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Genotypes of less than rank 1 can be considered redundant. Note, however, that
some redundancy in the gene pool is usually considered a good thing. In situations
where a single genotype must be selected, a rank 1 genotype is sometimes selected
based on its uniqueness relative to the current population (Neufeld et al.
2008
,Ross
and Zhu
2004
, Greenfeld
2003
).
Both weighting and Pareto ranking are approaches to the more general problem
of multi-objective optimisation. For multidimensional aesthetics a computational
evaluation system will have to deal with multi-objective optimisation either explic-
itly as above, or implicitly as is done in the extensions to evolutionary computation
noted below.
10.2.11 Biologically Inspired Extensions to Simple Evolutionary
Computation
Evolutionary art faces significant challenges beyond machine evaluation-based fit-
ness functions. For example, the expression of genes in nature doesn't happen in a
single step. There is a cascading sequence of emergence across a number of scales
from DNA, to proteins, organelles, cells, tissues, and finally organs resulting in an
individual. Life's capacity for complexification is unmatched in the known universe.
By comparison evolutionary computing systems are simple in that they typically
only support a single level of emergence, i.e. the genotype directly generates the
phenotype (Casti
1994
, Galanter
2010
).
And so current evolutionary computing technologies have a very limited capacity
for the creation of complexity. This isn't a problem in most industrial applications
because their solution spaces are well explored by the search and optimisation strate-
gies evolutionary computing offers. But art is one of the most complex activities of
the arguably most complex unitary system known, the human mind.
A number of nature-inspired extensions for evolutionary art have been explored
in part to meet this need for increased complexity. Each suggests new perspectives
regarding computational aesthetic evaluation. For example, with the addition of co-
evolution two or more species may compete for survival. This can create an evolu-
tionary “arms race” making fitness a moving target for all. But it is also possible that
species will coevolve to fill mutually beneficial symbiotic roles, and possibly exhibit
convergent aesthetics. In such systems the ecology is a dynamic system offering in-
creased complexity. Some species will specialise and dominate an ecological niche
while others remain flexible generalists. And some species may in fact alter the ecol-
ogy creating a niche for itself. Meanwhile, within a species individuals may interact
via social transactions further modulating what constitutes fitness. These extensions
are explored in the following sections.
