We show how Richard Jeffrey's The Logic of Decision provides the proper formalism for calculating expected fitness for correlated encounters in general. As an illustration, some puzzles about kin selection are resolved.

We show how Richard Jeffrey’s The Logic of Decision provides the proper formalism for calculating expected fitness for correlated encounters in general. As an illustration, some puzzles about kin selection are resolved.

Altruism is a central concept in evolutionary biology. Evolutionary biologists still disagree about its meaning (E.O. Wilson 2005; Fletcher et al. 2006; D.S. Wilson 2008; Foster et al. 2006a, b; West et al. 2007a, 2008). Semantic disagreement appears to be quite robust and not easily overcome by attempts at clarification, suggesting that substantive conceptual issues lurk in the background. Briefly, group selection theorists define altruism as any trait that makes altruists losers to selfish traits within groups, and makes (...) groups of altruists fitter than groups of non-altruists. Inclusive fitness theorists reject a definition based on within- and between-group fitness. Traits are altruistic only if they cause a direct and absolute fitness loss to the donor. The latter definition is more restrictive and rejects as cases of altruism behaviors that are accepted by the former. Fletcher and Doebeli (2009) recently proposed a simple, direct and individually based fitness approach, which they claim returns to first principles: carriers of the genotype of interest “must, on average, end up with more net direct fitness benefits than average population members.” This seductively simple proposal uses the concept of assortment to explain how diverse kinds of altruists end up on average with more net fitness than their non-altruistic rivals. In this paper I shall argue that their approach implies a new concept of altruism that contrasts with and improves on the concept of the inclusive fitness approach. (shrink)

Inclusive fitness theory provides conditions for the evolutionary success of a gene. These conditions ensure that the gene is selfish in the sense of Dawkins (The selfish gene, Oxford University Press, Oxford, 1976): genes do not and cannot sacrifice their own fitness on behalf of the reproductive population. Therefore, while natural selection explains the appearance of design in the living world (Dawkins in The blind watchmaker: why the evidence of evolution reveals a universe without design, W. W. (...) Norton, New York, 1996), inclusive fitness theory does not explain how. Indeed, Hamilton’s rule is equally compatible with the evolutionary success of prosocial altruistic genes and antisocial predatory genes, whereas only the former, which account for the appearance of design, predominate in successful organisms. Inclusive fitness theory, however, permits a formulation of the central problem of sociobiology in a particularly poignant form: how do interactions among loci induce utterly selfish genes to collaborate, or to predispose their carriers to collaborate, in promoting the fitness of their carriers? Inclusive fitness theory, because it abstracts from synergistic interactions among loci, does not answer this question. Fitness-enhancing collaboration among loci in the genome of a reproductive population requires suppressing alleles that decrease, and promoting alleles that increase the fitness of its carriers. Suppression and promotion are effected by regulatory networks of genes, each of which is itself utterly selfish. This implies that genes, and a fortiori individuals in a social species, do not maximize inclusive fitness but rather interact strategically in complex ways. It is the task of sociobiology to model these complex interactions. (shrink)

In recent years, much has been learned about the strategic and organizational contexts of suicide attacks. However, motivations of the agents who commit them remain difficult to explain. In part this is because standard models of social learning as well as Durkheimian notions of sacrificial behavior are inadequate in the face of the actions of human bombers. In addition, the importance of organizational structures and practices in reinforcing commitment on the part of suicide recruits is an under-explored factor in many (...) analyses. This essay examines the potential applicability of evolutionary models of altruism to the understanding of commitment to suicide on the part of terrorist organizational recruits. Three evolutionary models of sacrificial behavior in nonhuman species and many categories of human behavior are explored cross-organizationally: reciprocity, inclusive fitness theory, and induced altruism. Reciprocal altruism is unlikely to be a major motivator in suicide attacks because the costs exhibited by attackers are too high to be adequately compensated. However, the role of evolved self-deception in perceptions of personal death, and thus of rewards in the afterlife, is potentially illuminating. Inclusive fitness theory can help explain the motivations of attackers because rewards to kin often are offered by organizations to suicide recruits. However, suicide bombers also often act out of revenge for the loss of or injury to relatives, and inclusive fitness theory generally, as well as more specific theoretical models of retaliatory aggression, may not adequately account for the bombers' actions. Predictions from induced altruism theory appear to be well supported because suicide terror organizations tend to be tightly structured around practices intended to maintain and reinforce commitment though the manipulation of kinship-recognition cues. (shrink)

