Should we have bunches of neutral body parts?

Let me throw in a few thoughts that might just be helpfull.Light sensitivity seems to be a pretty common feature of most all living critters. For example, many, many plants exhibit light conciousness, either opening or closing under certain light conditions, growing towards light sources or turning to present the largest surface area towards the sun.None of these are a true eye or vision, but they do show some of the simple reactions possible towards the stimulus of light. In the simple animal category there are floating critters like jellyfish that rise or fall in the water column based on light. Again, no real vision but yet response to light.So the basic parts seem to be pretty common. From that it is but a few steps to develop a true eye. Here's a link to some info on how it might have happened.

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Aslan is not a Tame Lion

Hi gman,I wanted to look at this question from a slightly different angle. You are half right when you say that we should have bunches of neutral body parts. Your problem is that you are looking at a very high level of organization - organs, physiological structures, etc. Now it's pretty clear that, at this level of organization, organisms are generally pretty well adapted and sleek. The selective forces that maintain a well-organized eye are quite strong, so we generally don't find new physiological structures appearing in the eye that don't carry out a useful function.If you are willing to look at a lower level of organization i.e. the molecular level, you will find exactly what you predict: huge numbers of neutral traits. To take an example, consider the human mitochondrion. Everybody needs a mitochondrion, and all of the genes it carries are essential to human life. So you don't find "bunches of neutral genes" or anything like that just appearing in the mitochondrion. But if you compare the mitochondrial DNA sequence of a sample of human beings, you will find a huge number of neutral polymorphisms. See http://www.mitomap.org/cgi-bin/mitomap/tbl7gen.pl for example. These are the "bunches of neutral parts" that you predict. You see, even in a gene of essential function, that is under strong selection not to change too much, you find a huge amount of neutral variation.You probably won't find this satisfying, because you specifically asked about neutral body parts. But biologists recognise that selection acts in different ways at different levels of organization. By only considering "irreducably complex" systems, which I take to mean coadapted physiological systems, you are only looking at half the story. Neutral evolution is occuring at the molecular level, and it might only surface in the phenotype once those neutral polymorphisms take on an adaptive function under changing environmental conditions.CheersMick

If you are considering 'body parts' to mean large collections of cells, then Jacen has already pointed out that there can be no such thing as a 'neutral' body part. Such parts would still impose a finite cost to the organsim without any benefit in return, and would therefore be weeded out by natural selection.This would seem to be a very satisfactory answer to your inital question.

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So would it be correct to say that the retina would prabably evolve first and then the rest of the eye would, through mutational trial and error build upon that foundation (each step being helpfull) until it is an eye?
Do you know of any resources that would go through the process of how a retina would evolve from the light-sensitive chemicals?

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The retina would be the most common-sensical first step since it is the photosensitive part of the eye. All other additions make "seeing" better, such as a concave retina and a lens.All you need is for a light sensitive chemical to start a nerve impulse. You mentioned earlier that you need a "brain" and nervous system before the signal can be used. This isn't necessarily true. If nerve cells previously used for touch became light sensitive, then light would be analogous to being touched. This would make the organism shy away from light, a very advantageous feature for hiding in dark areas and for foraging on food that is only found in dark places. This may have been what happened with planaria, a very simple flatworm with a ladder like nervous system (ie no brain). It has two photosensitive eyespots that allow the planarian to stay in dark places where it is both protected and where it can find suitable food. The eyespot is also concave which give the planaria an idea of which direction the light is coming from.Planaria:

Correct me if I'm wrong, but wouldn't the human appendix and coccyx fall into the category of 'large collections of cells' which are essentially neutral and of no benefit to the organism?

If you find the appendix and coccyx a puzzle it is because you are unable to visualise the magnitude of the time-scales involved. If there was no "garbage collection" we'd be totally weighed down by vestigial equipment like this. Besides, the appendix helps maintain the bowel-blood barrier for bacteria in this region, so is still of some benefit and the coccyx is simply left there to give creationists something to worry about.

Is that why? I thought it was because I was answering this statement of yours: So are you claiming that any 'neutral' body parts I find in organisms are simply garbage collection?

Once again I draw your attention to timescales. The time taken for natural selection to effect such changes might be beyond your comprehension. That would account for why you're suprised to find such depreciated items still present(albeit in reduced form) and I'm not. Standing this on its head, if "garbage collection" was not performed then over such extended periods the so-called "neutral body parts" would outnumber the active ones.

Actually what I'm surprised by is your condescension. I am well aware of the timescales. I was providing an example to see how you would respond, but I wasn't aware your responses would center on your misperception of my temporal cognitive abilities. You sort of dodged my question: are you claiming that ANY neutral body part is simply a result of garbage collection? Because now it sounds as though you allow for the possibility of neutral body parts in organisms, but that they will be outnumbered by 'active' ones - which is NOT what you said in your earlier post; nor was it what HC said: "neutral body parts don't exist b/c natural selection gets rid of them" (paraphrase).

