Wednesday, February 17, 2010

Eyes and Balls

The eyes are the window to the soul, they say. I find it so amusing just how much my cat communicates with his eyes... the fact that he will sit there and wait until we've made eye contact, and then tilting his head to one side, he meows in an attempt to tell me just exactly what he would like me to do for him. He looks so funny when he looks to one side and the whites of his eye appears. This got me thinking...besides the fact that he's another species altogether, why are his eyes larger...or the whites of his eyes smaller, than mine. Yours. Humans. I wondered if there was a reason, or if it just simply was. Of course, I had to go investigate. Curiousity killed the cat, but it only makes us humans all the wiser.

What I learned was... and I'm sure this was covered in my high school bio class in between pushup competitions against the instructor and discussions on her picking up poop along trails to figure out what kind of animal pooped it. I will never forget that crazy woman, Ms Ferbie.... the white of the eye is called the "sclera" and basically it is white because there is no pigment. (Really?!) Also, the sclera of a child is quite thin so it appears slightly blue (as it shows the underlying pigment) and the sclera of an old timer is yellowish because of fatty deposits.

There are actually some theories out there as to why our eyes have more visible white than other mammals. In fact, humans are the only mammal in which this occurs. Think about it.



Even the cold-blooded. Lizards:

Why is this?

The Cooperative Eye Hypothesis... which suggests that the eyes evolved this way to make it easier for humans to follow each others gaze while communicating or working together on something (especially while in close contact, or in silence - ie. hunting). This theory was tested out with infants and apes using 4 different movement scenarios... the apes were more inclined to pay attention when the entire head moved, whereas the infants noticed the eyes.

Other theories suggest perhaps they are white to show a sign of good health, for potential mating. Physical attraction. Or to promote altruistic behaviour within the social group. Once we knew that cooperation was beneficial, if not necessary for survival - we developed language, social rules, norms, etc., to honour this idea of unselfish concern for others. Communicating with the eyes is probably what started it all. If you think about when one is angry and frowning, the whites of the eye gets smaller, hidden in a way. As if to hide the intention. To ready oneself for battle? And if a physical fight were to occur, this would be an aide, no doubt. It closes the communication, leaves the next move to guesswork.

So very interesting, the whites of the eyes.

But if you would prefer another colour, there's always the option.

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