02 Feb 09
1 edit
It has been traditionally thought by evolutionists that eyes between at least some of the main animal groups had evolved independently from each other and more than once.
The bases for this assumption was simply because it is hard to imagine how the eye of, say a fruit fly with its compound eye and, say, the human eye could have a common ancestral eye because the eyes are just so totally different in structure.
But, recently, a gene called the pax-6 gene has been discovered that is responsible for both the development of the fruit fly eye and the human eye!
http://www.pbs.org/wgbh/evolution/library/04/4/text_pop/l_044_01.html
(There are almost certainly another thread about this (somewhere) because many of you must already heard of this but I think it is interesting enough to make this new thread about it here)
Not only that -it has been found in virtually all the main animal groups with eyes! -and in each one, it is responsible for either part or all of eye development.
For this to have come about by chance can be calculated to be less than one in a trillion! -therefore, we can assume this is no coincidence and that virtually all animals that have eyes share one common ancestor which had eyes that must have been a very very simple animal with two very very simple eyes -just like some very simple primitive worms that are alive today with such eyes.
The consequences of this discovery are obvious; the eye didn’t evolve independently many times over but, surprisingly given the vast range and seemingly incompatible designs of various eyes, evolved just once!
The pax-6 gene has evolved to change its function in eyes many times so that, for example, it is responsible for just the development of just the iris of the eye in humans while it is responsible for the development of the whole of the compound eye in fruit flies. In some causes, multiple copies of the pax-6 gene has evolved in an animal with each one responsible for the development of a different aspect to the animal's eye (haven’t been able to find a link about this but I have heard of it from somewhere -I don’t remember where).
02 Feb 09
Originally posted by Andrew HamiltonI always get very uncomfortable when someone throws out a large figure without any real context.
For this to have come about by chance can be calculated to be less than one in a trillion! -therefore, we can assume this is no coincidence and that virtually all animals that have eyes share one common ancestor which had eyes that must have been a very very simple animal with two very very simple eyes -just like some very simple primitive worms that are alive today with such eyes.
What on earth do you mean by less than one in a trillion? Do you mean one in a trillion universes or one in a trillion species or one in a trillion unique individuals? Surely there are over a trillion living things on the planet, so does they gene evolve anew every few days?
And how was it calculated in the first place?
Further the fact that the gene is obviously very useful for eye development does not guarantee that it evolved for sight or that the first animal to have it could see or that sight evolved only once.
Is the gene also used by organisms that respond to light but have no eyes? Are the other genes that are required for sight? The fact that the gene occurs in almost all animals simply implies it is an old gene but surely all animals have quite a lot of genes in common.
02 Feb 09
3 edits
Originally posted by twhitehead…What on earth do you mean by less than one in a trillion?…
I always get very uncomfortable when someone throws out a large figure without any real context.
What on earth do you mean by less than one in a trillion? Do you mean one in a trillion universes or one in a trillion species or one in a trillion unique individuals? Surely there are over a trillion living things on the planet, so does they gene evolve anew ...[text shortened]... als simply implies it is an old gene but surely all animals have quite a lot of genes in common.
I mean if all the genes where randomly generated (by natural mutations) for the eyes for each of the “main groups” of animals with eyes (and there are many species within each main group and all invertebrates being a whole of one of these “main groups“ and arthropods being another and perhaps all worms being yet another etc -basically, purely in this narrow context, group them according to the most fundamental differences in eye structure) with the eyes evolving completely separated and independently in each of these “main groups“ then the chances of ALL those “main groups“ evolving to have precisely that same gene for the eye just by coincidence can be calculated to be less than one in a trillion.
…Is the gene also used by organisms that respond to light but have no eyes?
….
As far as I am aware -no.
….Are the other genes that are required for sight?..…
Yes, of course.
….The fact that the gene occurs in almost all animals simply implies it is an old gene but surely all animals have quite a lot of genes in common.