Phenomena like meat sharing in hunter-gatherers, altruistic self-sacrifice in intergroup conflicts, and contribution to the production of public goods in laboratory experiments have led to the development of numerous theories trying to explain human prosocial preferences and behavior. Many of these focus on direct and indirect reciprocity, assortment, or (cultural) group selection. Here, I investigate analytically how genetic relatedness changes the incentive structure of that paradigmatic game which is conventionally used to model and experimentally investigate collective action problems: the public (...) goods game. Using data on contemporary hunter-gatherer societies I then estimate a threshold value determining when biological altruism turns into maximizing inclusive fitness in this game. I find that, on average, contributing no less than about 40% of individual fitness to public goods production still is an optimal strategy from an inclusive fitness perspective under plausible socio-ecological conditions. (shrink)

Hamilton introduced two conceptions of social fitness, which he called neighbour-modulated fitness and inclusive fitness. Although he regarded them as formally equivalent, a re-analysis of his own argument for their equivalence brings out two important assumptions on which it rests: weak additivity and actor's control. When weak additivity breaks down, neither fitness concept is appropriate in its original form. When actor's control breaks down, neighbour-modulated fitness may be appropriate, but inclusive fitness is (...) not. Yet I argue that, despite its more limited domain of application, inclusive fitness provides a distinctively valuable perspective on social evolution. (shrink)

Proponents of the standard evolutionary biology paradigm explain human “altruism” in terms of either nepotism or strict reciprocity. On that basis our underlying nature is reduced to a function of inclusive fitness: human nature has to be totally selfish or nepotistic. Proposed here are three possible paths to giving costly aid to nonrelatives, paths that are controversial because they involve assumed pleiotropic effects or group selection. One path is pleiotropic subsidies that help to extend nepotistic helping behavior (...) from close family to nonrelatives. Another is “warfare”—if and only if warfare recurred in the Paleolithic. The third and most plausible hypothesis is based on the morally based egalitarian syndrome of prehistoric hunter-gatherers, which reduced phenotypic variation at the within-group level, increased it at the between-group level, and drastically curtailed the advantages of free riders. In an analysis consistent with the fundamental tenets of evolutionary biology, these three paths are evaluated as explanations for the evolutionary development of a rather complicated human social nature. (shrink)

The significance of scientific research into the evolution of altruism for environmental ethics can be highlighted through an analysis of recent debates over William Hamilton’s theory of inclusive fitness. Recent debates over how to explain altruism have become particularly charged with ideological weight because they are seen to have some consequence for how we understand the human moral project, especially with regard to nonhuman life. By analyzing the place of evolutionary theory in the work of environmental (...) ethicists some conclusions can be drawn about the extent to which these debates, and evolutionary research into behavior more generally, are and are not significant for environmental ethics. In particular, the most important issues at stake for environmental ethicists concern the conditions under which altruistic forms of behavior can thrive and the degree to which we can consider intensive forms of altruism to be unstable and anomalous, or rather stable and predictable outcomes of social evolution given favorable conditions. (shrink)

The puzzle of how altruism can evolve has been at the center of recent debates over Hamilton’s Rule, inclusive fitness, and kin-selection. In this paper, I use recent debates over altruism and Hamilton’s legacy as an example to illustrate a more general problem in evolutionary theory that has philosophical significance; I attempt to explain this significance and to draw a variety of conclusions about it. The problem is that specific behaviours and general concepts of organism agency (...) and intentionality are defined in terms of concepts of evolutionary “costs” and “benefits,” and these terms have determined the role that agency should play in evolutionary explanation. However, costs, benefits, and agency are not only or even best conceived through evolutionary effects in a biological context. The paper proceeds as follows: first, I explain how the issue of agency relates to the evolutionary puzzle of altruism. Next, I discuss how questions about agency have figured in recent debates over Hamilton’s legacy. In the final section, I argue that Denis Walsh’s “situated Darwinism,” which attempts to return the organism to central status in biological explanation, offers a more productive route for thinking about different forms of costs, benefits, and agency. Finally, I argue that the upshot of all this is that there may be many different, and equally valid, ways to express what organisms are doing and how they are behaving based on different currencies of cost and benefit—even if these may stand in some tension. I illustrate this through returning to the case of altruism and using examples to show that even in non-humans there can be many forms of altruism, even if they are not all biological altruism as defined in the conventional evolutionary terms. (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)

