View Full Version : Evolution of the eye..
blike
07-11-2002, 12:36 PM
From what I understand, evolution is gradual, taking many many many generations to take place.
So how did something like the eye evolve? In early stages of the eyes development, it would be unusable. Many things have to take place for the eye to function properly, and since evolution doesn't just pop out new features overnight, many hundreds of generations of animals would find the primitive parts for the eye a waste of energy. Last night I was reading in my anthropology book about how this generation of human's wisdom teeth aren't as developed as some of the previous generations. It gave the explanation that since we aren't using them, there is no longer a need for them. The eye is a very complex organ, so its not like one random mutation would produce a functioning eye. So why wasn't the eye eliminated in its early, unusable stages?
fafalone
07-11-2002, 03:55 PM
I'd have to say it started with basic photoreceptors, where having a more sensitive one is an advantage, since the eye is nothing more than a whole lot of specialized photoreceptors, it could easily have evolved from these.
Hmm... to comment on Blike's wisdom teeth comment...
I am not born with them... Fear me for I am an advanced species... or something :D
kenel
07-12-2002, 01:26 PM
Very simple answer to a very complex question; If the eye was eliminated during evolution....we wouldn't be able to see, DUH! That's why it remains. DUH!
blike
07-13-2002, 07:36 AM
Thank heaven for kenel's genious. :)
Kurieuo
07-14-2002, 09:14 AM
Blike,
Here's a site that recently went online that might appeal to your liking - Eye Design Book (http://www.eyedesignbook.com/ch1/contentsch1.html)
- Kurieuo.
The great thing is that there are (I think) 3 different types of eyes in different animals today. They were evolved separately and do not seem to have a "common ancestor." This is a counterpoint to that of creationists who say that there is no way for an eye to evolve. I think this was mentioned in a recent issue of Discover or Scientific American.
blike
07-14-2002, 07:24 PM
Well, I believe their only common ancestor didn't have eyes :)
Perhaps it was coded into the genes, but not expressed for some reason?
anyhow, the creationists will tell you how unlikely that is.
Thanks for the link Kurieuo!!
Just to inform you, I believe the God of the hebrew bible used evolution to create the earth. So in a sense, I'm a creationist, but I believe in evolution.
Kurieuo
07-14-2002, 10:56 PM
Just to inform you, I believe the God of the hebrew bible used evolution to create the earth. So in a sense, I'm a creationist, but I believe in evolution.I don't believe in biological evolution in the sense that life somehow evolved from chemical origins or that heritable changes could lead to such diverse ranges of life. Seeing as no mechanism of evolution has been found or settled on (Evolution is a Fact and Theory (http://www.talkorigins.org/faqs/evolution-fact.html) ), I feel evolution can only be seen as a fact to those who conform to a purely natural worldview. Hence, what they see has to be explained naturally - so evolution has to be fact. However if the mechanism for evolution isn't known, then it I think it to be far from fact. Only the data we possess can remain the facts, of which a lot are forced to fit with different theories of evolution.
I myself am a progressive creationist, believing God created life over several long periods of time. I believe this idea is also supported by the sudden bursts of life (for example the Cambrian explosion) we see in the geological record.
All the best,
- Kurieuo.
Radical Edward
07-19-2002, 04:42 AM
it's not that hard:
you start with photoreceptive cells (not so hard to imagine since even amoeba can display photokinesis)
this would give the creature the ability to distinguish between light and dark, and using it, possibly find food sources/evade predators or whatever.
the next step is a thin ridge around the photoreceptive patch. this would allow shadow, and hence a slight amount of directionality.
the ridge gets higher, eventually curling round to a ball, the ideal shape if you want to localise a spot somewhere on the photoreceptive patch, improving direction et al. (note the nervous system also has to improve to cope with this additional information, but it's all gradual)
then you have imaging and so on, which granted is more complicated, but still doable.
Infrared sensors would probably be the first sensors to develop since an organism would want to stay in a temperature that is not lethal and migrate to a warm temperature when it is cold. Since infrared is at the bottom of the visible spectrum any improvements on that would be beneficial.
