In this paper we combine foraging theory and population biology models to simulate dynamic relationships between hunter-gatherers and their prey resources. Hunter-gatherer population growth responds to the net marginal rate of foraging; prey population growth responds logistically to exploitation. Thus conceived, the relationship between forager and prey biomass is time-dependent and nonlinear. It changes from stable equilibrium to damped and stable cycles with modest adjustments of input parameters. And, it produces the largest sustainable human population at intermediate levels of individual work effort. At equilibrium the forager takes all prey types with a pursuit and handling rate greater than or equal to its maintenance foraging rate. The structural properties of the model compel us to reject standard anthropological interpretations of the carrying capacity concept; they provide new insights on old issues such as original affluence and intensification. Analysis of the interaction of human population, diet selection, and resource depletion requires microecological models in part because the relevant processes occur on time scales largely invisible to both ethnography and archaeology. © 1988.

The Younger Dryas impact hypothesis posits that a cosmic impact across much of the Northern Hemisphere deposited the Younger Dryas boundary (YDB) layer, containing peak abundances in a variable assemblage of proxies, including magnetic and glassy impact-related spherules, high-temperature minerals and melt glass, nanodiamonds, carbon spherules, aciniform carbon, platinum, and osmium. Bayesian chronological modeling was applied to 354 dates from 23 stratigraphic sections in 12 countries on four continents to establish a modeled YDB age range for this event of 12,835-12,735 Cal B.P. at 95% probability. This range overlaps that of a peak in extraterrestrial platinum in the Greenland Ice Sheet and of the earliest age of the Younger Dryas climate episode in six proxy records, suggesting a causal connection between the YDB impact event and the Younger Dryas. Two statistical tests indicate that both modeled and unmodeled ages in the 30 records are consistent with synchronous deposition of the YDB layer within the limits of dating uncertainty (∼ 100 y). The widespread distribution of the YDB layer suggests that it may serve as a datum layer.