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How the zebra came by his stripes.
February 9, 2012 7:22 AM   Subscribe

How the zebra came by his stripes. "Why zebras evolved their characteristic black-and-white stripes has been the subject of decades of debate among scientists. Now researchers from Hungary and Sweden claim to have solved the mystery."
posted by estherhaza (35 comments total) 3 users marked this as a favorite

 
I hate to be a Debbie Downer, but no they didn't...

"[They] recognise this in their study, and my hunch is that there is not a single explanation and that many factors are involved in the zebra's stripes.
posted by inthe80s at 7:27 AM on February 9, 2012


Interesting. 'Camouflage' never really seemed to make sense, say what you like about dazzle.

"for this explanation to be true, the authors would have to show that tabanid fly bites are a major selection pressure on zebras, but not on horses and donkeys found elsewhere in the world... none of which are stripy"

I don't think that's true. Not all animals facing the same issues have to evolve the same solution - that's sort of what evolution is about, isn't it?
posted by Segundus at 7:36 AM on February 9, 2012 [1 favorite]


The stripes, they say, came about to keep away blood-sucking flies.

Arrrgh. I know they're writing for a lay audience, but would someone please explain to the BBC how adaptation and evolution works?

The stripes were a random mutation that proved to be a helpful survival mechanism, so they were passed on to surviving descendents. The stripes came about randomly and were maintained and evolved because they were useful.
posted by zarq at 7:39 AM on February 9, 2012 [9 favorites]


There still has to be some kind of predator dazzle effect because otherwise you'll have a hard time explaining why something that looks so little like grass can hide in grass.
posted by DU at 7:42 AM on February 9, 2012


I thought it had to do with a mischievous orang-utan who was trying to settle a score with the dour tiger.
posted by Alvy Ampersand at 7:44 AM on February 9, 2012 [2 favorites]


"...many factors are involved in the zebra's stripes.

Scientists: "The zebra's stripes have evolved to make the animal less attractive to a particular biting insect."

Evolution: "Not guilty. This one was really just random and the female Zebras sort of dug it and there you have it, but if it helps with the insects too, well then, jolly good for us."
posted by three blind mice at 7:45 AM on February 9, 2012 [1 favorite]


Everyone knows the donkeys got a shaman to paint them so they could avoid working for the villagers.
posted by freecellwizard at 7:52 AM on February 9, 2012 [5 favorites]


...otherwise you'll have a hard time explaining why something that looks so little like grass can hide in grass.

IANAScientist, but don't most predators see in black and white, to emphasize movement? In B&W, zebra stripes may look more like grass than it does to us. (But idunno, and I gratefully yield to anyone with actual knowledge in the matter.)
posted by Capt. Renault at 7:56 AM on February 9, 2012


Capt., I think it's been shown that small cats, at least, can see in color perfectly well - they just don't respond to differences in color, because color is not relevant to their interests (that is, things that move, and can potentially be caught and eaten). I suppose the same is true for big cats as well.
posted by Curious Artificer at 8:01 AM on February 9, 2012


One of my daughter's favorite stories that I made up involves the fact that zebras used to just be black, but then they were putting the first asphalt highway through the African savanna, and this one mischievous young zebra named Sue disobeyed her parents and crossed this ribbon of road, just as the striper truck was coming through. The accident gave Sue these white stripes, which horrified the adult zebras, but the other teenage zebras HAD to have these stripes, so they started hanging out by the highway, and, offering the guy in the striping truck a quarter each for stripes like Sue's and pretty soon everyone had to have them and the adults eventually came around on this issue.

My daughter never did ask where you'd keep a quarter, if you were a zebra.
posted by Danf at 8:03 AM on February 9, 2012 [8 favorites]


Zebras keep their quarters in a safe place, obv.
posted by Capt. Renault at 8:16 AM on February 9, 2012 [3 favorites]


Maybe their hindquarters.
posted by Capt. Renault at 8:16 AM on February 9, 2012 [6 favorites]


IANAScientist, but don't most predators see in black and white, to emphasize movement? In B&W, zebra stripes may look more like grass than it does to us.

