Thursday, October 3, 2013

Stephen Meyer Says that "Homology" Is a Problem in Molecular Evolution

Stephen Meyer argues (in Darwin's Doubt) that the Cambrian explosion cannot be explained by evolution but it can be explained by Intelligent Design Creationism.

His main thesis is that all the animals appeared suddenly in the Cambrian and there's no evidence that they arose from ancestors living earlier in the Precambrian. Unfortunately for him, there IS plenty of evidence in the form of molecular evolution. By comparing genes and proteins we can show that all the animal groups are related to one another and that their common ancestors are spread out over a considerable period of time as shown in the phylogenetic tree below from a paper by Dunn et al. (2008).

This evidence is a serious problem for Meyer so he has to deal with it in his book. He tries to discredit the entire field of molecular evolution by challenging the basic assumptions [Stephen Meyer Says That Constant Mutation Rates Are a "Questionable Assumption"], by setting up a strawman [Stephen Meyer Says Molecular Data Must Be Wrong Because Different Genes Evolve at Different Rates], and by pointing out that molecular dating is not precise [Stephen Meyer Says Molecular Evidence Must Be Wrong Because Scientists Disagree About the Exact Dates]. His most ridiculous argument1 against molecular evolution is that the results must be wrong because there are no transitional fossils from before the Cambrian Explosion! [The Cambrian Conundrum: Stephen Meyer Says (Lack of) Fossils Trumps Genes]

None of those arguments stand up to close scrutiny but, as I warned you last week, there are actually five arguments against the validity of molecular evolution [Darwin's Doubt: The Genes Tell the Story?].

Are you ready for the final argument showing that molecular evidence must be discounted?

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