Human life histories: primate trade-offs, grandmothering socioecology, and the fossil record

Human life histories differ from those of other animals in several striking ways. Recently Smith and Tompkins (1995, p. 258) highlighted the combination of "slow" and "fast" features of human lives. Our period of juvenile dependency is unusually long, our age at first reproduction is late, and we have the maximum life span of the terrestrial animals. Yet we wean babies relatively early, and we space births closely. We also have (midlife) menopause. Smith and Tompkins predicted that the evolution of our life cycles would be explained by a combination of developments in life history theory with increasingly sophisticated techniques for extracting information from the fossil record. Their prudent guess was that "no new sunburst theory-in which all human characteristics are drawn from one adaptive shift is - likely" to emerge (1995, p. 274).