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Darwin vs neoDarwin

Giovanni Maga maga at vetbio.unizh.ch
Wed Apr 5 02:04:30 EST 1995


In article <Pine.SGI.3.91.950404110703.3318B-100000 at bambi.ccs.fau.edu>,
tomh at BAMBI.CCS.FAU.EDU (Tom Holroyd) wrote:

> Hey, has anybody read _How the Leopard Changed its Spots_ by Brian
> Goodwin? He points out how far neo-Darwinism has drifted from Darwin, and
> reminds us that there are several scientific objections to a strict
> interpretation of neo-Darwinism, such as the fact that there are animals
> that have heritable traits that are not encoded in the genome, such as the
> melon-stripe variant of paramecium.  Goodwin reminds us that the organism
> is a unity, in principle irreducible.  To the extent that neo-Darwinism
> does this reduction, it throws away important levels of organisation. 
> For example, processes of self-organisation can occur at the level of the
> organism that have a large effect on selection independent of "survival of
> the fittest," such as the oscillatory dynamics of several predator-prey
> populations. 
> 
> Tom Holroyd

Sorry, but I did not get what you are saying. What do you mean by heritable
traits not encoded by the genome? I do not know about paramecium, but even
if I can think (and indeed is the case of course) that some structures
(like organelles) are inherited directly and not simply as DNA (cytoplasmic
heredity is well known), at the end in a complex organism these organelles
have to be multiplied and replaced by new ones. Where is the information to
do that? It is the genotype of the parental generation which determines the
genotype of the outcome. If that's not true, then Lamarck lives again.
Again, it is not clear to me how the oscillatory dynamics of predator-prey
populations do not have any impatc on the process of selection. I think
this kind of phenomena are well known to ethologists (but I'm not such, so
I cannot go in more details) and can be addressed in terms of natural
selection.
What do you mean that the organism is a unity? Indeed it is not true from a
biological point of view: complex organisms are the result of the
composition of billions of cells (themselves unique entitites) as different
as neurons and epithelial cells. But these cells will not be an organism if
they weren't connected and organized in increasing degrees of complexity.
Neo-Darwinism does not deny this notion. It simply offer an explanation of
how this complexity can be packed in a single cell and passed from a
generation to another one, with some variations during the time. I think
it's still a valid one.
mag at vetbio.unizh.ch 



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