...…
But it isn’t just an “old gene” -it is a gene that has a specific function in helping the development of the eyes of very different animals with some very different eye-structures when that same gene could have evolved to have a completely different function that had nothing to do with the eye but it didn’t but instead evolved specifically for the eye in all those animals -surely this implies that the gene originated in an animal for the eyes of that animal when that animal was in fact the ancestor of vertually all the other animals that exist with eyes today?
02 Feb 09
Originally posted by Andrew HamiltonSounds a bit vague, don't you think?
[b]…What on earth do you mean by less than one in a trillion?…
I mean if all the genes where randomly generated (by natural mutations) for the eyes for each of the “main groups” of animals with eyes (and there are many species within each main group and all invertebrates being a whole of one of these “main groups“ and arthropods being another ...[text shortened]... t animal was in fact the ancestor of vertually all the other animals that exist with eyes today?[/b]
02 Feb 09
Originally posted by Andrew HamiltonThat is a fascinating discovery, but I didn't see any mention of the probability of each different type of eye evolving separately in this article. I bet if you took that part out, you wouldn't be getting such a hard time from these guys. 😉
It has been traditionally thought by evolutionists that eyes between at least some of the main animal groups had evolved independently from each other and more than once.
The bases for this assumption was simply because it is hard to imagine how the eye of, say a fruit fly with its compound eye and, say, the human eye could have a common ancestral ...[text shortened]... able to find a link about this but I have heard of it from somewhere -I don’t remember where).
02 Feb 09
Originally posted by PBE6…but I didn't see any mention of the probability of each different type of eye evolving separately in this article.
That is a fascinating discovery, but I didn't see any mention of the probability of each different type of eye evolving separately in this article. I bet if you took that part out, you wouldn't be getting such a hard time from these guys. 😉
.…
-that’s because there is no such talk of probability in these articles -my assertion of probability is my own judgement based on my limited knowledge of genetics combined with my own personal intuition.
I made a guess that there are many millions of roughly equally likely sets of genes that could have evolved for the eye other than the set of genes that actually did evolve for the eye. So I judge that the probability that exactly the same gene would independently evolve in two very different animals with very different eye structure to be a “small” one -I admit I don’t know how to do the actual mathematical calculation to estimate the probabilities and thus I cannot judge exactly how “small” that “small” is, but I am confident enough of my judgement of probabilities that I think it has to be by any stretch of the imagination, “small” -at least less than one in a ~million? (my best guess)
If the probability of two groups of animals independently evolving exactly the same gene specifically for the eye and nothing else is, say, less than one in a million, then the probability of it happening to four such groups of animals independently would be less than one on a trillion -that’s where I got my figure from.
03 Feb 09
1 edit
Originally posted by Andrew HamiltonI disagree. I very much doubt that we know all the possible functions of the gene past and present. Many genes serve more than one function and are used differently in different organisms at different times. Many genes evolve with one function and later take on a different one.
But it isn’t just an “old gene” -it is a gene that has a specific function in helping the development of the eyes of very different animals with some very different eye-structures when that same gene could have evolved to have a completely different function that had nothing to do with the eye but it didn’t but instead evolved specifically for the ey ...[text shortened]... t animal was in fact the ancestor of vertually all the other animals that exist with eyes today?
It could be that this gene happens to do something that is particularly useful in eyes, and has been used for that purpose multiple times.
I do agree that it is a strong indicator of common ancestry, but I disagree that it is conclusive evidence, and I think your probability calculation is a shot in the dark with not nearly enough background information to make even an informed guess, and certainly not enough information for anyone to understand the implications of the probability. As I pointed out, if we have a trillion life forms evolving, then why isn't the gene appearing regularly?
Some genes evolve from a prior gene by merely changing one base pair. The probability of this occurring more than once is actually extremely high. What matters is how useful the resultant gene really is.
03 Feb 09
Originally posted by twhiteheadOne thing I see at fault in your logic is talking about a trillion 'life forms' evolving. By 'life forms', I assume you to mean species, fi so, there has been nowhere near that many, so your assumptions may be off base.
