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.
Okay then. The second law describes the total entropy of the closed system. Local minima or maxima do not violate the second law, so long as we understand that the total entropy of the entire system always increases. It is a misreading of the second law to say that entropy must always and everywhere increase - that's only true for the system as a whole, and only if it's a closed system.
You have repeatedly asserted that we are misguided. I asked for your help to understand the truth. You are the person who asserts that faith is folly. You therefore must have absolute conviction and evidence that Mr. Ole Cracker and I am wrong in our understanding. I am not changing the rules. I await your instruction as your student. I am eager to learn...especially scientic fact of origin. I have long been interested in this subject. I have finally found the expert to instruct me. That is you. So, respectfully, please continue in your instruction.
Again you dispose of the law of entropy. Please do not ask me to accept your excusing the 2nd Law of Thermodynamics as science. I understand how you might want to say that to bolster your position. I simply do not have that much faith. So again please don't tell me to conveniently violate an inviolable law of physics.
Ah, well then, there's the problem - you appear to think that it says something it doesn't, hence your misunderstanding.
Who is this mysterious Señor Olé Cracker?
You saying what you said does not make it so. Please dispose of adhominems and take me back to origins. If you would like to include the 1st Law also, perhaps that will help you clarify for me. You must understand, I'm just a small town boy for the heart of east Texas, and I just want to be educated by you. I am quiet serious about that. But I cannot allow you to violate the Laws of physics in our conversation because too many people may be listening in and they might get confused.
later reading
I am asking the questions, you and your friend are my teacher. Am I trolling? Please don't leave me with that as your final instruction. People might say you do not know of what you speak. I simply want you to tell me about origins. That is not a trick question. You asserted that nonevoltionists are misguided and I have repeatedly asked you to correct me scientifically. I can't get to macroevolution or punctuated equilibrium evolutionary theory without NH3,O2,H2O. We don't seem to be getting clarity on the 1st and 2nd law of th. First things first.
My problem is not understanding entropy? Educate me.
LMAO, very good!
I already did - I can't help you if you don't believe me...
Your problem is that you stubbornly and dishonestly insist that general_re has asserted that it is possible to violate the "law of entropy", when he has said no such thing.
And finally, I do believe that you believe that. That is your right. Search for the answer to what you believe in the realm of science. But because you believe it but cannot scientifically explain it you must agree that your belief is an article of your faith. You believe but you do not see...that is the very definition of faith. If you follow your logic and are honest...you must finally conclude through your science that matter and energy can neither be created nor destroyed and that time,energy,matter continuum has been running down like a clock since before the beginning and all of the atomic particles, subatomic particles, wave energy should by scientific law, be wash out into a cosmic ocean of nothingness approaching absolute zero. That is back to the void. Nirvana. This is the heart of Budhism. Your obstinence will lead you there if you are honest with yourself. It is not a new concept. It has been around for 5000 years of recorded human history. Just as a scientific exercise please contemplate the scientific explaination of the concepts of love, justice, beauty, forgiveness. These are worthy endeavors. But in the end you must answer one final question, either this side of the grave, or the other and that question is "Who is Jesus Christ"? He does not do away with science. He is the author of science and physics.I know it grates on you to have these questions posited to you. You want to recoil in insolence. But while noone is looking, consider the possility that He may have been who He said He was. At least start at the beginning. Don't start at the point where you say "I will consider all possibilities except the possibility that God is who He says He is." You do yourself a great disservice. You do not have to dispose of the mantle of science to understand your relationship to the creator of the universe. Be patient with yourself, but be true to your prescription of scientific enquiry. You will one day bump up against a position which will force you to choose against the Laws of Physics in order to explain your science or examine the possibility that science cannot explain many things and you may quietly peak over the edge of origins and eternity to arrive at the Cross. I wish you well in your journey. I have taken the same long journey. I am so thankful He was patient with me. One last thought.. consider loosing unto death the person you love the most in this world. You cannot avoid the questions we all have at those times. Even the atheist comes to know God in a foxhole. These are times you might considering preparing for. If you have children, God forbid, should something happen to one of them, where would you find the strength to go on. The eternal destiny of the soul rests on you answering these questions I have put to you. Perhaps the distiny of the souls of those you love. If you will be honest you will arrive at the answer.
Try Fermi's Thermodynamics (1937) for a thorough introduction. I'm sure your local community college or other institution of higher learning can point you to some other thermodynamics texts as well - you may want to insure that your calculus is up to snuff if you intend to investigate in depth - but the format here is not conducive to an extended discussion/tutorial on statistical mechanics or Boltzmann's H-theorem. Sorry.
