(Sexual Swimmers)

2 Related Work

The blossoming field of Artificial Life (Langton, 89) includes contributions from many disciplines. Computer animation techniques which complement traditional animated scripting with autonomous agents have made possible complex life-like systems composed of many distributed elements (Reynolds, 87). Physically-based modeling techniques and virtual motor control systems inspired by real animals are used to automate many of the subtle, hard-to-design nuances of animal motion (Badler, 91). In task-level animation, (Zeltzer, 91), and the space-time constraints paradigm, (Witkin and Kass, 88), these techniques allow an animator to direct an autonomous agent on a higher level.

Genetic algorithms (Holland, 75), (Goldberg, 89) have been applied towards artificial evolution of goal-directed motion in physically-based animated figures (Ventrella, 90). These include techniques for evolving stimulus-response mechanisms for locomotion (Ngo and Marks, 93), and for morphological variation in 3D forms (Sims, 94-1, 94-2), (Ventrella, 94). These techniques have been developed most comprehensively in the virtual creatures of Sims, through genetic programming (Koza, 92), and include evolution of locomotion in viscous fluids. An extensive model of fish locomotion, with perception and learning has been developed by Terzopoulos (94), and generates beautifully realistic animations.

The modeling of adaptive organisms imbedded in artificial ecosystems takes genetic algorithms a step further towards a Darwinian definition of fitness by allowing reproduction to occur spontaneously (Ray, 91). "Electronic primordial soups" involving spatiality, such as Yaeger's Polyworld (94), demonstrate artificial ecosystems in which mating, eating, learning, and even social behaviors, evolve within the simulated world.

Todd and Miller (91) have demonstrated how assortative sexual selection can drive a population to have arbitrary phenotypic features, above and beyond the features resulting from natural selection. They demonstrated how mate preference mechanisms could result in sympatric populations - breaking off into distinct non-interbreeding groups.

3 The Swimmer World

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