Subsistence strategies and early human population history: an evolutionary ecological perspective.

One of the keystones of the evolutionary ecological approach is the concept of energy budget, in which time and energy allocation is conceptually divided into somatic effort (growth, development and maintenance, and includes subsistence activities) and reproductive effort (which is further divided into mating effort and parental effort). Time and energy allocated to one component must be traded off against allocation to another. Using this energy budget approach in conjunction with some of the general implications of foraging theory, this article will explore the relationship between population dynamics and subsistence intensiŽcation. My discussion will revolve around two basic propositions regarding long-term human population history: 1) the near-zero growth rates that have prevailed through much of prehistory are likely due to long-term averaging across periods of relatively rapid local population growth interrupted by infrequent crashes caused by density-dependent and density-independent factors; and 2) broad changes in population growth rates across subsistence modes in prehistory are probably best explained in terms of changes in mortality due to the dampening or buffering of crashes rather than signiŽcant increases in fertility.