Dave,
I am going to lead my larding by resending what I sent before, because nobody seems to have read it. Wow, Dave! I will "lard" this by Friday! Watch this space. For the moment, let me say only the following. The hyena story, pushing 50 years by now, does have the feel of a well worn tale. I have not been back to visit that literature since forever, so you are right to be suspicious. But remember, the tale is told only to argue for what a spandrel might be, if ever there was a spandrel. So we have two separate issues. One is the definition of a spandrel; the other is the question of whether any spandrels exist. Please keep that separation in mind as we discuss this further. I further confess my fondness for Kipling (See attached). I am probably in the last generation of grandparents to read Kipling's Just So Stories to his grand children; they are, occasionally, so casually racist that I have to edit as I read. And yes you do point to a terrible weakness in all evolutionary explanation. They are historical explanations based on the comparative method, with all the perils that that sort of explanation entails. (John Dodson take note.) But, after all, so is cosmology, and plate tectonics, so let's not panic yet. This passage was meant to concede much about Darwinian Explanation and the text to illustrate how any reasonably alert human being (like a child, for instance) can expose its weaknesses. I don't think there was anything bendy about it. For the promised larding, please look down. Nick Thompson thompnicks...@gmail.com <mailto:thompnicks...@gmail.com> https://wordpress.clarku.edu/nthompson/ From: Friam <friam-boun...@redfish.com <mailto:friam-boun...@redfish.com> > On Behalf Of Prof David West Sent: Tuesday, March 23, 2021 9:12 AM To: friam@redfish.com <mailto:friam@redfish.com> Subject: [FRIAM] Friday Fodder Because I left before it ended, I have no idea how the spandrel discussion ended. Nick requested an explanation/elaboration/justification for my continued skepticism/resistance (other than being willfully obstinate for no reason) to the notion of spandrel. Hence the following - elaborated beyond the specific question of spandrel as fodder for continuing discussion next Friday. I am convinced that evolutionary biologists are secretly required to read Rudyard Kipling as prerequisite to the granting of a Ph.D.. Because, every story about the evolution of a specific feature - Friday it was the pseudo-penis of female hyenas - sounds like, and is as convincing as, one of Kipling's Just So stories. [Yes, trolling.] [NST==> This is why it so important to understand the limitations of any historical explanation and particularly any explanation that purports to be of a one-off event. In order to be explained, the explained event has to be seen as a member of some sort of class of events, which have, hitherto, behaved in some sort of rule full way. What I tried to do in the vignette was offer a proper darwinian explanation in a Kiplingesque style. The child's last question are supposed to expose the perils of adhockery <== nst] 1. 2- Pseudo-penis as spandrel: a- Testosterone flooded female hyenas are selected because aggressive females have survival value in matriarchal hyena society. This really seems, to me, to pose a chicken-egg problem: matriarchy or female bullies first? [NST==> Should I be afraid of chicken egg problems? It just seems like positive feed back to me. <== nst] b- Testosterone flooding creates a space - a spandrel - a space that is then "decorated." One example of 'decoration' is the pseudo-penis. [NST===>I think your evocation of a space was insightful and it sparked a conversation amongst after you left of what we came to call reductive evolution. The flooding produced a bunch of consequences, some positive, some negative. You would expect, now, that natural select would prune the effects by knocking out androgen receptors in all the processes that respond with deleterioius effects. What makes the hyena case so striking is that such selection has not [yet?] occurred. Ok, so we need to have a way of distinguishing between spandrels and their elaborations. I would suggest that anything we get along the line of penis development by taking a female dog pup and lacing it with testosterone is a decent model; anything we don't get, is presumably an elaboration in the hyena. So, for instance, I don't think you would get the colorations or the pseudoscrotum, so I would think of these as secondary elaborations or "exaptations." <===nst] c- by what mechanism does the decoration come about? Nick said it was a direct result of testosterone flooding, that "all" such results would appear, that none of them was independently 'selected for." This is a specific area where I fail to understand what Nick is saying and need correction. If I heard correctly that all effects of testosterone flooding would appear - Nick emphatically said "all" and "will" in his explanation - then: -- we should not only see a clitoris run amok, but also beards, rock hard pecs instead of pillow-breasts, 20-inch biceps, denser bones, and overall greater muscle mass.[NST===>Well, I don't think hyenas grow beards, but the other stuff does "come along" in female hyenas. <===nst] -- the "purpose" of the pseudo-penis is aggression display and reproductive-act dominance. [NST==> I wouldn't quite put it that way. I would say that the purpose of the coloration is all of those things. In the first place, the pseudo-penis is "just" a consequence of these other effects. <== nst] But, of all the results of testosterone flooding that "will" result, a big penis seems the least useful for that purpose. Muscles and size would seem more than sufficient. [NST==> Well, this explanation is too strong, because it predicts that display structures would never evolve. Aggressive animals, even hyper-aggresssive ones, are presumably (note weasel word) selection for avoiding conflict where they can. <== nst] Consider Arnold in the role of Terminator. He managed to convey a lot of menace and dominance simply from size and overall shape; never once brandishing his penis to intimidate anyone. (And if we assume he was as liberal a user of steroids in his body-building career as many of his colleagues, his penis would not have scared a squirrel.)