The impact of abrupt warming on cultural evolution:
the Late Glacial Interstadial Complex in Europe

Leads: Ariane Burke, Francescso Pausata, Timothée Poisot

Members: Patrick Nantel, Thinhinane Terkmani, Faedrette de Chardon, Emile Chanel Agouès, Costanza Del Gobbo

Collaborators: Matt Grove

A major goal of climate science is to understand how humans perceive and respond to climate change and identify sources of vulnerability and resilience with the aim of informing global climate action. The archaeology of climate change contributes to this endeavour by providing richly contextualised information about past human-climate interactions and their outcomes, isolating sources of human resilience and vulnerability. Archaeologists harness the analytical power of models to study the impact of past climate events on human populations but the causal links between climate events and changes in the archaeological record are often inferred rather than demonstrated. This hinders our understanding of the complex interactions between natural and human systems. A major challenge that this research is designed to meet, therefore, is to integrate these systems and to identify the causal mechanisms linking climate-driven changes in the biosphere and patterns of cultural transformation.

Objectives

This research has two main objectives:

  1. to explore the impact of abrupt climate change on patterns of human migration and cultural diversity during the Late Glacial Interstadial Complex (LGIC) of Europe. The LGIC (also known as the Bølling/Allerød interstadial) is a warm interval lasting from 14,690 to 12,890 years ago (14.7 ka - 12.8 ka) initiated by an abrupt warming event. During this timeframe the European landscape was transformed, human populations expanded into previously uninhabited regions and an increasing number of cultural entities are identified in the archaeological record.

  2. The extent to which climate change influences patterns of human migration and cultural diversity is a question that has been addressed elsewhere, e.g., including the Late Glacial including and the LGIC, but little attention has been paid to identifying causal mechanisms or the potential role of internal drivers of cultural change. The second goal, therefore, is to address the problem of causality by testing the novel proposition that causal relationships exist between rates of cultural innovation and variability, population structure and connectivity, and the structure of the environment which is ultimately influenced by climate change.

To this end the project is designed around a modelling pipeline that:

  1. documents the impact of abrupt warming events on the human “niche” using habitat suitability (HS) modelling;

  2. uses the resulting HS models to estimate the size and structure of human populations at the regional level;

  3. quantifies the connectivity between constituent groups within social networks using circuit theory;

  4. interprets the results using cumulative culture hypothesis, which generates predictions about the causal relationship between rates of innovation and cultural variability and, in the final analysis, tests these predictions against the archaeological record using matrix correlation statistics.

Workpackages (WP)

  • WP1, under the direction of F. Pausata, will leverage existing climate simulations (data from the isotope-enabled Transient Climate Experiment for the last deglaciation available at: https://www.cesm.ucar.edu/working-groups/paleo/simulations/cesm1-itrace) to produce high-resolution climate outputs using dynamic downscaling techniques for three timesteps (before, during and after the transition to the LGIC). Climate data produced in WP1 will be used:

    a) to produce vegetation and biomass simulations in WP3, under the direction of T. Poisot,
    b) to produce a list of candidate climate variables for WP2.

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  • WP2, directed by A. Burke, will complete the list of candidate environmental variables and produce a library of securely dated archaeological sites (Project 2.1, T. Terkmani and F. de Chardon). Project 2.2.1 (P. Nantel) will produce habitat suitability (HS) models for the three timeframes of interest. Abrupt climate events are excellent opportunities for studying the limits of human resilience, but they also pose serious methodological challenges for archaeological modelling because they are brief by nature: the transition to the LGIC, for example, lasted ~100 years. As a result, these events are poorly represented in the archaeological record and the margin of error for radiocarbon dates often exceeds their duration. To counter this difficulty, WP2 will produce habitat suitability (HS) models for two intervals, prior to and just after the climate transition, and project the results onto the climatology of the transition itself (WP1).

    Finally, Project 2.2.2 (P. Nantel) will look at indices of innovation and cultural complexity in the material culture record of the LGIC, leveraging existing databases and recently proposed statistical approaches for the study of cultural variability. The focus, however, will be on stylistic elements, an aspect of LGIC material culture production that is still understudied. A matrix of cultural variability will result that will feed analyses in WP4 (Project 4.2).

  • WP3, Landscape connectivity and fragmentation : directed by T. Poisot. Project 3.1 will use climatology produced in WP1 to drive LPJ-GUESS, a dynamic global vegetation model. The model will be used regionally (over Europe) producing estimates of net primary productivity for the three timeframes of interest as a basis for estimating landscape potential for sustaining human population. Project 3.2 will use the results of WP2 to quantify the spatial connectivity between core regions using circuit theory.  Functional landscape connectivity approaches can be used to produce estimates of a species' dispersal capacity, based on the composition of its immediate environment and its affinity for different environments. WP3 will develop a general approach to landscape functional connectivity models based on the results of WP2. The application of the connectivity models will enable us to identify possible areas of range contraction and expansion over time, with a view to explicitly including climatic data.

  • WP4 Final analysis and synthesis. (Burke, Pausata, Poisot, M. Grove & P. Nantel)

    Project 4.1 will use climate models (WP1), habitat suitability modelling (WP2) and network analysis (WP3) to reach our first objective: to explore the impact of abrupt climate change on patterns of human migration with a focus on the Late Glacial Interstadial Complex (LGIC) of Europe. Project 4.2 will interpret the results of the modelling pipeline (WP1 to WP3) using the cumulative culture hypothesis as a conceptual framework. WPs 2 & 3 will produce regional estimates of population size, will identify networks of social interaction and quantify their interconnectivity. The cumulative culture hypothesis suggests these variables predict rates of cultural innovation, patterns of transmission and complexity. WP4 will test this hypothesis, using the results of the modelling pipeline to predict hypothetical patterns of cultural innovation and transmission before and after the LGCI transition - comparing them to observable patterns of variability in the material culture record.

    The results should provide a deeper understanding of the sources of cultural variability in the archaeological record of Europe during a key climate transition and test the proposition that climate change is causally linked to cultural transformation using principles derived from cultural evolutionary theory.