This is what I argued at EvC off and on from my very first post: What is called "evolution" is merely the variations that occur in species of living things from generation to generation, a phenomenon which has been known from the beginning of history and exploited by farmers and husbandmen all that time to maximize chosen qualities in their animals and plants.
Yet a century and a half ago some decided to pretend this well-known phenomenon isn't limited to each of the species but is open-ended so that species may keep on varying into other species over time. The same processes that ALWAYS brought about the variations, simple sexual reproduction for starters but also selection processes that isolate portions of a population from the rest, including what came to be called Natural Selection, were now made to justify the claim that all species come from former species.
As I've said before here many times, this is an hypothesis, fine, but it cannot be proved and has never been proved.
As for the question what prevents micro-evolution from becoming macro-evolution, it's the simple fact, a fact which is testable and falsifiable, that the processes that bring about new variations require the elimination of competing genetic potentials until a particular "evolving" line of a population may end up quite a striking variation in itself, highly specialized but with no further ability to evolve at all, even with fixed loci and no ability to breed with the mother population, no genetic options to develop in its own line.
Soon as someone gets around to making the necessary test, either in the field or in the laboratory, I have no doubt this will be demonstrated.
Meanwhile, yes, it is just an hypothesis, just as their answer is: oh but MUTATIONS enter in to prevent this kind of dead-end fixation of genetic variation. Based on what? On observation? Nope, never seen this, it's merely assumed. On testability? Nope. Just stuff with bacteria that have not been shown to have any bearing on this development in sexually reproducing animals. Nope, it's all purely hypothetical, yet as usual they assert it as if it were fact.
The fact is that IF mutations DID keep interfering with the isolating processes that are necessary to developing new variations / or species, you'd never GET new variations or species, you'd just get a continuing hodgepodge of genes that keep on blending back into the general species characteristics and never differentiating. NOT evolution.
Nope, the natural processes that bring about variation -- mistaken for open-ended evolution -- NATURALLY lead to genetic depletion. Conservationists know this only too well and it is an endless headache to them. It's the natural built-in mechanism for variation to occur within species but undesirable as well as desirable variations may be the result of random natural processes.
If death had never entered the world back in Eden, life forms would simply continue to vary and genetic depletion would not be a problem, merely a mechanism for variation, exhibiting the creative potentials of life in wondrous ways. But since death entered, all life is gradually approaching extinction -- some ways off yet I trust -- and the natural isolating processes that bring about variations only speed up its approach.
That's my answer and I stand by it. But here's another on that same thread I link above, from another creationist, who takes them up on their mutations theory:
I'll put it in the most basic form I can think of.Translation: To the extent that mutations ARE observed happening, they do not supply the kind of positive variations that evolutionists assume (and cannot demonstrate). The actual evidence is that mutations overall play a destructive role, either by replacing a functioning part of the genetic code with non-coding gobbledygook, or by actually coding for something harmful. Very very occasionally the harmful change may happen to have a beneficial side effect but it's always a trade-off. This is not the kind of upward-and-onward life vigor that the theory of evolution requires. In other words, one way or another mutations only contribute to the death processes that the Fall introduced.
Both groups observe Mutations happening. Both group realize that these muations are copying errors during the transcription of the genetic code.
Both groups will observe that some of these mutations will become fixed in a population. This is what both will call micro-evolution
Both group will observe that therefore, these copying errors will accumulate in a population, driven sometimes by factors such as natural selection, but also sometimes simply through genetic drift.
But each group has a different opinion on the eventual outcome of all this accumulation of mutations:
- Neo-Darwinian evolutionists will say that these will accumulate to the point that new features, organs, etc. will appear in the population, showing an ever evolving and changing trend in biological populations. This is what they will cal macro-evolution.
- Creationists will say that these will accumulate to the point that the mutational burden will become much too high, and this will lead the population down a spiralling path to genetic meltdown. Macro-evolution will therefore never happen.
Creationist will often complain when evolutionist use examples of micro-evolution to prove that macro-evolution will happen, because it simply does not discard the possibility that accumulating mutations could lead to genetic meltdown.
