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Journal Articles

Integrating ecology and society to navigate turbulence

Gunderson, L.H., C. Folke and M.A. Janssen (Editorial)

2005 Ecology and Society 10(1): 39.

Evolution of institutional rules: an immune system perspective

Janssen, M.A.

2005 Complexity 11(1): 16-23.


This article discusses the evolution of institutional rules, the prescriptions that humans use to shape their collective activities. Four aspects of the rules are discussed: coding, creation, selection, and memory. The immune system provides us a useful metaphor to relate these four aspects into a coherent framework. For each aspect, the relevant dynamics in social systems and immune systems are discussed. Finally, a framework for a computational model to study the evolution of rules is sketched.


Computational models of collective behaviour

Goldstone, R.L. and M.A. Janssen

2005 Trends in Cognitive Sciences 9(9): 424-430.


Computational models of human collective behavior offer promise in providing quantitative and empirically verifiable accounts of how individual decisions lead to the emergence of group-level organizations. Agent-based models (ABMs) describe interactions among individual agents and their environment, and provide a process-oriented alternative to descriptive mathematical models. Recent ABMs provide compelling accounts of group pattern formation, contagion and cooperation, and can be used to predict, manipulate and improve upon collective behavior. ABMs overcome an assumption that underlies much of cognitive science – that the individual is the crucial unit of cognition. The alternative advocated here is that individuals participate in collective organizations that they might not understand or even perceive, and that these organizations affect and are affected by individual behavior.


Adaptive capacity of social-ecological systems: lessons from immune systems

Janssen, M.A. and E.E. Osnas

2005 Ecohealth 2(2): 93-101.


How do systems respond to disturbances? The capacity of a system to respond to disturbances varies for different types of disturbance regimes. We distinguish two types of responses: one that enables the system to absorb disturbances from an existing disturbance regime, and one that enables a system to reconstruct itself after a fundamental change in a disturbance regime. We use immune systems as a model for how systems can deal with disturbances, and use this model to derive insights in adaptive capacity of social-ecological systems. We identify a tension between the two types of responses where one benefits from learning and memory while the other requires fast-turnover of experience. We discuss how this may affect building up adaptive capacity of social-ecological systems.

Keywords: disturbance regimeadaptive capacitysocial-ecological systemsimmune systemsresilience


The Limits of Economic Incentives: Initial results from a survey among non-industrial private land owners in Monroe County

Janssen, M.A. and A.M. York

2005 The Woodland Steward 14(1): 13-14 .

Book Chapters

Agent-based modeling

Janssen, M.A.

2005 In Modelling in Ecological Economics, edited by J Proops and P. Safonov, pp. 155-172, Edward Elgar Publishers. Edward Elgar Publishing, Cheltenham.

Incentives affecting decisions of nonindustrial private forest landowners about using their land

York, A.M., M.A. Janssen and E. Ostrom

2005 In Handbook of Environmental Politics, edited by P. Dauverge, pp. 233-248,  Edward Elgar Publishers, Cheltenham, UK.

Book Reviews

Bentley, R. A. and Maschner, H. D. G. (eds.), (2003). Complex Systems and Archaeology: Empirical and Theoretical Applications. University of Utah Press

Janssen, M.A.
2005 American Journal of Archaeology 109(3): 568-569.


Foraging of Homo ergaster and Australopithecus boisei in East African environments

Janssen, M.A., J.M. Sept and C.S. Griffith
2005 paper presented at the Center for Computational Analysis of Social and Organizational Systems (CASOS) Summer Institute. June 25 - 30. Pittsburgh, PA.


In this paper, we present the initial results of an agent-based model of foraging of hominids. The model represents foraging activities in a landscape that is based on detailed measurements of food availability in the modern East African environments. These current landscapes are used as a model for the environment of the hominids one million years ago. We explore the spatial and temporal consequences of foraging patterns in different types of semi-arid landscapes and different types of hominids (Homo ergaster and Australopithecus boisei) who are defined with different abilities and preferences.

Keywords: foraging, hominids, field data


Learning to play nice: strategy evolution in the National Hockey League

Ahn, T.K., M.A. Janssen, D.S. Reinders and J.E. Stake
2005 unpublished mimeo.


The effect of increased monitoring and rule-enforcement in National Hockey League (NHL) games is analyzed at two levels (player and team). The economic theory of crime predicts a reduction of rule-breaking due to increased deterrence. No change is observed in behavior at the player level. At the team level, however, we find a change in composition in the type of players. Private rule enforcers, the goons, become more costly and less necessary when official monitoring is increased. We observe a decrease in the salaries of the players with a high level of goonnesss as our game-theoretic model predicted.

Keywords: National Hockey League, monitoring, rule-breaking, team composition, goons


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