The Demographic Impact of the Agricultural System in Human History

Abstract

Mark Cohen’s instructions for the workshop were to present “the state of work in your field and how work in your field relates to the other areas to be discussed.” This comment therefore focuses on the signal of a major demographic shift during the transition from the forager to the farming system, which has been detected in paleoanthropological cemetery data. This signal is interpreted as having been produced by the Neolithic demographic transition (NDT; Bocquet-Appel 2002, 2008a; Bocquet-Appel and Naji 2006). A demographic transition can be defined as a quantitative leap in the selfregulated flow of population inputs and outputs that is determined by a qualitative change in the causal mechanisms underlying the regulation. Two figures presented during the workshop (figs. 1, 3) are commented on; there follows a short reflection concerning both the link between demographic pressure and cultural change and the significance of the NDT from the perspective of human demographic history, continuing a discussion that initiated 50 years ago (Deevey 1960). We know that the shift from a foraging to a producer economy coincided with an unprecedented increase in the amount of archaeological data in the Levant (Bar-Yosef and Belfer-Cohen 1991; Goring-Morris and Belfer-Cohen 2008) and elsewhere in the world (Bellwood and Oxenham 2008). This increase was interpreted for a long time in terms of demographic growth (Kuijt 2008). But was this growth slow or rapid? Was it due to an increase in fertility and/or a reduction in mortality? What was the intensity of the shift, that is, its level (as plotted in fig. 1) and its speed? Was the intensity the same in the centers of agricultural invention and in their peripheral expansion zones? The signature of the NDT was detected in the paleoanthropological data of cemeteries, but it is not directly visible to archaeologists unless they use an archaeometric procedure that combines the variation in a paleodemographic indicator, represented by the proportion of the immature skeletons in a cemetery (called 15p5), with a specific chronological frame, in relative chronology (called dt; Bocquet-Appel 2002). Figure 1 shows the signature of the NDT obtained from 133 cemeteries containing more than 50 skeletons (5 years old) in the Northern Hemisphere, excluding the Levant. This signature therefore represents an average pattern. It is characterized by a noticeable increase in the proportion of immature skeletons, from 22% to 28%, during the forager/farmer transition. Also noticeable is the weak pre-NDT depression, where the proportion of immature individuals (as well as the birth rate and fertility) decreases, which suggests a population experiencing hardship. During the middle of the forager period ( ) and up p # 100 p 22% 15 5