It is shown that populations of individual signal patterns in the central n
ervous system, may be adapted for maximum mean fitness in about the same ma
nner as populations of organisms in the Darwinian evolution of natural syst
ems. This is also consistent with the Hebbian rule of associative learning
and the maximum-entropy-principle according to the second law of thermodyna
mics. (C) 1999 Elsevier Science Inc. All rights reserved.