In that case, there needs to be an explanation of why most animals *aren't* black and white. And vertically striped, in the case of things like antelopes.
posted by DU at 8:28 AM on February 9, 2012


DU: " In that case, there needs to be an explanation of why most animals *aren't* black and white. And vertically striped, in the case of things like antelopes."

Adaptation is the result of random mutations. Just because a particular trait is useful to one species, does not mean that it will develop naturally in another. Or that it must.

Coloration is only one way that some animals avoid predators. It is not the only way. Nor is it the primary defense mechanism for every animal.
posted by zarq at 8:34 AM on February 9, 2012 [1 favorite]


Since I came in here to make a Pepe Le Pew joke, I really appreciated your story Danf. Followed up by a pun, I feel like this thread has been secretly written for me.

Segundus: "Interesting. 'Camouflage' never really seemed to make sense, say what you like about dazzle."

Before reading the rest of the thread (and, you know, actually thinking), I thought that you had forgotten to capitalize a word, and that Dazzle was one of those My Little Ponies I keep hearing so much about. I need to spend less time online (or watch MLP, one of those.)
posted by MCMikeNamara at 8:36 AM on February 9, 2012 [2 favorites]


Adaptation is the result of random mutations.

I don't think this is sufficient to explain the uniform system of coloring non-zebras have.
posted by DU at 8:51 AM on February 9, 2012 [1 favorite]


'Camouflage' never really seemed to make sense, say what you like about dazzle.

Ever seen video of zebras running in a tight, dusty herd while chased by lions?
Imagine a lion trying to pick out a point of attack in that dazzling, shifting maze without getting a hoof in the chin.
It's the most awesome camouflage ever, for two reasons:
>It doesn't depend on a botanical background--zebras carry their background with them.
>It works even as the prey is being attacked by the predator.
posted by weapons-grade pandemonium at 8:57 AM on February 9, 2012 [2 favorites]


I often wondered why humans and more animals do not have stripes, seeing as how we evolved under the same conditions as zebras
posted by Renoroc at 9:01 AM on February 9, 2012


DU: " I don't think this is sufficient to explain the uniform system of coloring non-zebras have."

What uniform system? Zebras live on savannahs. In Africa, their non-predator neighbors include:

* Elephants, which are gray.
* Rhinos, which are also gray.
* Giraffes, which are tan with reddish-brown blotches.
* Meercats, which can be tan, silver, orange or brown.
* African Wild Dogs, whose coats incorporate a wide range of patterns using one or all of the following colors: red, brown, black, white and yellow.
* Cape Buffalo which range from dark brown to black.
* Antelope: (red lechwe, sable, dik dik, impala, gazelles, oryx, roan, kudu, gerenuks etc., etc.,) whose coloration incorporates many different colors depending on subspecies.

And this list doesn't even include the various bird species or other mammals, like the mongoose.
posted by zarq at 9:03 AM on February 9, 2012 [1 favorite]


Perhaps zebras aren't striped to camouflage themselves in grass -- they're striped principally to camouflage themselves in a herd of zebras. Striped fish in schools would seem to enjoy similar benefits. The variation in pitch of vertical stripes makes it hard to visually estimate horizontal speed when the animal is moving, pitch varies with projection, and dazzle works to suppress boundaries among multiple moving individuals. Under these circumstances, it's challenging for a predator to track and coordinate an attack on an individual moving in a group.
posted by 0rison at 9:13 AM on February 9, 2012 [3 favorites]


I'm still holding tight to the Ford Prefect theory of giraffe neck length
posted by Mchelly at 9:31 AM on February 9, 2012 [1 favorite]


Horses have special muscles that move their skin in order to shake off files, do zebras have these muscles?
posted by Ad hominem at 9:32 AM on February 9, 2012


I always thought the stripes functioned to make the zebra's edges very hard to distinguish visually, especially in a group, but also in a context of grass, and thereby made it more likely that strikes from predators would gang aft agley, a view I think finds support in the fact (when last I read) that despite many, many attempts, no one has successfully tanned zebra hide because of the way it tends to break apart into chunks-- bite-sized breakaway chunks-- which would seem to be a predator evasion mechanism that would go hand-in-hand with making the boundaries of the zebra hard to see.

