The Zebra’s Stripes and the Importance of Testing Ideas

By it’s definition, science is a way of knowing, understanding, and predicting the natural world through observation and experimentation. The natural world is anything with which humans can interact and experience directly or indirectly. There’s a whole lot of natural world out there: a near infinite amount of things to know.

One of the aspects of science which sets it apart from other disciplines is the constant examining of knowledge already gained. However, authority, tradition, and biases, lead us to confidence in untested truths. Without testing, there is no way to know if our beliefs are correct or unsupported.

Case in point: The zebra’s stripes. What is the explanation for the zebra’s stripes? Is it an adaptation? And if so what advantage do the zebra’s stripes give the species?

I would assume (not being scientific) many people would suggest the hypothesis that the zebra’s stripes are for a camouflage strategy: a way for the zebras to visually blend in with their surroundings and hide from African

Zebra and Equipment from the most recent study
Image Credit: (Tim Caro/UC Davis)

predators. This belief has been cast in the shadow of doubt by Tim Caro and associates from University of Calgary and UC Davis.

A quick search of scholarly and peer-reviewed articles shows Dr. Caro has dedicated serious thought to the origins of these stripes. But the way Cara has approached this problem was surprisingly ignored: categorization, experimentation, and carefully controlled comparisons studies (Caro et al, 2014). You know? The scientific method.

 

Through his studies, Caro has found evidence against the most common hypotheses about the function of zebra stripes. The most recent studies show the distance at which the zebra’s stripes would offer camouflage against their natural habitat would be too close to serve as an advantage against a predator. A predator at distances which it would see the stripes would be able to sense the zebras using other methods.

Additionally, the stripes are likely not used as recognition for the zebras (another hypothesis for the stripes). Closely related unstriped species can recognize individuals with no problem at the same distances the stripes would be visible to the zebras.

Can we tell for certain that the zebras do not use their stripes for camouflage or recognition? No. Could there be a future study which refutes these findings? Certainly. As new evidence comes to light, knowledge will get ever closer to the truth.

In the case of the zebra’s stripes however; there are now a series of systematic experiments and observations which do not back up the camouflage or social hypotheses for the function of the stripes. Additional studies need to be done to determine through evidence the function and more studies need to confirm Caro’s findings. However, at this moment Cara suggests the most plausible function of the stripes is to help the zebra ward off parasitic biting flies.

 

Caro, Tim, et al. “The function of zebra stripes.” Nature communications 5 (2014)

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