[FRIAM] Spandrel

[Prof David West]

Nick,

first apologies for arrogance in first reply. I should have said that I find the definition derived from Bonner to be more understandable — to me — and, I think, it offers an actual mechanism / rationale that is absent, again to me, than "elaboration of epiphenomenon."  I am enjoying the essay and i see an interesting connection with Wegner's *Arrival of the Fittest* book. That means Jenny Q will have to read it because and I are working on a paper in that area.

davew


On Sat, Mar 13, 2021, at 5:37 PM, thompnickson2 at gmail.com wrote:
> Bonner's a great guy, but I think he's wrong on that, or you're wrong 
> in interpreting him.  The whole thrust of Lewontin and Gould's work is 
> that there are developmental constraints in evolution.  Even according 
> to orthodox Darwinian theory, mutation is random, but only with respect 
> to the opportunities a mutation affords.  Nothing says that a mutation 
> can' be predictable, yet random in this sense.  Any "random" assertion 
> requires a point of view from which the stated variable is random.  Any 
> geneticist can tell you which mutations are more likely than others.  
> 
> Nick 
> 
> Nick Thompson
> ThompNickSon2 at gmail.com
> https://wordpress.clarku.edu/nthompson/
> 
> -----Original Message-----
> From: Friam <friam-bounces at redfish.com> On Behalf Of Prof David West
> Sent: Saturday, March 13, 2021 6:04 PM
> To: friam at redfish.com
> Subject: Re: [FRIAM] Spandrel
> 
> Nick, thank you. I get the metaphor but I think my “definition” is more 
> correct than ‘elaboration of epiphenom’.   I get that notion from an 
> essay I am reading on randomness in evolution by John Tyler Bonner
> 
> Davew
> 
> On Sat, Mar 13, 2021, at 2:08 PM, thompnickson2 at gmail.com wrote:
> > Hi Dave,
> > 
> > Ok, since you are also a metaphor enthusiast, let me explain a 
> > spandrel in terms of its root metaphor.  A spandrel, originally, is a 
> > decoration on the curved triangular spaces formed by the intersection 
> > of two perpendicularly intersecting archways.  The decorations are so 
> > suited to their settings that one might imagine that the hallways were 
> > designed to accommodate them, but, of course, it is they that are 
> > suited to fit the spaces affording by the intersecting hallways.  The 
> > same confusion exists with the human nose.  The nose is presumably 
> > what was left over when the brain expanded, and the gut and the jaw 
> > shrank.  It has been elaborated since to accommodate its new position, 
> > but the nose it self is the result of other adaptations, not of an 
> > adaptation FOR a nose.  The most graphic example, of course, of a 
> > spandrel is the erectal and colored pseudopenis (hypertrophied 
> > clitoris) born by the female stripped Hyena.  It is not an adaptation 
> > itself, but a consequence of powerful selection between female 
> > genealogies for feeding competition at the kill, which has select for 
> > high levels of testosterone in females.  (The females are heavier than 
> > the males, and, in general more nasty in every way
> > -- definitely examples of testosterone poisoning.)  The coloration of 
> > the pseudopenis is the spandrel-part, because selection has 
> > subsequently led to its "decoration".  Put another way, a spandrel is 
> > a phenomenon which is an elaboration of an epiphenomenon.
> > 
> > Does that help at all?
> > 
> > Nick     
> > 
> > Nick Thompson
> > ThompNickSon2 at gmail.com
> > https://wordpress.clarku.edu/nthompson/
> > 
> > 
> > -----Original Message-----
> > From: Friam <friam-bounces at redfish.com> On Behalf Of Prof David West
> > Sent: Saturday, March 13, 2021 2:43 PM
> > To: friam at redfish.com
> > Subject: [FRIAM] Spandrel
> > 
> > A while back there was a lot of discussion of spandrels that I failed 
> > to grasp.
> > 
> > Is a spandrel a stable morphological trait that results from random 
> > chance rather than natural selection?
> > 
> > Or am I still ignorant.
> > 
> > Davew
> > 
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