The nature of the self has always been an unsolved problem. This study combines a biological theory of the essential features of life with a review of views of the self in philosophy, brain science, mathematics and artificial intelligence. Combining the primary needs of living things with evolutionary theory, a new explanation of the fundamentals of life is provided. The primary needs of life are centred on energy and the transmission of information about oneself. These two intrinsic needs combine with the environment to form a new universal need and a necessary mechanism. And driven by the needs, the organism’s perception of its own needs and state gives rise to self-awareness. Based on this new theory, an iterative model of the evolution of needs and an evolutionary model of the self are proposed. These models are alternative interpretations of the self and self-awareness, and offer improved directions for machine simulation of artificial intelligence.