Casual observation and controlled experiments show that humans display great heterogeneity in their tendency to exploit others or invest in mutual cooperation. This chapter reviews models in the economics literature that can explain the coexistence of free riders ( exploiters) and cooperators (investors). A distinction is made between models of full and bounded rationality. Although some models provide tentative explanations, there is a large gap between the empirical and theoretical literature, and there has been little effort to integrate long- and short-run models.

In many situations across biology and economics, there is often one individual, or “agent,” that invests effort into a benefi cial task and also one individual that, in contrast, foregoes the effort of investing, and instead simply exploits the efforts of another. What makes an individual choose to invest in production versus exploiting the efforts of another? If everyone invests, then exploitative strategies become very profi table; however if everyone is exploitative, there will be no investments to exploit. How does natural selection resolve this dilemma? What can economic institutions do to encourage investment? Can biologists and economists learn from the approach of each other’s discipline? This chapter outlines the commonalities and differences in approach of the two disciplines to the general problem of investment versus exploitation. It develops a model to encapsulate the general features of many scenarios (“games”) involving potential exploitation and explores the benefi ts of a unifi ed approach, outlining current limitations and important areas for future investigation.

Humans are currently using natural resources at unprecedented rates and it is not difficult to extrapolate how this could lead to global catastrophes of various kinds. To mitigate eventual consequences, our understanding of the processes involved must be improved. Since resource use frequently involves groups, free-riding behavior (i.e., exploiting the efforts of others) must be expected. Recent evolutionary studies indicate that exploitation of others’ efforts can dramatically alter how resources are utilized. Two types of effort are exploitable: the harvesting and maintenance of resources. This chapter argues that the exploitation of harvesting efforts can be analyzed as a producer–scrounger evolutionary game. The presence of scroungers (exploiters) in a group usually decreases the overall use of resources by the group. Factors that increase the proportion of scroungers (e.g., energy reserves, existence of dominance hierarchy, or prevalence of relatedness) can further decrease resource use. By contrast, aggression and the compatibility of scrounger and producer strategies elevate resource use. In temporally unstable patches, scrounging does not affect resource use in groups that are at equilibrium. Encouraging scrounging may lower resource use, even in humans, but this raises a moral dilemma: individual scrounging is bad, reduced resource overuse by the population is good. Surprisingly, only a small portion of the literature has considered the consequences of cheating in terms of the natural resource management—a situation that demands attention in future research.

Community-based natural resource management (CBNRM) initiatives aim to link socioeconomic development with sustainable natural resource use and the conservation of biodiversity of natural resources. The principal ethos of CBNRM relies on the concept that rights, responsibilities, and authority for natural resource management decisions should rest, at least in part, with local communities, and there is an increasing recognition among policy makers and practitioners that the decentralization of natural resource management is central to a rights-based sustainable development approach. Although there has been a global push to decentralize natural resource governance over the past two decades, outcomes have been mixed, with many initiatives failing to reach their intended goals of both natural resource conservation and socioeconomic development. Over the past few decades, much research has focused on identifying the kinds of enabling conditions and accompanying institutional arrangements needed to promote collective action (investing) and reduce free riding (exploitation) to bring about more sustainable and equitable management of shared resources. This chapter reviews the theory and conditions thought to aid and allow communities collectively to manage resources more equitably and sustainably. The management of community forests is used to explore current knowledge gaps related to collective resource management and discuss what these gaps represent for sustainable development interventions.

Renewable resources have the potential to be used in a sustainable manner but typically are not, often due to the existence of exploiters or free riders. This chapter analyzes free-riding behavior using the prisoner’s dilemma-based public goods model and the producer–scrounger model. Overuse of renewable resources is examined under four investor–exploiter scenarios that are derived from modifications of the classic producer–scrounger model, and which vary in the degree of excludability of a discovered resource and in the cost of adopting each strategy. Two important factors are found to reduce overuse: when a finder’s advantage can be created for investors, and when the costs of playing exploiter are increased relative to the costs of playing investor. Applying the investor–exploiter model to a fisheries scenario, discussion follows on how interventions designed to reduce overuse may be consistent with the existence of a finder’s advantage. A variety of existing interventions can be seen as increasing the costs of adopting the exploiter strategy.

