Marine resource abundance drove pre-agricultural population increase in Stone Age Scandinavia

J P Lewis,P J Reimer,S Mcgowan,J Olsen,K.-.L Knudsen,D B Ryves,N J Anderson,L G Van Der Sluis,P Rasmussen,S Juggins

doi:10.1038/s41467-020-15621-1

Abstract

How climate and ecology affect key cultural transformations remains debated in the context of long-term socio-cultural development because of spatially and temporally disjunct climate and archaeological records. The introduction of agriculture triggered a major population increase across Europe. However, in Southern Scandinavia it was preceded by ~500 years of sustained population growth. Here we show that this growth was driven by long-term enhanced marine production conditioned by the Holocene Thermal Maximum, a time of elevated temperature, sea level and salinity across coastal waters. We identify two periods of increased marine production across trophic levels (P1 7600–7100 and P2 6400–5900 cal. yr BP) that coincide with markedly increased mollusc collection and accumulation of shell middens, indicating greater marine resource availability. Between ~7600–5900 BP, intense exploitation of a warmer, more productive marine environment by Mesolithic hunter-gatherers drove cultural development, including maritime technological innovation, and from ca. 6400–5900 BP, underpinned a ~four-fold human population growth.

Highlights

How climate and ecology affect key cultural transformations remains debated in the context of long-term socio-cultural development because of spatially and temporally disjunct climate and archaeological records
The landscape of Southern Scandinavia was completely reconfigured during the Early Holocene by rising sea levels[33,34,35] which flooded huge tracts of land, including the land bridge between Denmark and Sweden, and turning large parts of Denmark into a series of islands
At the same time increasing temperatures associated with the onset of the Holocene Thermal Maximum[36,37] (Fig. 2a) drove terrestrial vegetation development, with open ground vegetation and pioneer tree taxa being replaced by dense mixed deciduous woodland[38]

Summary

Introduction

How climate and ecology affect key cultural transformations remains debated in the context of long-term socio-cultural development because of spatially and temporally disjunct climate and archaeological records. The repeatable, but regionally variable boom and bust pattern has generated considerable debate with regard to the possible drivers of human population responses to a multitude of factors and stressors, including, socio-economic status, disease, war, environmental and climatic change as well as resource availability[3,14,20,21,22]. Some recent studies have identified rapid pre-agricultural population shifts, linked to the abundance of key natural (both terrestrial and aquatic) resources, and likely driven by environmental and/or climatic conditions[4,23]. This sequence suggests that between ca. 8400 and 5900 BP either, more cost-effective (terrestrial) resources were in short supply, or that marine resources were more cost-effective than terrestrial plants and animals (and more cost-effective than agriculture between ca. 6600 and 5900 BP)

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Conclusion