The wisdom of worms


In my previous post about Paul Nelson's weirdly ignorant view of nematode evolution, Kevin Anthoney made a prescient comment:

Remember that Nelson’s got this bizarre linear view of evolution which starts with a single cell creature, which evolves into a creature with a few cells, which evolves into one with a few more cells, and so on until you reach the 1031 cells in the nematode today. It wouldn’t surprise me at all if Nelson thought that the creature at the 150 cell stage in this process had to be like a modern nematode at the 150 cell stage of development.

The Discovery Institute has responded. I got as far as the massive projection in the following paragraph before giving up.

He acknowledges that the unit of selection (the stage of an organism's life cycle that natural selection selects) is the individual capable of reproduction -- in other words, the adult. And I infer from this that he believes there must have been a step-wise selectable pathway from a single cell to multicellular adult, each step of which was both viable and capable of reproduction. [Their emphasis --pzm]

No, I don't think that. It seems Anthoney was right: these people have this imaginary model of development and evolution in their heads, in which the 150-cell stage had to have been viable and free-living, and capable of reproduction, in order for it's specific pattern of differentiation to have been selected. I'm arguing the exact opposite.

A functional end result was selected for, just like in a game of poker, where a winning hand is 'selected' -- however it got to that point. A full house is a full house whether it was dealt straight to you, whether you drew one card or two. As I mentioned in the previous post, there are multiple ways for development to produce a working worm, and I cited a paper that discussed the taxonomic variation present in various nematode species and genera.

Just to add another detail that kills their design model: that pedigree of cell divisions that produces the adult worm yields 1,090 cells…but 131 of them die during development, leaving no descendants, to produce a canonical nematode with 959 cells. That's a wastage of 12%! Shouldn't it be obvious that this animal was not optimized at each stage of development?

Expect to see more from the Discovery Institute on nematodes in the future. It doesn't matter how often they are refuted, or that all of the investigators of worm development use evolution as a framework to understand what's going on -- they'll just hammer that dead worm into the ground.


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@1 Samuel

Shurely you jest! How can you say such a thing about a journal with such a distinguished editorial board? Err... oh, I see.

By jrkrideau (not verified) on 03 May 2015 #permalink

All I know is that Canonical Nematode is going to be the name of my new band!