Divergent population dynamics in the middle to late Holocene lower Fraser valley and mid-Fraser canyon, British Columbia

Abstract

Modelling in demographic ecology offers insights into population stability and instability in village societies. In this study we explore the hypothesis that among storage dependent fisher-hunter-gatherers, access to high resource diversity favors reduced demographic volatility over time. To better understand this relationship, we generate summed probability distributions (SPDs) from legacy radiocarbon records to model the population histories of Middle to late Holocene groups residing in the Mid-Fraser Canyon and the Lower Fraser Valley, British Columbia. Our analysis indicates that Lower Fraser populations (with high subsistence resource diversity) were highly stable after 4000 years ago. In contrast, Mid-Fraser populations (with lower subsistence resource diversity) were very low 2000–4000 cal. BP, peaked at high densities by ca. 1200–1300 cal. BP, and were again low until the final centuries before first contacts with Europeans. We argue that climate related impacts on anadromous fish resources likely affected Mid-Fraser populations to a more substantial degree than those of the Lower Fraser. These results offer wider implications concerning demographic volatility and its effects on cultural stability and social change. Our study offers a means by which legacy radiocarbon data may be studied using a permutation-based statistical inference of SPDs.