expect every once in a while a fly will try to bite a Zebra and make it, and if food was limited, that fly could have an advantage.

    • I read other articles that said the scientists basically found a correlation between heavy populations of biting flies and intensely stripped zebras. All they have is some statistical analysis that says these populations overlap. They [the scientists] then say that this is intriguing and someone should figure out if the stripes actually protect the zebras.

      that's fine. it's good science. It's the journalists that are claiming, that flies have an aversion to striped surfaces.

      For all we know, the heavy
      • by Joce640k (829181)

        I read other articles that said the scientists basically found a correlation between heavy populations of biting flies and intensely stripped zebras. All they have is some statistical analysis that says these populations overlap. They [the scientists] then say that this is intriguing and someone should figure out if the stripes actually protect the zebras.

        that's fine. it's good science. It's the journalists that are claiming, that flies have an aversion to striped surfaces.

        Or.... maybe the flies have a good reason to avoid zebras - Zebra blood tastes bad or something.

        The 'camouflage' explanation isn't very good either. I don't see many African soldiers wearing black/white striped uniforms, do you?

        My theory? Zebras live in a land full of hoofed animals and the stripes let them know which other animals they're supposed to hang out/mate with. ie. Zebra eyes find stripes irresistible.

    • by jeffmeden (135043)

      You know, if you're going to just copy and paste part of the article as your summary, you might as well post the last paragraph, and get to the actual explanation:

      Zebras have stripes because biting flies have an aversion to landing on striped surfaces.

      Yep, or put another way:
      "Getting bitten by flies because your hair is too short? Fuck longer hair, let's get some stripes! Because evolution!"

    • Thank you. Bloody summary doesn't make sense without that nugget.

    • by Gothmolly (148874)

      You know, I was going to make a Roland Picquipaille joke, and then I looked, and lo it was Hugh Pickens, the second copypasta/clicktroll master.

    • Zebras have stripes because biting flies have an aversion to landing on striped surfaces.

      Which article is that the last paragraph of? I don't see it.

      AFAICS, they seem to have got as far as identifying that it has something to do with biting insects, but the specifics are not known yet.

    • by urbanriot (924981)
      Thank you. I read the summary and then re-read the summary many times thereafter and wasn't entirely sure if they figured it out or didn't figure it out. "Scientists figured it out..." "... but then they realized that what they figured out didn't make a difference."

      It seems submitters and moderators aren't actually summarizing but rather, they're cutting up quotes and links in ways that don't jive with the post title.
  • by OzPeter (195038) on Thursday April 03, 2014 @08:09AM (#46647771)

    Are Zebras Black with White stripes or White with Black stripes?

    • Re: (Score:2, Informative)

      by Anonymous Coward

      Are Zebras Black with White stripes or White with Black stripes?

      Black with white stripes. Their snouts are black making them their stripes white.

  • by Grantbridge (1377621) on Thursday April 03, 2014 @08:10AM (#46647775)

    Relevant quotes missing from summary:

    "researchers built horse mannequins, painted them in a variety of patterns, coated them with sticky stuff, and found that horseflies seemed to avoid landing on the fake horses that were painted with black and white stripes."

    "The proposed explanation was that the flies preferred to land on dark surfaces. Such surfaces reflect the kind of polarized light that reminds the flies of the water or mud where they breed. Light surfaces aren't as attractive, but dark-and-light patterns are even worse — perhaps because such patterns confuse the flies' navigational sense."

    • by lazarus (2879)

      I am totally trying this with body paint next time I go to the beach.

    • Relevant quotes missing from summary:

      "researchers built horse mannequins, painted them in a variety of patterns, coated them with sticky stuff, and found that horseflies seemed to avoid landing on the fake horses that were painted with black and white stripes."

      "The proposed explanation was that the flies preferred to land on dark surfaces. Such surfaces reflect the kind of polarized light that reminds the flies of the water or mud where they breed. Light surfaces aren't as attractive, but dark-and-light patterns are even worse — perhaps because such patterns confuse the flies' navigational sense."

