WHAC2026

 Workshop Topic

WHAC series aims to address a specific topic in each edition. Topics are related to historical issues and addressed with computational methods in the form of a data challenge, where a novel dataset is shared between participants.

WHAC2026 is focussed on the impact of climate on cultural evolution and social resilience. The dataset is based on Wirtz et al 2024 whose model is depicted below:

Solar activity influences climate stability, which in turn has an effect on subsistence success or failure. Mortality, partially dependent on population density, determines the relative growth rate of human populations, wich has boom and busts. During a boom, climate stability favors subsistence success, enabling positive and high relative growth rates (orange states). During a bust (blue colors), variations in climatic conditions induce subsistence failures, which in turn, enhance mortality (e.g., through malnutrition). 

The dataset is also based on Celli and Basile 2024 who annotated historical decades of different societies with secular cycle phases based on the Structural Demographic Theory, depicted below:

The structural-demographic cycle is a theoretical historical pattern of societal change driven by the balance between population, resources, and elite competition. It begins with an Expansion Phase (1), characterized by increasing social cohesion, often followed by demraphic growth. This eventually transitions into a Population Immiseration Phase (2), where population growth outpaces resources, leading to Elite Overproduction Phase (3) with falling wages, and a bloated elite class fighting for a fixed number of power positions. This tension culminates in a State Stress Phase (4), marked by state fiscal collapse, intense elite infighting, and widespread civil unrest or revolution. Finally, a Crisis Phase (5) marks an intercycle period, where population and elite numbers are drastically reduced through conflict, eventually resetting the social "carrying capacity" and clearing the path for a new cycle.

What are the relations between the two models? The WHAC2026 dataset combines both sources. Read the call for papers to download the dataset and participate to the workshop