The adequacy of currently popular accounts of the genetic basis for psychological altruism, including inclusive fitness, reciprocal altruism, sociality, and group selection, is questioned. Problems exist both with the evidence cited as supporting these accounts and with the relevance of the accounts to what is being explained. Based on the empathy-altruism hypothesis, a more plausible account is proposed: generalized parental nurturance. It is suggested that four evolutionary developments combined to provide a genetic basis for psychological (...) altruism. First is the evolution in mammals of parental nurturance. Second is the evolution in humans of the ability to see others as sentient, intentional agents and, thereby, to recognize other's needs, even subtle ones. Third is the evolution in humans of tender, empathic emotions as an important component of parental nurturance. Fourth is the evolution in humans of cognitive capacities that make it possible to generalize tender, empathic feelings and, thereby, altruism beyond offspring. (shrink)

Inclusive fitness has been under intense scrutiny in recent years, with many critics claiming the framework leads to incorrect predictions. We consider one particularly influential heuristic for estimating inclusive fitness in the context of the very case that motivated reliance on it to begin with: the Sir Philip Sidney signalling game played with relatives. Using a neighbour-modulated fitness model, we show when and why this heuristic is problematic. We argue that reliance on the heuristic rests (...) on a misunderstanding of what it means for two organisms to be related and perpetuates a mischaracterization of the role of the ‘relatedness’ parameter in inclusive fitness. _1_ Introduction _2_ Heuristic Inclusive Fitness _3_ The Sir Philip Sidney Game _4_ Model _5_ Results _6_ Conclusion Appendix. (shrink)

Individual-as-maximizing agent analogies result in a simple understanding of the functioning of the biological world. Identifying the conditions under which individuals can be regarded as fitness maximizing agents is thus of considerable interest to biologists. Here, we compare different concepts of fitness maximization, and discuss within a single framework the relationship between Hamilton’s (J Theor Biol 7:1–16, 1964) model of social interactions, Grafen’s (J Evol Biol 20:1243–1254, 2007a) formal Darwinism project, and the idea of evolutionary stable strategies. We (...) distinguish cases where phenotypic effects are additive separable or not, the latter not being covered by Grafen’s analysis. In both cases it is possible to define a maximand, in the form of an objective function ϕ(z), whose argument is the phenotype of an individual and whose derivative is proportional to Hamilton’s inclusive fitness effect. However, this maximand can be identified with the expression for fecundity or fitness only in the case of additive separable phenotypic effects, making individual-as-maximizing agent analogies unattractive (although formally correct) under general situations of social interactions. We also feel that there is an inconsistency in Grafen’s characterization of the solution of his maximization program by use of inclusive fitness arguments. His results are in conflict with those on evolutionary stable strategies obtained by applying inclusive fitness theory, and can be repaired only by changing the definition of the problem. (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)

ABSTRACT In social evolution theory, biological individuals are often represented on the model of rational agents, that is, as if they were ‘seeking’ to maximize their own reproductive success. In the 1990s, important criticisms of this mode of thinking were made by Brian Skyrms and Elliott Sober, who both argued that ‘rational agent’ models can lead to incorrect predictions when there are positive correlations between individuals’ phenotypes. In this article, I argue that one model of rational choice—namely, Savage’s model —can (...) actually be vindicated in evolutionary biology, provided that the pay-offs are computed in inclusive fitness terms. I also show that the use of this model is better avoided when pay-offs are non-additive, or when certain causal influences affect the outcome of natural selection. The result is a partial rehabilitation of this mode of thinking, conditional on both the additivity of the pay-off structure and the absence of any form of manipulation or coercion. _1_ Introduction _2_ When Natural Selection and Rational Deliberation Part Ways _3_ A Simple Solution: Redefining the Pay-offs in Inclusive Fitness Terms _4_ Sober on Inclusive Fitness Maximization _5_ Inclusive Fitness with Non-additive Pay-offs _6_ Causal Influences and the Savage– Hamilton Model _6.1_ Reciprocity and partner choice _6.2_ Coercion and manipulation _7_ Conclusion Appendix. (shrink)

