Kim Sterelny's book The Pleistocene social contract provides an exceptionally well-informed and credible narrative explanation of the origins of inequality and hierarchy. In this essay review, we reflect on the role of rational choice theory in Sterelny's project, before turning to Sterelny's reasons for doubting the importance of cultural group selection. In the final section, we compare Sterelny's big picture with an alternative from David Wengrow and David Graeber.

Both biosemiotics and evolutionary epistemology are concerned with how knowledge evolves. (Applied) Evolutionary Epistemology thereby focuses on identifying the units, levels, and mechanisms or processes that underlie the evolutionary development of knowing and knowledge, while biosemiotics places emphasis on the study of how signs underlie the development of meaning. We compare the two schools of thought and analyze how in delineating their research program, biosemiotics runs into several problems that are overcome by evolutionary epistemologists. For one, by emphasizing signs, biosemiotics (...) needs to delineate a semiotic threshold, which is a problem not encountered by evolutionary epistemologists. Instead, the latter recognizes that all organisms are knowers that evolve knowledge, which they recognize to extend toward phenomena produced by organisms such as behavior, cognition, language, culture, science, and technology. Secondly, biosemiotics attempts at continuing adaptationist notions on how organisms relate to their environment, while especially Applied Evolutionary Epistemology comes to redefine the nature of the organism–environment relationship in such a way that it recognizes the spatiotemporal boundedness of existence, which in turn makes adaptationist accounts obsolete. (shrink)

This essay offers some reflections on Samir Okasha’s new monograph Agents and Goals in Evolution, his style of doing philosophy, and the broader philosophy of nature project of trying to make sense of agency and rationality as natural phenomena.

Darwin provided us with a powerful theoretical framework to explain the evolution of living systems. Natural selection alone, however, has sometimes been seen as insufficient to explain the emergence of new levels of selection. The problem is one of “circularity” for evolutionary explanations: how to explain the origins of Darwinian properties without already invoking their presence at the level they emerge. That is, how does evolution by natural selection commence in the first place? Recent results in experimental evolution suggest a (...) way forward: Paul Rainey and his collaborators have shown that Darwinian properties could be exogenously imposed via what they call “ecological scaffolding.” This could solve the “black box” dilemma faced by Darwinian explanations of new levels of organization. Yet, despite “scaffolding” recently becoming a popular term in the study of cognition, culture, and evolution, the concept has suffered from vagueness and ambiguity. This article aims to show that scaffolding can be turned into a proper scientific concept able to do explanatory work within the context of the major evolutionary transitions. Doing so will allow us to once again extend the scope of the Darwinian model of evolution by natural selection. (shrink)

Social evolution theory provides a wide array of successful evolutionary explanations for cooperative traits. However and surprisingly, a number of cases of unexplained cooperative behaviour remain. Shouldn’t they cast doubt on the relevance of the theory, or even disconfirm it? This depends on whether the theory is akin to a research programme such as adaptationism, or closer to a theory – a set of compatible, confirmable hypotheses. In order to find out, we focus on the two main tenets of social (...) evolution theory, namely reciprocity explanations and kin selection. Reciprocity-based explanations are extremely hard to confirm. This is due, first to the multiple realisability of explanatory processes, factors and strategies, despite apparent reasons to the contrary; second, to the high quantity, and limited availability of data needed to eliminate or back up such explanations. One of our target cases vividly illustrates these limitations. Moreover, kin selection, while relatively easy to disconfirm in particular cases, seems to enjoy a more limited explanatory scope than previously thought. Overall, social evolution theory turns out to be neither a research programme nor a theory, but a heterogeneous scientific entity, composed of parts that are amenable to confirmation and others barely so. (shrink)

Abstract In The Descent of Man (1879), Charles Darwin proposed a speculative evolutionary explanation of extended benevolence—a human sympathetic capacity that extends to all nations, races, and even to all sentient beings. This essay draws on twenty-first century social science to show that Darwin’s explanation is correct in its broad outlines. Extended benevolence is manifested in institutions such as legal human rights and democracy, in behaviors such as social movements for human rights and the protection of nonhuman animals, and in (...) normative attitudes such as emancipative values and a commitment to promote the rights or welfare of animals. These phenomena can be substantially explained by cultural evolutionary forces that trace back to three components of what Darwin called the human “moral sense”: (1) sympathy, (2) our disposition to follow community rules or norms, and (3) our capacity to make normative judgments. Extended benevolence likely emerged with “workarounds,” including political ideologies, that established an inclusive sympathetic concern for sentient life. It likely became as widespread as it is now due to recently arisen socio-economic conditions that have created more opportunities for people to have contact with and take the perspective of a broader cross-section of humanity, as well as other species. (shrink)

