And this is a case in point.
Faith used to back her affected agrument by incredulity with specious appeals to "genetic meltdown". Her favorite example was the amazing cheetah.Lessee, of course you must use all the most derogatory terms you can think of to poison the well against the argument for starters, such as "affected" and "specious," to be sure nobody could possibly think the argument had any merit. Oh and be sure to call it an "argument by incredulity" even though it is no such thing -- that's SUCH a no-no.
I also don't recall ever using the term "genetic meltdown" so it shouldn't be in quotes in reference to my argument.
Now he goes on in a way that is rather hard to follow, kind of a word salad approach that serves mostly to obscure and in any case doesn't get anywhere near the argument I was always trying to make by referring to the cheetah:
He's had it rough as the poster-child for reduction of genetic diversity. Due to depopulation, isolation and inbreeding his genetic variability is so low that skin grafts between unrelated animals do not result in immunological rejection! And so on, there are a lot of lovely fables in this area.IS that a fable? I don't think I ever used that particular example but everything I've read about the cheetah does say that the genetic variability IS so low that individuals are almost like clones of one another. Is he trying to dispute that even after declaring it?
But contrary to popular belief, this is nothing new for the cheetah.Contrary to popular belief? Whose belief? I never said it was "new?" What does its being new or old have to do with anything? The point is that the cheetah is a prime example of extremely reduced genetic variability. He seems to affirm this yet also try to deny it. This is a very confused piece of writing.
Well, now here comes the Evo Fairy Tale. Get some popcorn, pull up a chair:
It began thousands of years ago, toward the end of last ice age,Yes, long long ago ...
in a fairly ordinary genetic bottleneck.
... in a land far far away ...
Did anyone ever suggest the bottleneck was not "ordinary?" The point about a bottleneck is that it eliminates a bunch of genes all at once, leaving a very few individuals to form a new population with the reduced genetic variability they share, whether it's an "ordinary" or extraordinary bottleneck, whatever that might be.
And as result of this process, the cheetah has become the least "feline" of all the big cats.Well, it has a smallish head as felines go but otherwise it's plenty feline it seems to me. But apparently saying it's less "feline" is supposed to imply that it's an example of evolution. Sigh. Are we getting anywhere with this little dissertation? Doesn't it seem to be wandering around trying to obscure the issue?
So now we go from this completely subjective notion that it's less feline looking to this HUGE jump:
In another million years or so, he may look something like this [here we get a picture of -- a hyena? A doglike animal with some cheetah-like coloring and markings]Oh brother. Because the cheetah just sort of looks less feline to this guy it's evolving and is going to look even less feline in a million years. Sigh.
The point about such drastically reduced genetic variability is that EVOLUTION HAS COME TO A STOP. That is the point of using the cheetah as an example. The cheetah is NOT EVOLVING. It's reached a genetic dead end. When you have no new genetic possibilities there is simply no direction in which the animal COULD evolve. It goes on producing individuals that hardly vary at all from each other, to the point that they are truly like clones. You CANNOT GET EVOLUTION FROM THAT POINT.
A bottleneck is what happens when for some reason you have just a few individuals inbreeding among themselves to form a new variation of a species. A bottleneck is simply the most drastic way animals get "selected" -- randomly in this case -- and isolated, these being the "mechanisms" or conditions that bring about new gene frequencies, which is supposedly the basis for evolution. And it IS, it is the basis for MICROevolution, or the variation that commonly occurs from generation to generation in any species. If part of a population gets isolated from the rest it develops characteristics to some extent different from the former population with its own reduced gene pool. But it WILL have a reduced gene pool, it WILL have reduced genetic variability compared to the previous population. A bottleneck will simply bring about a DRASTICALLY reduced genetic variability compared to the usual reduction because it involves so few individuals. This is what makes such examples the best for making the point about how evolution comes to an end by simply following out the normal processes that create new varieties, or microevolution. ALL reduced populations tend in the same direction of reduced genetic variability but the extremely reduced populations are where you see the tendency itself in action, where it's hardest to ignore it, the tendency, that is, toward the complete inability to evolve further somewhere down the road.
Of course fantasy can surmount any obstacle thrown up by reality, and here we have Iblis totally ignoring this point and assuming that the cheetah is going to go on evolving although it doesn't have the genetic means to go on evolving:
The misadventures of these fellows actually provides the key to your whole puzzle. You see, when the gene pool is large and conditions remain stable, the overwhelming majority of even the effective, non-neutral mutations are quickly lost in the shuffle. They are outnumbered and as they provide no selection advantage, there is no reason for them to be preserved.If mutations are going on at the rate they assume, then there is no such thing as their not having an effect. A mutation is a change in a gene, it is a substitution of a new coding sequence for another. If it has no effect all that means is that it has no detectable effect, no effect that they know of. But the very fact that a coding part of the DNA has been changed means that SOMETHING HAS CHANGED in whatever that segment formerly coded for. It can't be a good thing that a formerly coding sequence no longer codes for whatever it used to code for. At the very least something has been killed, some part of the organism no longer functions, a very tiny hardly discernible part no doubt, something beneath the detection capacity of the instruments available, but how can the death of a coding portion of DNA ever be just "neutral?" And most mutations supposedly have this non-effect. But that means that most mutations are killing off genes coding bit by coding bit. This is no doubt how "junk DNA" gets formed and there's an awful awful lot of junk DNA in the genome of most creatures, certainly the human genome. But that's a whole nother subject.
When the gene pool is greatly reduced however, either due to large-scale changes in the environment in terms of selection factors or to the spreading out of outliers of a population into a new area or niche, this changes. The cow's primary source of genetic diversity is, other cows with somewhat different genes.Exactly, this is how genetic diversity is maintained in most large populations of any animal. Individuals vary from each other, they have different genetic possibilities that can combine with those of other individuals to create the variation that shows up in the next generation.
The cheetah's, though, is mutation.Uh huh. Mutation is the only thing left to the cheetah, and this is true. But consider the RATE situation now. How many of the expectable mutations provide any kind of change that could be useful to the animal? Actually, it's pretty much zip. You get all those "neutral" mutations and you get deleterious mutations. Those are known. The useful ones are purely imaginary.
Each new trait produced by mutation is valuable to a reduced species and likely to be preservedPure fantasy. There ARE no new "traits" known to be produced by mutation. All that is KNOWN to be produced are degenerative changes and "neutral" changes, that, as I point out above, aren't really neutral because they DESTROY genes.
resulting in large-scale morphological changes over a relatively short period of time. Still in the high thousands and millions though.Man these guys love their theory. They NEVER have to come down to reality and actually PROVE anything, they're quite content to affirm the fairy tale of beneficial mutations that drive evolution even in the face of EVIDENCE that, as in the case of the cheetah, evolution is simply no longer possible.
And this is the main factor underlying Gould's "punctuated equilibrium". For ten million years, everything is fine. Then things change; and when they do, things change. Eerie. But not mysterious, simple statistics.Eventually you'd think a brain would simply implode from the strain of having to invent all those fictions to support all the imaginary notions that support the imaginary theory.
But thanks for the mention, Iblis, gave me the opportunity to restate my favorite argument.