Just aman
Radical Edward
07-20-2002, 01:01 AM
I doubt it. light would be more useful when considering it as an energy source, and location of food, such as algae and such things. Thermal detection (and hence thermokineses) can be achieved in other ways.
What other ways do you suggest that might not evolve into sight?
I don't know myself and would appreciate your help.
Just aman
Radical Edward
07-20-2002, 11:55 PM
well like us, we have a nervous response to heat. mind you, I'm not entirely sure what the mechanism that these nerves use to convert temperature into a signal in the nerves, but I suspect the general layout of the cells would be quite different to that of the rods and cones and such.
The cells you talk about sense heat upon contact which in our early developing world could be to late. Also warm areas might be missed by a matter of degrees which might also be lethal because of starvation. I still think these sensory cells might differentiate into cillia or antenna to extend their range and then progress to longer range sensors. Finally eyes. Makes sense to me.
Just aman
Radical Edward
07-21-2002, 11:30 PM
hmm.. it seems a little unlikely to me, but then it could have some truth to it, as goldfish and other fish can see in the IR, and when considering the thermal vents (on the base of the oceans, and one possibility of where life may have evolved) there may be some truth in it, since this would allow stuff to navigate between one vent and another. still, it's conjecture, I'll look into it, as I don't know anything much about the properties of life round these vents.
NapoleonGH
11-02-2002, 03:33 PM
Originally posted by blike
Just to inform you, I believe the God of the hebrew bible used evolution to create the earth. So in a sense, I'm a creationist, but I believe in evolution.
too bad that that is an illogical view. There is a philosphical concept that is the corner stone for almost all modern thought, that is applied to engineering, all forms of theoretical sciences, mathematics, and well everything. It is the concept of "Occams Razor" Which states that when you have two theories that predict the same results and are in all ways equal but 1 theory is more complex than the other (ie it encorporates redundancy think math you could have 1 + 1 -4 + 4 = 2 or you could have 1 + 1 = 2 the first includes redundnacy which should be removed) the less complex theory should be chosen because it does not encorporate the redundancy that the more complex theory does. Under these results, your beliefs are illogical as God is a redundant concept and thus logically must be removed from the concepet
If there are bacteria fossils in meteorites then they are only a few DNA steps from creatures with eyes. Locating food is a great pressure for evolution.
Just aman
NapoleonGH
11-02-2002, 11:04 PM
Originally posted by aman
If there are bacteria fossils in meteorites then they are only a few DNA steps from creatures with eyes. Locating food is a great pressure for evolution.
Just aman
valid point there. we got bacteria from about 3.5million years ago (i think) in earth based fossiles too, and before someone says it, yes we do know they COULD be of terrestrial evolution, there has been a workable theory of ambiogenesis for quite a while.
blike
11-03-2002, 08:36 AM
Philosophical concepts have no place in science, otherwise science should likely recognize a God.
"Plurality should not be posited without necessity."
The problem you're having is that you are viewing Occam's Razor as the answer-all solution. That is an incorrect view. It merely removes concepts that are not needed to explain the phenomenon. However, modern science has yet to come up with a suitable explanation for our origins. We have some of it right, but there are many things left unexplained. So, do we have a necessity? Perhaps. Maybe we just havn't discovered underlying principles that guide the universe. Regardless, with your idea of Occam's Razor, there is no necessity, and therefore nothing new should be discovered regarding our origins.
What would Occam's Razor say about quantum mechanics? Sometimes nature takes the scenic route.
NapoleonGH
11-03-2002, 10:02 AM
what do you mean "modern science has yet to come up with a suitable answer to our origins"? Evolution and the concept therein is one of the most well supported theories and most commonly observed facts out of all of science. The Big Bang likewise isn't a theory it is an observed fact (its effects are at least).
and Occams Razor would support quantum mechanics because as i already said it only deals with 2 theories that have the SAME PREDICTIONS. Hence it would be between Quantum mechanics and another theory that proposes the exact same results in all cases under all circumstances which includes greater complexity
fafalone
11-03-2002, 12:53 PM
blike doesn't believe in evolution, he thinks it's a joke, and apparently so does the research he's misinterpretting.
blike
11-03-2002, 02:35 PM
Evolution and the concept therein is one of the most well supported theories and most commonly observed facts out of all of science.
