Raffaele Calabretta, Stefano Nolfi, Domenico Parisi and Günter
P. Wagner
Abstract. The origin and structural and functional significance
of modular design in organisms represent an important issue debated in
many different disciplines. To be eventually successful in clarifying the
evolutionary mechanisms underpinning the emergence of modular design in
complex organisms, one should be able to cover all different levels of
biological hierarchy. Specifically, one should be able to investigate modularity
at the behavioral level - the level on which natural selection operates
- and understand how this level is related to the genetic level – the level
at which natural selection works through mutation and recombination. We
describe a simulation of the evolution of a population of robots that must
execute a complex behavioral task to reproduce. During evolution modular
neural networks, which control the robots’ behavior, emerge as a result
of genetic duplications. Simulation results show that the stepwise addition
of structural units, in this case genetic and neural 'modules', can lead
to a matching between specific behaviors and their structural representation,
i.e., to functional modularity.