The question of how to achieve open-ended emergence in an artificial
evolution system is addressed. Such inexhaustible novelty is necessary
for the generation of complex entities beyond our manual design
capability. The use of artificial selection rather than ``truly
natural selection is argued to have been the most common barrier to
date and further requirements for perpetual emergence are outlined.
These include considerations of what to evolve and how to encode/
decode the genetics. An artificial life system constructed to satisfy
these requirements is described and emergent behaviours reported.
These experiments indicate a possible further requirement concerning an
upper bound on the hierarchical level of initial system specification,
outlining the next step of research in this area.