The evaluation of physical artifacts for fitness determination
can be traced back to the origins of evolutionary
computation; for example, the first evolution strategies (ESs)
were used to design jet nozzles with a string of section
diameters, which were then machined and tested for fitness
[13]. Other well-known examples include robot controller
design [14], electronic circuit design using programmable
hardware [15], product design via human provided fitness
values [16], chemical systems [17], and unconventional computers
[18]. Evolution in hardware has the potential to benefit
from access to a richer environment where it can exploit
subtle interactions that can be utilized in unexpected ways.
For example, the EA used by Thompson [15] to work
with field-programmable gate array circuits used some subtle
physical properties of the system to solve problems
where the properties used are still not understood. Humans
can be prevented from designing systems that exploit these
subtle and complex physical characteristics through their lack
of knowledge, however, this does not prevent exploitation
through artificial evolution. There is thus a real possibility
that evolution in hardware may allow the discovery of
new physical effects, which can be harnessed for computation/
optimization [19].