Re: Behaviorism vs. evolutionary psychology

JGCASEY <jgkjcasey@xxxxxxxxxxxx> wrote on Tue, 10 Jul 2007:
In theory yes they stripes or dots may have evolved purely by chance to
then be selected for the reproductive advantage they gave the owner. But
did they occur by chance? Or are they are common outcome due to the
physical nature of things?

Well, surely the physical world is the context in which natural selection
takes place. If you're going to wind up as a flying animal, I sure bet that
your bones are going to be very light. This isn't really a consequence of
mutation, or of natural selection, but perhaps most easily understood as
a consequence of gravity and aerodynamics.

Sure, fine.

That just tells you that evolution is "looking" for a solution to a problem,
and the problem is (partially) posed by physics (as well as partially by the
ecosystem of other existing lifeforms).

But the _mechanism_ for the actual appearance of phenotypes is: mutation +
natural selection. Agreed, those two won't tell you where a species will end
up; it only tells you that IF there is a possible solution in the universe,
evolution may be able to find it. But it offers no guides as to what the
solution will be.

Evolution doesn't explain why or how these molecules or laws are primed to
evolve. What basic structures can come into existence, by chance, to be
selected in stages and that these stages in turn have the right stuff to
produce more complex structures, by chance, which in turn can be selected.

I'm not sure how much of an explanation you're looking for. The first
question is whether you can ever have a self-reproducing molecule. DNA
basically works, as do some crystals.

Once you get to a level of a single-cell with DNA which can replicate, the
rest of life is pretty straightforward, don't you think? I'm not sure where
your big question is. Are you most concerned:
1. How the universe gets from dead rocks to the first reproducing organic
molecules ("abiogenesis");
2. How single molecules turn into cells;
3. How single cells turn into the huge variety of complex life forms that we
observe on Earth today ("evolution").

There are explanations for each of these. Evolution is mostly about #3.
Your comments seem to suggest concern about other areas, but I'm not quite
sure which.

Take reinforcement learning and the combinational explosion. In theory
trial and error should, given enough time, bring about any pattern to be
selected. But in fact the Universe will not be around long enough for that
to happen. Somehow there are constraints in these systems that mean that
they can, within a reasonable time limit, produce the right patterns to
actually be selected.

Are you suggesting ("somehow there are constraints") that it's a hard,
unsolved problem, how evolution produced life in as short a time (a few
billion years) as it appears to have taken? That the search space is too
big, and there wasn't enough time?

Because that's not the situation. Geologic time, plus the rate of DNA
mutations, plus how genotypes get expressed as phenotypes, is all sufficient
to make the evolution story hang together.

If you mean something more basic, like that Earth happens to have liquid
water, or that the six (?) fundamental constants of physics just happen to
allow stable matter, etc. That's a somewhat more difficult philosophical
puzzle (but not without proposed solutions), and you may want to explore the
Anthropic Principle:
http://en.wikipedia.org/wiki/Anthropic_principle

The constraints make it possible. They deliver possible things to be
selected within a reasonable time limit. That is not to be found in the
mutation or selection process.

I can't really make sense of this, unless you're referring to one of the
things I described above. Perhaps you can give me a concrete example.
What is a specific constraint you have in mind, that is not mutation or
selection, yet allows complex life to evolve ("within a reasonable time"
instead of taking longer than the age of the universe)?

The idea of reinforcement is the easy part. Natural selection of mutations
is the easy part. That those mutations are ever worth selecting is the hard
part to explain.

So you have a bunch of fish in the ocean, and their DNA slowly mutates, and
one begins to develop the ability to extract oxygen from air instead of only
from water (the beginnings of a lung instead of a gill).

And your question is, how did any mutation to DNA ever result in a proto-lung?
And what answer do you give (different from mutation + natural selection)?
Are you getting at how genotypes (DNA) turn into phenotypes (the large-scale
appearance of an individual organism)? It's pretty cool, and pretty complex,
but is it really as big a mystery as you seem to be suggesting?

-- Don
_______________________________________________________________________________
Don Geddis http://don.geddis.org/ don@xxxxxxxxxx
There are two theories about what happens to a skunk if he gets into heaven.
One is that he no longer stinks. The other is that his stink is super strong.
Both these theories are by me. -- Deep Thoughts, by Jack Handey [1999]
.

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