And along come the evolutionist answers of course:
Starting with Percy :
This isn't an accurate characterization of what evolutionary biologists say. Through natural selection, deleterious mutations are removed and advantageous mutations retained. It is advantageous mutations (and to be more complete, also mostly neutral mutations) that accumulate, not all mutations.Sure sounds good in theory. In actuality it appears that genetic diseases accumulate in the population faster than they are removed. And that is just a partial list of all the genetic diseases too.- Creationists will say that these will accumulate to the point that the mutational burden will become much too high, and this will lead the population down a spiralling path to genetic meltdown. Macro-evolution will therefore never happen.Because your characterization of the position of evolutionary biologists was incomplete, this characterization of the position of creationists fails to address the fact that deleterious mutations are removed from populations by natural selection and are not included among the mutations that accumulate.
There are thousands of genetic disorders in humans. Some are common whereas quite a few are rare. Whatever be their incidence, what is most vexing about these disorders is that scientists are still trying to find cures for these disorders. While some headway has been made in the direction, a lot more research is required.THOUSANDS. THOUSANDS. Documented thousands of deleterious mutations that DIDN'T get selected out and continue to plague their possessors. And meanwhile the notion that it's the advantageous mutations that accumulate as Percy states above, has NO evidence for it WHATEVER, it is purely an assumption based on the theory that says it must be that way. Another Hypothesis that cannot be tested, alas.
But all those genetic diseases are sure a reality. Wonder how that happened if it's advantageous mutations that accumulate but deleterious ones don't? Oh I'm sure they have a rationalization, of course, they're good at that, but the plain facts OUGHT to make the party line spelled out above a laughing stock.
But then Wounded King comes through with some common sense and agrees with what I say above, that the reality doesn't meet the theory as Percy states it, a common sense he does occasionally show in spite of his diehard evolutionist commitment:
[Percy] Because your characterization of the position of evolutionary biologists was incomplete, this characterization of the position of creationists fails to address the fact that deleterious mutations are removed from populations by natural selection and are not included among the mutations that accumulate.At least there IS that evidence, and as I keep saying it would not be hard to get the evidence that it is generally the case wherever selection and isolating processes are operating, however less drastically. Collect a good number of samples from various populations of a ring species, or set up your own ring species in a laboratory, and look at their DNA, and you'll get the necessary evidence. But at least there IS that much evidence from the drastically reduced populations, and there is NO evidence WHATEVER that BENEFICIAL mutations accumulate, NONE NONE NONE NONE NONE. ALL they have is the THEORY which tells them that they MUST and they believe it to the point of declaring that it actually occurs in reality when there is NO evidence for it. They will call creationists all kinds of names for suggesting that they don't have evidence because they really have deluded themselves that they do.[WK] I'm not sure why you think this. There is plenty of pop. gen. and comparative genetic evidence for fixation of deleterious mutations. Certainly the trends for beneficial and deleterious mutations are as you desribe, but in the real world there is plenty of evidence of deleterious mutations accumulating.
The real question is, as Slevesque posits, whether such mutations are balanced by compensating beneficial mutations or conversely whether organismal fitness is in an irreversible decline, for which there is no evidence except in some organisms with drastically reduced population sizes.
Then WK goes on to chide the creationist for not getting all his terminology accurate. Oh come on, if you want to talk to molecular biologists then stop talking to creationists, we do the best we can to get the terminology straight, and beyond that it's your obligation as the expert to translate if necessary. We'll learn that way but not by being told we have to get a degree in the relevant science first. It's clear that you DO understand what slevesque was saying and are only nitpicking about the words to pull rank. The important thing is the topic. Clarify if you really don't understand, but it's clear that you do, WK, so cut the guff.
And a last point for this thread: Coyote chimes in mentioning a creationist, Sanford, who argues that the genome is deteriorating. I didn't know about this man, but obviously he is on the right track. If I can ever afford it I'll get his book, but that will be a while the way things are going lately.
