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Investors and Exploiters in Ecology and Economics

Principles and Applications

Edited by Luc-Alain Giraldeau, Philipp Heeb and Michael Kosfeld

“Evolutionary biologists and economists have a shared interest in understanding why some individuals in a group behave as ‘free riders’, benefiting from the efforts of others. If free riding is a good strategy, what limits its spread in a population? This edited book explores both the underlying science and its practical applications, for example in vaccination policy. It is a very valuable up-to-date summary of knowledge in an important area of interdisciplinary science.

John Krebs

Emeritus Professor of Zoology, University of Oxford

Cheats, exploiters, and scroungers have forever been the bane of evolutionary models of cooperation and altruism. This remarkable volume, which brings together leading biologists and economists, sheds new light on understanding a world where investors and exploiters can be found in every nook and cranny of social dynamics.

Lee Alan Dugatkin

Professor of Biology, University of Louisville; coauthor of How to Tame a Fox (and Build a Dog): Visionary Scientists and a Siberian Tale of Jump-Started Evolution

Economists hesitate to learn from biologists and vice versa. Investors and Exploiters in Ecology and Economics shows that this can be overcome. This fascinating book sheds new light on cooperation, exploitation, and conflict. Natural resource exploitation and free riding in health are cases in point covered in the volume, yet by extrapolation the insights may even hint toward fundamental forces behind phenomena like populism, protectionism, and inequality.

Joachim von Braun

Professor for Economic and Technical Change, Director, Center for Development Research, Bonn University, Germany; coeditor of Marginality: Addressing the Nexus of Poverty, Exclusion and Ecology

Experts from the natural and social sciences examine the coexistence of productive and exploitative behavior strategies observable in many species at many levels.

In the natural world, some agents (investors) employ strategies that provide resources, services, or information, while others (exploiters) gain advantages through these efforts. This behavior coexists and can be observed in many species and at many levels. For example, bacteria depend on the existence of biofilms to synthesize constituent proteins; cancerous cells employ angiogenesis to feed a tumor; and parents forgo vaccinating their children yet benefit from herd immunity. Two independent research traditions have developed to analyze this behavior—one couched in evolutionary theory championed by behavioral ecologists, the other in social science concepts advocated by economists. In this book experts from economics, evolutionary biology, behavioral ecology, public health, and anthropology look for commonalities in understanding and approach.

The contributors consider parasitic strategies in ecological and economic terms; the governance of natural resources, with insights from “producer-scrounger models,” forest management, and game theory; human health, discussing therapeutic opportunities, public health economics, and the integration of perspectives; and behavioral, social, and institutional consequences of exploitation strategies.


Michal Arbilly, Zoltán Barta, Jan Börner, Sam P. Brown, Max Burton-Chellew, Juan Camilo Cardenas, Sasha R. X. Dall, Miguel dos Santos, Frédérique Dubois, Paul W. Ewald, Gigi Foster, Paul Frijters, Luc-Alain Giraldeau, Ben Greiner, Reem Hajjar, Philipp Heeb, Markus Herrmann, Tatsuya Kameda, Alex Kacelnik, Kiryl Khalmetski, Andrew J. King, Hanna Kokko, Michael Kosfeld, Wolfgang Leininger, Arnem Lotem, Kimberley J. Mathot, John M. McNamara, Friederike Mengel, Johan A. Oldekop, Daniel Pauly, Benjamin Roche, Devesh Rustagi, William J. Sutherland, Frédéric Thomas, Thomas J. Valone, Joël van der Weele, Björn Vollan, Claus Wedekind, Bruce Winterhalder

Evolutionary and Economic Strategies for Benefitting from Other Agents’ Investments

Luc-Alain Giraldeau and Philipp Heeb, Chairs

Program Advisory Committee

Luc-Alain Giraldeau, Philipp Heeb, Alex Kacelnik, Michael Kosfeld, Julia R. Lupp, and Frédéric Thomas


When goal-driven agents, such as humans, other organisms, or institutions, seek resources (including services or information) in the presence of others, they can invest effort directly to obtain the resource or indirectly, by exploiting others’ producing activity. Such situations of “social parasitism” create social dilemmas where some individuals pay production costs whilst others can obtain some benefits through some form of free-riding. In foraging ecology such strategies have been studied, for example, using the game-theoretical model known as “producers and scroungers,” but many other models that concern social and economic interactions also address these problems.

Examples of real-life systems where the problem is prevalent include:

  • Some species provision their dependent offspring while others specialize on letting offspring be nourished by members of other species.
  • In humans, cooperation and solidarity norms develop that can sometimes provide opportunities for free-loading and exploitation.
  • Governments affect their own countries’ climate prospects by managing their own greenhouse emissions and by attempting to impose restraint on other countries.
  • Individuals can influence their own probability of infection by vaccination or indirectly by taking advantage of the lowered disease incidence that results from the vaccination of others.
  • Among cancerous cell societies, some cancerous cells stimulate angiogenesis in tumors while others benefit from the extra oxygen and nutrients, without investing in the stimulants.
  • Among manipulative parasites, not all individuals within a given host invest energy into the manipulative effort but all benefit from the changes induced in the behavior of the host.
  • The use of antibiotics combats infection but also increases pathogen resistance through natural selection. The therapeutic benefit to the individual often feeds on the restrained use of the antibiotic by others.
  • In natural resource use, humans can pay the cost of being ecologically prudent and/or address effort to impose frugality in others.

We aim to promote integration between studies in these different contexts, extracting lessons that could inform action where human interests are involved (e.g., in conservation, public health, market stability, etc.). This Forum will discuss case studies, compare alternative modeling approaches and explore the potential for regulation environments.

This Forum is supported by the Deutsche Forschungsgemeinschaft

The German Research Foundation

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  • To explore real-life cases and theoretical models that deal with impacts of “social parasitism” in humans and other organisms.
  • To bring together evolutionary biologists, economists and other social scientists to benefit from commonalities between them.
  • To work toward a common synthesis that would promote a unified framework and explore implications for public health, natural resource use, and the design of institutions.

We will approach these goals from four perspectives:

  • Ecological and Economic Conditions of Parasitic Strategies
  • Governance of Natural Resources
  • Human Health
  • Consequences for Individual Behavior, Social Structure, and Design of Institutions

This Forum is supported by the Deutsche Forschungsgemeinschaft

The German Research Foundation

DFG logo