The Transition from Adolescence to Adult Life: Physiology of the ‘Transition’ Phase and Its Evolutionary Basis

The human life span is comprised of several life phases, each characterized by its own physiology. These phases (pre-natal, neonatal, infancy, childhood, juvenile, puberty, adolescence, prime and senescence) are important for the development of many biological and psychological processes. The ‘transition’ from adolescence to adult life in the human is a lengthy process in comparison with other species, and its evolutionary development has been long and complex. In this article, the characteristic features of this transition will be discussed, as well as the theory that the transition from adolescence to adult life should be considered as a life phase in its own right.