It very well may be, but evolution doesn't explain abiogenesis. It doesn't account for how the Big Bang happened, nor where the initial matter/energy came from. It fails to explain sudden the sudden explosion of single-celled life, and the development of many complex organs. Therefore there is a necessity. Pluralty should not be posited without necessity.
The Big Bang likewise isn't a theory it is an observed fact (its effects are at least).
Nothing in science is fact. Nothing in science is law. They are all only observable, testable theories. I'm not disagreeing with scientific opinion, I'm merely stating that science changes. Look how many timse in the past century we've had to revise theories and laws. Thats the beauty of science; it is self-correcting.
Occams Razor would support quantum mechanics because as i already said it only deals with 2 theories that have the SAME PREDICTIONS.
Ok, now address the necessity.
blike doesn't believe in evolution, he thinks it's a joke, and apparently so does the research he's misinterpretting.
Back up your claims puuuhleeeasee. First, at what point did I claim evolution was a falsehood? Second, I only claimed convergent evolution was a joke.
NapoleonGH
11-03-2002, 02:45 PM
Bilke, no. Observations are "facts" theories are what explain the obersved facts. Hence evolution being a fact and a theory.
Ambiogenesis, protiens were syntehsised in 1954 based on stuff that was present on earth back in the day, and single cells need not arrise like magic, there is a well thought out progression between cells and protiens about 15 steps i think.
Big Bang: As i said an observed phenomina like the existance of a force pulling us to the earth. Where it all came from, the cosmic egg, which has been hypothesised to be a giant singularity, or a collapsed previous universe, but it doesnt need to come from anywhere, because it existed outside of the universe before time existed, hence the rules applying to the cosmic egg dont need to include law of conservation of mass energy.
blike
11-03-2002, 02:51 PM
Bilke, no. Observations are "facts" theories are what explain the obersved facts. Hence evolution being a fact and a theory.
Us being here, having this discussion is a fact; explaining that we arrived at this point by means of evolution is a theory.
Ambiogenesis, protiens were syntehsised in 1954 based on stuff that was present on earth back in the day, and single cells need not arrise like magic, there is a well thought out progression between cells and protiens about 15 steps i think.
"there is a well thought out progression between cells and protiens about 15 steps i think." Very interesting, let me see.
Unfortunatly, single cells did arise like magic. See:
this thread (http://www.scienceforums.net/forums/showthread.php?threadid=352)
A few amino acids are a long way from a functioning cell.
A virus is a long way from life also. There is a key that we don't have yet but it might be found by one of the searching geniouses here. What caused these amino acids to align into RNA. There has to be an observable recipe following the natural rules that builds these blocks.
Just aman
NapoleonGH
11-04-2002, 01:43 PM
Originally posted by blike
Us being here, having this discussion is a fact; explaining that we arrived at this point by means of evolution is a theory.
"there is a well thought out progression between cells and protiens about 15 steps i think." Very interesting, let me see.
Unfortunatly, single cells did arise like magic. See:
this thread (http://www.scienceforums.net/forums/showthread.php?threadid=352)
A few amino acids are a long way from a functioning cell.
NO NO NO NO NO NO NO NO NO NO NO. and NO. Evolution is an observed fact, we have observed speciation, we have bred for specific traits etc, darwinian evolution is quite real and an observed fact.
http://www.talkorigins.org/faqs/evolution-fact.html (i suggest looking up Stephen Jay Gould's essay "Evolution as fact and theory" in its entirety, only a tiny bit is included here.
Here are some obseved instances of speciation:
http://www.talkorigins.org/faqs/faq-speciation.html
what is a theory is the theory of natural selection. Common decent is as true as gravity
About ambiogenesis et al
http://www.talkorigins.org/faqs/abioprob/abioprob.html this should clear up the creationistic pseudoscience you are spreading
fafalone
11-04-2002, 01:58 PM
Evolution is a FACT.
