Darwin's Dangerous Idea

Hi,

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. So much so that I read, and re-read his
definition of adaptionism to see if I'd misunderstood, but he seems to
leave himself no wiggle room. The wikipedia entry on adaptionism would
seem to confirm that definition - "all or most traits are optimal
adaptations".

The first sample he gives is that of the appearance of structures
clearly related to reptilian jawbones in the mammalian ear. While I am
of course entirely happy to accept that the obvious inference one
draws from this is that those structures are evolutionary adaptations
of the reptile jaw, how can they be said to be *optimal*? Can one
seriously argue that a structure which evolved from much more humble
and less elaborate beginnings, or even from some other bone, might not
have served the purpose better and provided for the potential for more
acute hearing?

The second example is the flatfish. He makes it clear that he believes
the fact that a flatfish is actually a fish lying on its side with one
eye moved halfway round its head is a prime example of adaptionism.
Again, I find it hard to understand that he's seriously arguing that
this way of "making" a flastfish is in some way more optimal than
having the fish lie on its stomach with its eyes on the top of its
head. To further confuse the issue he later criticises Gould's concept
of developmental bauplane as constraints on evolution, which would
seem to me to be the one saving grace for his position.

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?

I'd be grateful if anyone could help shed some light on these issues
for me. Incidentally, am I the only person who, on reading his parable
of "Twin Earth" and the evolution of meaning, thought he'd left open
the back door to allow a valid a postmodern critique of science?

Cheers,
Matt

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Relevant Pages

  • Re: Evolution increases the computational ability of organisms.
    ... (i.e. complex adaptive systems capable of some form of evolution) ... exhibit instances of ever greater complexity with time. ... go on to list the current dominant ideas about evolution, ... adaptionism that goes hand in hand). ...
    (talk.origins)
  • Re: Evolution increases the computational ability of organisms.
    ... (i.e. complex adaptive systems capable of some form of evolution) ... exhibit instances of ever greater complexity with time. ... of progress like "computational complexity" ... adaptionism that goes hand in hand). ...
    (talk.origins)
  • Re: Evolution increases the computational ability of organisms.
    ... (i.e. complex adaptive systems capable of some form of evolution) ... exhibit instances of ever greater complexity with time. ... go on to list the current dominant ideas about evolution, ... adaptionism that goes hand in hand). ...
    (talk.origins)
  • Re: Why does language evolution get a pass, with less evidence?
    ... I've seen a lot of creationists who ... very well that they don't all accept language evolution, ... Even IDers go all he way from YECs to the theistic evolution that dare not speak its name. ... evidence for macroscopic changes, ...
    (talk.origins)
  • Re: Word evolution
    ... rapidity of language evolution, the research teams conclude in the ... history of major language families, reconstructing ancient tongues, ... Erez Lieberman and his coworkers measured the rate at which English ... The team compiled a list of 177 irregular verbs in Old English. ...
    (uk.philosophy.humanism)