I disagree. I very much doubt that we know all the possible functions of the gene past and present. Many genes serve more than one function and are used differently in different organisms at different times. Many genes evolve with one function and later take on a different one.
It could be that this gene happens to do something that is particularly usefu ...[text shortened]... than once is actually extremely high. What matters is how useful the resultant gene really is.
03 Feb 09
Originally posted by twhitehead…I disagree. I very much doubt that we know all the possible functions of the gene past and present. Many genes serve more than one function and are used differently in different organisms at different times. Many genes evolve with one function and later take on a different one.
I disagree. I very much doubt that we know all the possible functions of the gene past and present. Many genes serve more than one function and are used differently in different organisms at different times. Many genes evolve with one function and later take on a different one.
It could be that this gene happens to do something that is particularly usefu ...[text shortened]... than once is actually extremely high. What matters is how useful the resultant gene really is.
.…
-not sure where I said or implied this wasn’t the case -if anything I thought I had clearly implied that many genes DO evolve with one function and later take on a different one. You may have somehow misread what I said.
03 Feb 09
Originally posted by sonhouseWell it all depends on what is probability calculation is based on - which is not at all clear.
One thing I see at fault in your logic is talking about a trillion 'life forms' evolving. By 'life forms', I assume you to mean species, fi so, there has been nowhere near that many, so your assumptions may be off base.
I was referring to individual organisms not species. If the probability of an organisms offspring having the new gene pax-6 that was not in the parent is one in a trillion then we simply total up the number of organisms and average out the length of a generation. Whether the new gene becomes species wide then depends on its usefulness.
But it seems his probability calculation was not referring to what I initially thought, but something else altogether. I still think that it is irresponsible to quote a probability figure without stating how it was arrived at or what it means - especially when it is really a shot in the dark anyway.
Also even if it is unlikely for a gene to evolve in different organisms and then be used for the same purpose, the conclusion that the common ancestor used the gene for the same purpose is not the only explanation available.
I doubt that enough studies of the prevalence of various genes has been made to compare the situation with other known traits which are either known to have common ancestry or known to not do so.
04 Feb 09
Originally posted by Andrew HamiltonJust so I know, how do you know it isn't because of a common design
It has been traditionally thought by evolutionists that eyes between at least some of the main animal groups had evolved independently from each other and more than once.
The bases for this assumption was simply because it is hard to imagine how the eye of, say a fruit fly with its compound eye and, say, the human eye could have a common ancestral ...[text shortened]... able to find a link about this but I have heard of it from somewhere -I don’t remember where).
and not a common ancestor?
Kelly
04 Feb 09
2 edits
Originally posted by KellyJayActually, I think it is both. It is both a common design of evolution (using the non-standard meaning of the word “design” that doesn't imply intent and the gene itself is the bit that they have in common) AND a common ancestor.
Just so I know, how do you know it isn't because of a common design
and not a common ancestor?
Kelly
I think I have already explained my reasons why I think it was a result of a common ancestor -not sure what the premise would be that it was as a result of a god nor what the motive would be that such a god would give them all the same gene to have a deferent functions but all these functions involving the eye.
04 Feb 09
Originally posted by Andrew HamiltonYou fed the troll. And you used the word "design". Have fun!
Actually, I think it is both. It is both a common design of evolution (using the non-standard meaning of the word “design” that doesn't imply intent and the gene itself is the bit that they have in common) AND a common ancestor.
I think I have already explained my reasons why I think it was a result of a common ancestor.
04 Feb 09
1 edit
Originally posted by KellyJayThere's no way to detect design unless you know something about how the designer designs things. Since God supposedly designed everything, there's no way to separate the "designed" from the "non-designed", if that's your implication, and who else would it be? Why would someone think the eye is designed and, say, rocks are not?
Just so I know, how do you know it isn't because of a common design
and not a common ancestor?
Kelly
When we find an arrowhead or a mysterious set of symbols carved in on a rock...well we KNOW humans do these things so we kind of suspect a human designer.