Natural selection is a THEORY.
blike
11-04-2002, 02:13 PM
What faf said ^.
"Bilke, no. Observations are "facts" theories are what explain the obersved facts. Hence evolution being a fact and a theory. "
So, hang on, did we observe natural selection bringing us to our present day stage? No!
Evolution is a fact as far as we can tell. (But remember, so was the second law of thermodynamics.) We have observed evolution in many instances [the famous guppy experiment]. In no way am I denying that. I'm simply stating that saying we originated from a single cell, and, through natural selection, we are what we presently are IS A THEORY. A theory is a well supported idea, saying that it is merely a theory is saying alot about its credibility. In other words, based on the data, this is what happened.
Unfortunatly you seem to have added something I never said.
Remember, always be careful when claiming something as "fact" or "law"; its been the downfall of many.
And if you think that article cleared up the abiogenesis you are sadly mistaken. I never attacked abiogenesis with the statistical model, only convergent evolution. Abiogenesis has issues well beyond statistics.
Interesting you should call my thoughts creationist psuedoscience, though. I havn't quoted a creationist yet, as I tend to disagree with the large majority of them. Most everything I've used comes from the rabidly creationist journals Science, Nature, and the magazine Scientific American.
Sayonara³
11-04-2002, 02:20 PM
Originally posted by blike
but evolution doesn't explain abiogenesis. It doesn't account for how the Big Bang happened, nor where the initial matter/energy came from. It fails to explain sudden the sudden explosion of single-celled lifeUmmm... should it?
I was rather of the opinion that evolution dealt with continuation, not origins.
NapoleonGH
11-04-2002, 03:12 PM
Bilke:
first off we have observed it, to the extent that we have observed napoleon winning waterloo. in otherwords, we have seen such a plethora of evidence demonstrating that we share a common ancestor with chimps and that goes back and back through the fossile record and genetics etc that it would be silly to think it hadn't happen, that is a scientific fact, as much as as gravity
it doesnt only give statistical bits aobut ambiogenesis, it also shows the steps it takes, its not "protien magically bacterium" as you suggested.
some of your comments followed typical creationist pseudoscientific arguments, hence my statement
fafalone
11-04-2002, 05:21 PM
and you know what we do to people who continuously spew pseudoscientific dribble around here....
blike
11-04-2002, 07:46 PM
[B]Sayonara: Ummm... should it?
No, it shouldn't. I said that because of this statement:
what do you mean "modern science has yet to come up with a suitable answer to our origins"? Evolution and the concept therein is one of the most well supported theories and most commonly observed facts out of all of science.
I was pointing out that evolution only accounts for the development of life on earth.
it doesnt only give statistical bits aobut ambiogenesis, it also shows the steps it takes, its not "protien magically bacterium" as you suggested.
The purpose of the other thread was to point out that as soon as conditions for life were met, life exploded. I did not address how fast life must have developed, but it is implied by the data that it must have been a fast development. This is not to say that it did not go through many steps, but there wasn't massive amounts of time for all this to occur.
fafalone
11-04-2002, 07:50 PM
(in chat)
blike again (9:49:09 PM): what fossil record?
I think this is a nice summary of blike's evolutionary knowledge :P
blike
11-04-2002, 07:52 PM
fafaIone (9:34:47 PM): ::changes blikes user status to "Pseudoscientist #2"
blike again (9:47:45 PM): too bad there's no data to back that up. anything i've said has come straight out of journals.
blike again (9:48:08 PM): 8-)
fafaIone (9:48:54 PM): no, everything you've said is your own little interpretation of journals
blike again (9:49:16 PM): eh, no.
fafaIone (9:49:25 PM): "the journal says blah, so therefore my blah is correct" no.
blike again (9:49:33 PM): until you can point out how i've misinterpreted journals, you cannot argue.
fafaIone (9:49:56 PM): the fossil record speaks for itself.
