This lack of quantitative thinking underlies a second, fatal blunder resulting from the mistaken assumptions Behe makes about protein interactions. The author has long been concerned about protein complexes and how they could or, rather, could not evolve. He argues that the generation of a single new protein-protein binding site is extremely improbable and that complexes of just three different proteins "are beyond the edge of evolution." But Behe bases his arguments on unfounded requirements for protein interactions. He insists, based on consideration of just one type of protein structure (the combining sites of antibodies), that five or six positions must change at once in order to make a good fit between proteins--and, therefore, good fits are impossible to evolve. An immense body of experimental data directly refutes this claim.Should we really be surprised that the creationists' arguments are getting worse and worse, and their arguments poorer and poorer? How could they not, given the slow steady advance of knowledge that further shores the validity of evolution every day?
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.
Is it possible that Behe does not know this body of data? Or does he just choose to ignore it? Behe has quite a record of declaring what is impossible and of disregarding the scientific literature, and he has clearly not learned any lessons from some earlier gaffes. He has again gone "public" with assertions without the benefit (or wisdom) of first testing their strength before qualified experts.
We see unbelievable stupidity crop up like this again with the Disco Institute's new "textbook".
I noted that Ralph Seelke is one of the authors of this"textbook" put out by the Disco Institute in an attempt to supplant quality texts (like Miller's) with their own dreck, to circumvent the issue of promoting creationism by substituting science with BS. He testified in the KS Kangaroo Court hearings, and so I checked out his webpage, which contains some materials which advertise his Christian background and anti-evolutionary positions. I was blown away with the paucity of his argumentation to reject evolutionary biology.
Note, in particular, his Why I am a doubter of evolution- 11/06. On slide six, he says:
Unbelievable. I can't believe this man is a tenured professor.•The main way evolution works is through random processes at low probability- ~ 1 in a million is a common probability that a mutation might occur.•So if you need one mutation, the odds are one in a million; if you need TWO- the odds are now one in a TRILLION!!!
First issue -- the only time you multiply probabilities is when they are independent, which is obviously not the case in something like a frameshift mutation or gene duplication.
Second -- 1 in a million is the probability that *A* mutation might occur? This is absolutely ridiculous. What he means is that this is the probability for a mutation *for each nucleotide*. And, considering that there are 3B of them in humans, this corresponds to 3000 mutations in each genome. Then, remember that this is per replication event = per cell.
How many cells are there in the body...how many replication events per cell...?
Hopefully you get the picture here.
This is such a bad argument I really couldn't believe that this man is a professor of anything, much the less microbiology!
From the peer-reviewed literature:
Many previous estimates of the mutation rate in humans have relied on screens of visible mutants. We investigated the rate and pattern of mutations at the nucleotide level by comparing pseudogenes in humans and chimpanzees to (i) provide an estimate of the average mutation rate per nucleotide, (ii) assess heterogeneity of mutation rate at different sites and for different types of mutations, (iii) test the hypothesis that the X chromosome has a lower mutation rate than autosomes, and (iv) estimate the deleterious mutation rate. Eighteen processed pseudogenes were sequenced, including 12 on autosomes and 6 on the X chromosome. The average mutation rate was estimated to be approximately 2.5 x 10(-8) mutations per nucleotide site or 175 mutations per diploid genome per generation. Rates of mutation for both transitions and transversions at CpG dinucleotides are one order of magnitude higher than mutation rates at other sites. Single nucleotide substitutions are 10 times more frequent than length mutations. Comparison of rates of evolution for X-linked and autosomal pseudogenes suggests that the male mutation rate is 4 times the female mutation rate, but provides no evidence for a reduction in mutation rate that is specific to the X chromosome. Using conservative calculations of the proportion of the genome subject to purifying selection, we estimate that the genomic deleterious mutation rate (U) is at least 3. This high rate is difficult to reconcile with multiplicative fitness effects of individual mutations and suggests that synergistic epistasis among harmful mutations may be common.You really do have to be dumb to reject evolution these days. There's just too much evidence for any other explanation.
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