I thought I would start a different topic since everyone is probably tired of my libertarianism over on the healthcare thread.
I just downloaded Denis Alexander’s new book on purpose in biology. @jongarvey, if you haven’t checked it out, I think you’ll love it. @Eddie, you as well. I was very surprised to see Alexander bring Michael Denton’s hero Richard Owen into his conversation. He points out that recently, Owen’s “types” seem to be catching on. Alexander, like Denton, points to the pentadactyl lamb as a perfect example of a structure that has remained in place through many millions of years of evolution. He, like Denton, points to evo-devo as confirming some of Owen’s thought. Here are closing words on this issue:
“The bauplan is there alright, but not as a result of some inward driving force” on the part of living organisms, more as the fruit of millions of years of selective advantage, channeled by the contraints of living in this kind of planet with its gravity and other physical demands that determine what forms if life work best."
Denton has been clear in his new book on evolution and in nature’s destiny that he feels that the order in evolution is SCIENTIFICALLY the result of the laws of physics and emergent properties, but that from this, we can infer some sort of quasi-Platonic order within the universe.
I’m not sure if Denton and Alexander really differ here. I think Denton might take a stronger natural theology stand while Alexander would say that these features of evolution are VERY compatible with theism.
I’m posting this partly because I was excited to find Alexander talking about Owen (who believed in common descent), but also because I am interested to hear what everyone here has to say about structuralsm? @swamidass, what does the prevalence of the pentadactyl limb mean to you as an evolutionist? What does it mean to you as a Christian theist? That the number of petals on flowers often corresponds to a fibbonacci number? The structure of leaves? The insect body plan? @Patrick? @T_aquaticus@PdotdQ?
Must we look for adaptive purposes for all these trends?
There seems to be an order here (sure, based in the laws of physics, etc) that points to something beyond mere happenstance, no? Perhaps a Divine Mind or Platonic Forms?
Thanks for this note, Mark. What is the title of Alexander’s book?
If Alexander is now reading Owen, that is a good thing. It may slowly change the way he thinks about evolution. The quotation you give suggests, however, that Alexander is trying to incorporate a bit of Owen into a fundamentally Darwinian picture, rather than opting for Owen against Darwin. I don’t think Owen would attribute most of the bauplan to “millions of years of selective advantage”, even “channeled by etc.” Nonetheless, your news makes me think that maybe I should give Alexander’s new book a look.
Like you, I enjoy Denton’s comments on structuralism. Following up on Denton’s account of structuralism vs. adaptationism, I found that he was very much influenced by Gould’s account of the history of evolutionary thought, and that got me reading more of Gould’s big fat book, and I found it helpful. (I don’t mean that Gould himself defends structuralism, but only that Gould sets forth clearly the difference between structuralist and adaptationist approaches.)
The “selective advantage” that Alexander mentions is interesting. I will look, but I’m not sure he ever offers an explanation of WHAT the selective advantages are.
I’m not sure if I would opt for Owen OVER Darwin. I guess, from what I see, I feel like Lamarck, Owen and Darwin all have good contributions to make to modern evolutionary theory. Up until now, Darwin has unfortunately overly-dominated the show.
Yes, I agree. In fact, the real Lamarck (as opposed to the popular conception of Lamarck) has elements of Darwin-like and elements of Owen-like theory. Again, Gould’s discussion is helpful.
What does that mean? The pentadactyl limb has been maintained sometimes and not maintained other times. It seems to me that there are many more non-pentadactyl tetrapod species than there are pentadactyl ones. Does that fit the “types” theory?
@Mark, thanks for the heads-up. You’ve rightly spotted that one of my interests is digging into those people now proverbial for getting it wrong (think of Augustine, Aquinas, Lamarck, Paley - and not forgetting the English Puritans, with whom I started) and realising that (a) they are usually misrepresented and (b) they often had important things to say which have been ignored.
Without having read Alexander on this, it seems to me he’s glossed over structuralism’s arguments (as in Denton) against adaptive explanations of, specifically, the pentadactyl limb.
Clearly both approaches are compatible with Christianity, though there appears to be a significant difference in their compatibility with materialistic naturalism.
My most recent blog post touches on orthogenesis and the recent work suggesting that neither genetic nor emergent mechanisms may be sufficient to explain body forms (including bauplans, of course). I don’t think either Denton or Alexander quite go there: Denton’s “laws of form” are, I think, clearly “emergent” in the strict sense, rather than truly teleological. It’s an interesting field - and someone like Owen, with a very different approach from Darwin, can teach us not to take received wisdom as cut and dried.
Finally, I can’t resist blowing my own megoegophone by featuring the YouTube clip of my own research project on pentadactyly. I have to make a living somehow.
I was pleased to hear Alexander speak positively though without giving a full endorsement of Kevin Laland’s work on the EES. He said he simply doesn’t know enough about it.
Thanks for this post. Me and @Zachary_Ardern have been trying to do some work on this and this post has been a reminder that I need to get back to work on it. Structuralism is appealing and I think it’s true to a certain point. I’m still working it all out and trying to figure it all out. It does have some proponents today. People like Andreas Wagner, Gunter Wagner, Newman, Kauffman and I think Simon Conway Morris fits into that camp as well. Gould, who seemed sympathetic to it in his later days, wrote multiple chapters in Structure about it. So I recommend those. I like Denton’s work. Especially his stuff on protein folds. Though I think in his critiques of functionalism he is so hyper adaptationist. And some of his examples of non adaptive order actually have adaptive explanations. Like leaf shape. But I will have to pick up Alexander’s book for sure
Climate mainly. We use leaves found in the archaeological record to reconstruct past climates
If you go to areas that have a lot of strong winds you’ll notice a lot of the leaves will have slits on them so the wind will go through them and not destroy them.
Stuff like that. Sorry for being so brief. In the car.