The dominant theory of the evolution of moral cognition across a variety of fields is that moral cognition is a biological adaptation to foster social cooperation. This chapter argues, to the contrary, that moral cognition is likely an evolutionary exaptation: a form of cognition where neurobiological capacities selected for in our evolutionary history for a variety of different reasons—many unrelated to social cooperation—were put to a new, prosocial use after the fact through individual rationality, learning, and the development and transmission (...) of social norms. This chapter begins with a brief overview of the emerging behavioral neuroscience of moral cognition. It then outlines a novel theory of moral cognition that I have previously argued explains these findings better than alternatives. Finally, it shows how the evidence for this theory of moral cognition and human evolutionary history together suggest that moral cognition is likely not a biological adaptation. Instead, like reading sheet music or riding a bicycle, moral cognition is something that individuals learn to do—in this case, in response to sociocultural norms created in our ancestral history and passed down through the ages to enable cooperative living. (shrink)

What makes fast, cumulative cultural evolution work? Where did it come from? Why is it the sole preserve of humans? We set out a self-assembly hypothesis: cultural evolution evolved culturally. We present an evolutionary account that shows this hypothesis to be coherent, plausible, and worthy of further investigation. It has the following steps: (0) in common with other animals, early hominins had significant capacity for social learning; (1) knowledge and skills learned by offspring from their parents began to spread because (...) bearers had more offspring, a process we call CS1 (or Cultural Selection 1); (2) CS1 shaped attentional learning biases; (3) these attentional biases were augmented by explicit learning biases (judgements about what should be copied from whom). Explicit learning biases enabled (4) the high-fidelity, exclusive copying required for fast cultural accumulation of knowledge and skills by a process we call CS2 (or Cultural Selection 2), and (5) the emergence of cognitive processes such as imitation, mindreading and metacognition – ‘cognitive gadgets’ specialised for cultural learning. This self-assembly hypothesis is consistent with archaeological evidence that the stone tools used by early hominins were not dependent on fast, cumulative cultural evolution, and suggests new priorities for research on ‘animal culture’. (shrink)

We are all guided by thousands of norms, but how did our capacity for normative cognition evolve? I propose there is a deep but neglected link between normative cognition and practical skill. In modern humans, complex motor skills and craft skills, such as toolmaking, are guided by internally represented norms of correct performance. Moreover, it is plausible that core components of human normative cognition evolved as a solution to the distinctive problems of transmitting complex motor skills and craft skills, especially (...) skills related to toolmaking, through social learning. If this is correct, the expansion of the normative domain beyond technique to encompass more abstract norms of fairness, reciprocity, ritual and kinship involved the elaboration of a basic platform for the guidance of skilled action by technical norms. This article motivates and defends this “skill hypothesis” for the origin of normative cognition and sets out various ways in which it could be empirically tested. (shrink)

The impressive variation amongst biological individuals generates many complexities in addressing the simple-sounding question what is a biological individual? A distinction between evolutionary and physiological individuals is useful in thinking about biological individuals, as is attention to the kinds of groups, such as superorganisms and species, that have sometimes been thought of as biological individuals. More fully understanding the conceptual space that biological individuals occupy also involves considering a range of other concepts, such as life, reproduction, and agency. There has (...) been a focus in some recent discussions by both philosophers and biologists on how evolutionary individuals are created and regulated, as well as continuing work on the evolution of individuality. (shrink)

Part of Allen et al.’s criticism of Hamilton’s rule makes sense only if we are interested in social adaptation rather than merely social selection. Under the assumption that we are interested in casually modeling social adaptation, I illustrate how graphical causal models of social adaptation can be useful for predicting evolution by adaptation. I then argue for two consequences of this approach given some of the recent philosophical literature. I argue Birch’s claim that the proper way to understand Hamilton’s rule (...) is as providing an organizational framework for causal models is incorrect. I provide an account of a causally adequate decomposition of evolutionary change due to social adaptation and show that my account is superior to Okasha’s. (shrink)

