Bolder-dash's very own little thread

One of our members here at EvC, Bolder-dash, has on several occasions expressed a desire to discuss the strengths and weaknesses of evolutionary theory. The same has also, on several occasions, expressed concerns that his/her topic proposals have not been given a chance of promotion because, in his/her opinion, moderation here has an anti-Bolder-dash bias.Be that as it may, Bolder's topic proposals leave a lot to be desired. What aspects of evolutionary theory does Bolder want to discuss? What specific problems does he or she see with the TOE? What alternative model would Bolder like to propose in its place? What are the arguments for this model?This thread is meant to assist Bolder-dash in developing an OP and a set of arguments brilliant enough to bypass even the strict anti-Bolder-dash policy of this forum. So let's give it a go shall we?--------------------------------------------------------Bolder's OP:Hi, I would like to discuss aspect A of evolutionary theory.(Examples:
Natural Selection
Common ancestry of humans with Chimps and other apes
The emergence of sexual reproduction
The endo-symbiotic origin of the Eukaryotic cell
etc.)I believe aspect A of evolutionary theory has the following flaws:blablablablablablablablablabl ablablablablablablablablabla blablablablablablablablablab lablablablablablablablablabl ablablablablablablablablabla blablablablablablablablablab lablablabla blablablablablablablablablab lablablablablablablablablabl ablablablablablablablablabl ablablablablablablablablabla blablablablablablablablablablablablablablablablablablablablablab lablablablablablablablablabla blablablablablablablablablab lablablablablablablablablabl ablablablablablablablablabl ablablablablablablablablabla blablablabla blablablablablablablablablab lablablablablablablablablabl ablablablablablablablablablablablablablablablablablablabla blablablablablablablablabla blablablablablablablablabla blablablablablablablablabla blablablablablablablablablablablablabla blablablablablablablablablablabla blablablablablablablablabla blablablablablablablablablablablablablablablablablablabla(Note: With the bla's being replaced by arguments in his own words)
(Note: Bolder should put forth the arguments in his/her own words, while citing sources where appropriate)Now I propose alternative theory B as better explaining aspect A of evolutionary theory, and here's why:blablablablablablablablablab lablablablablablablablablabla blablablablablablablablablabl ablablablablablablablablablab lablablablablablablablablabla blablablablablablablablablablablabla blablablablablablablablablabl ablablablablablablablablablab lablablablablablablablablabla blablablablablablablablabla blablablablablablablablablablablablablablablablablablablablabla blablablablablablablablablabla blablablablablablablablablabla blablablablablablablablablabla blablablablablablablablablabla blablablablablablablablablabla blablablablablablablablablabla blablablablablablablablablabla blablablablablablablablablablablablablablablablablablabla blablablablablablablablablabl ablablablablablablablablablab lablablablablablablablablablabl ablablablablablablablablablabl ablablablablablablablablablabla blablablablablablablablablabla blablablablablablablablablablablablablablablablablabla(Note: Cite sources. Same as above)---------------------------------------I think if Bolder followed this simple outline he'd have a good chance at getting his topics promoted.Anyone else got suggestions?-MeldinoorEdited by Meldinoor, : No reason given.

Ah, now we're getting somewhere. So the aspect of evolution that you wish to discuss will be the formation of "new and unique body plans". Good.Now the next step is to specify a few examples of "new and unique body plans". For though it may seem obvious to you, I am (and presumably any reader of your proposal is as well) uncertain as to what constitutes a new and unique body plan. Most body plans have many things in common and are hardly unique. But give us some examples.Next explain why evolution could not produce these examples. Cite some sources, but give us the arguments in your own words.Then if you can think of a better explanation of these different body plans, feel free to offer it. Don't be afraid to take a stance.Then we can begin to discuss, and I promise not to tell you to read a magic book.Respectfully,-Meldinoor

Let's allow him to fully formulate an argument before we attack it. Wouldn't it be nice if we allowed him to present a specific well-formulated argument rather than bickering with him back-and-forth? This constant bickering is getting on my nerves, and it's not entirely his fault either. An unformulated argument is an argument not worth responding to. Let's get him on his feet before we start debating. That's what this topic is for after all.Respectfully,-Meldinoor