Here's the Wikipedia article on John C. Sanford :
Sanford has written a book entitled Genetic Entropy & the Mystery of the Genome (2005) in which he claims that the genome is deteriorating and therefore could not have evolved in the way specified by the Modern evolutionary synthesis. Sanford's claims have received little attention from the scientific community. Sanford has published two peer reviewed papers modeling genetic entropy.And here's his book at Amazon . There's a great review of it by someone who calls himself Saint and Sinner, posted in December 2006. Here's an excerpt:
Sounds to me like Sanford is right on, the bias-blinded Scientific Community's prejudices notwithstanding.
Here is where we start getting into the analysis of NDET [Neo-Darwinian Evolutionary Theory]. Sanford discusses the statistical distribution of mutational effects (i.e. the magnitude of good and bad mutations affecting fitness) and their frequency. Sanford points out a number of differences between NDET and reality:
A. NDET posits that most mutations are neutral. However, Sanford argues that there is no such thing as a truly "neutral" mutation. Rather, most mutations are "near-neutral" (whether increasing fitness or decreasing fitness). Even a single point-nucleotide mutation in a minor area of the genome disrupts the genetic code to some degree (no matter how small). This is key for the rest of his book.
B. The naïve view of mutational distribution is a bell curve (though many Darwinists recognize that the actual distribution found in nature is nothing like it). The real distribution is a Kimura curve (named after the *Darwinist* population geneticist who created it) where the *vast* majority of the curve is near-neutral. Sanford notes that if the normal distribution (i.e. "bell curve") was true, then an increase in complexity would be inevitable. However, with the Kimura curve, it is hard to see any substantial increase in fitness "getting off the ground" so-to-speak. [note: "naive" means theoretical, hypothetical, pure assumption, untested; "real" means what has been observed in reality. Clearly tons of evolutionary theory is a mere assumption or reification of theory that is untested. AS I KEEP SAYING.]
C. NDET acknowledges that most mutations are harmful, but doesn't suggest that the ratio is so small as to never allow an increase in fitness that would affect a population. Contrary to that assumption, the actual ratio, as noted by the population geneticists (most of whom are Darwinists!) whom Sanford cites, is so small that population geneticists don't even place the beneficiary curve on the distribution graph! The ratio that Sanford cites (again, from the population geneticists) is between 10,000 to 1,000,000 harmful mutations for every one beneficial (though probably closer to the former figure rather than the latter). Sanford chooses to be conservative, and for the rest of the book, he assumes the 10k ratio. Keep this in mind when the next point is cited.
D. NDET assumes that natural selection will take out all of the bad mutations and leave only the good (notice that that was a near quote of Darwin himself). However, citing the population geneticist, Kimura, for support, Sanford notes that there is a "zone of near-neutrality" on both the beneficial and harmful sides of the curve in which natural selection doesn't select for or against. This is due to the fact that most mutations are point-nucleotide mutations. These only cause an ever-so-slight decrease in fitness that natural selection can't "see" them 99% of the time. It would be like a single pixel on your television screen going out. Would you really be able to tell a difference? Furthermore, since the beneficiary mutations curve is so small (see point C. above), the "zone of near-neutrality" (a.k.a. the "no-selection box") covers 99% of the beneficiary mutation side of the distribution! This ensures that natural selection will never see 99% of the good mutations while allowing the bad (which are vastly greater in number) to accumulate. Thus, the genome will suffer from "genetic entropy" (and hence the title of the book).
Now, a typical reply (which is, in fact, found below in one of the negative reviews) is that biologists have witnessed and documented such beneficiary mutations that have given great benefit to organisms in their environment. However, many biologists are becoming aware that the vast majority of these changes in phenotype are due to "pre-programmed" changes in the genome, not random ones as NDET demands. Secondly, as Sanford points out in Appendix 4, many of these "beneficial" mutations actually end up giving the organism a net decrease in fitness (as in the case of homeostasis in cold-climate creatures to warm climates or drug-resistant bacteria) making them deleterious in reality!