A while back, I criticized this poorly implemented idea from Paul Nelson of the Discovery Institute, a thing that he claimed was a measure of organismal complexity called Ontogenetic Depth. I was not impressed. The short summary of my complaints:
- Unworkable idea: There was no explanation about how we could implement and test the idea, and despite promises at the time, Nelson still hasn’t produced his methods.
- False assertions and confusing examples: He claims that all changes in early lineages are destructive, for instance, which is false.
- Bad metaphors: He uses a terribly flawed metaphor of a marching band to explain how development works; I’d say that it’s a better example of how development doesn’t occur.
- No research: Which is really a major shortcoming for a research program, that no research is being done.
Recently, Nature published a paper by Azevedo et al. that superficially might resemble Nelson’s proposal, in that it attempts to quantify the complexity of developing organisms by looking at the pattern within their early lineages. The differences are instructive, though: this paper clearly explains their methodology, presents many of the limitations, and draws mostly reasonable conclusions from the work. It is an interesting paper and contains some good ideas, but has a few flaws of its own, I think. My main objections are that its limitations are even greater than the authors mention, and there are some conclusions that are driven by an adaptationist bias.