Hierarchy Entropy Degeneration Explains the Rat Utopia Population Collapse: The Role of Full Visibility and Isolation

2025-08-11

AI Summary

In Calhoun’s “mouse utopia” experiment, populations collapsed despite abundant resources—a phenomenon whose underlying mechanism remains unclear. This paper proposes the “entropy degradation hypothesis”: in fully isolated, visually unobstructed environments, social hierarchies (e.g., pecking orders) become highly visible and rigid, causing intergenerational uncertainty about rank—quantified as information entropy—to decay progressively. This entropy loss erodes individuals’ motivation for socially adaptive behavior, ultimately triggering systemic collapse. Methodologically, we innovatively integrate information-theoretic entropy into animal social behavior modeling, developing a game-theoretic intergenerational evolutionary matrix model and validating it via multi-agent simulation that reproduces the full population trajectory (growth, stagnation, collapse). Results reveal a critical positive feedback loop: increasing rank determinacy amplifies behavioral demotivation, driving irreversible societal disintegration. This framework offers a novel theoretical lens for understanding structural decline in highly interconnected societies.

Technology Category

• Game Theory and Economic Paradigms: Imperfect Information
• Cognitive Modeling & Cognitive Systems: Social Cognition And Interaction
• Multiagent Systems: Mechanism Design

Application Category

• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• Web Mining and Content Analysis: Models for Web evolution
• Social Networks and Social Media: Computational social science

Abstract

Calhoun's Rat Utopia experiments demonstrated a puzzling population trajectory: initial growth, plateau, and eventually a total collapse of the rat population despite abundant resources. This paper proposes a hypothesis that the enclosure's design enabled full visibility of the social hierarchy (pecking order), leading to entropy degeneration: progressive loss of uncertainty in rats' perceived ranks over generations. High initial uncertainty drives engagement in dominance, reproduction, and care; as visibility solidifies the hierarchy over the generations, uncertainty vanishes, nullifying perceived gains from social activities. Simulations reproduce the experimental arc which rely on a game theoretic matrix that is parameterized by the uncertainty (entropy) in the hierarchy which changes over rat generations.

Problem

• Explains rat population collapse in utopia experiments
• Examines full visibility causing social hierarchy entropy degeneration
• Models how hierarchy uncertainty loss drives reproductive decline

Innovation

• Full visibility hierarchy entropy degeneration
• Game theoretic matrix with uncertainty parameter
• Simulations reproducing population collapse arc