pangloss

And the creationists were given the last word, I thought I would present a reply to ReMine that I submitted yesterday...

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And? Since you did not even attempt to do so in your book, perhaps now you can finally reveal at least a hint of the evidence that indicates that 1667 beneficial substitutions cannot account for human evolution from an ape-like ancestor. While you are at it, you should also identify this ape-like ancestor so the reader can assess for him or herself whether or not this “chasm” is too large for 1667 adaptive (and some number of neutral) substitutions to account for. Surely, you can do both, right? If not, it seems that you main ‘argument’ is nothing but emotive rhetoric. This is a reckless misrepresentation by Walter ReMine. I provided citations and IN CONTEXT quotes from just a few that in fact point out Haldane’s assumptions and why they are not ‘set in stone’ as well as offering ‘solutions’ to the so-called dilemma. Walter ReMine, as is obvious in this thread, opts to simply ignore them or wave them off as irrelevant. That is non-controversial. What is controversial is your continued insistence that Haldane’s model is all-encompassing, and that by virtue of Haldane’s model, in you unsupported and unsubstantiated personal opinion, humans could not have evolved from an ape-like ancestor given the number of substitutions ‘allowed’ under Haldane’s model. Unfortunately for Walter ReMine, personal opinions unsupported by evidence are worthless in science. Why not tell us the rest of the story Walter ReMine? Tell us about Haldane’s other assumptions, which are not ‘identical’ to what is ‘prevalent’ today? You have been repeatedly asked to justify your claim that Haldane used an “elevated” starting frequency. You have repeatedly ignored the requests and simply re-state your opinion that the starting frequency is elevated.

Please explain WHY Haldane’s initial frequency is elevated. Also please explain why the modifications of such models by others such as Felsenstein, Hartl, etc. , are always so terribly flawed, at least according to you.

Most importantly, of course, please explain – supported with documentation, of course – how many beneficial substitutions are required to account for specific adaptive traits. You seem to know, since you write that evolution would require more than 500,000 to “get a sapien from a simian.” Misrepresentation. The mischief that I am fighting against is the common creationist habit of making broad-based malicious claims while being wholly unable or unwilling to support the claims. Such as the quotes from your book that I provided that you ignored in your last reply.

MrDarwin

Perhaps this has already been covered, but how on earth did Haldane calculate any kind of numbers given that at the time (I believe this was back in the 1950s) nobody knew (a) how many genes humans have, (b) how many genes our nearest relatives have, (c) how many genetic differences there are between them, (d) what those genetic differences are, and (e) how long ago we diverged from our nearest living relatives? It seems to me that Haldane must have been pulling numbers out of thin air.

I'm curious to know who labeled it "Haldane's Dilemma"--I have only seen this phrase used in reference to creationist arguments. I have been unable to find the phrase in any of my genetics or population biology books (I know, the creationists claim it's a conspiracy to cover up an embarassing "disproof" of evolution).

KC

Haldane's paper in 1957, 'The Cost of Natural Selection', was a theoretical treatise on how the substitution of a beneficial allele could have a 'cost', represented by genetic deaths, on a population. The original scenario Haldane used was for an allele that was disadvantageous (being kept in the population purely by mutation pressure), suddenly becoming beneficial due to a change in environmental conditions. The cost in this case was the genetic deaths attributed to the other genotypes being selected against. Haldane's point in all of this was, there was a limit to the number of substitutions a population could absorb before the cost outweighed the benefits. In the scenario described, Haldane estimated one substitution every 300 generations was the mean limit.

The 'dilemma' (which I think was Van Valen's term), was that such a limit seemed unrealistic. Subsequent work by many population geneticists, such as Felsenstein and Ewens, showed that Haldane's limit simply does not apply in many cases, and that his number is highly dependent on the initial assumptions. One such assumption was that the initial frequency of the allele at the time it becomes beneficial had to be very low, around 10^-4. Haldane noted that this assumption was a problem--he specifically said, in a subsequent paper, that his limit did not apply in situations where the allele may have attained high frequencies before becoming selected for (an example being an initially neutral allele rising in frequency due to genetic drift). Other assumptions also make this number inapplicable. A large population is required,for example, as well as selection that isn't particularly strong.

It is clear that this 'limit' was not some universal brake on the rate of evolution.
Of course, that hasn't stopped creationists applying the 1 substitution per 300 generations universally, and coming up with some outrageous claims. ReMine applied this limit to the human/chimp divergence, and decided that 1667 allele substituitions were all that could have occurred since that divergence. His argument is that this number is too low to explain the observed DNA differences between man and chimp. Since REMine has misapplied Haldane's figure, his conclusions are invalid. Not that creationists care--most have never bothered to actually read Haldane's paper in the first place.


Cheers,

KC