      Flies don't like to land on moving surfaces from what I've seen. They prefer stationary targets which won't move while they're trying to land, are less likely to be able to swat them, whatever.

      If you can't keep moving all the time (and in tropical regions, you'd really prefer not to), then the alternative is to provide the illusion of movement. As a fly approaches a striped object, those compound eyes are going to register a veritable pyrotechnic display of apparent movement, since the fly is moving relativ

      • Your is a reasonable hypothesis. I would offer another hypothesis: that stripes seen through multifaceted eyes resemble flashes of light -- which is you only tell tale sign you are about you get caught in a spider web; thus flying insects will turn away from the perceived flashing object.
        • by matfud (464184)

          Sort of.
          Insects with multifaceted eyes tend to only see montion flow. Changes in intensity moving from facet to facet. stripes can cause problems with this scheme due to what is in essence the equivenent of aliasing.

          I'm not saying this is why Zebra have stripes.But from what is known of compound eyes and the processing happening it is plausable. Even humans can suffer from a very similar problem. Drive past a bar fence (fence made of vertical metal plates close together) when the sun is setting behind it. N

  • by YalithKBK (2886373) on Thursday April 03, 2014 @08:22AM (#46647841)

    I thought the stripes broke up the outlines of individuals and made it harder for predators to single one out of a crowd? Or did no actual research go into that claim?

    • by Joce640k (829181)

      I think flies are allowed to evolve to overcome things like this, but what do I know, right?

      • As other posters have pointed out, chances are that one of three things happened:

        1) The flies were doing well enough even with the zebra's stripe-protection and so there wasn't a strong evolutionary pressure to get past this.

        2) The stripe-aversion consisted of a benefit (e.g. kept them from landing on surfaces that could harm them) and this outweighed any benefit of being able to get past the zebra stripes.

        3) The biological cost involved with overcoming the stripe-aversion (e.g. better eyes) was too grea

    • by alfredo (18243)
      Our hair serves more than one purpose, so why shouldn't Zebra stripes?
  • Hypothesized in 1982 (Score:5, Interesting)

    by DarwinSurvivor (1752106) on Thursday April 03, 2014 @08:54AM (#46648069)

    Zebra stripes have traditionally been thought of as an adaptation against detection by vertebrate predators such as lions and hyaenas. A different hypothesis is suggested: that the stripes are an adaptation against visually orienting biting flies and act by obliterating the stimulus presented by a large dark form, which is important in host-finding by many Diptera. This hypothesis is supported by some indirect evidence, and by a field experiment in Zimbabwe in which biting fly catches were compared on moving and stationary black, white and striped models. Striped models caught significantly fewer tsetse (Glossina morsitans) Westwood and other flies (including tabanids) than solid black or white models, but this difference was much reduced in the presence of olfactory attractants.

    ~Waage, J. K. (1981) [lifedesks.org]

    Maybe people studying zebras should start by reading the zebra wikipedia page [wikipedia.org].

    • I don't think the article's particularly clear about this, but these guys aren't necessarily claiming to be the first with the idea. They've just done the work to back it up.

      • by BitZtream (692029)

        No, they didn't. They didn't do anything other than look at the number of flies in relation to number of zebras in a particular area and made some random guesses.

        • Oh, what a shame that Nature Communications wasted all their time with their silly peer-review process when they have just asked Professor BitZstream from the University of... where was it again?

          Are you sure you're not just mad because you always felt so clever when you told people at parties that zebras had stripes to confuse lions?

    • AFAIK the Waage study did not map the respective habitats of zebras and flies; that is what is actually new in this study, and it supports the Waage hypothesis.
      • Tested? They compared fly population levels to zebra stripe quantities. The study in this article could have just as easily determined that stripes cause fly populations to increase! The 1981 study actually did tests with different colored dummies and checked which ones had more flies attracted to it.
  • Why does the title claim this is solved? Even the summary calls it a hypothesis
  • Zebras evolved to hide from German U-boats [wikipedia.org]
  • All other hooven animals in Africa found it easier to evolve longer hair to thwart the flies. Why Zebra did not choose that path? It is easier for the fly to adapt to landing on striped surfaces (change a few neurons reconnection in the brain, more like software update) than to evolve longer proboscis (more tissue, weight limit on flying organisms, more like hardware refit).

