Re: Darwin's Dangerous Idea
- From: Robert Carnegie <rja.carnegie@xxxxxxxxxx>
- Date: Tue, 18 Dec 2007 06:36:02 -0800 (PST)
On 17 Dec, 13:34, MattDP <matt_thro...@xxxxxxxxxxx> wrote:
Hi,
Perhaps this is a bad place to post this. If so, apologies, and
suggestions would be appreciated on where I should post it.
Some 15 years ago now I studied for a PhD in Molecular Biology which
included elements of Molecular Evolution - the result being that I
remained ignorant of some of the trends in broader evolutionary
biology. I did not go on to pursue a job in science but I maintain an
active interest and frequently pick up pop science books on the
subject.
My latest one is Daniel Dennett's "Darwin's Dangerous Idea". I've
found it very thought provoking. However ever since I reached his
critique of Stephen Jay Gould, I've been struggling with some of the
concepts around "adaptionism" and the arguments for and against it. I
wondered if I presented my nagging doubts about what's being said
here, someone might be kind enough to help me resolve them.
The issue is this - Dennet characterises adaptionism as the belief
that *all* characteristics of an organism can be explained in terms of
*maximal* evolutionary advantage (my emphasis is important). This
seems to me to be self evidently and obviously false and what's
further confusing me is that some of the examples he gives would seem
to be self contradictory. Consider the flatfish for instance - how
can you seriously imagine that moving the eyes in such a way as to
align them on one side of a organism which is lying on it's side is a
*maximally* better way of making a flat swimming organism than having
the thing lie on it's stomach with it's eyes on top? How does one
explain functionally pointless elements of human anatomy such as the
appendix, the coccyx and the tonsils?
My confusion reached tipped point and prompted me to write this post
in the chapter on Chomsky. Here, Dennett outline three positions, all
of which are given out of context and without evidence and so are
difficult to assess. Chomsky, he claims, says that language cannot be
a characteristic which has evolved. Gould is pictured as saying
language is a characteristic that might not have evolved (i.e. been
selected for) but might have been a by-product of something else, such
as increased processing capacity in the brain. Steven Pinker is then
presented as having the viewpoint that language must have evolved, a
view which Dennett heartily endorses. What bugs me about this is that
although it seems both plausible and likely that language is an
advantageous feature which could be a product of selection, how can
Dennett - or anyone - so completely dismiss the suggestion that it (or
any other aspect of an organism) could have come about as a by-product
of selection for something else?
Upon "adaptionism", if that's a doctrine that evolution produces
results equal to the best intelligent designer, I think the arguments
that you mention against it are strong. Evolution mostly works by
small changes in previously existing complex biological systems,
arising by mutation. This is rather like building a stepladder out of
spent matches. A better ladder could be made by different means, but
you work with what you have.
And if it's a doctrine that evolution, or the interesting part of
evolution, consists entirely of adaptation towards fitness, that seems
to be wrong as well. Genetic drift can put characteristics into a
majority of a species from a minority, that have no perceptible
benefit in fitness at all. Sexual selection, also, seems to make
species do astoundingly silly things, such as grow fantastic tail
feathers.
http://en.wikipedia.org/wiki/Adaptationism says however "Adaptationism
is a set of methods in the evolutionary sciences for distinguishing
the products of adaptation from traits that arise through other
processes. It is employed in fields such as ethology and evolutionary
psychology" [i.e. human and other animal behaviour] "that are
concerned with identifying adaptations." I am not sure why the
restriction, but adaptation is not the whole of evolution, and not
only because Wikipedia says so.
Here in 1997 http://www.nybooks.com/articles/1151
Gould makes a counta!erblast to Dennett. I'm not sure what's going
on, to be honest.
However, language seem to me clearly an adaptation towards increased
fitness:
(1) A large number of species communicate amongst themselves, not only
humans. Language is more efficient communication.
(2) If any aspect of language is disadaptive, people could just keep
their mouths shut.
On the other hand, if sexually selected characteristics are not
necessarily adaptive, one observes the number of "lonely hearts"
adverts that ask for "good sense of humour". As a language behaviour,
humour may be a form of sexual or peer display; a device to
demonstrate virility, individual fitness - but being not fitness
itself but a symbol of it. If you have a normal sense of humour then
you have a reasonably healthy brain. But laughing at a dangerous
predator, hmm...
.
- References:
- Darwin's Dangerous Idea
- From: MattDP
- Darwin's Dangerous Idea
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