The issue of the biological origin of consciousness is linked to that of its function. One source of evidence in this regard is the contrast between the types of information that are and are not included within its compass. Consciousness presents us with a stable arena for our actions-the world-but excludes awareness of the multiple sensory and sensorimotor transformations through which the image of that world is extracted from the confounding influence of self-produced motion of multiple receptor arrays mounted on multijointed and swivelling body parts. Likewise excluded are the complex orchestrations of thousands of muscle movements routinely involved in the pursuit of our goals. This suggests that consciousness arose as a solution to problems in the logistics of decision making in mobile animals with centralized brains, and has correspondingly ancient roots.