Re: The evolution of "evolution"

From: Chris Taylor (
Date: Fri 28 Oct 2005 - 09:25:59 GMT

  • Next message: Chris Taylor: "Re: The evolution of "evolution""


    >>God? Intelligence? What's all this about then?
    > Intelligence is integral to evolution. While many adaptations may very well
    > result from spontaneous mutation, in general if a species alters its
    > behavior and ultimately its form to better fit a given environmental niche,
    > this results from the will and the intelligence of individual organisms
    > making decisions that will improve their lives.
    > evolution becomes a purely mechanical process involving mutation and natural
    > selection, leaving no room for will and intelligence, the hallmarks of life.
    > Reductionism substitutes life with organic machinery and tries to explain
    > that instead.

    I just don't see the problem tbh. What is it that cannot currently be explained? What requires more than the standard model of the generation of novelty (mostly by recombination with a tiny, geological-timescale contribution from changes in methylation, and mutation) and selection acting on that?

    > How does the cell know which types of glycoproteins to produce? How does it
    > avoid making the wrong types? How much information would have to be encoded
    > in its genes in order to ensure that it makes the right decision? Given the
    > vast number of possible mistakes, wouldn't the cell's genome have to store
    > vast amounts of information? Could all that information really fit in
    > there? Keep in mind the cell has to do a lot of other things besides
    > combining sugars and proteins.

    Okay, I'm sure you know this but anyway... Enzymes work almost exclusively on shape. Often they'll have two stable conformations, corresponding in a sense to the before and after of the reaction they catalyse (i.e. the active site changes from the 'impression' or counter-shape or anti-shape or complement or whatever of the before shape in the acted-on molecule(s) to the
    'impression' of the after shape. Therefore they are _very_ specific in the reaction they can catalyse and this is what massively reduces the range of available glycoproteins. To access that huge potential variety, you would need an equivalently heee-uge set of enzymes.

    Basically there is one small set of genes that encode enzymes that produce a basic glyco complex (this is evolutionarily extremely ancient) and this is then ornamented in one of a small set of very specific ways (for example the blood types). The vast array of 'possible' glyco structures is just plain inaccessible to us. It is a little like navigating through a city by street names when you only know a handful of them and you always start from the same place. There is only a limited number of places you can get to, regardless of the number of places that there are.

    > The only reason to assume genetic reductionism is the belief that no other
    > options are conceivable within a scientific framework. This is where
    > memetics enters the picture. We might call it the transubstantiation meme,
    > wherein one substance-- a chromosome-- substitutes for the man, much as a
    > wafer substitutes for the Son of Man. To deny genetic transubstantiation is
    > as unthinkable for a reductionist as the denial of communion would be for a
    > Catholic.

    Nope. Just Occam again... We are not in awe of genetics. It is though demonstrably key to a whole load of stuff -- there is no future for the denucleated cell! If there was a clear-cut case where the available biology just could not conceivably explain what is there, then any sensible scientist would put the razor away and go into open-minded mode.

    > Indeed, there are numerous parallels between the Christian meme and the
    > reductionist-science meme. Determinism, which originally held a theological
    > connotation, is essentially another word for creationism. Instead of God
    > creating species, a combination of mutation and selection determines it.
    > Part of the allure of genetic engineering is that it provides us with the
    > godlike power of making new species. Instead of the millenium we have "the
    > future," a magical time that never quite arrives in which all reductionist
    > assumptions are at last bolstered with the kind of hard evidence so
    > conspicuously lacking at the present.

    I just don't see the world this way! I take the point about
    _some_ folks being of a mindset that causes them to latch on to the most significant thing in the scientific canon and trying to explain everything with it, but that is just short-sighted. For example, maternal effects are not explained by gene _sequence_; they are though adequately explained by a combination of methylation and the internal environment of the egg cell. Again I have to say that I don't see what it is that (in biology) we can't (at least partially) explain at present (with no 'fear' of the gaps). The lack of all the pieces for a jigsaw does not mean that one is wrong to think that it is a jigsaw in the first place, just that one needs to have a more intensive root down the back of the sofa.

    >>The point being that genes were never in blueprint form. They
    >>are the brain of the cell, not the bauplan.
    > Clearly, a blueprint requires a brain to interpret it. This is part of the
    > problem of genetic reductionism. Genome is both information and the program
    > that manipulates it. What you really mean to say is that the genome is a
    > computer. Yet a computer is a human artifact. Again, we're theorizing life
    > not according to nature but according to our own artifice, which we project
    > onto the organism, casting it in our own image as God molds us in His.

    Nah I'm afraid you are taking this in the wrong direction. The fundamental misconception here (and this relates to the Hoyle's fallacy thing also) is that there is a moment of creation. The genome clearly does take part in computation, literally, not just figuratively, but as an inseparable part of the cell, just as the brain is an inseperable part of the body. There is never a 'make the cell from scratch' step the way there is for a human artefact; cells divide and that is all, they never _create_ other cells. Organisms are classical Von Neumann machines, but for that system to work you have to have one to start with! This is why the genome (and the rest of the cell) being both performer and subject of calculation is not a problem; there is no 'start' to the process to contend with.

    And at the risk of provoking you back into the 'no matter what you say I just don't believe you' absolutism of a few months ago, I still fail to see what it is that requires that we invoke additional mechanisms? All of life could be a simulation in some alien ubercomputer, but there is no utility in supposing that, because nothing requires it and it adds nothing.

    Cheers, Chris.


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