Re: Darwin and Lamarck

t (Mario.Vaneechoutte@rug.ac.be)
Wed, 28 Apr 1999 09:32:00 +0200

From: <Mario.Vaneechoutte@rug.ac.be>
Date: Wed, 28 Apr 1999 09:32:00 +0200
To: memetics@mmu.ac.uk
Subject: Re: Darwin and Lamarck

Gatherer, D. (Derek) wrote:

> Chris:
>
> What are your thoughts re the various data in the New Scientist
> article I posted ?
>
> Derek:
>
> I think genomic imprinting is very interesting, but mostly from the point of
> view of developmental biology. I don't think it constitutes any threat to
> Darwinism. If you read Dennett's 'Darwin's Dangerous Idea' you can see that
> a lot of new theories that are apparently anti-Darwinian can actually easily
> be accomodated.

What you call anti Darwinian is actually anti neodarwinian. Darwin believed in
inheritance of acquired characteristics.

> Dennett discusses imprinting in that book. [Mind you, I do
> think that Dennett goes a bit far in that book in his criticism of SJ Gould,
> but that's another matter]

I as well am not all that impressed by the methylation, whether or not
inheritable, of DNA as a mechanism of epigenetic inheritance (main topic of
Jablonka & Lamb). After all, it is rather random (epi)genetic alteration. It's
importance is however broader than development only.

But some recent publications on the influence of double stranded RNA on the
phenotype (inheritable over several generations) provide a better candidate for
'guided' evolution.

You should read this one:
Tabara, H., A. Grishok, & C.C. Mello. 1998. RNAi in C. elegans: soaking in the
genome sequence. Science 282: 430-431.

>
>
> Regarding memetics, if you look at Fig. 1 of Jablonka you can see genetic
> assimilation effects are proposed for both behavioural and linguistic
> mechanisms. So although we (or rather our ape ancestors) had to learn a lot
> of new behaviours at various times during our past, many of these are now
> instinctive (or instinctual, what's the right word?).

Genetic assimilation seems just a just-so story to me. If it happens than some
unknown mechanisms (like dsRNA interference?) must occur.

> The single salient
> example would be language itself (Pinker 1994),

I don't understand what this means.(And: if I had to choose between books of
chomskyan Pinker and Deacon, I'd pick Deacon to rely upon.)

> and even once language had
> developed, it might via genetic assimilation drive a lot of selection (I
> think Nick Humphreys has made this point but I don't have a reference).
>
> This has been modelled memetically (Laland 1992). The conclusion of that
> simulation was that it can happen, but it must only happen quite rarely!
> The reason is, as Laland shows, that memetic selection pressures must be
> very hight to overcome genetic ones. The genes nearly always win, if
> Laland's model is correct.

All this if you assume that we needed new genes to speak. The more plausible
solution is that language is a cultural phenomenon emergent from the combination
of other preadaptations.

>
>
> Laland KN (1992) A theoretical investigation of the role of social
> transmission in evolution. Ethology and Sociobiology 13, 87-113.
>
> Pinker S (1994) The Language Instinct. Allen Lane/The Penguin Press

Mario Vaneechoutte

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