    Using painted fake horses and sticky glue is does not mimic a real zebra skin that emits sweat & odors. Real skin has subtle temp

    • Likely the stripes give the animal multiple advantages. Predators and biting insects. Possibly the long hair might also confer some negatives in terms of being able to disparate heat, etc.
  • The zebra hid from leopards among forests and developed stripes to make it easier to hide among the "stripy, speckly, patchy-blatchy shadows".

    I was told 'Just So' by Rudyard Kipling:

    How the Leopard got his spots [gutenberg.org]

  • Those stripes are actually some very evolved bar codes. No one would admit that though since it would establish prior art and invalidate all the lucrative bar code patents. :-)
  • Why would zebras evolve to have stripes whereas other hooved mammals did not?

    I don't think that's true. I distinctly remember seeing a shot of a mustang (not the car, the horse) with stripes on its hindquarters. These are wild horses descended from escaped Spanish horses in the western US. I distinctly remember the announcer saying their wild ancestors probably had stripes, and after half a millennium of independent evolution, some were regaining stripes.

    According to this link [aaanativearts.com] the horses the Blackfeet used often had these stripes. Despite what their legends may say, Native America

  • The Onion guys figured this out a long time ago

    https://www.youtube.com/watch?... [youtube.com]

  • by cstacy (534252)

    I remember reading an article on Snopes about this, quite a while ago.

    As I understand it, the fly's visual system evolved a beneficial mutation that glitches what they see. Zebras are in reality just black horses (look at their snout), but the fly's retina paints those white stripes on them. This allows the fly to more easily attack the zebra, although not as effectively as if the animal was all white. This effect is well known in our domesticated horses -- horseflies are attracted to light colored anima

  • Causation?

    I didn't see where zebra coloring schemes was demonstrated to repel or confuse pests like tsetse flies. Have these scientists demonstrated something about flies vision that the stripes interfere with? Do flies even depend upon vision to locate prey?

    I had heard the theory that zebra striping was a kind of dazzle camouflage [wikipedia.org] which confused larger predators when trying to pick out one animal to pursue. I just didn't think flies could see that well.

    • Re:Correlation? (Score:4, Informative)

      by wonkey_monkey (2592601) on Thursday April 03, 2014 @10:58AM (#46649343) Homepage

      Have these scientists demonstrated something about flies vision that the stripes interfere with?

      That much has already been shown to be the case - or at least, that flies have an aversion to landing on striped surfaces.

      I had heard the theory that zebra striping was a kind of dazzle camouflage [wikipedia.org] which confused larger predators when trying to pick out one animal to pursue.

      It can, of course, be both.

  • I recall hearing this theory a short while ago and rolling my eyes at the ridiculous reach of "insect repellent." Goes to show you what a great experiment can reveal. Some of the ideas that natural science types come up with to test hypotheses are as simple and elegant as they are revealing.

  • by X10 (186866)

    Do tigers have stripes for the same reason? If not, how do we know that Zebras don't have them for the same reason as tigers?

  • Polkadots made them look fat, and floral prints are not suitable for the dry season.
  • I have a theory on why the stripes may confuse flies. Compare it to driving in sunlight and then entering a tunnel. Your eyes take a while to adjust to the tunnel's dimmer light, and then have to re-adjust on the way out of the tunnel. When you are fly-sized, you'll have a somewhat similar issue near black and white stripes. The changing light levels may make it hard to identify enough surface details to land properly. When your eyes adjust to the white areas enough to make out hair clumps, you then are in

  • So why doesn't this theory apply to Holstein cows? Just because of the stripes vs splotches of black and white?

In order to dial out, it is necessary to broaden one's dimension.

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