A demographic transition can be defined as a quantitative leap in the self-regulated flow of population inputs and outputs which is determined by a qualitative change in the causal mechanisms underlying this regulation. This entry briefly describes the two demographic transitions which occurred during the Holocene, the Neolithic Demographic Transition (NDT) and the Contemporary Demographic Transition (CDT), and their underlying biodemographic mechanisms - the demographic, epidemiological, psychosociological, and cultural consequences - are set out in parallel and discussed from the perspective of human evolution over time.
