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Are We Stuck with Evolution?

 

We talk about evolution in a strange way.  This is probably why we have difficulty understanding it.

How it works

When we say "animals adapt to their environment" what we really mean is:

Individual animals do not adapt to their environment;  they don't change genetically during their lifetime.

You can experiment with a small demonstration program called "Is it Chance?".

A negative mechanism

Selection acts mainly by preventing some copies to reach replication age.

Useless characteristics may come into existence for which there is not much negative selection before replication age.  These traits then do replicate, perhaps for a long time.  Sometimes a new trait may give such an advantage that other, negative traits are not removed.  For example, mammals have eyes whose receptors are "inside-out":  the nerves have to carry the visual signal from the front of the retina and then go back out in a bundle through the rear of the eye (the reason for the "blind spot", where all those nerves traverse the retina).  Therefore mammal eyes are not as good as they could be.  Mammals also can't see in the ultraviolet as birds can.  Their retinas are prone to becoming unstuck, but this happens usually only after reproduction time hence this eye-disadvantage does get reproduced.  Mammals survived despite relatively bad eyes because they had other advantages.

A dynamic situation

The environment changes:  ice ages come and go, new predators move into the neighbourhood.  Animals (and plants of course) are never completely adapted to their environment.  To say that in nature everything is marvellously adapted for the best is therefore nonsense:  organisms may be very well adapted, but they can always improve.  The situation is dynamic, the goal is always moving.  The advantage is also to the organisms that are able to adapt fast, i.e. a fairly high mutation rate and a short life cycle.  That is what allows bacteria to become resistant to antibiotics and why it is easier to select for vegetable varieties than for trees.

An unfortunate choice of name

The biological evolution mechanism is also called "Darwinian evolution".  Its main characteristic is removal of unfit copies from a large pool of slightly differentiated copies.  It is a negative mechanism:  it weeds out the bad.

I find that using the name "Darwinian evolution" contributes to the confusion:  it sounds as though there is a choice of evolutions that the user can shop for.  But this is not so:  there is only one kind of evolution at work in nature.  Darwin (and Wallace) just happened to have described it.

See the page about communicating science.

Discussions...

I am totally convinced that evolution explains all of biological life as we see it on Earth.  Very good explanations and description of evidence can be found in the books of Richard Dawkins and Steven J. Gould.

Evolution is also mentioned as the "normal" way of change in other areas:  the economics of the free market have characteristics similar to evolution; technological advances do too, and recently programming has been done by "genetic algorithms" which reproduce and adapt to the solving of a problem.

Some people still have trouble with the reality of evolution, notably creationists and advocates of intelligent design.  It's interesting to read the transcript of the 2005 Dover trail, and it is equally interesting to reflect upon the nature of "design" itself.

Is it fundamental?

Are we stuck forever with Darwinian evolution?  Are there other mechanisms for progressing towards a goal?

In other words, is Darwinian evolution a constant of Nature built into its very mathematics, coming out beautifully in biology, but in fact also unavoidable anywhere else, in any changing information system?

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next planned revision: 2009-11