Early postglacial hunter-gatherers show environmentally driven “false logistic” growth in a low productivity environment

Abstract

Studies that employ probability distributions of radiocarbon dates to study past population size often use exponential increase in radiocarbon dates with time as a standard of comparison for detecting population fluctuations. We show that in the case of early postglacial interior Scandinavia, however, the summed probability distribution of radiocarbon dates has best fit with a S-shaped logistic growth curve. Despite the logistic growth model having solid grounding in ecological theory, we further argue that what our data indicate is not logistic growth in the population ecological sense but “false logistic” growth that mainly follows from climatic and environmental forcing. In the initial postglacial phase, 9500–7500 BCE, human settlement was located almost exclusively along the Scandinavian Atlantic coast and the use of the mountainous interior remained low. Thereafter the formation of separate inland adaptations resulted in population growth in tandem with increasing climatic warming and environmental productivity. Some millennia later, when environmental productivity started to decrease after the Holocene Thermal Maximum, hunter-gatherer population size in interior Scandinavia reached a plateau that lasted at least 2000 years. Lowering productivity prevented any population growth that would be detectable in the available archaeological record.