Archaeology, climate, and global change in the Age of Humans

We live in an age characterized by increasing environmental, social, economic, and political uncertainty. Human societies face significant challenges, ranging from climate change to food security, biodiversity declines and extinction, and political instability. In response, scientists, policy makers, and the general public are seeking new interdisciplinary or transdisciplinary approaches to evaluate and identify meaningful solutions to these global challenges. Underrecognized among these challenges is the disappearing record of past environmental change, which can be key to surviving the future. Historical sciences such as archaeology access the past to provide long-term perspectives on past human ecodynamics: the interaction between human social and cultural systems and climate and environment. Such studies shed light on how we arrived at the present day and help us search for sustainable trajectories toward the future. Here, we highlight contributions by archaeology—the study of the human past—to interdisciplinary research programs designed to evaluate current social and environmental challenges and contribute to solutions for the future. The past is a multimillennial experiment in human ecodynamics, and, together with our transdisciplinary colleagues, archaeology is well positioned to uncover the lessons of that experiment.

Climatic changes cause synchronous population dynamics and adaptive strategies among coastal hunter-gatherers in Holocene northern Europe

Synchronized demographic and behavioral patterns among distinct populations is a well-known, natural phenomenon. Intriguingly, similar patterns of synchrony occur among prehistoric human populations. However, the drivers of synchronous human ecodynamics are not well understood. Addressing this issue, we review the role of environmental variability in causing human demographic and adaptive responses. As a case study, we explore human ecodynamics of coastal hunter-gatherers in Holocene northern Europe, comparing population, economic, and environmental dynamics in two separate areas (northern Norway and western Finland). Population trends are reconstructed using temporal frequency distributions of radiocarbon-dated and shoreline-dated archaeological sites. These are correlated to regional environmental proxies and proxies for maritime resource use. The results demonstrate remarkably synchronous patterns across population trajectories, marine resource exploitation, settlement pattern, and technological responses. Crucially, the population dynamics strongly correspond to significant environmental changes. We evaluate competing hypotheses and suggest that the synchrony stems from similar responses to shared environmental variability. We take this to be a prehistoric human example of the “Moran effect,” positing similar responses of geographically distinct populations to shared environmental drivers. The results imply that intensified economies and social interaction networks have limited impact on long-term hunter-gatherer population trajectories beyond what is already proscribed by environmental drivers.

Convergent catastrophes and the termination of the Arctic Norwegian Stone Age: A multi-proxy assessment of the demographic and adaptive responses of mid-Holocene collectors to biophysical forcing

Using multiple archeological and paleoenvironmental proxies, this paper makes the case for a climate-induced convergent catastrophe among the human population of terminal Stone Age Arctic Norway. We show that climatic changes correlate with the termination of the so-called Gressbakken phase (4200–3500 cal BP), and unpack the middle-range mechanisms linking the Gressbakken termination to contemporaneous changes in the biophysical environment. We show that what was a Holocene extreme, and likely volcanically-induced, climate deterioration around 3550 cal BP coincided with a population decline as reflected in the frequency of radiocarbon-dated archeological sites along with major changes in material culture and settlement pattern. Together, these proxies suggest a return to forms of social and economic organization based on lower population densities, higher residential mobility, and reduced locational investments. In establishing the middle-range ecological mechanics mediating these changes into archeologically observable patterns, the results indicate that the Gressbakken termination was the result of a particularly unstable climate period characterized by regional paludification, increased effective precipitation, forest decline, and likely impacts on reindeer populations and their migratory behavior, with drastic human implications. We argue for a convergent catastrophe-scenario in which a series of hardships between 4000 and 3500 cal BP exceeded the adaptive mitigation capabilities of the contemporaneous Arctic Norwegian population. Our study supports the notion that increased sedentism and locational investment actually increases vulnerability in the face of rapid biophysical change and contributes to the growing database of past human ecodynamics that speak to current socio-ecological concerns.

Human resilience and resettlement among the Islands of Four Mountains, Aleutians, Alaska

Combined archaeological, ecological, and geologic research on Chuginadak and Carlisle Islands in the Islands of Four Mountains (IFM) probed questions about the sustainability of human settlements over the past 4000 years in the face of geologic, ecological, and social hazards. We use a human ecodynamics approach to frame the investigation and present original archaeological evidence from this poorly known region of the remote Aleutian Islands. Several village sites occupied during the last four millennia are clustered in locations that were not damaged by earthquake-induced tsunamis; however, new geologic evidence indicates that at least one volcanic eruption forced humans to abandon one or more prehistoric village sites. Combined archaeological, ecological, and geologic analyses demonstrate resilient Unangax̂ occupations of the IFM through long-term climate change as well as earthquakes, tsunamis, and volcanic eruptions with occasional community vulnerability to volcanic eruptions.