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Author Topic:   Can sense organs like the eye really evolve?
ANI
Junior Member (Idle past 4635 days)
Posts: 3
From: Australia
Joined: 10-06-2011


Message 1 of 242 (636389)
10-06-2011 8:39 AM


We do not see with the eyes but with information gathered by the eyes and processed in the brain /mind. An organism can't make use of a mutation that gives it sensory information as for instance photosensitive cells as to have an advantage over another organism without that mutation, if it has not already developed a brain with the capacity to process that information. The brain has to have developed first in anticipation of the eye developing. This means that a brain with the capacity for processing signals from a photosensitive cells develops in anticipation for such an event by natural selection? We are not talking here about one or two chance mutations that might be useful sometime later but a capacity to give some degree of sight to an organism no matter how slight. I cannot see how this is possible by natural selection. What do you think?
Edited by Admin, : Fix title.

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Admin
Director
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From: EvC Forum
Joined: 06-14-2002
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Message 2 of 242 (636391)
10-06-2011 8:42 AM


Thread Copied from Proposed New Topics Forum
Thread copied here from the Can sense organs like the eye really evolve? thread in the Proposed New Topics forum.

  
Taz
Member (Idle past 3370 days)
Posts: 5069
From: Zerus
Joined: 07-18-2006


(4)
Message 3 of 242 (636393)
10-06-2011 8:46 AM
Reply to: Message 1 by ANI
10-06-2011 8:39 AM


I'm feeling particularly cranky this morning, so forgive my crude language.
But do you honestly think scientists care whether you can see or not see how the process worked?
Others may try to put this in layman's term for you, but let me be blunt. Evolutionary biology takes a life time to study. If you're interested in the subject, then go take some classes. In the mean time, don't expect us to teach you evolutionary biology in a few posts on an online internet forum.
You seem like someone who's at least taken algebra in school, correct? Can you imagine teaching someone algebra in a couple online forum posts?
Added by edit.
You have 2 choices here. Either go to school and actually learn something or go to bible school and learn the goddunit answer for everything. Enough said.
Edited by Taz, : No reason given.

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frako
Member (Idle past 384 days)
Posts: 2932
From: slovenija
Joined: 09-04-2010


(1)
Message 4 of 242 (636394)
10-06-2011 8:46 AM
Reply to: Message 1 by ANI
10-06-2011 8:39 AM


i see no problem all you need is a cell that reacts to light and is stimulating a nerve when its hit by light, you dont need a whole region of the brain devoted to despiper the light stimulus in to a picture all you need is a stimuly that shows the critter wheter its light or dark evolution takes over from there to make all kinds of eyes you want and all kind of brain regions that despipher the stimulie of light

Christianity, One woman's lie about an affair that got seriously out of hand
Jesus was a dead jew on a stick nothing more

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jar
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Posts: 34048
From: Texas!!
Joined: 04-20-2004
Member Rating: 5.7


(3)
Message 5 of 242 (636398)
10-06-2011 9:02 AM
Reply to: Message 1 by ANI
10-06-2011 8:39 AM


no brain needed.
Hi ANI, Welcome home.
I think some pastor or minister or teacher mentioned that to you and at first glance it seemed reasonable, but of course it is utterly wrong.
Stop and think for a moment.
Plants sense light and respond, yet they have no brain.
Many bacteria sense light and respond, yet they have no brain.
A brain is simply not needed and in fact what we see is yet another example of just what the Theory of Evolution predicts.

Anyone so limited that they can only spell a word one way is severely handicapped!

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caffeine
Member (Idle past 1103 days)
Posts: 1800
From: Prague, Czech Republic
Joined: 10-22-2008


(3)
Message 6 of 242 (636400)
10-06-2011 9:37 AM
Reply to: Message 1 by ANI
10-06-2011 8:39 AM


Jellyfish
For a practical example of an animal with light-sensitive organs but without a brain to respond to them, consider jellyfish. Some jellyfish have light-sensitive organs, but none of them have brains. Jellyfish can't see an image, since they have no image processing hardware, as you say. Instead, the light sensitive organs simply connect to nerves, which connect to muscles, to bring about automatic reactions like swimming towards and away from light.
However, once nerves have clumped together to form a brain, with the capacity for evolving image-processing capabilities, the light-sensitive organs are already there, ready to be co-opted for just such a purpose.
Edited by caffeine, : Because 'automative' isn't a word.

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New Cat's Eye
Inactive Member


(2)
Message 7 of 242 (636412)
10-06-2011 11:21 AM
Reply to: Message 1 by ANI
10-06-2011 8:39 AM


An organism can't make use of a mutation that gives it sensory information as for instance photosensitive cells as to have an advantage over another organism without that mutation, if it has not already developed a brain with the capacity to process that information.
As others have pointed out with reference to plants and jellyfish, that is simply not true.
I thought I'd offer you some other food for thought: did you know that iguanas have a third eye on the top of their head? Its rudimentary and not really for "seeing" but allows them to sense light and shadows above them. Its called a parietal eye, here's a link:
Parietal eye - Wikipedia
Have fun learning!

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Dr Adequate
Member (Idle past 363 days)
Posts: 16113
Joined: 07-20-2006


(1)
Message 8 of 242 (636415)
10-06-2011 11:29 AM
Reply to: Message 1 by ANI
10-06-2011 8:39 AM


Let's add scallops to the list.
Plenty of eyes, but no brain.

