There is no selective advantage for the chemicals to form increasingly complex
patterns. There are just so many chemicals all bouncing around and reacting
with each other somewhat randomly on a huge planet, and in places, certain
chemical systems *happen* to form which, because of the particular way they
are arranged, happen to have the property of causing the surrounding
environment to form very similar chemical systems, which also have the
property of causing very similar systems to be formed. The systems happen to
have the property of reinforcing themselves, of maintaining their integrity
and of causing more, similar systems to form.
Because the environment in which these chemical systems form is varied, the
"copied" systems are often disturbed in different ways, and they end up with
different properties, sometimes becoming diffused, and sometimes becoming more
self-reinforcing. Because they are self-reinforcing and self-propogating,
they tend to stick around and to spread; that's just the properties they have.
Variations appear, and some *happen* to be more self-reinforcing and/or more
prolific (i.e. have more offspring).
There is no *drive* towards complexity. It's just that when a random change
happens to these self-propogating, self-reinforcing chemical systems that
boosts these features, it tends to stick around, *by its very nature*.
Organisms are not *trying* to be healthier or have more children; it's just
that when a modification comes along which *happens* to make them or their
offspring healthier or more prolific, it sticks around, precicely *because* it
caused the organism to have the property of being more successful in its
environment.
The environment that organisms evolve in is quite varied; there are lots of
different chemicals and lots of different temperature ranges, etc. Because of
these varied conditions, organisms that are more responsive and adaptive to
their changing environment will tend to stick around. More complex organisms
tend to be more flexible and adaptive than simpler ones and can maintain their
integrity better and have offspring more successfully than simpler ones, in a
varied environment. It's just the nature of the situation that the more
complex organisms will be more successful in general than the simpler ones.
Also, these complex organisms cause the environment to become even more
varied, requiring even greater complexity to stick around and generate
offspring. Although, there are certain niches which don't vary all that much
and organisms which have the properties of doing well in that niche remain
fairly simple.
The only *drive* to complexity is a varied environment. All that does,
though, is make it so that more elaborate systems will tend to be more
successful than simpler ones in maintaining their integrity and generating
offspring. So when a random change comes along which mutates a system into a
slightly more complex and successful system, it does better, simply because it
*happens* to be more successful. I'll just note that the mutated system only
has to be more *successful*, not necessarily more *complex* to do better; it's
just that a highly varied envionment seems to favor more complex systems, in
general.
Nothing really mysterious about it, any more than rolling a bunch of dice and
keeping the sixes whenever they happen to come up and rolling the rest
repeatedly until they come up sixes. It's no surprise that you soon end up
with nearly all, or all, sixes. Just random variation and selection at work.
In this example, the selection criteria was that the die came up as a six.
Reality's selection criteria is that the system is able to maintain itself and
produce more of itself. Why this is the selection criteria is obvious, if you
think about it: the systems with those properties are the only ones that will
stick around for long, *precicely because of those properties*. They have the
property of sticking around, so they *do* stick around.
Sorry to belabour the point, for those who already understand this stuff, but
it's amazing how few people really *understand* this simple concept.
- David Musick
"Tradition is easier than thinking." - Richard Brown