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
> 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
>
[hidden email]
>
https://wordpress.clarku.edu/nthompson/>
>
> -----Original Message-----
> From: Friam <
[hidden email]> On Behalf Of Prof David West
> Sent: Saturday, March 13, 2021 2:43 PM
> To:
[hidden email]
> 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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