blike again (9:49:57 PM): with specific instances.
blike again (9:50:04 PM): what fossil record?
blike again (9:50:12 PM): for what?
fafaIone (9:50:16 PM): rofl
fafaIone (9:50:18 PM): thats going on the site
fafaIone (9:50:24 PM): blike again (9:49:09 PM): what fossil record?
blike again (9:50:42 PM): eh, what are you trying to use the fossil record to prove?
fafaIone (9:51:03 PM): just about everything i've said.
blike again (9:51:15 PM): gee, how vague.
in context. all you said was the fossil record. Great argument. Like I had any idea what you were speaking about.
fafalone
11-04-2002, 08:14 PM
fafaIone (9:51:21 PM): but arguing with you about this is worse than arguing with zarkov
blike again (9:52:36 PM): because you accidentally said common ancestor had ANYTHING to do with it
fafaIone (9:52:57 PM): common ancestors and convergent evolution are two different topics
blike again (9:53:07 PM): which it does not. if you'd read any research journal you'd see them explaining how the eye evolved seperatly and independantly many different times.
fafaIone (9:53:48 PM): thats called convergence
fafaIone (9:54:16 PM): different species developping similar features is convergence.
blike again (9:54:37 PM): thanks, cpt. obvious. but yesterday you said it was because of a common ancestor
fafaIone (9:54:50 PM): you said convergence didn't happen.
fafaIone (9:54:59 PM): "its a joke"
blike again (9:55:00 PM): i did, and I made my case for it.
fafaIone (9:55:15 PM): but you just admitted your own argument was obviously convergence
blike again (9:55:52 PM): no, you said that its called "convergence". thats true, thats what its called, but i think convergence is highly unlikely.
fafaIone (9:56:11 PM): so it's highly unlikely a whole bunch of organisms have developped eyes?
fafaIone (9:56:36 PM): ::looks around:: i don't think so
blike again (9:57:16 PM): no, its highly unlikely that they would all evolve the same trait because of convergence. that was in support of "Theory of Life: We're Programmed".
fafaIone (9:57:28 PM): vision was a favored trait for an environment and group, therefore photoreceptors became more complex. there is no "useless intermediate"
blike again (9:58:16 PM): why aren't more traits convergent among the 5 phyla?
blike again (9:58:23 PM): that share eyes
fafaIone (9:58:50 PM): jointed appendages?
fafaIone (9:59:01 PM): ceolem development?
fafaIone (9:59:55 PM): the same basic eukaryotic cell structure?
blike again (10:00:15 PM): thats not because of convergence, thats because of ancestors.
fafaIone (10:00:26 PM): ...and the previous two
fafaIone (10:01:36 PM): fins? gills?
fafaIone (10:02:05 PM): hearts?
blike again (10:02:19 PM): common ancestors.
fafaIone (10:02:32 PM): all of those?
blike again (10:02:43 PM): no, probalby not jointed appendages
fafaIone (10:03:06 PM): so how did those come about?
fafaIone (10:04:54 PM): ...
fafaIone (10:06:45 PM): plant roots for example... plants in different orders have developped similar features separetely
fafaIone (10:07:10 PM): there was no "master ancestor" that explains the same basic shape that occures so many times in sea creatures
fafaIone (10:09:07 PM): in fact, whales descended from 4-legged mammals
fafaIone (10:12:10 PM): ... you got quiet
I believe you lose my dear USF student :P
Once life evolved and differentiated at least as far as the carbon based organism, if a feeding niche was available and it was not too far a stretch than something filled it. Even vastly different evolved "by now"species. Maybe the world was filled by marsupials in isolated places on the Earth long before Australia split away.
I've got to think on it more.
Just aman
fafalone
11-04-2002, 10:16 PM
They have marsupials in a few other places, like madagascar.
Another isolated island. In isolated areas the evolution may have been arrested by an abundance of energy and separation but maybe the world was covered by marsupials before regular mammals evolved. There really isn't any way to tell from fossils, is there?
Just aman
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