The Whites of Our Eyes

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One difference which is very noticeable, but rarely commented upon, between ourselves and most other animals is that the white parts of our eyes (corneas) are clearly visible all the time, rather than just when we look to the extreme left or right.

Don't you think this is odd? Why is it the case? At what stage of our evolution did the change happen (if indeed we can know)?

― MarkH (MarkH), Sunday, 4 April 2004 12:43 (twenty-one years ago)

If you've never thought about this before, then consider how odd artistic representations of animals look with human-like, cornea-revealing eyes. Indeed, it was the current advert for Switch featuring two penguins in front of the Eiffel Tower which inspired the question!

― MarkH (MarkH), Sunday, 4 April 2004 12:46 (twenty-one years ago)

That's not your cornea. That's your sclera. The cornea is the clear part over your iris and pupil.

― Stuart (Stuart), Sunday, 4 April 2004 13:03 (twenty-one years ago)

Ra-ta-ta-ta-tat.

― Johnney B, Sunday, 4 April 2004 13:06 (twenty-one years ago)

cheers Stuart. I think those penguins I referred to might be by Joel Veitch incidentally...they're certainly in a similar style to the spong monkeys, Zoolgy Dragon etc on rathergood.

― MarkH (MarkH), Sunday, 4 April 2004 13:07 (twenty-one years ago)

I never thought of this, but it does explain why the animals I draw look weird when I make the iris small and you can see the white part.

― Aja (aja), Sunday, 4 April 2004 13:20 (twenty-one years ago)

now is it that the actual structure of the eyeball's different? Or just that the skin around the eyes of animals covers more of it so you can't see the sclera (or as much of it)?

― MarkH (MarkH), Sunday, 4 April 2004 13:26 (twenty-one years ago)

I'm not sure. I mean, try to think of an animal with bigger eyes than us. The first thing I think of is the giant squid. Huge eyes and the eye lids show a lot of its eyes, but isn't it all just one color?

― Aja (aja), Sunday, 4 April 2004 13:29 (twenty-one years ago)

trouble is, no-one's seen a live giant squid and the eyes are one of the first things to decompose when they wash up on a beach. I don't think comparisons with squid are a good starting point in any case, because whilst the squid eye is superficially like that of a mammal it is a slightly different structure which evolved entirely separately.

The thing that intrigues me is even our "closest relatives" (chimp, gorilla, orang utan) don't have the visible sclera, so it may been a mutation on the human branch of the evolutionary tree.

― MarkH (MarkH), Sunday, 4 April 2004 13:35 (twenty-one years ago)

It's what makes us more God like.

But seriously, I don't know what it is. I alway used to say how big my cat's eyes looked because I could mainly just see the iris. I loved looking at her eyes.

Maybe all mammals have the same sized eyes but our eye lids are wider?

― Aja (aja), Sunday, 4 April 2004 13:41 (twenty-one years ago)

hmm, possibly. Another point: does it actually confer any advantage? Does it give us superior vision?

― MarkH (MarkH), Sunday, 4 April 2004 13:46 (twenty-one years ago)

Well, we do have better vision than some animals, but there are animals with better vision than us.

Or, maybe the animals that can see really far away or in the dark really well, maybe that is the only time they see clearly. Maybe birds that can see things from way up in the sky can't see things too well up close.

― Aja (aja), Sunday, 4 April 2004 13:49 (twenty-one years ago)

I can't see how it would have any effect on our vision at all.

― Martin Skidmore (Martin Skidmore), Sunday, 4 April 2004 13:50 (twenty-one years ago)

Well of course you can't see it.

― Aja (aja), Sunday, 4 April 2004 13:54 (twenty-one years ago)

And why do cat's pupils turn into slits when they get smaller?

― Aja (aja), Sunday, 4 April 2004 13:59 (twenty-one years ago)

Ever noticed goat pupils?

― Stuart (Stuart), Monday, 5 April 2004 02:40 (twenty-one years ago)

It's that the eyes are the window to the soul, and animals have no souls.

― A Nairn (moretap), Monday, 5 April 2004 02:46 (twenty-one years ago)

Neither do people!

I find it strange that koalas have catlike, eliptical pupils.

― latebloomer (latebloomer), Monday, 5 April 2004 02:59 (twenty-one years ago)

That's why they're only fit to be placed in tacos.

― Ned Raggett (Ned), Monday, 5 April 2004 04:09 (twenty-one years ago)

― latebloomer (latebloomer), Monday, 5 April 2004 04:09 (twenty-one years ago)

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