Re: Convergence

From: Dace (
Date: Fri Aug 10 2001 - 06:44:07 BST

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    Subject: Re: Convergence
    Date: Thu, 9 Aug 2001 22:44:07 -0700
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    From: Chris Taylor

    > > Random mutation (within the same range of genetic possibilities),
    > > followed by selection by similar environments for similar niches
    > > should just about do it. Notice the word 'similar'; they are not the
    > > same (or they could interbreed).
    > There's another part to this story; as well as convergent evolution,
    > there are 'morphogenetic attractors' which species are morphologically
    > drawn to. This covers all the stuff that convergent evolution can't get.
    > Brian Goodwin (inter alia) did some good stuff on these morphogenetic
    > constraints (although I don't agree that his work 'challenges' Darwinism
    > - just dust cover blag methinks).

    Waddington referred to the basins at the ends of developmental pathways as
    attractors. The question is what these attractors are made of. Do they
    just float in a sort of mathematical ether? This seems to be where Goodwin
    is coming from. They also seem to imply teleology. Are the attractors
    literally situated in the future pulling the system into it?

    Sheldrake gets around both of these problems. Rather than being expressions
    of eternal, mathematical truths, form-giving fields are products of past
    systems with similar forms. A baby elephant follows the developmental
    pathway for elephants because its initial similarities to that form channel
    it in the right direction. Thus it's not the future adult elephant
    providing the attractor but only the future of past elephants guiding it
    along. In other words, it's still the past, not the future, causing the

    > Additionally, for the tree with similar leaves, this could
    > also/alternatively be a side effect of one or more traits of the
    > organism that *are* truly evolutionarily convergent (answering the same
    > question with the 'obvious' answer); this is known as pleiotropy (for
    > the non-biologists here who may not have heard the word, its the
    > situation where genes affect multiple traits, necessitating trade-offs).

    Could be.

    > We don't need no hoodoo here. We just have to look hard for a good
    > explanation, rather than running for the nearest shaman.

    For me, the "hoodoo" is the idea of a design which exists independently of
    the thing designed. I suppose the design meme is a function of the
    still-potent anthropomorphosis meme. We used to like to project our
    consciousness onto everything. In the modern age we project our
    techno-logic, with its separation of design and execution, onto the natural


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