This article examines the nature of affective states across biological taxa. It argues that affect constitutes a primary form of consciousness. Creatures capable of affect are sentient of their bodily states and can behave in ways intended to maintain or restore them to a homeostatic range. After reviewing and critiquing neurobiological and philosophical theories of the evolution of consciousness, this article argues that some possible creatures are limited to self‐directed affective states, even if those creatures are capable of exteroception. Such (...) creatures enjoysolipsistic sentience: awareness of their own selves and bodily demands, but unawareness of their exogenous environments. (shrink)