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 worms 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 todays 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.
Nobody can make you see things you don't want to see. Enjoy the darkness.
No we don't. We have knowledge, understanding, and evidence.
You have to start by believing evolution in order to believe that these findings support evolution any more than they support a creator God.
No we don't, but I suppose it might look that way to someone unfamiliar with the subject.
Please explain, for example, why you think that differences between the genomes of two species would match to a high degree the statistical pattern of random silent mutations in divergent lineages from a common ancestor one would expect from an evolutionary process, is somehow equally good support for "a creator God". Why do you suppose God would always make his handiwork look as if it was the result of an evolutionary process, when there are an almost infinitely many other configurations he could have used for his purposes without being constrained to evolutionary plausible ones?
Please explain.
After you're done with that one, please explain why He is in the habit of faking all that apparent endogenous retrovirus evidence, and so on.
We'll wait.
It's fascinating that your description bears an incredible resemblance to the very first result one finds (after skipping the two programming links) when doing a Google search on "inductive logic":
Keynes (1921: 8) describes a logical relation between two sets of propositions in cases where it is not possible to argue demonstratively from one to another.So is it just an incredible coincidence that you would happen to echo this obscure quote in response to general_re's mention of inductive logic -- or did you have to go look it up to see what it meant, then just parrot it back in the hopes it would make it appear that you knew what he was talking about?
-- From Inductive Logic: Brief Historical Background and Motivation
By the way, you misspelled "Keynes".
And no, people actually familiar with the subject of inductive logic would be highly unlikely to describe it in such a stilted manner, so don't try that excuse. Instead, the vast majority of people comfortable with the subject would describe it in a manner similar to how dictionary.com defines "inductive reasoning" (which is another term for the same thing):
inductive reasoning n : reasoning from detailed facts to general principles
While this is very useful in many cases,
That's putting it mildly... Most of the reasoning that people do on a daily basis is inductive logic.
my point stands.
No, actually, it doesn't. And that's the point general_re was making, which sailed right over your head.
No hard scientific proof. Just speculation and hope.
Again, there is no such thing as "hard scientific proof". Science doesn't work that way. The fact that you think it does reveals your lack of understanding on the whole subject. And inductive logic is far more than "just speculation and hope", which you might have learned if you had bothered to read and understand more of the information your websearch turned up, instead of just seizing on the first thing which would help you (transparently, alas) fake it.
Science and technology are based in huge part on inductive logic, and always on *evidence* -- not on "speculation and hope", which are much more the province of religions.
As John F'n Kerry asked, "Is that all you've got, Mr. President?"
All that, and much more. What've you got?
LOL - shoulda known...
Like Beowulf and the Iliad? Fascinating.
[Thunderous applause!]
LOLOLOL
We don't even know when Beowulf was written, where it was written or the who the author was.
Now, the Iliad -- which is history in the sense that Shakespeare's Julius Caesar is history i.e. drama based on an historical event -- has significant historical value. The existence of Troy has been confirmed as has its destruction in battle about the time Homer claimed it was.
Troy was considered mythological not too long ago, btw.
Now the Iliad was written in 800-900 BC and described events which occurred about 100-200 years before. Our earliest copy is from about 400 BC.
So despite these handicaps, and despite its purpose being drama rather than data, we glean some truth from it.
Now, the New Testament was written in 40-100 AD. Our earliest bits come from 130 AD. It was not written as drama but as simple reporting. It includes witnesses and researches to the events who did not appear to collaborate.
The Bible is by far the most reliable book of antiquity.
You asked about the eternal situation of the Jewish people and I answered your question according to what the Lord Jesus Christ says. Jesus Christ was a Jew, as were all the apostles and disciples with the possible exception of Luke. Where is the nonsense to which you refer?
Does that mean "yes, the Jews are screwed" or not? And the same for all Hindus, Buddhists, Shintoists, Raelians, and our Friends-From-Frolix-8?
On the other hand, anyone who bows to Jesus Christ in this life and unashamedly professes Him as the only true Savior and Lord over all will be accepted into the kingdom of God. Their abode will be Heaven. Jew or Gentile, it makes no difference.
Judgement Day is fast approaching. What have you to lose by tasting the freedom that the Good Shepherd, Jesus Christ, has to offer? He wants to be your savior and friend.
The title:
Darwin's greatest challenge tackled
One of the first lines:
Researchers provide concrete evidence about how the human eye evolved
Honestly, has the evolution of the human eye (Darwin's greatest challenge) now been tackled by this concrete evidence as the article implies?
Assertion Without Proof. The premise was, "everything has a First Cause."
Why is it not believable that God didn't have a first cause, but everything else did?
Because it invalidates the first premise.
Science isn't about believing or 'not believing' anything, but experience and evidence.
He tells me so in His word . . .
I had written a bunch of stuff and bailed the third or fourth time you used this argument. Fallacy of Appeal to Authority. You don't know it's "His Word" - only that it is claimed to be. Fallacy of Reification for word "Word."
Well, the debate never ends. It just moves from one issue to another. It's really about belief. You can't answer where things came from unless you were there. You can only conjecture.
Some people trust too much in science. Those who do so are quick to forget its failures and just as quick to quote its successes. How many times have scientists ridiculed and even tried to silence colleagues for suggesting some unorthodox view, only to have the unorthodox view win out later. But then, the new idea is just as vulnerable to being otherthrown. It isn't knowledge, it's theory. And faith.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.