The application of artificial-life principles for artistic use has its origins in the early works of Sommerer and Mignonneau, Sims and Latham. Most of these works are based on simulated evolution and the determination of fitness according to aesthetics. Of particular interest is the use of evolving expressions, which were first introduced by Sims. The author documents refinements to the method of evolving expressions by Rooke, Ibrahim, Musgrave, Unemi, himself and others. He then considers the challenge of creating autonomously evolved artworks on the basis of simulated aesthetics. The author surveys what little is known about the topic of simulated aesthetics and proceeds to describe his new coevolutionary approach modeled after the interaction of hosts and parasites.