1. A method of evolving a representation of a molecule with a set of desired properties by successively generating a sequence of populations, each of said populations comprising a plurality of member representations of the chemical composition and connectivity of member molecules, said method comprising the steps of: a) comparing each member representation of a present population of said sequence of populations with said set of desired properties to assign to each compared member representation a numerical value dependent on how closely said compared member representation corresponds with said set of desired properties; b) selecting said member representations of said present population dependent on their respective numerical values and changing the chemical composition and connectivity of at least one of said selected member representations to be reproduced within a next population of member representations of said sequence of populations, said selecting and changing being performed on a computer; and c) repetitively executing steps a) and b) at least one time, each execution of steps a) and b) producing said next population of said member representations within said sequence of populations.