Chimpanzee Sanctuary Northwest

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  1. Angela Derriso says

    I’ve always wondered why chimps and other primates lack the whites of the eyes like humans. Though I have seen only two chimps in the past that had this trait; one was an albino with two differently colored eyes, and the other was an older male from one of Jane Goodal’s group. I don’t remember his name, but he definitely looked to have human eyes.

    I just wonder why there’s a difference in our eyes, and what purpose it might serve.

    Glad to see everyone’s doing well. 🙂

    • Debbie says

      Angela, that’s so interesting that you’ve seen chimps with different colored eyes! As you know most chimps have brown irises and no white sclera (instead it is black). Unfortunately I am not an expert in this area, but my best guess would be that over the course of evolution, humans migrated from areas where there was a lot of sun and thus some populations lost pigment in their skin and eyes. Brown eye color is genetically dominant in humans, so the majority of humans do have brown eyes. It’s possible that since chimps live and have lived in equatorial Africa for millions of years, they simply have not been in an environment where they could spare to lose any pigment in their skin and/or eyes. However, like I said, I’m not an expert in genetics or evolution – it’s just my best guess!

      This article summarizes a study that proposes the “reason” for white sclera and colorful irises in humans is because we depend more on eye movement alone for communication and cooperation than other great apes.

      http://www.msnbc.msn.com/id/15625720/ns/technology_and_science-science/t/did-evolution-make-our-eyes-stand-out/#.TmcA6-ufsb4

      I’m hesitant to completely support this hypothesis, mostly because I’m afraid it may mislead people to believe that chimps are not cooperative or do not have complex communication. In reality, they are very social critters and thus rely a lot on cooperation and communication between individuals. I haven’t read the actual study yet to see if there were any confounding variables (such as the atypical environment that the chimps are in — most of these cognitive studies look at chimps in a cage versus humans in their comfortable home environment, which to me could completely bias the results!) but it is an interesting hypothesis nonetheless.

  2. Chris says

    If the eyes are truly windows into the soul, then we are looking into some of the most beautiful, ancient souls on earth….