Fair enough. Get proposing then. As long as the topic is reasonably narrow and delineated. The mechanisms that cause long-term evolutionary change must be the same that cause short-term evolutionary change, but over a longer period of time. Think about it. If it were not so, then different mechanisms must have existed in the past but not today, and a uniformitarian approach to the evidence would more or less rule that out.The mechanisms that cause evolution are the ones that Dr A pointed out. Natural Selection, Sexual Selection, and Random mutation are commonly discussed. Geographic isolation serves to isolate populations and produce new species. One of my favourite examples is that of the Ensatina Salamanders surrounding the Californian Central Valley. They constitute so-called "ring-species" because the population of salamanders are distributed around the valley in an almost complete ring, but with a gap caused by geographic barriers. Sort of like a horse-shoe. Adjacent populations within this "horse-shoe" are sexually compatible because they hybridize and have not strayed far from each-other genetically. But the species at either end of the horse-shoe are incompatible, and have formed truly separate species that will not interbreed when re-introduced to each-other.
This is an irrefutable example of speciation, caused by random mutation and genetic drift.When you're looking at larger scale evolution it is hard to find neat examples like Ensatina. This is because intermediates are obviously no longer around for study. Of course, the fossil record is replete with examples of transitional fossils, including Archaeopteryx, Sinosauropteryx, and Dromaesaurids constituting transitionals between older forms and more modern forms (in this case illustrating transitions between the dinosaur theropods and modern birds).Of course, merely seeing the transition in the fossil record does not necessarily tell us the mechanisms of these evolutionary changes. It could have been via naturalistic means, or there may have been a trickster god that created new species based off of older species as the old ones went extinct (something like this seems to be Hugh Ross' point of view). The key to understanding the mechanism of how evolution works lies in searching out the genetic similarities between different species. For instance, humans and chimps share an overwhelming portion of transcribed DNA. The differences between chimp and human DNA are due to mutations in existing DNA, or the activation/deactivation of genes that both share. As far as I know there are no difference that can not be explained through various types of mutation.Natural selection is a mechanism that we know has always acted on populations of organisms. Try to conceive of a world where the individuals with the most offspring did not out-compete those with less. It doesn't make sense does it?So since we have evidence of mutation in our DNA, and a tell-tale genetic similarity with other species (even including ERV's and other genetic "junk"), and since we know that natural selection is a factor in any population of replicating individuals with differential levels of success, we have two key mechanisms by which organisms have evolved.The Ensatina salamanders provide an example of Allopatric speciation by Geographic isolation and genetic drift, thus validating these mechanisms as well.Respectfully,-Meldinoor

Thank you Bolder-dash.And now I can finally understand your argument, at least regarding the problems you see with mutations and natural selection.Ok, so if the effects of a mutation are too small natural selection won't have anything to act upon. I'll give you that. But how much of an effect does a mutation need to have for natural selection to "take notice"? First of all, some mutations (in fact, most I think) are neutral or nearly neutral because they are either synonymous (they do not change the protein expressed by the gene) or because they are never transcribed (they never get read by the protein-making process at all). You probably have many such mutations that your parents didn't already have, but you won't notice them because they didn't have (much of) an effect on your phenotype.Most non-neutral non-synonymous mutations are deleterious (see Prevalence of positive selection among nearly neutral amino acid replacements in Drosophila). But not all. Famous examples of small mutations being selected for are the Peppered Moth, Darwin's "Finches" and The Sickle-cell gene. More recently, the rather large-scale changes in Italian Wall Lizards that were transplanted to a new island environment are of interest. Apparently they changed their diet, the shape of their heads, the strength of their bite, and developed cecal valves in their digestive tract to facilitate their new mostly herbivorous diet.
See National Geographic Article.That is an example of a new body function emerging in a species.Respectfully,-Meldinoor

