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Cost of natural selection is prohibitive (Talk.Origins)

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Response Article
This article (Cost of natural selection is prohibitive (Talk.Origins)) is a response to a rebuttal of a creationist claim published by Talk.Origins Archive under the title Index to Creationist Claims.


Claim CB121:

J. B. S. Haldane calculated that new genes become fixed only after 300 generations due to the cost of natural selection (Haldane 1957). Since humans and apes differ in 4.8 × 107 genes, there has not been enough time for difference to accumulate. Only 1,667 gene substitutions could have occurred if their divergence was ten million years ago.

Source: ReMine, Walter J., 1993. The Biotic Message, St. Paul Science, Inc


CreationWiki response:

The rebuttal of ReMine's claim actually rests on misreading what ReMine wrote, and debating mostly irrelevant examples (See Haldane's Dilemma). There are only a few sources even listed:

However, there are many other resources that are interesting in this:

Apparently, ReMine has been trying to get a paper of his into a peer-reviewed journal, but has not been able to because the peer-reviewers say that while he is completely correct all his information is already well-known. Is it well-known? It doesn't appear to be.

Talk Origins' first response is a criticism of Haldane's assumptions. The second response is a criticism of ReMine's assumptions.

(Talk.Origins quotes in blue)

Haldane's "cost of natural selection" stemmed from an invalid simplifying assumption in his calculations. He divided by a fitness constant in a way that invalidated his assumption of constant population size, and his cost of selection is an artifact of the changed population size. He also assumed that two mutations would take twice as long to reach fixation as one, but because of sexual recombination, the two can be selected simultaneously and both reach fixation sooner. With corrected calculations, the cost disappears (Wallace 1991; Williams n.d.). Haldane's paper was published in 1957, and Haldane himself said, "I am quite aware that my conclusions will probably need drastic revision" (Haldane 1957, 523). It is irresponsible not to consider the revision that has occurred in the forty years since his paper was published.

You can read the references for more details, but modern peer-reviewed material (see Nunney) gives confirmation of Haldane's work with only minor modifications.

Then, Talk.Origins criticizes ReMine:

ReMine (1993), who promotes the claim, makes several invalid assumptions

The assumptions which Talk.Origins attributes to ReMine are mostly plain false.

  • The vast majority of differences would probably be due to genetic drift, not selection.
ReMine has an entire chapter on neutral evolution and how it doesn't help Haldane's dilemma.
  • Many genes would have been linked with genes that are selected and thus would have hitchhiked with them to fixation.
Gene linking has very little effect in sexually reproducing populations.
  • Many mutations, such as those due to unequal crossing over, affect more than one codon.
Haldane's dilemma does not rest on whether or not a mutation affects multiple codons, and in addition the vast majority of mutations are single codons anyway.
  • Human and ape genes both would be diverging from the common ancestor, doubling the difference.

ReMine did not calculate the difference as being from modern apes.

  • ReMine's computer simulation supposedly showing the negative influence of Haldane's dilemma assumed a population size of only six (Musgrave 1999).

This does not refer to ReMine's calculations of Haldane's dilemma, but to his analysis of Richard Dawkins' Weasel program. Dawkins' program has been shown to be irrelevant for many reasons, and the fact that ReMine uses Dawkins' own starting point for Dawkins' irrelevant simulation does not really have anything to do with the argument at all. ReMine's conclusions and calculations about animal populations have absolutely NOTHING AT ALL to do with a population of size 6, and implying so means that either they didn't read ReMine or are being intentionally disingenuous.

Updated Material on the Cost of Natural Selection

The paper The Cost of Natural Selection Revisited (see link in resource list above) has made some updates to Haldane's calculations. This paper asserts that Haldane was basically right, but adds that rather than a purely additive cost per loci, there is a fixed cost plus an additive cost per loci. It also mentions that the beneficial mutation rate has a lot to do with the outcomes. One thing missing, though, was the fact that modern research has shown that combining beneficial mutations are just as often harmful as they are synergistic, a fact which this computer simulation does not bring up or take into consideration. Nor does it mention the problems of pleiotropy and mutations.

The paper also mentions that soft selection really only deals with intraspecies competition and not a changing environment, and therefore could hardly be considered to be a primary influence of change as some have proposed.

On a slightly different topic, the mutation rate needed to have the divergence between humans and apes is way too high to have occurred in the timeframe needed and not have destroyed the populations through an overly high genetic load. See Monkey-Man Hypothesis Thwarted by Mutation Rates.

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