PHYLOGENETIC RECAPITULATION IN THE ONTOGENY OF ARTIFICIAL NEURAL NETWORKS

The order in  which anatomical characteristics develop in an individual from 
conception to maturity (ontogeny) may repeat the evolutionary history of the
individual's  species (phylogeny).  Phylogenetically  older  characteristics 
often   develop  earlier   during   ontogeny  and  more  recent phylogenetic 
characteristics   develop   later.   We   show   evidence   of  phylogenetic 
recapitulation in the development of the nervous system of simple artificial 
organisms which  are  evolved using  a  genetic  algorithm technique. In our 
simulations  we  found  evidence of both acceleration and retardation in the 
ontogeny  of  characters   acquired   during   phylogeny.  The prevalence of 
accelerations   with  respect  to  retardations  explains why characters are 
usually   anticipated  during  ontogeny   and,  therefore, why  ontogeny may 
recapitulate philogeny. Such  acceleration  and retardation phenomena appear 
to affect  only  functional characters,  i.e. characters that play a role in 
determining the fitness of individuals.