No, they are actually more fit. Being more fit means having a greater chance of surviving and producing offspring. In areas where the sickle-cell gene has been successful, the side-effects of sickle-cell anemia are not as bad as Malaria. Hence, people are better off with a bit of sickle-cell anemia than malaria. At least when a carrier only has one copy of the allele. It is when you have two copies of the gene that the deleterious effects of sickle-cell anemia become truly a problem. The theory of evolution predicts that genes that improve the fitness of a population will spread, even if these same genes might prove detrimental in another population under different selection pressures. That's why sickle-cell anemia isn't prevalent in, say, Russia, where having it doesn't confer an advantage to one's survival. Exactly. But you asked me to illustrate the mechanisms of evolution, not to demonstrate examples of speciation. I gave you the Ensatina salamanders and the Italian Wall Lizards as examples of that. I could provide the Herring Gull as another example of a ring species where a clear speciation has taken place.But the finches of Galapagos, and the peppered moth both illustrate very well the powers of natural selection, and that was the reason I brought them up. Do you not agree that natural selection is what causes the beaks of the finches to vary, and the peppered moths to become darker?Respectfully,-Meldinoor

About 40 years. Not true. In small populations with short generations, beneficial mutations can become fixed very quickly. All four. And why not? Natural Selection is by no means restricted to selecting for only one trait. I'm no biologist, so I can't tell you exactly how many mutations were required to produce the cecal valves. But it is clearly a useful innovation for a mostly herbivorous lizard, so it is easy to see why non-random selective forces would preserve the trait and eventually fix it within the population. But, at most it took about 40 years. Why do you see a problem with that? Remember, in small populations with faster generations a lucky mutation, be it good or bad, could easily become fixed within the population in a short time. Populations adapting to selection pressures in the environment? Yup, it sounds like evolution by natural selection. When a lizard in a large population has a neutral mutation that doesn't catch on I'm not surprised that it isn't noticed. Natural selection tends to produce bigger changes when selective pressures are higher.Respectfully,-MeldinoorEdited by Meldinoor, : No reason given.

That depends on your definition of "body plan". But if the "crippling disease" was genetic in nature, and if being crippled somehow magically made an individual more fit within a certain environment, then yes, NS would select for "cripples".Respectfully,-Meldinoor

I think I overlooked this part of your argument, and as I re-read your posts I think this seems to be the main objection you've raised to the naturalistic origin of body parts and functions. Let's see if I understand you correctly first. Essentially what you're saying is: "If random mutation can produce entirely new body parts and functions, why don't we see these randomly appearing in populations today? Even if they're not selected for." Is that the jist of your argument?I think the problem is that you're looking for the wrong kinds of evolutionary developments. Evolution rarely produces truly novel traits in a population. Mostly (as I suspect it was with the Italian Wall Lizard's cecal valves) it gets by by just molding existing structures to produce new functions. A creature that is born with some new appendage or tissue would be more likely to be considered a "freak" than the originator of some new large-scale evolutionary development, because such large-scale mutations are generally not beneficial.Small changes to existing systems, however, can be and quite often are beneficial, such as with the peppered moths or the lizards. For example, nobody believes that a complex organ such as the eye just popped into existence through some lucky slew of mutations, but through the modification of earlier eyes. That's why we don't expect a brand new complex organ to pop into existence randomly, or even to recognize the first steps in the evolution of some system.Consider this: Imagine if you had lived some 800 million years ago and had no knowledge of eyes, simply because no creature at that time had them. Assume you were studying some simple pre-cambrian creatures and noticed that some of them had developed photo-sensitivity. Without knowing the future, how could you know that this was the beginning of a path that would produce complex systems such as the camera eye. You probably would not see the significance of this minor trait even as it was right there before you. Similarly, today it is impossible to look at a population and point out the beginning of "new and unique body plans" (as you put it), because we do not know where they're going to go. Evolution is not teleological (means "directed").Anyway, I hope that helped explain my point of view. Hopefully someone more knowledgeable of the subject matter will correct me if I'm wrong, but I think this should address at least this quibble that you have with evolution.Respectfully,-Meldinoor