Tolerated Theft

Tolerated theft, also known as tolerated scrounging, describes a specific form of resource sharing observed in many animal species, including humans. It occurs when an individual (the possessor) has exclusive control over a resource, but allows another individual (the scrounger or thief) to take a portion of that resource, even if the possessor is capable of defending the entire resource. This phenomenon is not explained by kin selection or direct reciprocity, but rather by an economic model that considers the costs and benefits of defense versus sharing.

The Argument

The theoretical foundation for tolerated theft was developed by Blurton Jones (1984, 1987) and further elaborated by others, particularly in the context of human foraging societies. The core argument rests on two main principles:

1. Diminishing Returns on Resource Value: The subjective value of a resource to an individual is not linear; it typically decreases as the amount of the resource possessed increases. For instance, the first unit of food might be critically important for survival, while subsequent units provide less additional benefit, especially if they exceed immediate consumption needs or storage capacity. This means that the marginal value of an additional unit of food to a well-fed individual is lower than to a starving individual.
2. Costs of Defense: Defending a resource carries costs, including energy expenditure, risk of injury (which could impair future foraging or reproductive success), and opportunity costs (time spent defending cannot be spent foraging or engaging in other fitness-enhancing activities). These costs can be substantial, especially if the potential thief is strong or persistent.

Combining these principles, the model suggests that a possessor will defend a resource only up to the point where the marginal benefit of retaining an additional unit of the resource outweighs the marginal cost of defending it. If the marginal value of a portion of the resource to the possessor is very low (e.g., they already have more than enough), and the cost of defending that portion is high, it becomes economically rational for the possessor to tolerate its theft. The 'thief' gains a high marginal benefit from the resource (because they likely have little or none), while the 'victim' incurs a lower cost by allowing the theft than by engaging in a costly defense.

This framework predicts that tolerated theft is more likely when:

• The resource is large and difficult to consume or transport entirely by one individual (e.g., a large carcass).
• The possessor is satiated or has a surplus.
• The cost of defense is high, perhaps due to the strength or number of potential scroungers.
• The scrounger is in greater need, making the marginal value of the resource higher for them.

Evidence

Empirical support for tolerated theft comes from observations across various species and human societies.

Non-Human Animals

In many social carnivores, such as lions and hyenas, dominant individuals or groups often tolerate the presence of subordinate individuals at kills, allowing them to feed, especially after the dominant individuals have eaten their fill. While aggression may occur, complete exclusion is rare, particularly with very large carcasses. Similarly, in some primate species, individuals who find a large, indivisible food item (like a fruit tree) may tolerate others feeding alongside them, rather than expending energy to defend the entire resource (e.g., chimpanzees, baboons).

Human Foraging Societies

Blurton Jones (1984) initially developed the concept to explain food sharing among Hadza hunter-gatherers in Tanzania. He observed that successful hunters often shared large game with others, even non-kin, without overt demands or expectations of immediate reciprocity. This sharing was not always voluntary in the sense of a generous gift, but rather a strategic allowance. A hunter returning with a large animal might find it difficult to consume or store all of it before spoilage, and the costs of defending it from hungry camp members (who might be strong or numerous) could be high. Allowing others to take portions minimized conflict and defense costs, while the hunter still retained a substantial share. Kaplan and Hill (1985) further documented similar patterns of sharing in Ache hunter-gatherers, where large game is widely distributed, contrasting with smaller, privately consumed resources.

This phenomenon is distinct from reciprocal altruism (Trivers, 1971), where sharing is contingent on future returns, or kin selection (Hamilton, 1964), where sharing benefits genetic relatives. Tolerated theft operates on an immediate, self-interested calculation of costs and benefits, even if it results in a distribution of resources that appears altruistic.

Critiques and Nuances

While the tolerated theft model provides a parsimonious explanation for certain forms of sharing, it has also faced scrutiny and refinement.

Some critics argue that distinguishing tolerated theft purely from other forms of sharing (like reciprocal altruism or costly signaling) can be difficult in practice. For example, a hunter who shares a large kill might still gain reputational benefits or strengthen social bonds, which could lead to future reciprocity, even if the immediate motivation is to avoid conflict. Hawkes (1991, 1993) proposed the 'showing off' hypothesis, suggesting that successful hunters might share to gain status and attract mates, which is a form of indirect reciprocity or costly signaling, rather than purely avoiding defense costs.

Another point of discussion concerns the precise measurement of 'costs of defense' and 'diminishing returns.' These are often inferred rather than directly measured, leading to debates about the relative importance of different factors. The model also assumes a degree of rationality in decision-making that might not always hold, particularly in species with less cognitive complexity.

Furthermore, the concept does not fully explain all forms of food sharing. For instance, sharing of small, easily defensible, or highly valuable resources among close kin is often better explained by kin selection. Sharing in situations where the possessor is not satiated and the costs of defense are low also points to other mechanisms, such as active reciprocity or cultural norms of generosity.

Open Questions

Future research continues to explore the interplay between tolerated theft and other sharing mechanisms. How do individuals assess the marginal value of resources and the costs of defense in real-time? What are the cognitive mechanisms underlying these decisions? To what extent do cultural norms and individual reputations modulate the dynamics of tolerated theft in human societies, potentially blurring the lines between pure tolerated theft and other forms of reciprocal or status-driven sharing? Understanding these interactions provides a more complete picture of the complex evolutionary landscape of cooperation and resource distribution.