Date: Tue, 21 Sep 1999 19:34:58 +1000
From: John Wilkins <wilkins@wehi.edu.au>
Subject: RE: implied or inferred memes
To: memetics@mmu.ac.uk
In-Reply-To: <2CDFE2C8F598D21197C800C04F911B203493A6@DELTA.newhouse.akzonobel.nl>
On Tue, 21 Sep 1999 09:06:03 +0200 D.Gatherer@organon.nhe.akzonobel.nl
(Gatherer, D. (Derek)) wrote:
>Derek:
>
>But, and this is a big but, we should remember Fisher's dictum
>(mentioned in John Wilkins' JoM paper) that the mutation rate, ie. the
>rate at which novelty is generated, needs to be an order of magnitude
>less than the selection pressure.
>
>Bill:
>
>Exactly what is that a condition for? Thanks. <s>
>
>Derek:
>
>Well, I think John can explain it better than I can, but basically it's
>a
>condition for evolution to be able to respond to selection. If the
>background level of mutation is too high, there's too much of a chance
>that
>a selectively advantageous mutation will mutate into something else
>before
>it has a chance to spread. One might argue (not necessarily correctly
>but
>still one might argue...) that modern multimedia cultures are too
>novelty-prone in most areas. There's no time for a trend to take a
>grip
>before the next craze replaces it. This is (was) (perhaps) less the
>case in
>so-called less developed societies.
I'm stepping into this thread late, so I may be missing the point but
here goes:
Fisher was dealing with the recently accepted particulate theory of
inheritance (Mendelian population genetics as he and others set it up).
He was therefore discussing in the first chapter of Genetical Theory
what this did to the arguments Darwin adduced in the third (IIRC) and
subsequent editions of the Origin to deal with Fleeming Jenkins'
argument that selection would fail if inheritance were blending (the
classic case of a "superior" white man on an island of "inferior"
natives).
Fisher showed that if inheritance were blending, any novelty would be
swamped by the population norm within a thousand generations, and so
blending inheritance required a much higher rate of novelty for
selection to be effective. But, effective it could be if there was
sufficient novelty and high rates of selection. Of course, if heredity
were particulate (we would now say modular), then it could persist for
very long periods, and even infinitesmal amounts of selection
coefficients (in panmictic, that is, universally interbreeding, and
effectively infinite, populations) could result in geologically rapid
evolution.
Almost as soon as Fisher had published this, Sewall Wright showed that
in small populations with structured breeding, selection could be
swamped by stochastic drift, from which Mayr, Carson and others derived
the notion of a founder-flush origin of novel lineages. In these cases,
a novelty would soon meet a copy of itself, and random assortation could
account for the fixation of novel mutants.
If cultural transmission were blending, then it would need to have rapid
mutation and strong selection for effects to persist in a large
population. But cultural organisation is non-random in its assortation,
and cultural populations tend to be small. If you'll permit me some
speculation, I would expect that the greatest change will occur in small
structured populations (cultural communities), and rapid expansion of
novelties will always derive from these founder populations. I would
equally expect that larger populations (traditional cultures, for
example) will be resistant to novelties in inverse proportion to the
structural restrictions on transmission.
On the question of adaptiveness: I would rather (in biology and culture
alike) seek to ascertain what gets relatively optimised than ask what is
adaptive, because when the question is posed in that way, you can treat
traits as being optimised without needing to ask, "adaptive for what
entity?" or "adapted to what environment?". We spend a lot of time
trying to figure out how a meme is adaptive for an organism, or how a
meme constitutes a social or cultural entity or behavior. If memes are
modular packets of inheritance in culture, then we can expect that they
will be optimised at their own level, and there need not be any single
class of entity that answers to the term "meme".
So, religious memes are optimised in a religiocultural context for
transmission in that context. If they happen to be biologically
maladaptive (ie, for the organism that carries it, and its own
biological inheritance) then that means there will usually be a
Pareto-tradeoff between the two conflicting lines of inheritance. It may
not need to, though - it may be that the one triumphs over the other
(think of the celibate Cathars, or the Shakers). I think that conflict
of evolutionary levels is very interesting and I hope some competent
analyst does some work on it soon.
--John Wilkins, Head, Graphic Production The Walter and Eliza Hall Institute of Medical Research Melbourne, Australia <mailto:wilkins@WEHI.EDU.AU><http://www.wehi.edu.au/~wilkins> Homo homini aut deus aut lupus - Erasmus of Rotterdam
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