Bacterial virulence (damage to host) is often cooperative, with individual cells paying costs to promote collective exploitation. This chapter reviews how cooperative virulence traits offer novel therapeutic avenues involving either the genetic introduction or chemical induction of “cheats” that can socially exploit cooperative wild-type infection. Issues of efficacy and evolutionary robustness are discussed, and evidence of an evolutionarily robust therapeutic that targets bacterial social behaviors is highlighted.

Public health faces novel challenges because of rising bacterial resistance to antibiotics and the possible fatal spread of highly communicable viral infections. Multiple economic agents interact in the use and provision of anti-infective drugs, without accounting for their impact on others, and this gives rise to positive and negative externalities. Furthermore, anti-infective drugs may be linked on the supply side depending on the particular epidemiological context. A common example is that of antibiotic treatment effectiveness, which can be lost over time, affecting various antibiotics belonging to the same antibiotic family. This chapter describes how conflicting private objectives among economic agents may lead to exploitation strategies that lower the overall social welfare. Important open research questions are highlighted and various possible public policies addressed that can help address the problem of antimicrobial resistance.

Human infectious disease results from many factors (e.g., human behavior, disease organisms, institutions) that often interact as opposing agents in accordance to the investor–exploiter dichotomy. Directing interventions to influence these opposing roles may improve human health by differentially influencing the success of exploiters and investors. Alterations made on one level may change outcomes on other levels and affect the impact of disease on states of health. These interactions need to be incorporated into economic models to inform the assessments of interventions to improve health.

Cooperation within larger groups is often endangered by incentives to free ride. One goal of market and institutional design is to create environments in which socially efficient cooperation can be achieved. The main point in this chapter is that only considering first-order incentives to cooperate within a larger group may not be sufficient, as subcoalitions display reciprocal behavior despite the incentives to renege. Three related complications are discussed: (a) exploitative behavior is often coordinated in subgroup coalitions, (b) natural within-group resistance to exploitation already exists, and (c) the actions of group members can often only be imperfectly monitored. Given these realities, implications of current research for applied market and institutional design are outlined.

This chapter addresses the behavioral consequences of individuals (exploiters) that use the investments of others (investors) rather than investing time or effort in procuring a resource themselves. The optimal exploitation strategy has been traditionally studied in behavioral ecology using the producer–scrounger (PS) model, a simple evolutionary game theoretic model in which producers (investors) search for resources while scroungers (exploiters) use the resources found by producers. For simplicity, a key assumption of the PS model is that the producer remains passive toward scroungers. As the presence of scroungers is costly, both empirical and theoretical evidence is reviewed that one major consequence of having exploiters is the adoption by producers of strategies that reduce the benefits of scroungers, giving rise to countermeasures by scroungers. In addition, scroungers have effects on population structure, notably by generating consistent differences among individuals and affecting spatial preferences within groups. Finally, although the PS game reviewed here is set in an explicit social foraging context, it is argued that it can be generalized to a large number of situations of social exploitation. Reviewing the impact of scrounging on populations should help generate parallels to explore the consequences of such exploitative behavior in economics and public health.

“Exploitation” or free riding are names for strategies by which agents benefit from other agents’ investments. This chapter reviews the consequences of these exploitative strategies for individual behavior, social structure, and design of institutions. From an evolutionary perspective, it begins by outlining how natural selection should act to construct behavioral connections that maximize the benefits and minimize the costs of sociality for individuals. Individuals are predicted to show specific leaving or joining decision rules that will construct groups composed of complementary strategies; alternatively, they should be plastic in response to their social environment, which can lead to conditional strategies and social niche construction. What happens on an individual level impacts, in turn, social structures. When individuals have fewer or more frequent interactions with a set of specific (known) individuals, “groupiness” may result to reduce uncertainty in interactions. In humans, common knowledge of within-group norms can further facilitate coordination on socially efficient equilibriums and establish cooperation. Once groups are maintained and cooperate to produce and share resources, they become open to exploitation by other groups, which is directly relevant to the design of institutions. Economic conflict theory offers a potential framework for understanding and predicting exploitative behavior between groups. Through a better understanding of exploitation at these different levels, it is hoped that the payoffs of specific interactions can be adjusted to reduce the negative impacts on a system.