[Taxacom] Re Teleology example

David Winter david.winter at gmail.com
Thu Mar 7 00:46:34 CST 2013

John Grehan has said:

At various times I have raised, in this and other lists, the continued
presence of intelligent design theology in science in the form of
explicit teleology. Often the response is "that is not what they
really intended".
Here's a nice explicit example: "it's hard to see how these hair-like
processes would evolve if they didn't serve a purpose." This from
David Winter, "a PhD student in evolutionary genetics who very
occasionally thinks he has something that the internet simply needs to
know..." See http://sciblogs.co.nz/the-atavism/tag/new-zealand/

John, that is not what I really intended.

In fact, it's fairly obvious from context there is no teleology in the
argument I was making (for a popular audience, in an informal

"I try very hard to avoid the sloppy thinking that presumes there is
an adaptive explanation for every biological observaton, but it’s hard
to see how these hair-like processes would evolve if they didn’t serve
a purpose. The larger hairs are presumably made from the same calcium
carbonate minerals as the rest of shell, and calcium is a precious
resource for snails (so much so that empty shells collected from the
field often show signs of having been partially eaten by living
snails). In those species with finer projections, the hairs are an
extension of the “periostracum”, a protein layer that covers snail
shells.  If we presume that snail hairs come at a cost, in either
protein or calcium, what reward are they hairy snails reaping from
their investment?"

That is

* Not everything in biology exists because it helps an organism
* That being said, the hair-like processes many snails sport cost
something (in terms of resources and energy)
* It is unlikely that a costly feature will be maintained if it
doesn't benefit the organisms carrying it (as mutants that don't have
the trait could out-compete those paying the cost)
* Given all of the above, it's reasonable to presume the hairs are
helping their carriers to survive and reproduce, so let's find and
tests hypotheses as to how that might happen.

Short of an alarm bell which might go off upon seeing the word
"purpose" in the widely-used phrase "serve a purpose" I can't see what
you object to.

I obviously need to update my biography, indidently, as I'm now a PhD
graduate who quite frequently has things the internet needs to know.

(BTW, I don't subscribe to taxacom - if anyone wishes to include me in
replies to this email you'll need to reply-all)

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