...in the "mutation" coffin. Sorry, I can't resist this one. It is an official publication of The National Academy of Sciences in conjunction with the Institute of Medicine, called, "Science, Evolution, and Creationism". This booklet of 54 pages is directed at those who instruct the sciences and are confronted with issues concerning evolution and its validity. It correctly defines science, and it correctly states the inability of science to deal with religious topics. And it defines evolution, pg 4:
"In addition [to normal gene combination by two parents], DNA can undergo changes known as mutations from one generation to the next, both in sexually reproducing and asexually reproducing organisms (such as bacteria).
When a mutation occurs in the DNA of an organism, several things can happen. The mutation may result in an altered trait that harms the organism, making it less likely to survive or produce offspring than other organisms in the population to which it belongs. Another possibility is that the mutation makes no difference to the well-being or reproductive success of an organism. Or the new mutation may result in a trait that enables an organism to take better advantage of the resources in its environment, thereby enhancing its ability to survive and produce offspring"
and then, pg 5:
"The differential reproductive success of organisms with advantageous traits is known as natural selection because nature "selects" traits that enhance the ability of organisms to survive and reproduce".
Other than the questionable statement that "nature 'selects' traits", the official position on what causes evolution is clear: mutation and selection.
Interestingly the booklet gives a loose definition of microevolution, and then proceeds to extrapolate all evolution from that, with no mention of any concept of macroevolution. And interestingly, all references to evolutionary examples are presented as fact, not as falsifiable propositions.
But the purpose here is to conclude the argument concerning whether the theory of evolution does or does not require mutation as a prerequisite, necessary but not sufficient condition.
It does.
5 comments:
Well, over time, microevolution results in macroevolution. And also, punctuated equilibrium actually does have evidence behind it. www.talkorigins.org again for more info on it.
And I'm glad they realize that science cannot study the spiritual or metaphysical.
New blog post, by the way.
Hi Alex,
The original meanings were as follows:
Microevolution: changes within a genome without modifications (mutations) to the DNA. I.e., normal DNA pairing of two parental DNA strands to produce a unique offspring.
Macroevolution: changes outside or beyond a genome due to modifications (mutations) within the DNA being passed to an offspring.
Under these understandings of the terms, microevolution can produce big dogs and little dogs, but they all are still dogs.
Macroevolution would have the capabilities of being detrimental (genetic discrepancies), neutral, or beneficial to the selection of the mutated organism. Only macroevolution could produce speciation, under this terminology. So there is a specific disconnect between micro- and macro-; they are not the same thing, nor one the extension of the other.
However, I have turned up enough sources committing to "mutation plus selection" as the current theory. So I'm satisfied with that and now I'm off onto the existence of any known, proven single mutations that produce speciations.
I never argued otherwise. Again, I think you're confusing mutation as the ultimate source of allelic variation with the proximal role of mutation in local evolution of populations. Evolution acts proximally on variation, which may or may not be the product of a recent mutation event. Your sources address the former claim, not the latter. You seem to be conflating the two, in my opinion.
So I'm satisfied with that and now I'm off onto the existence of any known, proven single mutations that produce speciations.
Nothing in modern theory rules out such 'saltations', what the geneticist Richard Goldschmitt referred to as 'hopeful monsters.'
But these are not what the modern theory predicts, Stan, nor are they required for evolution to occur. All that matters is that the isolated population changes sufficiently such that it is free to 'go its own way.' Again, you seem to be attempting to make an argument not against the modern theory, but against a misunderstanding of the modern theory.
I replied to the above this a.m., but it got dumped somewhere along the way. So I'll try again.
Scott, there is no mechanism involved in the statement, "free to 'go its own way.'
Without a mechanism, there is little to no meaning in that statement. As you know, science is about mechanisms; cause and effect. If you propose that "going its own way" is the process of evolution, well, there is nothing there to even discuss. No meat. No science.
But if you propose that "because of its isolation from the main population, the isolated population can incur mutations that might be selected in an evolutionary manner", then we have something to discuss.
I have looked at "modern theory", and I found that it says that evolution is "selection imposed upon mutation". If it does not say that, then what (and who says so) is the mechanism?
You have previously implied that there are a great many causes; But these are all under the same umbrella: selection imposed upon mutation.
You also claim that I misunderstand the modern theory. Well, I have looked and looked, and I am confident that selection on mutation is the modern theory.
If saltations on point or simultaneous mutations don't happen, then accumulations of mutations(capacitance) might happen. If capacitance doesn't happen, then what does happen? There have to be mechanisms involved, or evolution is just a story. It's not enough any more just to say that I don't understand. I am capable of understanding. I am capable of research. What I am looking for now is firm empirical data.
Oops, forgot to address this:
"Evolution acts proximally on variation, which may or may not be the product of a recent mutation event.
If you are saying that "proximally" is the key word, and that mutations exist but need not be recent, then, OK.
But if you are saying that it might not be acting on mutation, then not OK.
From the various sources I have already presented, this is definitely not the case, unless one conflates micro - with macro-.
This is frankly somewhat frustrating, in that there is an obvious difference between the two:
(a)the normal conjunction of two normal, non-mutated DNA strands, in the production of a unique offspring - which owns an individual genome thatexists within the existing genome of the group,
and,
(b)the conjuction, possibly flawed, of two strands of DNA, one or both of which contain errors or changes (mutations), in the production of a unique offspring which contains an individual genome that exists at least partially outside the group genome.
Example(a)is micro-, and example(b) is macro-. Even if these terms are rejected, the differences remain, no matter what the terminology.
Post a Comment