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Author Topic:   Did Eyelids Evolve?
TheDarin
Member (Idle past 5013 days)
Posts: 50
Joined: 01-04-2008


Message 1 of 117 (445885)
01-04-2008 9:57 AM


I am trying to understand positions on evolution...first question.

Let's take eyelids.

Is it the EVO position that early humans may not have had eyelids, but after millions of years the body started saying to its babies "form something over your eyes to keep foreign objects out" or "form something over the eyes that will help us rest for 8 hours"?

If no, what do EVO's believe on human evolution as it relates to the eyelid?

Asked sincerely.


Replies to this message:
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 Message 5 by jar, posted 01-04-2008 11:13 AM TheDarin has not replied
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AdminNWR
Inactive Member


Message 2 of 117 (445895)
01-04-2008 10:51 AM


Thread moved here from the Proposed New Topics forum.

  
macaroniandcheese 
Suspended Member (Idle past 3250 days)
Posts: 4258
Joined: 05-24-2004


Message 3 of 117 (445901)
01-04-2008 11:06 AM
Reply to: Message 1 by TheDarin
01-04-2008 9:57 AM


no. humans didn't evolve on their own, they are decended from primate ancestors. primates have eyelids.

see?

other mammals have eyelids too.

in fact, mammals aren't the only animals with eyelids. birds have eyelids

and reptiles (though theirs are different from ours. some reptiles, geckos, for example, don't have eyelids, but rather a clear membrane which protects their eyes.)

and amphibians (theirs are also different, they can't move their eyelids, but instead suck their eyeballs into their heads to allow the two to close.)

as it is, whatever gene codes for an animal's specific variety of eyelid can sometimes be turned off.cat born without eyelids. magical stuff, this dna.

and here's a page on eyelids.


This message is a reply to:
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Chiroptera
Inactive Member


Message 4 of 117 (445902)
01-04-2008 11:08 AM
Reply to: Message 1 by TheDarin
01-04-2008 9:57 AM


Hi, The Darin. Welcome to EvC.

Now that the politeness is over:

Is it the EVO position that early humans may not have had eyelids....

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:

quote:
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.


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

This message is a reply to:
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Replies to this message:
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jar
Member
Posts: 33957
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.0


Message 5 of 117 (445905)
01-04-2008 11:13 AM
Reply to: Message 1 by TheDarin
01-04-2008 9:57 AM


On mammalian eyelids.
Is it the EVO position that early humans may not have had eyelids, but after millions of years the body started saying to its babies "form something over your eyes to keep foreign objects out" or "form something over the eyes that will help us rest for 8 hours"?

No, that is not something anyone but a Creationist would say.

If no, what do EVO's believe on human evolution as it relates to the eyelid?

Humans are just another mammal. Mammals all have eyelids. But it is one of the last traits to develop during a pregnancy. Initially they are closed, sealed shut and in many mammals they stay that was until long after birth. Think about kitties and puppies and mice.

Even earlier ancestors such as reptiles and birds have a nictitating membrane.


Immigration has been a problem Since 1607!

This message is a reply to:
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subbie
Member (Idle past 577 days)
Posts: 3509
Joined: 02-26-2006


Message 6 of 117 (445906)
01-04-2008 11:13 AM
Reply to: Message 1 by TheDarin
01-04-2008 9:57 AM


Pay no attention to these godscoffers
It's obvious that eyelids are a gift from our lord since no other animal on the face of the planet has them.


Those who would sacrifice an essential liberty for a temporary security will lose both, and deserve neither. -- Benjamin Franklin

We see monsters where science shows us windmills. -- Phat


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jar
Member
Posts: 33957
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.0


Message 7 of 117 (445910)
01-04-2008 11:15 AM
Reply to: Message 4 by Chiroptera
01-04-2008 11:08 AM


on Sharks
Many Sharks have a nictitating membrane as well.


Immigration has been a problem Since 1607!

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TheDarin
Member (Idle past 5013 days)
Posts: 50
Joined: 01-04-2008


Message 8 of 117 (445931)
01-04-2008 1:57 PM
Reply to: Message 1 by TheDarin
01-04-2008 9:57 AM


Eyelids Period
OK. I am sorry that my question stressed you all out so much. Let me re-phrase the questions since the fact that narrowed the question down too much by saying HUMAN.

Is it the EVO position that early living beings with eyeballs may not have had eyelids, but after millions of years the the EVO-Code started saying to offspring "form something over your eyes to keep foreign objects out" or "form something over the eyes that will help us rest for 8 hours"?


