PLoS ONE | Kojima et al.

Scientists Painted A Cow To Figure Out What A Zebra's Stripes Are For

ryan.ford 10 Oct 2019

Science doesn't always take the straightest of lines to reach a conclusion. But then, the point is to get to the truth about a thing, and if that means an odd, meandering route, then so be it.

Which is perhaps how a bunch of biologists ended up in a pasture with buckets of livestock-grade paint.

Among the many questions biologists have asked for generations is, why do zebras have stripes?

Wikimedia | https://commons.wikimedia.org/wiki/File:Burchell%27s_zebra_(Equus_quagga_burchellii)_head.jpg

We know that a tiger's stripes help it remain unseen while it hunts through jungles and tall grasses. But zebras don't do a ton of hunting, and jungles aren't really their scene.

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As for tall grasses, well, yeah, they do hang around there, but does anybody think this zebra is really blending into the background?

Unsplash | Ron Dauphin

I'm sure that in certain environments, zebras have a bit of an advantage, but as clever camouflage goes, nature has come up with much, much better than this.

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The biologists' hypothesis is that a zebra's stripes serve a different, but no less important function — preventing bug bites.

Unsplash | Thomas Q

The thought is that the stripes might confuse a bug's ability to judge where and how to land, preventing them from biting.

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Flies are more than just a nuisance for the cattle industry.

Giphy

Bug bites are estimated to cost the U.S. cattle industry as much as $2.2 billion a year, as the animals graze less, sleep less, eat less, and get more stressed when they're harassed by flies.

Figuring out if zebra stripes do indeed prevent bites is easily a worthwhile study.

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So, naturally, a team of Japanese researchers looking to confirm that idea went out into a cow pasture and painted six cows to look like zebras.

PLoS ONE | Kojima et al.

They then spent three days observing and getting images of the cows in their zebra disguises, noting any other fly-repelling things they might be doing like flicking their tails or twitching their skin.

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They also painted the cows with black stripes for three days just to see if the paint might repel flies rather than the color of the stripes.

Unsplash | Conner Baker

Because who knows, the scent and fumes from paint could easily repel bugs. However, that was not the case.

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Sure enough, the cows with stripes received far fewer bites.

PLoS ONE | Kojima et al.

Zebra-striping not only reduced the number of flies around the cows, but also reduced those fly-repelling behaviors by about 20%, too.

So the cows weren't bothered as much by the bugs they did attract.

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And yes, the striping was the critical component.

Unsplash | Sunnie-Lee Davison

Holstein cows are black and white, just like zebras, but they're not striped, so they'll still feel the effects of bugs.

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Not only does that confirm that zebra stripes prevent bug bites, but it also gives hope for a low-cost solution to the problem of bug bites.

PLoS ONE | Kojima et al.

It has to be much preferable to spraying chemicals around. However, the researchers cautioned that more work needs to be done, including looking at a larger sample size, different breeds of cows, and over longer periods of time, especially during peak season for biting insects.

Check out the full paper in PLoS ONE.

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