I distinguish two roles for a fitness concept in the context of explaining cumulative adaptive evolution: fitness as a predictor of gene frequency change, and fitness as a criterion for phenotypic improvement. Critics of inclusive fitness argue, correctly, that it is not an ideal fitness concept for the purpose of predicting gene-frequency change, since it relies on assumptions about the causal structure of social interaction that are unlikely to be exactly true in real populations, and that hold as approximations only (...) given a specific type of weak selection. However, Hamilton took this type of weak selection, on independent grounds, to be responsible for cumulative assembly of complex adaptations. In this special context, I argue that inclusive fitness is distinctively valuable as a criterion for improvement and a standard for optimality. Yet to call inclusive fitness a criterion for improvement and a standard for optimality is not to make any claim about the frequency with which inclusive fitness optimization actually occurs in nature. This is an empirical question that cannot be settled by theory alone. I close with some reflections on the place of inclusive fitness in the long running clash between ‘causalist’ and ‘statisticalist’ conceptions of fitness. (shrink)

Should the norms of honor cultures be classified as a variety of morality? In this paper, we address this question by considering various empirical bases on which norms can be taxonomically organised. This question is of interest both as an exercise in philosophy of social science, and for its potential implications in meta-ethical debates. Using recent data from anthropology and evolutionary game theory, we argue that the most productive classification emphasizes the strategic role that moral norms play in generating assurance (...) and stabilizing cooperation. Because honor norms have a similar functional role, this account entails honor norms are indeed a variety of moral norm. We also propose an explanation of why honor norms occur in a relatively unified, phenotypically distinctive cluster, thereby explaining why it is tempting to regard them as taxonomically distinct. (shrink)

For decades Darwinian processes were framed in the form of the Lewontin conditions: reproduction, variation and differential reproductive success were taken to be sufficient and necessary. Since Buss and the work of Maynard Smith and Szathmary biologists were eager to explain the major transitions from individuals to groups forming new individuals subject to Darwinian mechanisms themselves. Explanations that seek to explain the emergence of a new level of selection, however, cannot employ properties that would already have to exist on that (...) level for selection to take place. Recently, Hammerschmidt et al. provided a ‘bottom-up’ experiment corroborating much of the theoretical work Paul Rainey has done since 2003 on how cheats can play an important role in the emergence of new Darwinian individuals on a multicellular level. The aims of this paper are twofold. First, I argue for a conceptual shift in perspective from seeing cheats as a ‘problem’ that needs to be solved for multi-cellularity to evolve to the very ‘key’ for the evolution of multicellularity. Secondly, I illustrate the consequences of this shift for both theoretical and experimental work, arguing for a more prominent role of ecology and the multi-level selection framework within the debate then they currently occupy. (shrink)

Biological market theory has in recent years become an important part of the social evolutionist’s toolkit. This article discusses the explanatory potential and pitfalls of biological market theory in the context of big picture accounts of the evolution of human cooperation and morality. I begin by assessing an influential account that presents biological market dynamics as a key driver of the evolution of fairness norms in humans. I argue that this account is problematic for theoretical, empirical, and conceptual reasons. After (...) mapping the evidential and explanatory limits of biological market theory, I suggest that it can nevertheless fill a lacuna in an alternative account of hominin evolution. Trade on a biological marketplace can help explain why norm-based cooperation did not break down when our late-Pleistocene ancestors entered new, challenging social and economic environments. (shrink)

Altruistic deception (or the telling of “white lies”) is common in humans. Does it also exist in non-human animals? On some definitions of deception, altruistic deception is impossible by definition, whereas others make it too easy by counting useful-but-ambiguous information as deceptive. I argue for a definition that makes altruistic deception possible in principle without trivializing it. On my proposal, deception requires the strategic exploitation of a receiver by a sender, where “exploitation” implies that the sender elicits a behaviour in (...) the receiver that is beneficial in a different type of situation and is expressed only because the signal raises the probability, from the receiver’s standpoint, of that type of situation. I then offer an example of a real signal that is deceptive in this sense, and yet potentially altruistic (and certainly cooperative): the purr call of the pied babbler. Fledglings associate purr calls with food, and adults exploit this learned association, in the absence of food, to lead fledglings away from predators following an alarm call. I conclude by considering why altruistic deception is apparently so rare in non-human animals. (shrink)