This message is a reply to:
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Replies to this message:
 Message 9 by Modulous, posted 01-04-2008 2:38 PM TheDarin has replied
 Message 10 by jar, posted 01-04-2008 2:52 PM TheDarin has not replied
 Message 12 by Rahvin, posted 01-04-2008 2:54 PM TheDarin has replied
 Message 14 by Chiroptera, posted 01-04-2008 3:19 PM TheDarin has not replied

  
Modulous
Member (Idle past 1427 days)
Posts: 7789
From: Manchester, UK
Joined: 05-01-2005


Message 9 of 117 (445945)
01-04-2008 2:38 PM
Reply to: Message 8 by TheDarin
01-04-2008 1:57 PM


Re: Eyelids Period
Is it the EVO position that early living beings with eyeballs may not have had eyelids, but after millions of years the the EVO-Code started saying to offspring "form something over your eyes to keep foreign objects out" or "form something over the eyes that will help us rest for 8 hours"?

It was probably more like what we are seeing as answers in this thread. Some kind of nictitating membrane, the ability to withdraw the eyes for protection and the like evolved first. There was no code to tell it to form something to keep objects out - those with better eye protection were better placed to take advantage of land resources for longer periods of time, increasing their fitness and increasing the ratio of beings with eye protection.

Until that point, vertebrates were limited to keeping close to water (either entirely aquatic or amphibious) where such things are less of a concern.


This message is a reply to:
 Message 8 by TheDarin, posted 01-04-2008 1:57 PM TheDarin has replied

Replies to this message:
 Message 11 by TheDarin, posted 01-04-2008 2:52 PM Modulous has replied

  
jar
Member
Posts: 33957
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.0


Message 10 of 117 (445951)
01-04-2008 2:52 PM
Reply to: Message 8 by TheDarin
01-04-2008 1:57 PM


Re: Eyelids Period
Is it the EVO position that early living beings with eyeballs may not have had eyelids, but after millions of years the the EVO-Code started saying to offspring "form something over your eyes to keep foreign objects out" or "form something over the eyes that will help us rest for 8 hours"?

No!

Many critters even today do not have eyelids or retractable eyes or nictitating membranes.

There is no goal or plan for evolution. It is not directed.

However the fact that all mammals do have eyelids is another pretty strong supporting part of Evolution.


Immigration has been a problem Since 1607!

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TheDarin
Member (Idle past 5013 days)
Posts: 50
Joined: 01-04-2008


Message 11 of 117 (445953)
01-04-2008 2:52 PM
Reply to: Message 9 by Modulous
01-04-2008 2:38 PM


Re: Eyelids Period
Modulus:

Please explain "ability to withdraw the eyes for protection and the like evolved first."


This message is a reply to:
 Message 9 by Modulous, posted 01-04-2008 2:38 PM Modulous has replied

Replies to this message:
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Rahvin
Member
Posts: 3966
Joined: 07-01-2005


Message 12 of 117 (445954)
01-04-2008 2:54 PM
Reply to: Message 8 by TheDarin
01-04-2008 1:57 PM


Re: Eyelids Period
OK. I am sorry that my question stressed you all out so much. Let me re-phrase the questions since the fact that narrowed the question down too much by saying HUMAN.

Is it the EVO position that early living beings with eyeballs may not have had eyelids, but after millions of years the the EVO-Code started saying to offspring "form something over your eyes to keep foreign objects out" or "form something over the eyes that will help us rest for 8 hours"?

Earlier forms of life (fish, insects, etc) did not (and their modern versions still do not) have eyelids. We also have examples of intermediate forms (you could call them "partial eyelids") like the previously mentioned nictating membranes found in reptiles.

But the real problem with your question wasn't that you narrowed it down specifically to humans. The problem is this part here:

after millions of years the the EVO-Code started saying to offspring "form something over your eyes to keep foreign objects out" or "form something over the eyes that will help us rest for 8 hours"?

There are several problems with your understanding of evolution demonstrated by this question, and it's these misunderstandings that are likely the cause of your confusion.

There is no "EVO-Code." It's a nonsense term. Its presence in your question implies that you believe that some intelligent factor somehow "told" organisms at a certain point in history to start growing eyelids. This is not even remotely close to the way evolution works. Evolution works primarily through very small random mutations that change incredibly minute things about an organism. A mutation will not, for example, cause an organism to spontaneously sprout an arm when the parent didn't have arms. Neither will it cause the sudden appearance of eyelids. The changes are much smaller than that. The reason the process takes thousands or millions of years to produce drastic changes is the same reason it takes you a very long time to walk from New York to Arizona - where you started from doesn't much look like where you wound up, but each individual step wasn't that much different from the step before it.

Mutations can be beneficial, or negative, or simply neutral. Most mutations are neutral, and don't really do anything at all individually.

