The confluence of virtual reality and artificial life, an emerging discipline that spans the computational and biological sciences, has yielded synthetic worlds inhabited by realistic artificial flora and fauna. Artificial animals are complex synthetic organisms that have functional, biomechanical bodies, perceptual sensors, and brains with locomotion, perception, behavior, learning, and cognition centers. Virtual humans and lower animals are of interest in computer graphics because they are self-animating graphical characters poised to dramatically advance the interactive game and motion picture industries even more so than have physics-based simulation technologies. More broadly, these biomimetic autonomous agents in their realistic virtual worlds also foster deeper computationally-oriented insights into natural living systems. Furthermore, they engender interesting applications in computer vision, sensor networks, archaeology, and other domains.