I imagine that there are a number of stories told by native peoples of Africa that explain the tear marks of the cheetah, which you can see in the picture above. The one that I have heard before (which you can read by clicking HERE) tells of the cheetah being told by lions that she was not a cat, and instead was a dog. The cheetah then went to talk with the wild dogs. But the wild dogs also kicked the cheetah out, saying that she was a cat and not a dog. The cheetah, sad with the fact that she did not seem to belong to either group, cried so much that the tear marks were burned into her face.
Big Cat Diary: Cheetah," Jonathan and Angela Scott propose an alternative hypothesis. Though they do mention the anti-glare hypothesis, the Scotts suspect that a more likely alternative is that the tear-marks serve to "accentuate facial expressions," which they say would be an "important consideration in social interactions with other cheetahs." The tear marks, "along with the growls and hisses that are an important part of a cheetah's defensive repertoire," might "deter competitors from approaching." While this is well and good for the cheetah, and is likely at least part of the reason why the cheetah has the malar stripes, I have a difficult time believing that this is the only reason why some animals evolved the stripes. We will get to my reasoning in a second.
|My cat Chimney. Notice her slit pupils. And the One Direction pillow in the background. Photo Credit: Dani Neher|
It’s meant to reduce glare by having the sun strike or be concentrated in the area beneath the eye, leaving the area above in proper contrast. The black lines under the eyes of cheetahs, most falcons (gyrfalcons and merlins being notable exceptions) and even flickers have malar stripes, though in flickers they serve as signals for courtship, not for better visibility of prey species!
|Other falcons that have the malar stripe include the American kestrel....|
|....and the peregrine falcon.|
|A Cuvier's gazelle at the San Diego Zoo, which also has very similar malar stripes.|
|A Speke's gazelle at the San Diego Zoo, yet another gazelle that has the same sort of malar stripes.|
I find it possible that coevolution has occurred in regards to the cheetah and its prey. Imagine if a certain lineage of cheetah evolved that had the black tear marks beneath their eyes, while the rest of their cheetah brethren did not have this black streak. If the black streak did help them see their prey a little better by reducing glare, then perhaps these cheetahs were more successful hunters, and produced more offspring because of it. Suddenly, the gazelles and impala are faced with a formidable foe that can suddenly see farther than they used to be able to. In order to compensate, it's possible that the antelope who also had black streaks under their eyes were able to see farther as well, and spot the approach of a predator from a greater distance. Strangely enough, I haven't been able to find anything anywhere suggesting that coevolution might have occurred here, so who knows! I'm just throwing this out there, I'm not saying that's definitely what happened, but it's a prospect which I find intriguing and thought worth sharing with all of you.
*To read more about species differentiation and the role it plays in the success of biological organisms and species diversity, click HERE to learn more about the effects of logging on a type of fish called cichlids.
An interview with Anne Price.
Anderson, Stanley H., and John R. Squires. The Prairie Falcon. University of Texas Press, 1997. (accessed December 16, 2013).
"General Information About the Cheetah." Cheetah Conservation Fund. http://www.cheetah.org/?nd=general_info (accessed December 16, 2013).
"How The Cheetah Got Its Tears." Cheetah Conservation Fund. http://www.cheetah.org/?nd=story_cheetah_tears (accessed December 16, 2013).
Stokes, Donald, and Lillian Stokes. The Stokes Field Guide to the Birds of North America. New York: Little, Brown and Company, 2010. (accessed January 23, 2014).