Phenomena like meat sharing in hunter-gatherers, self-sacrifice in intergroup conflicts, and voluntary contribution to public goods provision in laboratory experiments have led to the development of numerous theories on the evolution of altruistic in-group beneficial behavior in humans. Many of these theories abstract away from the effects of kinship on the incentives for public goods provision, though. Here, it is investigated analytically how genetic relatedness changes the incentive structure of that paradigmatic game which is conventionally used to model and experimentally (...) investigate collective action problems: the linear public goods game. Using recent anthropological data sets on relatedness in 61 contemporary hunter-gatherer and horticulturalist societies the relevant parameters of this model are then estimated. It turns out that the kinship patterns observed in these societies substantially reduce the negative effect of increasing group size on incentives for public goods provision. It is suggested, therefore, that renewed attention should be given to inclusive fitness theory in the context of public goods provision also in sizable groups, because its explanatory power with respect to this central problem in the evolution of human cooperativeness and altruism might have been substantially underrated. (shrink)

In social evolution theory, biological individuals are often represented on the model of rational agents, that is, as if they were ‘seeking’ to maximize their own (expected) reproductive success. In the 1990s, important criticisms of this mode of thinking were made by Brian Skyrms ([1994], [1996]) and Elliott Sober ([1998]), who both argued that ‘rational agent’ models can lead to incorrect predictions when there are positive correlations between individuals’ phenotypes. In this article, I argue that one model of rational choice—namely, (...) Savage’s model ([1954])—can actually be vindicated in evolutionary biology, provided that the pay-offs are computed in inclusive fitness terms. I also show that the use of this model is better avoided when pay-offs are non-additive, or when certain causal influences (due to manipulative behaviours) affect the outcome of natural selection. The result is a partial rehabilitation of this mode of thinking, conditional on both the additivity of the pay-off structure and the absence of any form of manipulation or coercion. 1 Introduction2 When Natural Selection and Rational Deliberation Part Ways3 A Simple Solution: Redefining the Pay-offs in Inclusive Fitness Terms4 Sober on Inclusive Fitness Maximization5 Inclusive Fitness with Non-additive Pay-offs6 Causal Influences and the Savage– Hamilton Model6.1 Reciprocity and partner choice6.2 Coercion and manipulation7 ConclusionAppendix. (shrink)

This article is about the analogy between inclusive fitness and utility. In behavioral ecology, it is often assumed that individual organisms behave as if they were “striving” to maximize their inclusive fitness—a measure analogue to the kind of utility function that is used to represent the preferences of rational agents. Here, I explore some conceptual puzzles related to this view and question whether the kind of biological utility posited by the advocates of the “maximizing agent analogy” (...) can be adequately interpreted in inclusive fitness terms. (shrink)

The biological world is full of phenomena that seem to run counter to Darwin's insight that natural selection can lead to the appearance of design. For instance, why do organisms in some species divide reproductive labor? The existence of non-reproducing organisms in such 'eusocial' species looks to be at odds with an evolutionary theory which posits traits exist because they help organisms survive and reproduce. What is the evolutionary advantage of an insect being distasteful to its predators? The distastefulness appears (...) designed to deter predators, but can only affect the predator's actions when the insect is eaten; it is hard to see how such a trait could be passed on. This Element will cover the shared foundations of evolutionary explanations for these and other seemingly puzzling phenomena, focusing on the concepts of inclusive fitness and kin selection. (shrink)

From mitochondria to meerkats, the natural world is full of spectacular examples of social behaviour. In the early 1960s W. D. Hamilton changed the way we think about how such behaviour evolves. He introduced three key innovations - now known as Hamilton's rule, kin selection, and inclusive fitness - and his pioneering work kick-started a research program now known as social evolution theory. This is a book about the philosophical foundations and future prospects of that program. [Note: only (...) the Introduction is available to download.]. (shrink)

Philosophers have shown that the Aristotelian conception of mind and body is capable of resolving the problems confronting dualism. In this paper the resolution of the mind–body problem is extended with a scientific solution by integrating the Aristotelian framework with evolutionary theory. It is discussed how the theories of Fisher and Hamilton enable us to construct and solve hypotheses about how the mind evolved out of matter. These hypotheses are illustrated by two examples: the evolutionary transition from cells to multicellular (...) organisms, and the evolutionary transition from babbling to doing things with words and later reasoning and giving reasons. The first transitions resulted in the sensitive psyche of the other animals, the second in the rational psyche of humans. It is discussed how exploratory behaviour of lower-level entities facilitated these evolutionary transitions. (shrink)

