The agricultural demographic transition during and after the agriculture inventions
Résumé
An abrupt increase in fertility has been recorded in data from 200 cemeteries and ethnographic data ranging from the Meso-Neolithic Eurasian center in the Levant to the arctic circle in the North American continent in the twentieth century AD. This shift has been called, synonymously, the Neolithic demographic transition or the agricultural demographic transition (ADT). It is interpreted as the effect on fertility of an abrupt change in maternal energetics that occurs during the transition from a mobile forager economy to a farming economy in any period, whether prehistoric or historical. The primeval prehistoric ADT was a loop of retroactions capable of rapidly raising the rate of population growth and in which the population was both the cause and the effect of the demographic shift. During the eighteenth century AD, new areas of demographic change appeared across this agricultural population area that were characterized by a drop in mortality and then in fertility and were determined by the introduction of new rules of hygiene along with medical and contraceptive techniques. This shift represents the contemporary demographic transition (CDT). The CDT occurred in reverse symmetry with the ADT. A unique phenomenon occurred at the margins of the residual area of the forager system with a quasi coincidence of the effects of both the ADT and the CDT.