Sugarscape

Sugarscape is an agent-based computational model used to study how simple, local rules can generate complex social phenomena. Developed by Joshua M. Epstein and Robert Axtell in 1996, it serves as a foundational example in their book Growing Artificial Societies: Social Science from the Bottom Up. The model is intended to illustrate how individual behavior can give rise to macro-level patterns such as wealth distribution, migration, and segregation.

The core setup consists of a two-dimensional, toroidal grid representing a landscape of sugar. Each cell has a sugar value that can regenerate over time. A set of agents inhabit the landscape, each endowed with attributes such as metabolism (the amount of sugar consumed per time step), vision (how far they can see to move), age, and wealth. Agents move across the grid to harvest sugar, typically seeking the richest available cell within their vision, and then consume the resource to sustain themselves.

Key dynamics include resource regeneration, consumption, and mortality. Agents die when their wealth falls to zero, and births occur when an agent’s wealth exceeds a reproduction threshold, producing offspring with inherited traits and occasional mutations. The model emphasizes local decision-making and simple rules to explore how inequality and other social patterns may emerge without presupposing sophisticated strategic behavior.

Sugarscape has influenced the field of agent-based modeling and complexity science, illustrating concepts such as emergence, adaptation, and the formation of macro-structures from micro-level rules. Variants and extensions have added trading, disease, culture, and more complex social processes to the basic framework.