Wah, I just know! I do!
Posted on 11/03/2004 5:11:47 PM PST by general_re
Darwin's greatest challenge tackled
The mystery of eye evolution
Researchers provide concrete evidence about how the human eye evolved
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, an 'organ of extreme perfection and complication' evolved through spontaneous mutation and natural selection. But he also reasoned that "if numerous gradations from a simple and imperfect eye to one complex and perfect can be shown to exist" then this difficulty should be overcome. 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.
"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."
The scientists discovered that two types of light-sensitive cells existed in our early animal ancestors: rhabdomeric and ciliary. In most animals, rhabdomeric cells became part of the eyes, and ciliary cells remained embedded in the brain. But the evolution of the human eye is peculiar it is the ciliary cells that were recruited for vision which eventually gave rise to the rods and cones of the retina.
So how did EMBL researchers finally trace the evolution of the eye?
By studying a 'living fossil,' Platynereis dumerilii, a marine worm that still resembles early ancestors that lived up to 600 million years ago. Arendt had seen pictures of this worm's brain taken by researcher Adriaan Dorresteijn [University of Mainz, Germany]. "When I saw these pictures, I noticed that the shape of the cells in the worm’s brain resembled the rods and cones in the human eye. I was immediately intrigued by the idea that both of these light-sensitive cells may have the same evolutionary origin."
To test this hypothesis, Arendt and Wittbrodt used a new tool for today’s evolutionary biologists – 'molecular fingerprints'. Such a fingerprint is a unique combination of molecules that is found in a specific cell. He explains that if cells between species have matching molecular fingerprints, then the cells are very likely to share a common ancestor cell.
Scientist Kristin Tessmar-Raible provided the crucial evidence to support Arendt's hypothesis. With the help of EMBL researcher Heidi Snyman, she determined the molecular fingerprint of the cells in the worm's brain. She found an opsin, a light-sensitive molecule, in the worm that strikingly resembled the opsin in the vertebrate rods and cones. "When I saw this vertebrate-type molecule active in the cells of the Playtnereis brain – it was clear that these cells and the vertebrate rods and cones shared a molecular fingerprint. This was concrete evidence of common evolutionary origin. We had finally solved one of the big mysteries in human eye evolution."
Source Article
Ciliary photoreceptors with vertebrate-type opsins in an invertebrate brain.
D. Arendt, K. Tessmar-Raible, Snyman, Dorresteijn, J. Wittbrodt
Science. October 29, 2004.
BTTT
"they come from an ancient population of light-sensitive cells that were initially located in the brain."
And where did these two "scientists" find this verifiable information?
Convergent evolution of the eye is a religious concept. Out of nothing the vertebrate eye is supposed to have developed completely separate from the squid and octopus which they (Darwinians) say developed from different phylogenetic lineages. Just got lucky I guess. When they say "If you put a chimpanzee in from of an IBM selectric typewriter and he struck 60 elements per minute,given enough time he would exactly duplicate the exact works of Shakespeare." That is an article of faith any way you slice it. Call it science if you like, but it aint.
One cannot deal with origins apart from faith. Observers were not there (except the God of the Universe)
Yes, a metaphysical origin ordered by a orderer to conform to the laws of physics.
Ah. So that's why OJ wasn't convicted. No eye-witnesses.
Mr Luton, Are you married? Do you love your wife? If so you must confess that if everything is the result of molecular and subatomic changes that occurred very slowly over time, then for you to say " I love my wife" is no more meaningful than to say a I have a gastrointestinal pain or an itch, because love is mediated at a molecular,neurochemical level just like an itch and is therefore meaningless. It leads you to nihilism and hopelessness. Please exlain to me where I am wrong.
Because you can't explain how it was created. You don't even propose a method for explaining how. You merely throw up your hands and say He did it and that's all anyone need know. That's not particularly satisfying to some. At least evolutionists attempt to explain things.
awwwwwwwwwwwwwwwwwwwwwwwww
Typical bicoastal, knee-jerk jerk.
Yes, I could, but I have neither the time nor the inclination to do so. You have already made up your mind, and as long as you can live with it, I can as well.
I have never claimed to have absolute knowledge, but I know Someone who does. I would never claim that I had a totally accurate interpretation of anything, much less the Bible. Apparently, you feel that you do. As I said before, as long as you can live with that, I can too.
As far as my use of Pascal's wager, it expresses my feelings on the subject accurately, so I'm not particularly concerned about your impression of my critical thinking ability. I'm not especially impressed with the thinking ability of anyone who uses science to disprove God.
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