From a review of Behe's book by Sean Carroll, the eminent microbiologist and science writer.
Behe, a professor of biochemistry at Lehigh University, has found an audience among various flavors of creationists who find Darwinian evolution incompatible with their religious views and see scientific validation in Behe's claims. Clearly, this book's main audience would be that constituency, although they will find some parts very discomfiting. For instance, Behe explicitly accepts the ability of random mutation and selection to account for the variation within and differences between closely related species (but not higher taxa such as vertebrate classes). He also accepts (as he has before) the 4.5-billion-year age of Earth and that we share a common ancestor with chimpanzees. That certainly won't go over well in some camps.
The problem is what Behe asserts Darwinian evolution can't do: produce more "complex" changes than those that have enabled humans to battle malaria or allowed malarial parasites to evade the drugs we throw at them. Behe's main argument rests on the assertion that two or more simultaneous mutations are required for increases in biochemical complexity and that such changes are, except in rare circumstances, beyond the limit of evolution. He concludes that "most mutations that built the great structures of life must have been nonrandom." In short, God is a genetic engineer, somehow designing changes in DNA to make biochemical machines and higher taxa.
But to arrive at this conclusion, Behe relies on invalid assertions about how genes and proteins evolve and how proteins interact, and he completely ignores a huge amount of experimental data that directly contradicts his faulty premises. Unfortunately, these errors are of a technical nature and will be difficult for lay readers, and even some scientists (those unfamiliar with molecular biology and evolutionary genetics), to detect. Some people will be hoodwinked. My goal here is to point out the critical flaws in Behe's key arguments and to guide readers toward some references that illustrate why what he alleges to be beyond the limits of Darwinian evolution falls well within its demonstrated powers.
Behe's chief error is minimizing the power of natural selection to act cumulatively as traits or molecules evolve stepwise from one state to another via intermediates. Behe states correctly that in most species two adaptive mutations occurring instantaneously at two specific sites in one gene are very unlikely and that functional changes in proteins often involve two or more sites. But it is a non sequitur to leap to the conclusion, as Behe does, that such multiple-amino acid replacements therefore can't happen. Multiple replacements can accumulate when each single amino acid replacement affects performance, however slightly, because selection can act on each replacement individually and the changes can be made sequentially.
Behe begrudgingly allows that only "rarely, several mutations can sequentially add to each other to improve an organism's chances of survival." Rarely? This, of course, is the everyday stuff of evolution. Examples of cumulative selection changing multiple sites in evolving proteins include tetrodotoxin resistance in snakes (3), the tuning of color vision in animals (4), cefotaxime antibiotic resistance in bacteria (5), and pyrimethamine resistance in malarial parasites (6)--a notable omission given Behe's extensive discussion of malarial drugresistance.
Behe seems to lack any appreciation of the quantitative dimensions of molecular and trait evolution. He appears to think of the functional features of proteins in qualitative terms, as if binding or catalysis were all or nothing rather than a broad spectrum of affinities or rates. Therefore, he does not grasp the fundamental reality of a mutational path that proteins follow in evolving new properties.
Very simple calculations indicate how easily such motifs evolve at random. If one assumes an average length of 400 amino acids for proteins and equal abundance of all amino acids, any given two-amino acid motif is likely to occur at random in every protein in a cell. (There are 399 dipeptide motifs in a 400-amino acid protein and 20 mult 20 = 400 possible dipeptide motifs.) Any specific three-amino acid motif will occur once at random in every 20 proteins and any four-amino acid motif will occur once in every 400 proteins. That means that, without any new mutations or natural selection, many sequences that are identical or close matches to many interaction motifs already exist. New motifs can arise readily at random, and any weak interaction can easily evolve, via random mutation and natural selection, to become a strong interaction (9). Furthermore, any pair of interacting proteins can readily recruit a third protein, and so forth, to form larger complexes. Indeed, it has been demonstrated that new protein interactions (10) and protein networks (11) can evolve fairly rapidly and are thus well within the limits of evolution.
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For instance, Behe once wrote, "if random evolution is true, there must have been a large number of transitional forms between the Mesonychid [a whale ancestor] and the ancient whale. Where are they?" (12). He assumed such forms would not or could not be found, but three transitional species were identified by paleontologists within a year of that statement. In Darwin's Black Box, he posited that genes for modern complex biochemical systems, such as blood clotting, might have been "designed billions of years ago and have been passed down to the present … but not 'turned on'." This is known to be genetically impossible because genes that aren't used will degenerate, but there it was in print. And Behe's argument against the evolution of flagella and the immune system have been dismantled in detail (13, 14) and new evidence continues to emerge (15), yet the same old assertions for design reappear here as if they were uncontested.
To me, mijo's arguments sound exactly like Behe's. I mean he doesn't go so far as to way it couldn't have happened randomly...but he goes out of his way to characterize evolution in the same way Behe does. If people don't believe bottom up design can happen because of such obfuscation...then they cannot understand evolution. Dennett refers to selection as similar to a series of cranes ratcheting up genomes.
Is evolution stochastic or deterministic? Random or non-random? Are these good terms to use? Does it help people understand evolution? Because such wording and the abuse of the word "fit" is a well documented part of the wedge strategy to confuse the issue. I don't know if Behe, Klein, or Mijo are aware of their logic snafus and seemingly purposeful way of minimilizing or not understanding natural selection. Maybe they really believe what they say. But as far as I can tell, none of them are saying anything and they miss the simplicity of the principle while playing semantic games with hypotheticals, exceptions, ambiguous wording, and so forth.
Mijo's argument is similar to Behe's. He's just not admitting the part about intelligent design. He's playing a semantic game so he can believe that scientists think this is all due to random chance or "stochastic processes" or non-uniform probabilities or whatever other vagaries he's deemed important.
Evolution fact. You can understand it. You can't discredit it by claiming it makes no sense to you. The only thing that leads to understanding about the facts is clear, simple, language. Details can come later. There are lots of ways to describe it...and lots of ways that it's not random (or that it would be misleading to define it as such.) But mijos assertion that because identical alleles can be selected or not selected in different ways including random acts--This makes the evolutionary process stochastic as opposed to "deterministic". I suspect if the input regarding evolution was as known as weather input (which mijo says is "deterministic"), then the outcome would be as predictable as weather...and thus deterministic--but I hate philosophy and semantic games.
We do know the input and output of every dead organism we can get DNA from...it's whole evolutionary history is in it's genes. We can predict that if we have DNA from any life form, we can tell how far back in time it shared a common ancestor with any other life form. We can SEE the mutations involved in speciation. So how is evolution more random than weather? And what does weather have to do with birth, death, and reproduction rates?
So, Mijo has boiled the answer to his question down to the following: evolution is a "stochastic process"....since you can't always tell if two organisms that are equally fit (per mijos definition of fit) will have the same number of grandchildren. But what the hell does that have to do with the topic question?
How is that more informative than all the other explanations including the one calling selection the "opposite" of random?
Life wasn't preplanned. It most definitely was cobbled together through time and designed from the bottom up...just as the internet is "designed". Replicators beget more replicators. Non-replicators die out and are pruned from the "process" via natural selection. It's so simple, and yet... mijo can't seem to clarify the process in any coherent or meaningful way...just like Behe.
Yes, in essence we exist because of "random chance". But evolution is not driven by random chance. It is driven by natural selection...the elimination rounds ever honing and paving the way the best replicators. No intelligent Design Proponent over 40 seems able to grasp this, no matter how intelligent he is.
