Did Eyelids Evolve?

Hi, The Darin. Welcome to EvC.Now that the politeness is over: What the hell are you talking about? All terrestrial vertebrates have eyelids. Eyelids evolved far, far back in the evolutionary history of terrestrial vertebrates.From Wikipedia:

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It has been suggested that eyelids evolved as a way to remove debris from the eyes. Given that fish have a constant stream of water flowing over their eyes, it is not surprising that they do not have eyelids or need specialized membranes to perform this function.

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He fought for the South for no reason that he could now recall, other than the same one all men fought for: because he'd been a damn fool. -- Garth Ennis

Hmm. If he gets responses, then his questions "stresses us all out so much." If he got no response, then we would have been trying to ignore an embarrassing question.You don't really want to discuss anything do you? What you really want to do is to provoke a response, isn't it?

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He fought for the South for no reason that he could now recall, other than the same one all men fought for: because he'd been a damn fool. -- Garth Ennis

None of this has to do with eyelids. The mods here pretty much try to keep the threads on the topic as stated in the original starting post.Usually I'm not a stickler for topicality like this, but I do get tired of creationists who can't admit that their objections have been answered and then try to change the topic.Before you bring up new issues, just say, "Oh, I see. I now see how eyelids could have evolved." Then we can move on. If you can't say it, then this original question has not yet been resolved, and further discussion is needed.

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He fought for the South for no reason that he could now recall, other than the same one all men fought for: because he'd been a damn fool. -- Garth Ennis

Then don't change the topic. The number one piece of evidence that creationists have little ability for rational discourse is their inability to stay focused.You started this thread on eyelids. Stick to eyelids.

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He fought for the South for no reason that he could now recall, other than the same one all men fought for: because he'd been a damn fool. -- Garth Ennis

That's usually a sign that you don't understand the subject very well.Maybe one of the mods will step in suggest a thread that discusses some of the basic issues.

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He fought for the South for no reason that he could now recall, other than the same one all men fought for: because he'd been a damn fool. -- Garth Ennis

Speaking of responding, when you are replying to a particular post, use the "reply" button at the bottom of that particular message. It will help the rest of us figure out with whom you are speaking, and it provides a link so we can go back and read that post.Use the "General Reply" button at the bottom of the entire page only when you are making a general comment that isn't a reply to any particular person's post.

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Few men and fewer women had the means or the desire to write a book on "How I failed to overcome my humble origins." -- Graham Robb

Hi, Aladon, and welcome to EvC. That's not quite right. Think about it; gall bladders are often removed, and the patients usually can lead a pretty normal life (although they might have to watch what they eat). So gall bladders are not required, but I don't think anyone will call them vestigial. This isn't meant to demean your attempt at a definition; I'm just pointing out that definitions can be tricky at times. Wikipedia seems to have a good description of what vestigial means:

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Vestigiality describes homologous characters of organisms which have lost all or most of their original function in a species through evolution.

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And:

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[Vestigial structures] are typically in a degenerate, atrophied, or rudimentary condition, and tend to be much more variable than similar parts. Although structures usually called "vestigial" are largely or entirely functionless, a vestigial structure may retain lesser functions or develop minor new ones.

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I will also say that Douglas Theobald has something interesting to say about vestigial structures in regards to evolution; I recommend reading his essay, although discussion of it would be appropriate for another thread.Edited by Chiroptera, : Added greeting; also added "This isn't meant...can be tricky at times."

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Few men and fewer women had the means or the desire to write a book on "How I failed to overcome my humble origins." -- Graham Robb