Hamilton’s Rule, named after the evolutionary biologist Bill Hamilton, and the related concepts of inclusive fitness and kin selection, have been the bedrock of the study of social evolution for the past half century. In ’The Philosophy of Social Evolution’, Jonathan Birch provides a comprehensive introduction to the conceptual foundations of the Hamiltonian view of social evolution, and a passionate defence of its enduring value in face of the recent high profile criticism. In this review essay, I first outline the (...) version of Hamilton’s Rule defended by Birch, dubbed Hamilton’s Rule General, and its derivation. With this in place, I then navigate through the fierce disagreements that Hamilton’s Rule generates among social evolution researchers and evaluate Birch’s central argument of the book that HRG serves as an organizing framework for social evolution research under which we can compare and interpret more detailed causal models. I then spend the remainder of the review discussing what I take to be three of the most exciting implications of Hamilton’s thinking raised by Birch: the extension of Hamilton’s Rule to mobile genetic elements, maximization of inclusive fitness models and the idea of adaptation as organism design, and the relationship between Hamilton’s approaches to social behaviour and the gene’s-eye view of evolution. (shrink)

This paper attempts to reconcile critics and defenders of inclusive fitness by constructing a synthesis that does justice to the insights of both. I argue that criticisms of the regression-based version of Hamilton’s rule, although they undermine its use for predictive purposes, do not undermine its use as an organizing framework for social evolution research. I argue that the assumptions underlying the concept of inclusive fitness, conceived as a causal property of an individual organism, are unlikely to be exactly true (...) in real populations, but they are approximately true given a specific type of weak selection that Hamilton took, on independent grounds, to be responsible for the cumulative assembly of complex adaptation. Finally, I reflect on the uses and limitations of “design thinking” in social evolution research. The debate about the foundations of inclusive fitness theory that has followed in the wake of Nowak, Tarnita and Wilson’s (1) critique has been remarkably polarizing. After several rounds of rebuttals and replies, there is still little evidence of any serious reconciliation between the theory’s critics (2-10) and its defenders (11-24). It doesn’t have to be this way. I believe that, on the main points of disagreement, it is possible to find a way forward that does justice to the insights of both camps. My aim in this paper is to find that way forward. (shrink)

Cultural selection models aim to explain cultural phenomena as the products of a selective process, often characterising institutions, practices, norms or behaviours as adaptations. I argue that a lack of attention has been paid to the explanatory power of cultural selection frameworks. Arguments for cultural selection frequently depend on demonstrating only that selection models can in principle be applied to culture, rather than explicitly demonstrating the explanatory payoffs that could arise from their application. Understanding when and how cultural selection generates (...) powerful explanations is crucial to evaluating cultural selection, as well as realising its promised epistemic and practical benefits. I argue that the ability for cultural selection to explain ‘design without a designer’ is crucial to successful and powerful cultural selection explanations. I introduce the strategy of comparing cultural selection to goal-directed agent accounts in order to evaluate when cultural selection can provide distinctive explanatory payoffs, drawing on two case studies to illustrate the benefits of this strategy. I argue that a focus on phenomena which cannot be explained through intention or agency-based explanations in particular could provide a fruitful avenue to identifying the cases where cultural selection can be insightfully applied. (shrink)

Cumulative cultural evolution is often claimed to be distinctive of human culture. Such claims are typically supported with examples of complex and historically late-appearing technologies. Yet by taking these as paradigm cases, researchers unhelpfully lump together different ways that culture accumulates. This article has two aims: (a) to distinguish four types of cultural accumulation: adaptiveness, complexity, efficiency, and disparity and (b) to highlight the epistemic implications of taking complex hominin technologies as paradigmatic instances of cumulative culture. Addressing these issues both (...) clarifies the cumulative culture concept and demonstrates the importance of further cumulative culture research into non-human animals and ancestral hominins. (shrink)