Remind me how we got to things being the result of garbage collection? Well, you might be able to imagine things dissapearing the very instant they are no longer required, but I can't and nobody has ever suggested this might happen due to natural selection. Which is why I keep reminding you about timescales. If you still fail to understand why species are not overburdened with neutral bodyparts, then it is probably because you fail to see the way in which they might be phased-out over time.

Dude, we are obviously miscommunicating here because I don't even know what you are arguing at this point.Let's start over. You posted this: I proffered the coccyx and appendix as examles of neutral body parts, you pointed out that these are vestigial in nature and not some benign mutation.I AGREE! Let's move on.I ask you again, do you still stand by this statement you made (above): "there can be no such thing as a 'neutral' body part?"If you do, then I shouldn't be able to find any organism that has some benign mutation (neutral body part) that doesn't currently or didn't PREVIOUSLY benefit the organism, correct?

Well after reviewing the disproportionate amount of effort required to gain your agreement above, I hesitate to continue... ...however seeing as you have clearly laid a clever trap it would be inconsiderate not to oblige: every collection of cells requires the host to expend resourses in maintaining them. Resources that being finite, may be used to the advantage of the organism elsewhere.So if, for want of a better term, the "bodypart" in question confers more cost than benefit then yes, it becomes a candidate for being weeded out over many generations. To become established in the first place requires a benefit to have been conferred at some point so the probability of finding a well-developed neutral bodypart is extremely low. This may not suit your BLACK and WHITE thinking, but I'm afraid it's how natural selection operates. We would therefore expect to see transitional stages in every species.Now you can tell me all about your example of a benign mutation that was never of any benefit to the host.

I'm not sure why you feel the need to be a total ass when I'm trying to have a simple discussion with you, but I think I'll do myself a good turn and NOT continue to subject myself to your posts.

I'm not at all sure you deserve to get away with such uncivil language. In all my replies I have tried to show where your thinking might be at fault and have patiently rephrased my answers several times over in an effort to show how there can be no such thing as a completely neutral bodypart. Not only have you disappointed me by resorting to calling me an ass, I expect you have also disappointed many people who were looking forward to your exceptional example.

I am somewhat concerned that we might be playing a bit too loosely with meaning of words, "null", "neutral", and "zero". I would have simply thought that there are NO body parts that have no "cost". It is possible for someone to propose a part has less cost and in terms of some maths it might even be possible for somegroup to assert that there arent much of an energetic 1st law necessity such as to equate little cost with zero in terms of what molecular motions might occuur. But if there wasnt a possibilty of getting these things confused then I would have expected the "Neutralist-selectionist debate" p539 INDEX to pages 474-477 to have overwhelmed the nonreligous aspects of evc and as existant on other web discussion forums but still instead I see this as a problem with Anglo Saxon biology only. Look if I had told Berberry that this is about the nullity of the difference between Metarie and the Turo Hospital parking lot compared with a neutral Missippian that would have gotten lost on a NATIONAL Audience but not on those quatered by the question.Provine thought it appropos to print, "If Wright were to accept the importance of Kimura's neutralist theory, he would have to repudiate what he had been saying about random drift for decades. But he did think seriously about the issue, thinking up scenarios in which he could accept at least some aspects of the theory. Kimura and his collegue Tomoko Ohta constanly reminded Wright that he, after all, was the one who had invented and mathematically developed the concept of random genetic drift and that he should share the credit for this new application of it."p474 Sewall Wright and Evolutionary BiologyI dont think Wright would have had had to if he had thought about nullity where the proponents only thought about a neturality or balance BETWEEN given genotype and phenotype data. You can shift a "zero" nullwise and still have neturality or not but that still only seems to indicate relative cost to me. One can assert neutrality. I dont have a tissue for that. But I wouldnt try blow my nose on it too many times. I am curious how neutrality is THOUGHT to scale across levels of organization within a shifting balance of selections' levels but this is such a sophisticated notion that I cant see how *that* is what inor out of dispute in this thread. Wright would have to "repudiate" what Provine and Gould might have thought but Croizat already prooved to me in ways that my sleekness and even handedness could already note that Gould is not God and that Provine was the stewed juice in my soup. It's harsh but lets all still be friends. ICR can not comment at this time on my proposal about a unversal probability bound as to whether it organizes this error in evolutionary thought but -that there is one and that it is not neutral- has been a "given" for me for quite some time. Sure their may be things effectively netural but being effectively dead it can not be.