But the beneficial mutations (like say, a slightly longer beak that is beneficial for pecking insects out of a tree, or a thin membrane over the eyes that adds just a tiny bit of protection) give an advantage to the organisms that posess them. Specifically, the bird that can get to food even a little easier is more likely to survive long enough to produce offspring to inherit the same positive mutation over a cold winter when food might be scarce. The creature with a membrane over its eyes may be less likely to go blind (and thus more liekly to survive long enough to procreate and pass on its mutation to its offspring) in a dusty environment. As the small population with positive mutations continues to out-reproduce those who don't have such advantages, over a very long time the changes can spread out to form the majority of the population. Further mutations add up to make more drastic changes from the older ancestor (just like that long walk from New York to Arizona - all those small steps add up).

The process isn't guided. There is no "instruction," or even a "suggestion" that something like an eyelid may help. It's random, and small, but even the smallest advantage helps, and the tiny changes add up to very large ones after many generations.

We see the process work most easily in organisms that reproduce quickly, because even with our short lifespans, we can observe hundreds of generations in a very short time - like bacteria, or fruit flies. Bacteria who have a very small mutation that changes just a single protein in their cell membrane can become extremely resistant to antibiotics. When exposed to antibiotics, the bacteria without the mutation all die off...while the resistant one lives on and continues to reproduce. From then on, all of the surviving bacteria in that population are not resistant to antibiotics. See how the random process of tiny changes can actually change the entire population?

This is how evolution works - through mutation (tiny changes in each generation) guided by natural selection (the creatures with an advantage are more likely to have offspring and pass the advantage on). Not with some strange "code" "telling" organisms to form a new appendage.

You could say that the genetic code "tells" an organism how to form, but not in the way you seem to mean. DNA is literally just chemistry. The specific chemical makeup of a DNA strand will cause different proteins to be formed (this is simplified, but hopefully should help you understand), which is what causes those tiny changes we call mutations. The copying process for DNA is imperfect, which is what allows the small changes to pass through instead of making exact duplicates for every generation. But it's literally a random process of imperfect copying, much like making a typo - there is no intelligence guiding the process, there is no decision or suggestion or instruction involved. The DNA strand copies with a small change because the chemical bonds work just as well with one base pair as with another. It's like legos - there are a limited number of peices, but they all fit together just fine. In DNA, the order of the peices is what determines the proteins and thus the expression in the organism, so even though the peices are basically mix and match, the small changes made with imperfect copying let small changes be made in the way the organism works. A single mutation may change the color of your eyes (I'm not positive - even something as tiny as that may be affected by multiple genes, but it's a good example), or many mutations over thousands of generations could change something significant, like certain primates having shorter and shorter tails, until eventually some of their descentants (that would be us) don't have tails at all.

That was a hell of a long post...but does this answer your question, and maybe clear up some misconceptions about evolution? It's a lot more complicated than they teach you in High School, and 100% different from what AnswersinGenesis or your local pastor are likely to tell you, so don't worry - most people don't know what the real Theory of Evolution is, either.


Every time a fundy breaks the laws of thermodynamics, Schroedinger probably kills his cat.

This message is a reply to:
 Message 8 by TheDarin, posted 01-04-2008 1:57 PM TheDarin has replied

Replies to this message:
 Message 13 by TheDarin, posted 01-04-2008 3:06 PM Rahvin has replied

  
TheDarin
Member (Idle past 5013 days)
Posts: 50
Joined: 01-04-2008


Message 13 of 117 (445959)
01-04-2008 3:06 PM
Reply to: Message 12 by Rahvin
01-04-2008 2:54 PM


Re: Eyelids Period
"The EVO-code" term was one that I jut made up for the question - I was not taught that there was such a thing.

I appreciate your thorough response - you type fast.

I'll move on with a "hmmmm" but the symmetry and order we see simply does not compute with randomness. May I move on since I've found someone that responds with words rather than attitude???

Your comments may address the question as it relates to cosmetic changes.

But how did randomness come up with the reproductive system as seen in Humans?


This message is a reply to:
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Replies to this message:
 Message 15 by Chiroptera, posted 01-04-2008 3:24 PM TheDarin has replied
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Chiroptera
Inactive Member


Message 14 of 117 (445964)
01-04-2008 3:19 PM
Reply to: Message 8 by TheDarin
01-04-2008 1:57 PM


We can't win!
I am sorry that my question stressed you all out so much.

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?


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

This message is a reply to:
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Chiroptera
Inactive Member


Message 15 of 117 (445967)
01-04-2008 3:24 PM
Reply to: Message 13 by TheDarin
01-04-2008 3:06 PM


One topic at a time.
...the symmetry and order we see simply does not compute with randomness....
But how did randomness come up with the reproductive system as seen in Humans?

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.


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

This message is a reply to:
 Message 13 by TheDarin, posted 01-04-2008 3:06 PM TheDarin has replied

Replies to this message:
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