[FRIAM] Spandrel

[Prof David West]

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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