Evolutionary transitions in individuality (ETIs) are events during which individuals at a given level of organization (particles) interact to form higher-level entities (collectives) which are then recognized as new individuals at that level. ETIs are intimately related to levels of selection, which, following Okasha, can be approached from two different perspectives. One, referred to as ‘synchronic’, asks whether selection occurs at the collective level while the partitioning of particles into collectives is taken for granted. The other, referred to as ‘diachronic’, (...) asks about the origins of the partitioning of particles into collectives. After having presented the two perspectives and a classical formalism used to deal with the levels-of-selection question in the literature, namely the multilevel version of the Price equation, I show that because this formalism treats the levels-of-selection question from a synchronic perspective, it is inadequate to explain ETIs. This is because a fundamental aspect of ETIs is the origin of collectives. From there, I develop a framework for levels of selection compatible with the diachronic perspective. This framework relies on the distinction between what I call, on the one hand, a ‘functional aggregative collective trait’, and on the other hand, a ‘functional non-aggregative collective trait’. After having presented this distinction, I implement it in the Price equation, leading to a new statistical partitioning of this equation which, I argue, represents a causal decomposition more relevant for ETIs. Finally, I exploit this partitioning to explain the critical stages of an ETI. In addition to its explanatory power, a measure of the degree of functional non-aggregativity could be used as a proxy for the degree of individuality of a collective. (shrink)

The Price equation is currently considered one of the fundamental equations —or even the fundamental equation— of evolution. In this article, we explore the role of this equation within cultural evolutionary theory. More specifically, we use it to account for the explanatory power and the theoretical structure of a certain generalised version of dual-inheritance theory. First, we argue that, in spite of not having a definite empirical content, the Price equation offers a suitable formalisation of the processes of cultural evolution, (...) and provides a powerful heuristic device for discovering the actual causes of cultural change and accumulation. Second, we argue that, as a consequence of this, a certain version of the Price equation is the fundamental law of cultural evolutionary theory. In order to support this claim, we sketch the ideal structure of dual-inheritance theory and we stress the unificatory role that the Price equation plays in it. (shrink)

This paper disputes the widespread assumption that beliefs and desires may be attributed as theoretical entities in the service of the explanation and predic- tion of human behavior. The literature contains no clear account of how beliefs and desires might generate actions, and there is good reason to deny that principles of rationality generate a choice on the basis of an agent’s beliefs and desires. An alter- native conception of beliefs and desires is here introduced, according to which an attribution (...) of belief is, in a certain sense, an assertion on the believer’s behalf and an attribution of desire is, in a certain sense, a command on the desirer’s behalf. In terms of this conception of the attribution of beliefs and desires, we can begin to understand how attributions of beliefs and desires can be explanatory, although we still cannot expect the attribution of beliefs and desires to generate predictions based on an assumption of rationality. Finally, the reality of beliefs and desires is likened to the reality of money; it is the reality of things governed by objective norms. (shrink)

Molecular methods have revolutionised virtually every area of biology, and metazoan phylogenetics is no exception: molecular phylogenies, molecular clocks, comparative phylogenomics, and developmental genetics have generated a plethora of molecular data spanning numerous taxa and collectively transformed our understanding of the evolutionary history of animals, often corroborating but at times opposing results of more traditional approaches. Moreover, the diversity of methods and models within molecular phylogenetics has resulted in significant disagreement among molecular phylogenies as well as between these and earlier (...) phylogenies. How should this broad and multifaceted problem be tackled? I argue that the answer lies in integrating evidence to infer the best evolutionary scenario. I begin with an overview of recent development in early metazoan phylogenetics, followed by a discussion of key conceptual issues in phylogenetics revolving around phylogenetic evidence, theory, methodology, and interrelations thereof. I then argue that the integration of different kinds of evidence is necessary for arriving at the best evolutionary scenario rather than merely the best-fitting cladogram. Finally, I discuss the prospects of this view in stimulating interdisciplinary cross-talk in early metazoan research and beyond, and challenges that need to be overcome. (shrink)

In this article, I consider the term “environment” in various claims and models by evolutionists and ecologists. I ask whether “environment” is amenable to a philosophical explication, in the same way some key terms of evolutionary theorizing such as “fitness,” “species,” or more recently “population” have been. I will claim that it cannot. In the first section, I propose a typology of theoretical terms, according to whether they are univocal or equivocal, and whether they have been the object of formal (...) or conceptual attempts of clarification. “Environment” will appear to be in a position similar to “population,” yet almost no extant attempt has been made to make sense of its meaning and reference. In the second section, I will present several theoretical claims or issues that refer to “environment” in apparently very diverse ways, but always supposing a contrastive term, which is not always the same. The third section directly considers models in evolution and in ecology, and asks “where” in them is the environment term. The fourth section proposes that “environment” refers to a distinction between a varying and an invariant term, but shows that this does not exhaust its meaning, which requires making more conceptual differences. Then, I take on the suggestion that there might be two “environment” terms, one in ecology and one in evolution, but show that is not the case. Finally I center on the specific notion of “complex environment,” which is the object of several research programs, and propose a typology of “complex environments” across theories. (shrink)