However, I also think the view espoused by the linked article is supported by the (unfortunately former) existence of the quagga, that had stripes on only its forequarters, which is just the part of the animal a switching tail cannot drive biting flies away from.
posted by jamjam at 9:34 AM on February 9, 2012 [1 favorite]


Ad hominem: "Horses have special muscles that move their skin in order to shake off files, do zebras have these muscles?"

Yes.
posted by zarq at 9:42 AM on February 9, 2012 [1 favorite]


"I thought that you had forgotten to capitalize a word, and that Dazzle was one of those My Little Ponies I keep hearing so much about."

You're thinking of Zecora.
posted by oddman at 10:00 AM on February 9, 2012 [3 favorites]


//they're striped principally to camouflage themselves in a herd of zebras//

This is the explanation that my daughter, who is a state hippology champion, gave to me when I asked her about the stripes a while back.
posted by COD at 10:15 AM on February 9, 2012 [1 favorite]


It's tempting but sometimes wrong to assign meaning where there may be none. Maybe zebras just got stripes cuz, you know, something mutated or whatever, and it wasn't THAT bad, and the stripey zebras had a lot of zebra sex, or at least enough to make more stripey zebras to stay ahead of the monocolored ones.

I mean, maybe there wasn't selection pressure, but the opposite. Something I like to call "selection whatever." Evolution don't give a shit about the stripes. They ok. Leave em be.

It's like with tuxedo cats, and I have one. Who the hell is able to explain why they're patterned the way they are? White paws, white belly, white nose and cheeks? We could easily make something up, like how this particular coloration was the result of selection pressure to cats of the tundra, who were cold as shit in the katabatic and got black fur to keep itself warm in the sun. Who hunted small mice in the snow and would dive their heads down into the frost for food. Whose principal enemy was, like, a prehistoric mini-Sarlacc-pit-thing that kept itself hidden under the snow, and hunted with a primitive eye. Sometimes the cat would cram its head into the mouth of the Sarlacc. Sometimes, though, the cat would escape detection a the cat's underbelly camouflaged itself perfectly with the white arctic sky.

Or whatever. Nature was just like "fukkit imagonna make some splotches BLADOW!" And it was fine. The predators didn't give a shit cuz the cats were, as they are now, lazy fucks, and color scheme didn't matter.

Basically, as far as I can tell, all the different species and colors and patterns of cats came about as total flooks: Nature tried to evolve the asshole-ishness of cats by any means possible, including making tuxedo cats. And thusly, perhaps, zebras, being the biggest dicks of the equine kingdom, got stripes.
posted by herrdoktor at 1:04 PM on February 9, 2012 [1 favorite]


Wow. That's about the worst lay explanation of polarized light I've ever seen.
posted by 7segment at 1:45 PM on February 9, 2012


OK I give! What is 'hippology'?
posted by Katjusa Roquette at 1:46 PM on February 9, 2012


Twenty bucks, same as out on the savanna.
posted by Capt. Renault at 1:55 PM on February 9, 2012 [2 favorites]


Katjusa Roquette: "OK I give! What is 'hippology'?"

Equine science.
posted by zarq at 2:42 PM on February 9, 2012


Sheeit, cuz zebra stripes are da pimp-ass shizzat. All the does be diggin the broes wit da stripes like doze. You knows? Das right.

All da mares be takin dares cuz dey stares all nights at teh stripes they be right black and white together amirite?

We know whys cuz da flies dey supersize no more lies well i tries
posted by Xoebe at 3:35 PM on February 9, 2012


Renoroc: well…
posted by stilist at 8:07 PM on February 9, 2012


Under these circumstances, it's challenging for a predator to track and coordinate an attack on an individual moving in a group.

That's what I've always heard. A lion sees a great number of moving stripes, but can't figure out which grouping is an actual target. Interestingly, bird biologists in Maine have told me that the large rafts of eider ducks in our area — often hundreds of mother birds surrounding chicks that have not yet developed their flight feathers — present their predators with the same problem. Confronted with a large, moving mass of birds, how do you locate one specific target?
posted by LeLiLo at 9:00 AM on February 10, 2012


This study completely fails to identify why horseflies evolved in a way to find zebras unattractive. Why would horseflies develop the ability to not find a zebra?
posted by BurnChao at 11:40 PM on February 10, 2012


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