Re: Convergence

Date: Fri Aug 10 2001 - 03:34:04 BST

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    Subject: Re: Convergence
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    On 9 Aug 2001, at 12:33, Dace wrote:

    > > > Dawkins discusses this dilemma in The Blind Watchmaker: "It is
    > > > vanishingly improbable that the same evolutionary pathway should
    > > > ever be followed twice. And it would seem similarly improbable,
    > > > for the same statistical reasons, that two lines of evolution
    > > > should converge on the same endpoint from different starting
    > > > points. It is all the more striking... that numerous examples can
    > > > be found in real nature, in which independent lines of eovlution
    > > > appear to have converged, from very different starting points, on
    > > > what looks very like the same end-point."
    > Joe Dees wrote:
    > > Random mutation (within the same range of genetic possibilities),
    > > followed by selection by similar environments for similar niches
    > > should just about do it.
    > Are you establishing yourself as a higher authority on these matters
    > than Dawkins? Of course, he's taking into consideration environmental
    > fitness and random mutation in his assessment. Learn to pick your
    > fights. Don't just assume that every assertion I make is unorthodox
    > or subject to debate.
    Appeal to Authority is another one of those 2500 year old Greek
    logical fallacies. In fact, my reply was logical, rational, reasonable,
    coherent, cohesive and cogent, and specifically addressed the
    referent conditions rather than someone else's opinion of them.
    > Bill Spight wrote:
    > > Dear Ted,
    > >
    > > > It's well known that atavistic traits commonly pop up among
    > > > developing organisms. A feral pig is liable to develop tusks.
    > > > Horses occasionally grow extra toes. Humans are sometimes born
    > > > with a small tail. Such
    > things
    > > > can be expected if we do indeed resonate with past forms. But
    > > > they can
    > also
    > > > be explained according to the genetic model. What can't be
    > > > explained genetically is parallel evolution, or "convergence."
    > >
    > > Convergent evolution is in fact a major support of the theory of
    > > evolution.
    > And as Hume said, "The green table is green."
    He's saying that the fact that similarly configured niche inhabitants
    evolve to occupy similarly configured environmental niches is an
    empirical corroboration of the power that natural selection exerts on
    random mutations, thus an empirical corroboration of evolutionary
    > > > Among plants and
    > > > animals, we continually find new examples of organisms widely
    > > > separated
    > in
    > > > their phylogenetic derivation which nonetheless develop remarkably
    > similar
    > > > forms. In New Zealand we find many kinds of leaves common to
    > > > Eurasia
    > which
    > > > serve to fend off herbivores that don't exist in New Zealand.
    > > > There
    > seems
    > > > to be no reason why marsupials and mammals would develop such
    > > > incredibly similar forms.
    > >
    > > Don't be silly.
    > See Dawkins above. He may not accept morphic resonance, but at least
    > he concedes that convergence is a mystery.
    It is less mysterious to Stephen Jay Gould (omidog - dueling
    authorities! <chortle>).
    > > > Why should butterflies or fish of different species in
    > > > different locations develop almost identical color patterns on
    > > > their
    > wings
    > > > or scales? In some cases animals mimic others that are poisonous
    > > > to predators and are thus avoided by predators along with the
    > > > poisonous varieties. But this explanation fails to apply in the
    > > > vast majority of cases.
    > > >
    > > > According to Sheldrake's model, organic systems resonate with
    > > > similar systems. We resonate with ourselves individually, with
    > > > our species, and with any other species which is similar enough to
    > > > our own. If flying squirrels, jerboas, and moles are all emerging
    > > > in both Australia and Eurasia, they will be drawn into similar
    > > > evolutionary pathways due to
    > their
    > > > resonance with each other. Outside of this model, there's no
    > explanation
    > > > for convergent evolution.
    > > >
    > >
    > > Puleaze!
    > >
    > > First, there is the simple explanation of similarity of
    > > environments. Aquatic mammals and fish provide a basic example.
    > >
    > > Second, there are physical and chemical constraints that impose
    > > structure. Example: similarities in structure of sunflowers, pine
    > > cones, snail and nautilus shells.
    > >
    > > Third, there is coincidence.
    > >
    > > You need to find characteristics that do not contribute to the
    > > fitness of the organism, and are not similar for physical or
    > > chemical reasons (such as minimizing the use of resources), and then
    > > compare their occurrence with a model that indicates how often such
    > > convergences occur at random, and show that they occur too often.
    > > Otherwise, don't waste your time.
    > To take a single example, the astonishingly similar color patterns on
    > the scales of fish of different species which inhabit different
    > African lakes cannot be explained by any known factor. It has nothing
    > to do with fitness or chemistry. You've got nothing here except
    > coincidence. And that's the point Dawins is making above. There's a
    > colossal coincidence at work here, and it's repeated *countless* times
    > across the earth. At least Dawkins is honest about the extreme
    > improbability of neo-Darwinian theory.
    You don't have other predator and prey species that share those
    lakes, and common underwater environmental color and
    configuration, which could cause similar selection? And these
    different species are not genetically related; say, in the same
    family? I'm quite sure that one or both of these conditions hold(s).
    > > The advent of computers has enabled us to see, by simulation, how
    > > frequent random coincidences are. It is human nature to seek
    > > explanations, and statistical argument alone leaves nagging doubts.
    > > Thus people can easily believe that Design, whether by supernatural
    > > or by as yet undiscovered natural means, is necessary to explain
    > > coincidences. It appears that morphic resonance is one such
    > > principle of Design.
    > Both creationism and neo-Darwinism are theories from design. In one
    > case, the design exists in the mind of God. In the other other case,
    > it exists in our chromosomes. The major alternatives to a design
    > theory are Darwin himself-- who explicitly rejected the notion of a
    > blueprint contained in our bodies-- and Sheldrake.
    Sheldrake just proposes a resonating wave function that functions
    as a newage Holy Ghost. It's junk science, which means it is
    pseudoscience trying to hide it's pseudo in the closet, and was
    probably published to make the author money, as sensationalistic
    'controversial' theories which are basically conjectural 'just so
    stories' with no empirical basis sell more to the great untutored
    than do serious and seriously dry academic tomes. From
    Velikovsky to Joseph Chilton Pearce, crackpots have made much
    money doing this sort of thing.
    > It is
    > > invoked without much consideration at all of other, scientific
    > > explanation.
    > Absolutely not. Sheldrake makes no claims without first carefully
    > scrutinizing the alternatives. Apparently you're not familiar with
    > his work. I recommend The Presence of the Past. The first eight
    > chapters provide a nice intro to his theory as well as a fascinating
    > account of the history of biological thought.
    Yeah, he's probably got a real franchise going, with no competition
    from reputable theorists.
    > > And it assumes that there is no coincidence.
    > Sheldrake does not assume there's no such thing as coincidence. On
    > the other hand, he doesn't assume that everything is explainable
    > according to coincidence. Maybe this whole world is just an illusion.
    > Maybe it's just a coincidence that when you drink water, you cease to
    > feel thirsty. Or maybe some things are indeed explainable through
    > reason and science.
    Some things are due to coincidence, and some things aren't, and
    in many cases, the occurence percentage of coincidence is
    statistically predictable within certain parameters. If you flip three
    coins, they will all come up the same way, either heads or tails, a
    quarter of the time.
    > Ted Dace
    > ===============================================================
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