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Author Topic: The Mystery Of Eye Evolution
Snuckles
rabble-rouser
Babbler # 2764

posted 01 November 2004 06:03 PM      Profile for Snuckles   Author's Homepage        Edit/Delete Post  Reply With Quote 
quote:
October 28, 2004 -- When Darwin's skeptics attack his theory of evolution, they often focus on the eye. Darwin himself confessed that it was "absurd" to propose that the human eye evolved through spontaneous mutation and natural selection. Scientists at the European Molecular Biology Laboratory (EMBL) have now tackled Darwin's major challenge in an evolutionary study published this week in the journal Science. They have elucidated the evolutionary origin of the human eye.

Researchers in the laboratories of Detlev Arendt and Jochen Wittbrodt have discovered that the light-sensitive cells of our eyes, the rods and cones, are of unexpected evolutionary origin – they come from an ancient population of light-sensitive cells that were initially located in the brain.


Read it here.


From: Hell | Registered: Jun 2002  |  IP: Logged
fuslim
rabble-rouser
Babbler # 5546

posted 01 November 2004 06:58 PM      Profile for fuslim     Send New Private Message      Edit/Delete Post  Reply With Quote 
quote:
…Darwin himself confessed that it was "absurd" to propose that the human eye evolved through spontaneous mutation and natural selection.

Because this is probably the most misused of Darwin quotes, I think it should be posted in full, in context.

Here it is, as it was in the first edition of ‘Origin’

[QUOTE] First Edition -- 1859

Organs of extreme perfection and complication.

To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree.

Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case;

and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real.

Emphasis added.


From: Vancouver BC | Registered: Apr 2004  |  IP: Logged
Agent 204
rabble-rouser
Babbler # 4668

posted 01 November 2004 07:27 PM      Profile for Agent 204   Author's Homepage     Send New Private Message      Edit/Delete Post  Reply With Quote 
quote:

"It is not surprising that cells of human eyes come from the brain. We still have light-sensitive cells in our brains today which detect light and influence our daily rhythms of activity," explains Wittbrodt. "Quite possibly, the human eye has originated from light-sensitive cells in the brain. Only later in evolution would such brain cells have relocated into an eye and gained the potential to confer vision."


It makes sense when you look at the picture, actually. Its exoskeleton is translucent enough that the cells can be in the brain- and the brain is the natural place for it to develop- the optic nerve presumably evolved later.

From: home of the Guess Who | Registered: Nov 2003  |  IP: Logged
Jingles
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Babbler # 3322

posted 02 November 2004 12:21 AM      Profile for Jingles     Send New Private Message      Edit/Delete Post  Reply With Quote 
I think it was David Suzuki who demonstrated on "The Nature of Things" Darwin's musings using the many species of mollusk as examples. From light sensitive cells to the complex eye of the octopus, they have the whole gamut.
From: At the Delta of the Alpha and the Omega | Registered: Nov 2002  |  IP: Logged
aRoused
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Babbler # 1962

posted 02 November 2004 05:40 AM      Profile for aRoused     Send New Private Message      Edit/Delete Post  Reply With Quote 
The problem is that people that don't understand how evolution works tend to think that the eye sprang, fully formed, from a single mutation. A similar, but reversed situation involves the blowhole of whales.

'Why don't we see a series of pre-whale mammals with noses higher and higher on their heads?'

Because in the case of nose position, it likely really *is* a single, or limited number, of genes controlling that, so its position can shift radically with a single mutation.


From: The King's Royal Burgh of Eoforwich | Registered: Dec 2001  |  IP: Logged

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