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Coragyps
Member (Idle past 813 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 9 of 242 (636423)
10-06-2011 12:23 PM
Reply to: Message 1 by ANI
10-06-2011 8:39 AM


Hi, ANI!!
Welcome to EvC!
You ask, "Can sense organs like the eye really evolve?"
Well, they DID - we see them all around us in the animal kingdom, in a couple of dozen configurations. So the answer must be, "yes, they can."

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Wollysaurus
Member (Idle past 4570 days)
Posts: 52
From: US
Joined: 08-25-2011


(2)
Message 10 of 242 (636427)
10-06-2011 12:56 PM
Reply to: Message 1 by ANI
10-06-2011 8:39 AM


I used to see a lot of strength in this sort of argument of "irreducible complexity". I didn't take any biology courses in college, but I did read _Darwin's Black Box_ by Behe and found it very convincing.
So convincing, in fact, that arguments like what you have outlined above served to really make me seek "design" in nature and think of a prime mover as being likely. I don't now discount the possibility of a designer outright, but the arguments like yours have fallen by the wayside as I've learned more through personal study.
If I could recommend a couple books that address this exact argument (among others), I might point to _Why Evolution Is True_ by Jerry Coyne and _The Greatest Show on Earth_ by Richard Dawkins.
I would actually recommend _Why Evolution is True_ over Dawkins, because in many ways his writing is sort of caustic (in my opinion) and his overt sarcastic tone regarding creationists or folks of belief would be a turn off to many, though the technical content is great. Coyne's book, by contrast, isn't quite as "harsh" on the intelligent design crowd and is technically a bit easier to digest.
I found both to be informative and good springboards to more sources.
But in regards to your specific point about the eye, this is exactly the sort of argument that has been addressed quite ably by evolutionary biologists. There are simply too many examples in nature ranging from camera-like eyeballs such as we have that are wired into powerful processing centers of the brain, down the spectrum to light sensitive cells hooked onto nerves. If you follow the spectrum, it becomes apparent how such basic light sensing systems could progress through selective pressures into what we have now.
And the eye isn't perfect by any stretch. Blind spots, different for photopic and scotopic vision, weird wiring... It is just too cobbled together, in my mind, to make sense as a deliberate design.
Edited by Wollysaurus, : Spelling, minor edit.

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Blue Jay
Member (Idle past 2776 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 11 of 242 (636432)
10-06-2011 1:31 PM
Reply to: Message 8 by Dr Adequate
10-06-2011 11:29 AM


Dr Adequate writes:
Let's add scallops to the list.
Plenty of eyes, but no brain.
Surely this depends on how you define "brain": scallops have a central nervous system, which includes ganglia for the processing of visual information and centralized coordination of reaction to visual stimuli.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

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jar
Member
Posts: 34048
From: Texas!!
Joined: 04-20-2004
Member Rating: 5.7


(1)
Message 12 of 242 (636433)
10-06-2011 1:35 PM
Reply to: Message 11 by Blue Jay
10-06-2011 1:31 PM


towards a brain
And that is another great piece of evidence supporting the Theory of Evolution.
Just as when we look at life around us we can find just about all the steps from simple light sensitivity to eyes, we can find all the various steps that lead to a brain.

Anyone so limited that they can only spell a word one way is severely handicapped!

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Blue Jay
Member (Idle past 2776 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 13 of 242 (636434)
10-06-2011 1:43 PM
Reply to: Message 10 by Wollysaurus
10-06-2011 12:56 PM


Aside: Coyne and Dawkins
Disclaimer: this post is off-topic, but I don't really want to start a new topic for it.
Hi, Wollysaurus.
Wollysaurus writes:
Coyne's book, by contrast, isn't quite as "harsh" on the intelligent design crowd and is technically a bit easier to digest.
I saw Jerry Coyne give a talk in promotion of that book (Why Evolution is True), and I was unhappy with it. His evidence for evolution was great, but his explanation of the scientific method made me sick, and he quickly turned his evolutionary talk into an argument that religion was the root of all societal problems today. All in all, it wasn't a very productive way of promoting evolution. I did not read the book, however.
Dawkins is speaking tonight to promote his newest book, and I just might go see him. If I go, I'll let you know what my thoughts are.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

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Dr Adequate
Member (Idle past 363 days)
Posts: 16113
Joined: 07-20-2006


Message 14 of 242 (636443)
10-06-2011 2:43 PM
Reply to: Message 11 by Blue Jay
10-06-2011 1:31 PM


It's not clear that one would call that a brain.
How do you feel about sea urchins?
Body of Sea Urchin Is One Big Eye :
Genetic analysis of sea urchins has revealed they have light-sensitive molecules, mostly in their tube feet and in tiny stalked appendages found in among their spines. As such, "it looks like the entire surface of their bodies are acting as one big eye," said researcher Snke Johnsen, a marine biologist at Duke University. [...] "Sea urchins have a pretty diffuse nerve net, where no region looks like a central processing unit as far as we can tell."

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New Cat's Eye
Inactive Member


(5)
Message 15 of 242 (636444)
10-06-2011 2:53 PM
Reply to: Message 14 by Dr Adequate
10-06-2011 2:43 PM


How do you feel about sea urchins?
Very carefully...

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