RE: Evolutionary computation (was: Where's the Evolution?)

Brian D Harper (
Wed, 07 Apr 1999 15:37:19 -0700

At 04:23 PM 4/6/99 -0500, Cummins wrote:


>You're trying to substitute your reasoning for direct observation. How
>about an empirical example of mutation and selection creating an indefinite
>increase in complexity? If it really is possible, a computer program should
>easily be able to demonstrate it. (a computer is just another lab

I'm glad to see that you accept results of computer simulations.
Perhaps the best (or at least best known) simulation of Darwinian
evolution is Tom Ray's Tierra World. For a summary I invite you
to point your web browser at:

and read the abstract.

Particularly interesting is Ray's claim (see last paragraph of
abstract) that evolution actually discovered an optimization
technique called "unrolling the loop". More about this can
be found in a section entitled, significantly :), <increasing
complexity>. This section is reproduced below:


The unrolled loop (the section ``an intricate
adaptation'') is an example of the ability of
evolution to produce an increase in complexity,
gradually over a long period of time. The
interesting thing about the loop unrolling
optimization technique is that it requires more
complex code. The resulting creature has a genome
size of 36, compared to its ancestor of size 80,
yet it has packed a much more complex algorithm
into less than half the space (Appendix E).

This is a classic example of intricate design in
evolution. One wonders how it could have arisen
through random bit flips, as every component of
the code must be in place in order for the algorithm
to function. Yet the code includes a classic mix of
apparent intelligent design, and the chaotic hand of
evolution. The optimization technique is a very clever one
invented by humans, yet it is implemented in a mixed up
but functional style that no human would use (unless
perhaps very intoxicated).


Not only does this show an example of increasing complexity
arising from "random bit flips", the final result is also
irreducible: " every component of the code must be in
place in order for the algorithm to function."

Brian Harper
Associate Professor
Applied Mechanics
The Ohio State University

"All kinds of private metaphysics and theology have
grown like weeds in the garden of thermodynamics"
-- E. H. Hiebert