Did the mid-Holocene environmental changes cause the boom and bust of hunter-gatherer population size in eastern Fennoscandia?

Abstract

Prehistoric hunter-gatherer population size is often assumed to follow climatic and other environmental forcings that affect environmental productivity and the availability of food for human foragers. We tested this assumption by studying the co-variation of archaeological and palaeoenvironmental records during the Holocene in eastern Fennoscandia. The reconstruction of population history is based on the summed probability distribution of archaeological radiocarbon dates, and environmental changes are tracked with locally available, high-resolution biological and physical proxies that are relevant in terms of hunter-gatherer food availability and population dynamics. The results show major population growth during the period of high summer temperature and high productivity of the terrestrial, lacustrine and marine ecosystems that occurred during 7500–5700 cal. yr BP. The growth was followed by an abrupt decline during 5500–4000 cal. yr BP correlating with the onset of late-Holocene cooling and a major forest ecosystem change brought about by the expansion of Norway spruce and the associated change from species-rich mixed forests to a conifer-dominated boreal ecosystem. Forest ecosystem changes likely enforced the negative effects of decreasing productivity on hunter-gatherer food availability. The link between population and environmental proxies breaks down along with the intensification of agriculture after 3500 cal. yr BP, which indicates that agriculture weakened the environmental forcing on long-term human population dynamics.

Holocene fire in Fennoscandia and Denmark

“…2d ) with poor regional coherency suggests an increase in the local-scale control of fire by humans. Prior to 3500 cal years BP, the human population was largely controlled by environmental factors (Tallavaara and Seppä 2012). The establishment and expansion of agriculture enabled population growth, and human influence is estimated as the strongest driver of forest compositional change (Reitalu et al 2013).…”

Palaeo-oceanographic development and human adaptive strategies in the Pleistocene–Holocene transition: A study from the Norwegian coast

“…Due to absence of datable material, this subject is less treated in Norwegian Early Mesolithic studies, but case studies from northern Europe show correlations between food abundance and hunter-gatherer population sizes (Tallavaara and Seppä, 2011), between climatic events and technological changes (Riede, 2009a), and between environmental changes and distribution of settlements (Crombé et al, 2011). If the PBO cold event had a sudden and severe effect on the economic basis of the marine foragers of Norway, we should look for a decline in site density and maybe even a subsequent change or loss in technology after 9300-9200 bc.…”

The advance of cultivation at its northern European limit: Process or event?

“…It is therefore most unlikely that the peak in archaeological radiocarbon dates around 4000 BC indicates the introduction of farming practices. This population increase coincides with several proxies indicating a broad climatic optimum: it has been mentioned that this led to a natural increase in productivity leading to a higher carrying capacity for hunter-gatherer populations (Tallavaara and Seppä, 2012). In eastern Finland, it may have been locally supported by landscape changes after the Vuoksi breakthrough occurred (Oinonen et al, 2014).…”

“…Within the study area, the population history has been assessed by recording radiocarbon dates obtained from Finnish archaeological finds Tallavaara and Seppä, 2012;Tallavaara et al, 2010). These population size estimates are based on radiocarbon dates from archaeological materials and are thus totally independent of our pollen-based analysis or radiocarbon dates obtained from the pollen cores.…”