[FRIAM] Spandrel

[Steve Smith]

> Steve, 
> Yes exactly! Humans were not selected "for noses." Humans were (the
> argument goes) selected for shorter jaws. The "protruding" nose is
> what you end up with after selection shrinks the jaw. So, if you
> notice that humans have noses, and you jump straight to asking "Why
> did protruding noses evolve? What adaptive function do they serve?"
> you are barking up the wrong tree. Ditto impacted wisdom teeth. It
> would be pretty silly to assert that impacted wisdom teeth were
> adaptive, even though they likely resulted from natural selection
> through the same pressures that led to noses.
>
> Now, the problem with the "nose" example is that, given the variation
> in noses around the world, it is actually quite plausible that nose
> size and shape IS adaptive. But that's a different issue ;- )
And impacted wisdom teeth have been exapted to provide a meaningful
coming-of-age ritual in first world contexts where oral surgeons exist
to extract them (2 or 4 at a time, with or without general anaesthesia,
and with or without chisels).   For my children, it was braces.  One
daughter needed them to have the proper bite and pretty smile that her
cohort had come to expect (well my cohort had come to expect for them)
while the other did not, and while the other did not lobby for braces
"just because", she *did* have friends who did (for whatever reason)
have "braces envy"...  go figure.