[NST===>Frankly, I don't know how far one can go toward masculinizing a human female by flooding embryo and then baby with testosterone, but I think its farer than you might think. <===nst] -- Why so baroque a decoration?[NST===>Not clear what's baroque about a penus<===nst] -- Why did testosterone cause the clitoris to merge with the urethra and the vagina? Did these not exist as separate organs in predecessor species to the hyena? How is that even possible? [NST===>Well, all the instructions for making a penis exist in both male and female sexes. Which sex characteristics develop depends heavily on the presence of testosterone. Also, development has to have tremendous capacity to buffer environmental vicissitudes, and those capacities can be captured for buffering against genetic change, as well. <===nst] is the pseudo-penis not a clitoris-urethra-vagina at all but some kind of evolution of an avian cloaca?[NST===>I have no idea which is more primitive, the penis or the cloaca. I am betting on the penis. They are widely distributed in insects. <===nst] -- This specific decoration seems to have anti-survival consequences (most firstborn hyenas are also stillborn) and yet this decoration seems immune to selection. Or maybe not, we have yet to see what might succeed hyenas a few million years from now. [NST===>Remember. According to the theory, the penis itself is not a decoration. It's an "unintended consequence". The coloration is the decoration (and the pseudoscrotum?) and these don't appear to cost the hyena anything at all. <===nst] 3- More general issue: whole-part evolution. Jon seemed to understand what I was trying to say last Friday on this matter.[NST===>I feel like I completely understand your problem, but cannot solve it. You point to, what is for me, the most bemusing problem in evolutionary theory, the evolution of natural selection. Given the developmental entanglement of traits, how do they become modules for the purpose of selection. The tension between developmental biologists and Dawkins-like biologists is around this poing. Nobody disagrees that there is a lot of entanglement and nobody disagrees that some traits get selected. I agree that the burden of proof lies on the side of selection theorist to explain how selection itself is possible! This what I find so tempting about Stephen's energy flow ideas. Is there a "least action" explanation for modularity? <===nst] a. Consider the peregrine falcon. Some of the traits/features that make it a formidable predator: very lightweight bones coupled with overdeveloped muscles which contribute to its ability to withstand G forces and make 200 mile per hour dives (and withstand the shock of kinetic energy when it hits its prey); razor sharp talons; notched beak to sever spinal columns; full-color binocular vision with resolution that allows seeing a pigeon at distances greater than a mile; nictating membrane to protect from wind force during dives; and ability to see into the ultra-violet spectrum. b- If I understand Darwin (a huge if): each of these features is the result of a sequence of selected/preserved minute changes in single molecules: e.g. keratin, opsins, crystallins. Each of these molecules are expressed as a sequence of amino acid 'letters', 20 in number. If the string of letters were 100 characters in length (crystallins and opsins are much longer) then the odds of any given string are 20 to the 100 power. By comparison, the number of hydrogen atoms in the universe is estimated to be 10 to the 90th power. c- If evolution proceeded with one amino acid letter pairing with a second, getting selected, then pairing with a third, etc., each addition being one of 20 equally probable options; then, coming up with the string that expresses, precisely, as the falcon's beak is fantastically improbable (winning the lottery every year since the Big Bang). d- This brings in the question of time. Has there been sufficient time for a process of random change / selection to allow the formation of such a string. This was a huge issue for Darwin because the prevailing scientific estimate of the age of the Earth was twenty-million years. [Lord Kelvin using the equations of thermodynamics.] This was not nearly enough time for Darwin's evolution and he was "greatly troubled by it." Rutherford, using radioactive decay equations, "saved" Darwin by extending the age of the Earth to 4.5 billion years. e- Kind-of. If evolution literally proceeds one amino acid letter at a time to assemble a specific string that has a probability of existing of 1 / 20 to the hundredth power (or more) - there is insufficient time since the Big Bang for that string to emerge via chance. f- it seems as if some kind of short-cut is essential. Suppose you have parallel/simultaneous evolution of 'sub-strings' and then 'main-line' evolution proceeds upon combinations (wholes) of these strings, Then, it is quite likely that 4.5 billion years provides sufficient time. This, it seems to me, suggests that evolution deals with an aggregate, a whole; not individual amino acids one-by-one, or even sub-strings one-by-one. g- Which circles back to the falcon. If each of the mentioned traits/features evolved independently and sequentially then we run out of time again. If each of the traits/features evolved independently then there seems to be a macro-problem of how they 'just happened' to occur simultaneously and apparently 'in concert'. So my conclusion, apparently wrong because it disagrees with the experts in the group, is that evolution must proceed whole-organism to whole-organism and not, feature-trait by feature-trait the way that it is presented. This also means, that individual feature-traits - as marvelous as the the falcon's eye or as silly as the pseudo-penis - cannot, and should not be "explained" independently. To do so is to focus on the 'noise' and not the 'signal'. Such efforts are the product of 19th century thinking and unworthy of complexity scientists like yourselves. davew Nick Thompson thompnicks...@gmail.com <mailto:thompnicks...@gmail.com> https://wordpress.clarku.edu/nthompson/
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