Why Cheetahs Have Big Eyes?

The fastest runner in the world of animals have eyes that are too big for their body size. The researchers found that the size of the eye affects the velocity of the animal.

“If you can think of mammals that are fast like a cheetah or horse, you can almost guarantee they’ve got really big eyes,” says Chris Kirk. “This gives them better vision to avoid colliding with obstacles in their environment when they’re moving very quickly.” (Picture from: http://gardenofeaden.blogspot.com/)

The bigger the eyes, the better the animal's vision. That was very helpful when the animals have to move fast. The results of this study were published in the journal Anatomical Record, Tuesday (May 1, 2012).

"The size of the eye is one of the most important factor for understanding the evolution of visual abilities and visual adaptation," said Chris Kirk, professor of the University of Texas at Austin, who was involved in the study. "In vertebrates, the increase in eye size can bring benefits, both sharpness and eye sensitivity to light."

Some animals rely more on other senses, like smell rather than sight. However, for other animals, it plays an important vision. This seems to apply to animals sprinter.

"Mammals are moving as fast as a cheetah or a horse could certainly have very big eyes," said Kirk. "The eyes of gave the vision of a better way to avoid a possible collision with the barrier in front of him when they move very fast."

To investigate the factors that influence the size of the eye, the researchers collected the eyes, body, and the running speed of 50 species of mammals. They found that 89 percent of the variation in the size of the mammalian eye is caused by the body mass and maximal running speed.

Cheetahs (Acinonyx jubatus) are the fastest land animal. These long-legged cats can run up to 65 miles per hour (100 kph) in short bursts when they are hunting. (Picture from: http://www.enchantedlearning.com/)

Interestingly, humans seem to not be affected this trend. We've got big eyes, the equivalent of a wolf, but the maximum human running speed is very lame compared to other mammals. "In humans, we conclude that the sprint is not a selective factor that led to the evolution of our eyes," said Kirk.

The study was published online on Wednesday (May 2, 2012), recorded by the anatomy of the journal, and presented at the American Association of Physical Anthropology in 2011 at the meeting. *** [LIVESCIENCE | TJANDRA | KORAN TEMPO 3871]

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