Evolution through natural selection has been going on for a very long
time. Evolution through artificial selection has been practiced by
humans for a large part of our history, in the breeding of plants and
livestock. Artificial evolution, where we evolve an artifact through
artificial selection, has been around since electronic computers became
common: about 30 years. Right from the beginning, people have suggested
using artificial evolution to design electronics automatically.l Only
recently, though, have suitable re- configurable silicon chips become
available that make it easy for artificial evolution to work with a
real, physical, electronic medium: before them, ex- periments had to be
done entirely in software simulations. Early research concentrated on
the potential applications opened-up by the raw speed ad- vantage of
dedicated digital hardware over software simulation on a general-
purpose computer. This book is an attempt to show that there is more to
it than that. In fact, a radically new viewpoint is possible, with
fascinating consequences. This book was written as a doctoral thesis,
submitted in September 1996. As such, it was a rather daring exercise in
ruthless brevity. Believing that the contribution I had to make was
essentially a simple one, I resisted being drawn into peripheral
discussions. In the places where I deliberately drop a subject, this
implies neither that it's not interesting, nor that it's not relevant:
just that it's not a crucial part of the tale I want to tell here.