Competition over reproductive opportunities among members of one sex often harms the opposite sex, creating a conflict of interest between individual males and females. Recently, this battle of the sexes has become a paradigm in the study of intersexual coevolution. Here, we review recent theoretical and empirical advances suggesting that – as in any scenario of intraspecific competition – selfishness (competitiveness) can be influenced by the genetic relatedness of competitors. When competitors are positively related (e.g. siblings), an individual may refrain (...) from harming its competitor(s) and their mate(s) because this can improve the focal individual's inclusive fitness. These findings reveal that population genetic structure might be of paramount importance when studying the battle of the sexes. We conclude by identifying some new lines of research at the interface of sexual selection and social evolution. (shrink)

This article analyzes the recent debate surrounding inclusive fitness and argues that certain limitations ascribed to it by critics—such as requiring weak selection or providing dynamically insufficient models—are better thought of as limitations of the methodological framework most often used with inclusive fitness. In support of this, I show how inclusive fitness can be used with the replicator dynamics. I conclude that much of the debate is best understood as being about the orthogonal issue (...) of using abstract versus idealized models. (shrink)

Inclusive fitness theory provides a compelling explanation for the evolution of altruism among kin. However, a completely satisfactory account of non-kin altruism is still lacking. The present study compared the level of altruism found among siblings with that found among friends and mates and sought to reconcile the findings with an evolutionary explanation for human altruism. Participants (163 males and 156 females) completed a questionnaire about help given to a sibling, friend, or mate. Overall, (...) participants gave friends and mates as much or more help than they gave siblings. However, as the cost of help increased, siblings received a progressively larger share of the help, whereas friends and mates received a progressively smaller share, despite the fact that participants were closer emotionally to friends and mates than they were to siblings. These findings help to explain the relative standing of friends and mates as recipients of altruistic aid. (shrink)

Cooperation is rife in the microbial world, yet our best current theories of the evolution of cooperation were developed with multicellular animals in mind. Hamilton’s theory of inclusive fitness is an important case in point: applying the theory in a microbial setting is far from straightforward, as social evolution in microbes has a number of distinctive features that the theory was never intended to capture. In this article, I focus on the conceptual challenges posed by the project of (...) extending Hamilton’s theory to accommodate the effects of gene mobility. I begin by outlining the basics of the theory of inclusive fitness, emphasizing the role that the concept of relatedness is intended to play. I then provide a brief history of this concept, showing how, over the past fifty years, it has departed from the intuitive notion of genealogical kinship to encompass a range of generalized measures of genetic similarity. I proceed to argue that gene mobility forces a further revision of the concept. The reason in short is that, when the genes implicated in producing social behaviour are mobile, we cannot talk of an organism’s genotype simpliciter; we can talk only of an organism’s genotype at a particular stage in its life cycle. We must therefore ask: with respect to which stage(s) in the life cycle should relatedness be evaluated? For instance: is it genetic similarity at the time of social interaction that matters to the evolution of social behaviour, or is it genetic similarity at the time of reproduction? I argue that, strictly speaking, it is neither of these: what really matters to the evolution of social behaviour is diachronic genetic similarity between the producers of fitness benefits at the time they produce them and the recipients of those benefits at the end of their life-cycle. I close by discussing the implications of this result. The main payoff is that it makes room for a possible new mechanism for the evolution of altruism in microbes that does not require correlated interaction among bearers of the genes for altruism. The importance of this mechanism in nature remains an open empirical question. (shrink)

Grouping severe mental disorders into a global category is likely to lead to a “theory of everything” which forcefully explains everything and nothing. Speculation even at the phenotypic level of the single disorder cannot be fruitful, unless specific and testable models are proposed. Inclusive fitness must be incorporated in such models. (Published Online November 9 2006).

Hamilton’s theory of inclusive fitness is a widely used framework for studying the evolution of social behavior, but controversy surrounds its status. Hamilton originally derived his famous rb > c rule for the spread of a social gene by assuming additivity of costs and benefits. However, it has recently been argued that the additivity assumption can be dispensed with, so long as the −c and b terms are suitably defined, as partial regression coefficients. I argue that this way (...) of generalizing Hamilton’s rule to the nonadditive case, while formally correct, faces conceptual problems. (shrink)

