Does evolution have a chance?

[Micaiah]

Just for the record, if the chance of two indentical paths of evolution occuring independently is 10^3000, then what is the chance of three paths of evolution occuring independently?

Since the events are independent the anwser is simply 10^3000 x 10^3000 = 10^6000.

That would give you a mere 75 universes of atoms fom which to choose your tagged atom, or if dealing cards from a shuffled pack in a specified order, we're now talking about 90 packs of cards.

 

[Jet Black]

Spetner cites Zuker with regard to the eye, stating that it was found there is a striking identity between the gene for eye control found in both the gene of the insect and the vertebrate.

you are talking about the eyeless/Pax-6/anirida gene, which are indeed strikingly similar, right down to the three intron sequences. So on what basis do you come to the conclusion that this gene is not a basal gene? It doesn't control any structure of the eye whatsoever, it only starts the eye forming.

 

[Micaiah]

And your point is? Are you claiming they did not develop independently?

 

[Jet Black]

And your point is? Are you claiming they did not develop independently?

I am not claiming anything, I am asking you a question. you can tell this by the question mark at the end of the sentence. I will hilight it for you:

So on what basis do you come to the conclusion that this gene is not a basal gene?

I freely confess that I assume that you have come to that conclusion, but it does seem to be implicit in your argument that you think that, if evolution were true, it must have actually evolved no less than three times.

 

[Micaiah]

I don't knwo what a basal gene is, hence my question. While you're at it, can you give a link to the article. I cannot access the article.

 

[Jet Black]

I don't knwo what a basal gene is, hence my question. While you're at it, can you give a link to the article. I cannot access the article.

well it is a very important word to know if you are going to have a discussion like this, in which you claim that a gene has evolved independently, more than once, or just once in a common ancestor.
Basal is basically a feature or something that has been inherited from a common ancestor. It seems from what Spetner is saying, that Zuker is claiming (I haven't read the article so as yet I am rather cynical about it and thinking it is a quote mine, but I have somebody getting the article for me, so I will get back to you in due course) that Pax6 must have evolved at least two times, and not evolved once in a common ancestor to mice and flies. Regardless of what Zuker was actually saying in his article, it certainly seems that this is what Spetner is claiming, and it also seems that this is what you are claiming. am I right?

 

[perplexed]

here is a relevant link (I think)
http://www.maayan.uk.com/evoeyes4.html

In the above article they conclude that the gene was in the common ancestor to most animals way back when.

 

[Micaiah]

Thankyou for your assistence Black Jack. My comments obviously indicate that I understand the two genes developed independently. You suggest they may be basal genes, ie these genes are shared by the hypothesised anscestor of both. In the article given above by Confused, we have the following quote:

Zuker (1994) This ancestral "eye" may have been just a single or a few photoreceptive cells, the development of which was controlled by genetic cascade from Pax-6.

There are however arguments against the hypothesis that Pax-6 illustrates the monophyly of extant eyes. Firstly there is evidence that Pax-6 homologues are expressed in sea urchins and nematodes, neither of which has eyes. Other evidence is that Pax-6 also plays a role in the development of other tissues in the brain and is not exclusively involved in eye development (Fernald,1997). Many homologous developmental patterns have been found between invertebrates and vertebrates, for example the hom/hox genes.Although there are homolgous molecules in the developmental cascades of diverse eyes, Fernald, 1997 argues that this does not mean that the structures themselves are. It is interesting to note that the evolutionary conservation of Pax genes is higher than for Hox genes (Quiring et al, 1994). The model of eye evolution that argues against the common origin of metazoan eyes, must therefore propose the independent recruitment of the Pax-6gene, after the eyes diversified. However (Sheng et al,1997) suggest that the model of a common ancestor of eyes is more parsimonous, since recruitment of Pax-6 would only have had to occur once. It is suggested that Pax-6 may be "locked in" to the regulation of eye development because of its ancient function of directly targetting photoreceptor molecule genes such as rh. It would be interesting now to see where if at all flatworms with primitive eye spots express Pax-6 (Sheng et al,1997, Zuker, 1994).

 

[Micaiah]

Sorry, not doing very well here. I've edited the reference at post 120, and hope this is more to the point.

 

[Jet Black]

Thankyou for your assistence Black Jack. My comments obviously indicate that I understand the two genes developed independently. You suggest they may be basal genes, ie these genes are shared by the hypothesised anscestor of both. In the article given above by Confused, we have the following quote:

the quote contradicts then what you said. Additionally Pax6, while involved in eye development, is also involved in a number of additional features, perhaps most importantly it is involved in the distinction between dorsal and ventral cell layers, it is involved in the formation of mouse noses, squid tentacles, the Central Nervous System, and other things. As the quote there points out, Pax6 is present in a number of organisms that don't even have eyes. So there is certainly no suggestion whatsoever that the gene would have had to evolve multiple times, since it exists in far more basal features than eyes (namely the bilateral symmetry) So what about it being integrated into the formation multiple times. Well there are a couple of ways of looking at this, one is that the initial thought that exe evolution occured a number of times, completely independently is wrong (this is my personal position on this - I think that primitive eyes on the lines of eye spots would have existed well before the diversification of the phyla and formation of more complex eye structures) and another with some, though more limited evidence, is that it just so happens to have been coopted into eye formation a number of times. One bit of evidence for this claim is that the dachshund gene in fruit flies has the same effect as the Pax6 gene, though it also produces short legs. That makes it clear that both of these genes are involved in some steps before the eye forms properly, and it could be that the genes do different things in different organisms, but both happen to be part of the genetic pathway towards eye formation. There are loads of other genes that have the same effect on drosophila, such as twin of eyeless, optix, eyes gone, sine oculis and the bizzarely named teachirt gene.

Both of these pose massive problems for spetner's claim as relates to eyes, since in the latter, the positioning of Pax6 is not a prerequisite for eye formation - pax6 just happens to be a basal gene that has been coopted into the formation of eyes multiple times, and in the former, it is basal in doing the same thinganyway and all that is wrong is the initial hypothesis that eyes formed completely independently.

My main reason for thinking that eyes did not form completely independently is this rather fascinating article about Cubozoan Jellyfish, which are the most basal organisms to have anything resembling an eye.
http://www.ijdb.ehu.es/ijdb200448089/ft719.pdf

 

[Jet Black]

Sorry, not doing very well here. I've edited the reference at post 120, and hope this is more to the point.

well for completeness, I will refresh the original reference, since I refer to it a couple of times:

Zuker, C. 1994. On the evolution of eyes: Would you like it simple or compound. Science 265(Aug. 5):742.

 

[Micaiah]

I hear your point Jet Black from an evolutionist's perspective. I'd be interested to see what the other reference says. Can any one help me finding the following reference:

Quiring, R., U. Walldorf, U.Kloter, and W.J. Gehring, (1994) "Homology of the eyeless gene of the Drosophila to the Small eye gene in mice and Aniridia in humans," Science, vol. 265, pp 785-789

 

[Jet Black]

I hear your point Jet Black from an evolutionist's perspective. I'd be interested to see what the other reference says. Can any one help me finding the following reference:

sorry, but what I am saying is a bit more than "just what I think happened from an evolutionists perspective" The issue at hand is that Spetner is implicitly claiming that this gene must have evolved multiple times if evolution is correct, and since the probability of the same gene evolving multiple times is incredibly small, then this would be evidence against evolution.

This is a really strange claim, since the gene exists in more basal organisms, and does far more than just this one thing. The only evidence I could see him having to support his position is if Pax6 did not exist in more basal organisms and did not do more (particularly more fundamental) things than be a member of the cascade leading to eye development. but it does exist in more basal organisms, and it is involved in far more fundamental things than just eye developement. so where is his argument?

 

[Jet Black]

I hear your point Jet Black from an evolutionist's perspective. I'd be interested to see what the other reference says. Can any one help me finding the following reference:

Quiring, R., U. Walldorf, U.Kloter, and W.J. Gehring, (1994) "Homology of the eyeless gene of the Drosophila to the Small eye gene in mice and Aniridia in humans," Science, vol. 265, pp 785-789

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7914031&dopt=Abstract

 

[Nightson]

I hear your point Jet Black from an evolutionist's perspective. I'd be interested to see what the other reference says. Can any one help me finding the following reference:

Quiring, R., U. Walldorf, U.Kloter, and W.J. Gehring, (1994) "Homology of the eyeless gene of the Drosophila to the Small eye gene in mice and Aniridia in humans," Science, vol. 265, pp 785-789

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?holding=npg&cmd=Retrieve&db=PubMed&list_uids=7914031&dopt=Abstract

Edit: Curses... too slow....

 

[Jet Black]

pwnt.

 

[Karl - Liberal Backslider]

sorry, but what I am saying is a bit more than "just what I think happened from an evolutionists perspective" The issue at hand is that Spetner is implicitly claiming that this gene must have evolved multiple times if evolution is correct, and since the probability of the same gene evolving multiple times is incredibly small, then this would be evidence against evolution.

This is a really strange claim, since the gene exists in more basal organisms, and does far more than just this one thing. The only evidence I could see him having to support his position is if Pax6 did not exist in more basal organisms and did not do more (particularly more fundamental) things than be a member of the cascade leading to eye development. but it does exist in more basal organisms, and it is involved in far more fundamental things than just eye developement. so where is his argument?

[tentatively moves Spetner from the "run of the mill Creationist" column to the "either completely scientifically inept or a LCW, you take your pick" column]

 

[Numenor]

It is so remote that it is impossible.

That's a lie and you know it. Something improbable is not impossible. As long as the odds aren't zero then it's not impossible. Stop lying.

 

[Nathan Poe]

Thankyou for your assistence Black Jack.

Who's Black Jack?

 

[Nathan Poe]

That is what is meant by an extremely remote chance. It is so remote that it is impossible.

You flunked math, didn't you?