Blastp results...
gi|52698314|gb|AAR36861.1| melanopsin [Felis catus] 235 2e-60 gi|51860765|gb|AAU11506.1| melanopsin [Phodopus sungorus] 232 1e-59 gi|53830702|gb|AAU95194.1| putative rhodopsin [Oncometopia ... 231 3e-59 gi|46561744|gb|AAT01077.1| putative rhodopsin [Homalodisca ... 230 5e-59 gi|2746077|gb|AAC41235.1| melanopsin [Xenopus laevis] 230 5e-59 gi|21928729|dbj|BAC05951.1| seven transmembrane helix recep... 229 7e-59[us] gi|4959075|gb|AAD34224.1| rhodopsin [Papilio glaucus] 229 9e-59 gi|4388595|emb|CAA56377.1| locus opsin 1 [Schistocerca greg... 229 1e-58
OOPS, almost forgot the query string.
>gi|19309911|emb|CAC86665.1| rhabdomeric opsin [Platynereis dumerilii]
Length = 382
Score = 784 bits (2025), Expect = 0.0
Identities = 382/382 (100%), Positives = 382/382 (100%)
Query: 1 MSRSEVLVPGSMSLDGLLTTAHPIGNDSIETILHPYWQQFDIENTIPDSWHYAVAAWMTF 60
MSRSEVLVPGSMSLDGLLTTAHPIGNDSIETILHPYWQQFDIENTIPDSWHYAVAAWMTF
Sbjct: 1 MSRSEVLVPGSMSLDGLLTTAHPIGNDSIETILHPYWQQFDIENTIPDSWHYAVAAWMTF 60
Query: 61 FGILGVSGNLLVVWTFLKTKSLRTAPNMLLVNLAIGDMAFSAINGFPLLTISSINKRWVW 120
FGILGVSGNLLVVWTFLKTKSLRTAPNMLLVNLAIGDMAFSAINGFPLLTISSINKRWVW
Sbjct: 61 FGILGVSGNLLVVWTFLKTKSLRTAPNMLLVNLAIGDMAFSAINGFPLLTISSINKRWVW 120
Query: 121 GKLWRELYAFVGGIFGLMSINTLAWIAIDRFYVITNPLGAAQTMTKKRAFIILTIIWANA 180
GKLWRELYAFVGGIFGLMSINTLAWIAIDRFYVITNPLGAAQTMTKKRAFIILTIIWANA
Sbjct: 121 GKLWRELYAFVGGIFGLMSINTLAWIAIDRFYVITNPLGAAQTMTKKRAFIILTIIWANA 180
Query: 181 SLWALAPFFGWGAYIPEGFQTSCTYDYLTQDMNNYTYVLGMYLFGFIFPVAIIFFCYLGI 240
SLWALAPFFGWGAYIPEGFQTSCTYDYLTQDMNNYTYVLGMYLFGFIFPVAIIFFCYLGI
Sbjct: 181 SLWALAPFFGWGAYIPEGFQTSCTYDYLTQDMNNYTYVLGMYLFGFIFPVAIIFFCYLGI 240
Query: 241 VRAIFAHHAEMMATAKRMGANTGKADADKKSEIQIAKVAAMTIGTFMLSWTPYAVVGVFG 300
VRAIFAHHAEMMATAKRMGANTGKADADKKSEIQIAKVAAMTIGTFMLSWTPYAVVGVFG
Sbjct: 241 VRAIFAHHAEMMATAKRMGANTGKADADKKSEIQIAKVAAMTIGTFMLSWTPYAVVGVFG 300
Query: 301 MIKPHSEMFIHPLLAEIPVMMAKASARYNPIIYALSHPKFRAEIDKHFPWLLCCCKPKPK 360
MIKPHSEMFIHPLLAEIPVMMAKASARYNPIIYALSHPKFRAEIDKHFPWLLCCCKPKPK
Sbjct: 301 MIKPHSEMFIHPLLAEIPVMMAKASARYNPIIYALSHPKFRAEIDKHFPWLLCCCKPKPK 360
Query: 361 AQLPSSTTKGSIASKTEADTSV 382
AQLPSSTTKGSIASKTEADTSV
Sbjct: 361 AQLPSSTTKGSIASKTEADTSV 382
Ignoramus. Don't even know what constellation you're in.
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