Darwin's Doubt: The Genes Tell the Story?

The main goal of Intelligent Design Creationism is to cast doubt on modern science, especially evolutionary biology. Most of the IDiot books are devoted to attacks on evolution. The underlying assumption is that if modern science is discredited then "god-did-it" becomes a viable alternative.

The latest book by Stephen Myer is no exception. The theme is that evolutionary biologists cannot explain the Cambrian Explosion; therefore, God must have created all the animals in the space of a few million years back in the Cambrian Era (about 530 million years ago).

Most of the book is about the lack of transitional fossils that document the slow transition from primitive worm-like creatures to modern phyla such as arthropods and chordates. Others have dealt with this and I'm not going to comment because it's outside of my area of expertise.¹

There is strong evidence from molecular evolution that the major animal phyla share common ancestors and that these common ancestors predate the Cambrian by millions of years. In other words, there's a "long fuse" of evolution leading up to the Cambrian Explosion. Meyer refers to this as the "deep-divergence" assumption.

There are many versions of these trees. The one shown here is from Erwin et al. (2011). It's the one shown in the book The Cambrain Explosion by Douglas Erwin and James Valentine. It isn't necessarily correct in all details but that's not the point.

The point is that molecular phylogenies demonstrate conclusively that the major groups of animals share common ancestors AND that the overall pattern does not conform to a massive radiation around 530 million years ago. Also, it's very clear that the pattern is consistent with evolution and not with God creating all the animals at once.

Stephen Meyer has to address this evidence because it casts doubt on his main theme (God did it). I suppose I don't need to tell you what he says ... it's typical creationist denial. He claims that the evidence doesn't exist. Here are his reasons ...

1. There are no fossils to support the earliest branches in the molecular phylogenies.
2. There are many different molecular trees and they don't all agree with each other in terms of branching order and timing.
3. Evolutionary biologists cherry-pick the data by only picking molecules that give reasonable trees.
4. The trees rely on questionable assumptions; namely, that the molecular clock ticks at a constant rate and that there is a universal tree.
5. The molecules being compared must be homologous but this is what is being tested so the argument is circular.

The conclusion is ....

Comparative genetic analyses do not establish a single deep-divergence point, and thus do not compensate for the lack of fossil evidence for key Cambrian ancestors—such as the ur-bilateran or the ur-metazoan ancestor. The results of different studies diverge too dramatically to be conclusive, or even meaningful; the methods of inferring divergence points are fraught with subjectivity; and the whole enterprise depends on a question-begging logic. Many leading Cambrian paleontologists, and even some leading evolutionary biologists, now express skepticism about both the results and the significance of deep-divergence studies.

I'm hoping to find time to go over each of Meyer's objections since they reveal a lot about IDiot misconceptions of evolution (and science) and a lot about how they employ strawmen, lies, quote-mining, and distortions in order to discredit an entire field (molecular evolution).²

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1. Most IDiots are experts in everything. I'm not as smart as they are.

2. It always amazes me to discover that IDiots like Stephen Meyer think they know more than thousands of expert biologists who do this sort of stuff for a living.

Erwin, D.H., Laflamme, M., Tweedt, S.M., Sperling, E.A., Pisani, D. and Peterson, K.J. (2011) The Cambrian conundrum: early divergence and later ecological success in the early history of animals. Science 334:1091-1097. [doi: 10.1126/science.1206375]

Posted in: Evolutionary Biology, Genes, Rationalism v Superstition