Multiple biological groups, such as ant colonies, appear to have a noteworthy inefficiency: they contain vast amounts of redundant members that are not strictly needed to maintain the group. Philosophers and biologists have proposed that such inefficiency is illusory because redundancy enhances the resilience of groups when living under harsh conditions. Still, this proposal is unsatisfactory in different respects. First, it is too vague to account for when redundancy is selectively advantageous. Furthermore, it overlooks cases in which redundancy fails to (...) increase the resilience of groups. This paper offers an account of group redundancy that addresses these difficulties. Specifically, it advances the hypothesis that the mere presence of harsh conditions is not what drives the evolution of redundancy; rather, it is the fact organisms are often unable to predict when they will face harsh conditions. Redundancy enables groups to properly respond to unpredictable circumstances without resorting to the unreliable detection systems of their members. A better understanding of the phenomenon of redundancy is likely to impact other key issues in philosophy of science, including the evolution of cooperation and transitions in individuality, and the role of redundancy in complex systems, be they biological or not. (shrink)

The validity and utility of the proximate-ultimate distinction in biology have recently been under debate. Opponents of the distinction argue that it rules out individual-level organismic processes from evolutionary explanations, thereby leading to an unfounded separation between organismic causation and evolutionary causation. Proponents of the proximate-ultimate distinction, on the other hand, argue that it serves an important epistemological role in forming different kinds of explanation-seeking questions in biology. In this paper we offer an interpretation the proximate-ultimate distinction not only as (...) a means of forming explanation-seeking questions, but also as a distinction that can help highlight the way in which individual-level organismic processes can be evolutionary causes. We do this by interpreting the distinction between proximate and ultimate causes as a distinction between structuring and triggering causes. (shrink)

There is a tension between, on the one hand, the view that natural selection refers to individual-level causes, and on the other hand, the view that it refers to a population-level cause. In this article, I make the case for the individual-level cause view. I respond to recent claims made by McLoone that the individual-level cause view is inconsistent. I show that if one were to follow his arguments, any causal claim in any context would have to be regarded as (...) vindicating a form of population-level cause view. I show why this is implausible and how a consistent individual-level cause position can be held within the interventionist account of causation. Finally, I argue that there is one sense in which natural selection might be said to refer to population-level causes of evolutionary change. The upshot is that, as noted by others, natural selection can be regarded as referring to a population-level cause in the context of frequency-dependent selection and other situations of fitness-altering interactions between the individuals of a population. But whether this statement is true will depend on the empirical case investigated, not some a priori conceptual distinction. Thus, even though situations of frequency dependence might be ubiquitous, it is orthogonal to the conceptual question of whether frequency-independent natural selection—McLoone’s target—refers to individual- or population-level causes. (shrink)

One curious phenomenon of several social groups is that they are ‘redundant’ in the sense that they contain more cooperators than strictly needed to complete certain group tasks, such as foraging. Redundancy is puzzling because redundant groups are particularly susceptible to invasion by defectors. Yet, redundancy can be found in groups formed by a wide range of organisms, including insects and microbes. Birch has recently argued that coercive behaviours might account for redundancy using insect colonies as a case study. However, (...) microbial examples suggest redundancy can evolve without coercive behaviours. This paper formulates an explanation for redundancy that does not require targeted punishment of defectors; instead, it proposes that redundancy might be due to ignorance. Specifically, it is suggested that redundancy evolves as a by-product of selection when group members have to opt whether to cooperate or not while being blind to the strategies of others. Accordingly, possessing information about the strategies of the group members might undermine rather than facilitate cooperation within groups. 1The Evolution of Redundancy 2Explaining Redundancy via Coercion 3Explaining Redundancy via Ignorance 3.1Cooperation behind the Darwinian veil of ignorance 3.2Modelling group tasks with a public goods game 3.3Group tasks under harsh environments 4Conclusion. (shrink)

Cooperation in the prisoner’s dilemma is possible if interactions are sufficiently correlated. We show that when conditions favorable to the evolution of cooperation hold (rb > c) tag-based strategies dominate. Thus, well-meaning interventions aimed at promoting cooperation may succeed but will often lead to in-group favoritism and ethnocentric behavior. Exploring ways that promote cooperation but do not usher in tag-based strategies should be a focal point of future work on the evolution of cooperation.