Received: by alpheratz.cpm.aca.mmu.ac.uk id HAA03230 (8.6.9/5.3[ref email@example.com] for cpm.aca.mmu.ac.uk from firstname.lastname@example.org); Sat, 25 Aug 2001 07:45:35 +0100 From: <email@example.com> To: firstname.lastname@example.org Date: Sat, 25 Aug 2001 01:49:39 -0500 Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Subject: Re: FW: Dawkins & Convergent Evolution- the final word (?) Message-ID: <3B870433.2457.6F0CF2@localhost> In-reply-to: <2D1C159B783DD211808A006008062D3101746043@inchna.stir.ac.uk> X-mailer: Pegasus Mail for Win32 (v3.12c) Sender: email@example.com Precedence: bulk Reply-To: firstname.lastname@example.org
On 24 Aug 2001, at 12:40, Vincent Campbell wrote:
> Again, for Ted (and anyone else who missed it).
When context is furnished, the contended chimera of a lacunae
vanishes. Thanks much for the expanded text.
> > ----------
> > From: Vincent Campbell
> > Sent: Wednesday, August 15, 2001 11:25 am
> > To: 'email@example.com'
> > Subject: Dawkins & Convergent Evolution- the final word (?)
> > Hi everyone,
> > Before the Joe/Ted dispute gets too personal (too late...) I though
> > I'd check out Ted's use of Dawkins to show that convergent evolution
> > can't be explained by genes alone, offering a hole for MR to fill.
> > I should say I don't believe Ted ever claimed Dawkins believes in
> > MR. But, this is the way Ted quoted Dawkins from 'The Blind
> > Watchmaker':
> > <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.">
> > This mis-represents what Dawkins was saying significantly. The
> > passage is from a chapter in the book where Dawkins is going through
> > various aspecys of natural selection- such as its gradual nature (he
> > does the classic 5% of the eye argument), and immediately prior to
> > the couple of paragraphs Ted quotes, he's talking about "Dollo's
> > Law" which says that evolution is irreversible- that is it is highly
> > statistically improbable that exactly the same evolutionary
> > trajectory could be followed twice in either direction (p. 94). He
> > concludes the paragraph with the sentence 'It [Dollo's Law] follows
> > simply from the elementary laws of probability'.
> > He goes on:-
> > 'For just the same reason, it is vanishingly improbable that exactly
> > the same evolutionary pathway should ever be travelled twice. And
> > it would seem improbable, for the same statistical reasons, that two
> > lines of evolution should converge on exactly the same endpoint from
> > different starting points.
> > It is all the more striking a testimony to the power of natural
> > selection, therefore, that numerous examples can be found in real
> > nature, in which independent lines of evolution appear to have
> > converged, from very different starting points, on what looks very
> > like the same endpoint. When we look in detail we find- it would be
> > very worrying if we didn't- that the convergence is not total. The
> > different lines of evolution betray their independent origins in
> > numerous points of detail. For instance, octopus eyes are very like
> > ours, but the wires leading from their photocells don't point
> > forwards towards the light, as ours do. Octopus eyes are, in this
> > respect, more 'sensibly' designed. They have arrived at a similar
> > endpoint, from a very different starting point. And the fact is
> > betrayed in details like this.
> > Such superficially convergent resemblances are oftene extremely
> > striking, and I shall devote the rest of this chapter to some of
> > them. They provide impressive demonstrations of the power of
> > natural selection to put together good designs. Yet the fact that
> > the superficially similar designs also differ, testifies to their
> > independent evolutionary origins and histories. The basic rationale
> > is that, if a design is good enough to evolve once, the same design
> > principle is good enough to evolve twice, from different starting
> > points, in different parts of the animal kingdom. This is nowhere
> > better illustrated than in the case we used for our basic
> > illustration of good desing itself- echolocation.'
> > [nb: original emphasis]
> > He goes on to talk about echolocation in two unrelated species of
> > bird, whales and dolphins; about electrolocation used by a couple of
> > unrelated species of weak electric fish- the remarkably similarity
> > between is spoilt by the rather obvious difference that the African
> > variety has a fin alll the way along it's back, the South American
> > variety, all along its belly; about periodical cicadas who all have
> > either 13 or 17 year long juvenile stages (he says no-one knows
> > exactly why, although the fact that 13 and 17 are prime numbers may
> > allow the cicadas to exploit gaps in the reproductive cycle of would
> > be predators); he gets broader in comparing at length the
> > development of the Old World, South America and Australia, comparing
> > different 'trades' (e.g. anteating) that produced similar animals
> > independently in these regions; he finishes with talking about
> > similarities and differences between ants and termites, and then
> > driver ants and army ants.
> > Dawkins seems to me to be very clear on the matter, and there's
> > nothing to suggest here that there's some mystery over convergence
> > that needs a theory like MR to explain it.
> > Sheldrake is equally clear (just visit his website) that he thinks
> > dogs are psychic and people can tell when they're being stared at.
> > Sheldrake seems to me be offering one of the most important lessons,
> > particularly for those of us in academia, that people who
> > successfully enter academia are not necessarily any more credible as
> > a result. Indeed they can be just as looney as anyone else. He
> > seems to me to be suffering from a very common problem, personal
> > incredulity at the wonder of the natural world stemming from such a
> > simple process that he has to believe there's something more to it.
> > I suppose at least he's come up with his own 'Answer', and not just
> > followed the the other true believer herds.
> > [An aside- the recent tribute to Douglas Adams on the BBC, included
> > a sequence from an interview with Adams where someone had said that
> > the answer to 'What is 6 times 9' did equal 42 in base 13...
> > Sheldrake strikes me very much as thinking in ways that characters
> > in Adams' books tend to.]
> > Vincent
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