Received: by alpheratz.cpm.aca.mmu.ac.uk id VAA08802 (8.6.9/5.3[ref pg@gmsl.co.uk] for cpm.aca.mmu.ac.uk from fmb-majordomo@mmu.ac.uk); Wed, 8 Aug 2001 21:24:50 +0100 From: <joedees@bellsouth.net> To: memetics@mmu.ac.uk Date: Wed, 8 Aug 2001 15:28:45 -0500 Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Subject: Re: Convergence Message-ID: <3B715AAD.9309.69CD01@localhost> In-reply-to: <002b01c12046$1ab2a780$6787b2d1@teddace> X-mailer: Pegasus Mail for Win32 (v3.12c) Sender: fmb-majordomo@mmu.ac.uk Precedence: bulk Reply-To: memetics@mmu.ac.uk
On 8 Aug 2001, at 13:09, Dace wrote:
> 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." 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. 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.
>
> 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."
>
> 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.
>
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).
>
> Ted Dace
>
>
> ===============================================================
> This was distributed via the memetics list associated with the
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===============================================================
This was distributed via the memetics list associated with the
Journal of Memetics - Evolutionary Models of Information Transmission
For information about the journal and the list (e.g. unsubscribing)
see: http://www.cpm.mmu.ac.uk/jom-emit
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