Darwin suggested considering heredity, variation, and selection as
3 seperate processes that together end up in biological evolution.
For didactical purposes it may be convenient to separate these
3 processes but in fact they are 3 different views on the same process.
You cannot define fitness without considering heredity. If an elephant
gives birth to a fish, there is no fitness and no natural selection.
All what you said is a good simplification which is nice for teaching
evolution at college. But it does not capture deeper layers. If you
define fitness as the mean number of offsprings per parent you will
soon discover that this fitness is not always maximized in evolution.
People try to handle it by inventing various patches because they
cannot leave the familiar dogma that heredity and selection are
separated processes.
Death is not defined by physical conditions because there are
various ways to live. In a way, death is optional. An organism
dies only if it could not find a good option of how to live.
>Possible, all kind of books have been written. But this is not the standard
view
> of
>biology and there are good reasons. (See Evolution by M. Ridley as cited in the
>language article (see below): Group selection can occur, but is limited and
> mostly
>to weak to overwhelm natural selection.
Standard view is not always the best one... Most of the critique
of group selection is based on misunderstanding. Models of
Maynard Smith consider temporary groups that are only partially
isolated. It is obvious that group selection is not very effective
if groups are not well isolated. However, species are very well
isolated and group selection at the level of species is a normal
thing.
Also, there is a false idea that any adaptation should be
either an individual adaptation or a group adaptation. Most biological
processes have their effect on multiple hierarchical levels. Thus,
they have meaning at several levels. Dawkins says that if we can
"explain" some adaptation by individual selection there is no sense
to look at group selection. This is stupid, because any individual
adaptation may have additional effects on higher hierarchical levels
and at longer time scales.
>I would be the first to say that natural selection has limited applicability.
> E.g.
>I' d say that the origin of life cannot be explained by NS, while the standard
> view
>is that of the RNA-world whereby 'self replicating' molecules undergo natural
>selection, because of differential reproduction rate (which by the way is not
> the
>same as differential survival rate: survival is unimportant in biology,
> reproduction
>is). Also selection comes only after variation has been 'created', through
> mutation
>and recombination (through symbiosis, sexual (bilinear) recombination or
> cultural
>(multilinear) recombination). A lot of evolution can be explained through the
>absence of selective constraints, e.g. when a new building plan comes into
being
>like was the case for animal multicellularity: at that moment any variation
goes
>because there is nothing like it and the niche is empty. This empty niche,
> always
>open for more complex organisms may explain why evolution almost inevitably
> leads to
>more complexity: there is always room for more complex organisation. Evolution
> is
>open ended towards more complexity, (more complex organisms initially have no
>competitors).
This sounds close to what I think.
When we found that some theory does not work reliably in all
areas we have 2 options: (1) delimit the area where the theory
seems to work more-or-less satisfactory, and invent patches for
those areas where it does not work, or (2) modify the theory so
that it will work well in a much wider range of situations.
Traditional Darwinism (including Dawkins and Gould) use the first
option. Some people including me use the second one.
>I'd hesitate to call mutation freedom, since it is deterministic, but still
then
>this has a different connotation than free will.
Why mutation is deterministic?
-Alexei
-------------------------------------------------
Alexei Sharov Research Scientist
Dept. of Entomology, Virginia Tech, Blacksburg, VA 24061
Tel. (540) 231-7316; FAX (540) 231-9131; e-mail sharov@vt.edu
Home page: http://www.gypsymoth.ento.vt.edu/~sharov/alexei.html