Due to the intense selection pressure against inbreeding, humans are expected to possess psychological adaptations that regulate mate choice and avoid inbreeding. From a gene’s-eye perspective, there is little difference in the evolutionary costs between situations where an individual him/herself is participating in inbreeding and inbreeding among other close relatives. The difference is merely quantitative, as fitness can be compromised via both routes. The question is whether humans are sensitive to the direct as well as indirect costs of inbreeding. (...) Using responses from a large population-based sample (27,364 responses from 2,353 participants), we found that human motivations to avoid inbreeding closely track the theoretical costs of inbreeding as predicted by inclusive-fitness theory. Participants were asked to select in a forced choice paradigm, which of two acts of inbreeding with actual family members they would want to avoid most. We found that the estimated fitness costs explained 83.6% of participant choices. Importantly, fitness costs explained choices also when the self was not involved. We conclude that humans intuit the indirect fitness costs of mating decisions made by close family members and that psychological inbreeding avoidance mechanisms extend beyond self-regulation. (shrink)

There is disagreement in the literature about the exact nature of the phenomenon of empathy. There are emotional, cognitive, and conditioning views, applying in varying degrees across species. An adequate description of the ultimate and proximate mechanism can integrate these views. Proximately, the perception of an object's state activates the subject's corresponding representations, which in turn activate somatic and autonomic responses. This mechanism supports basic behaviors that are crucial for the reproductive success of animals living in groups. The Perception-Action Model, (...) together with an understanding of how representations change with experience, can explain the major empirical effects in the literature. It can also predict a variety of empathy disorders. The interaction between the PAM and prefrontal functioning can also explain different levels of empathy across species and age groups. This view can advance our evolutionary understanding of empathy beyond inclusive fitness and reciprocal altruism and can explain different levels of empathy across individuals, species, stages of development, and situations. Key Words: altruism; cognitive empathy ; comparative; emotion; emotional contagion; empathy ; evolution; human; perception-action; perspective taking. (shrink)

Hamilton’s theory of inclusive fitness is a widely used framework for studying the evolution of social behavior, but controversy surrounds its status. Hamilton originally derived his famous rb > c rule for the spread of a social gene by assuming additivity of costs and benefits. However, it has recently been argued that the additivity assumption can be dispensed with, so long as the −c and b terms are suitably defined, as partial regression coefficients. I argue that this way (...) of generalizing Hamilton’s rule to the nonadditive case, while formally correct, faces conceptual problems. (shrink)

The kinship theory of genomic imprinting predicts that imprinted genes affect parent–child and child–child interactions. During prenatal and neonatal stages, patrigenes promote selfish and matrigenes altruistic behavior. Models predict that this imprinted gene expression pattern is reversed starting with the juvenile stage. This article explores possible effects of imprinted genes on nonverbal and simple and complex linguistic behaviors before and after the reversal. A hypothesis is discussed that is based on the observation language evolved as a new form of communicative (...) behavior. Inclusive fitness theory is used for explaining how and why new forms of communicative behaviors evolved as an extension of behaviors and gestures displayed by our predecessors. The hypothesis is elaborated through discussing a scenario of early language evolution. This scenario is used for explaining early stages in child development and for discussing possible effects of patrigenes and matrigenes on the development of children’s communicative behaviors. (shrink)

It’s recently been argued that biological fitness can’t change over the course of an organism’s life as a result of organisms’ behaviors. However, some characterizations of biological function and biological altruism tacitly or explicitly assume that an effect of a trait can change an organism’s fitness. In the first part of the paper, I explain that the core idea of changing fitness can be understood in terms of conditional probabilities defined over sequences of events in an (...) organism’s life. The result is a notion of “conditional fitness” which is static but which captures intuitions about apparent behavioral effects on fitness. The second part of the paper investigates the possibility of providing a systematic foundation for conditional fitness in terms of spaces of sequences of states of an organism and its environment. I argue that the resulting “organism–environment history conception” helps unify diverse biological perspectives, and may provide part of a metaphysics of natural selection. (shrink)

An understanding of the factors behind the evolution of multicellularity is one of today’s frontiers in evolutionary biology. This is because multicellular organisms are made of one subset of cells with the capacity to transmit genes to the next generation and another subset responsible for maintaining the functionality of the organism, but incapable of transmitting genes to the next generation. The question arises: why do somatic cells sacrifice their lives for the sake of germline cells? How is germ/soma separation maintained? (...) One conventional answer refers to inclusive fitness theory, according to which somatic cells sacrifice themselves altruistically, because in so doing they enhance the transmission of their genes by virtue of their genetic relatedness to germline cells. In the present article we will argue that this explanation ignores the key role of policing mechanisms in maintaining the germ/soma divide. Based on the pervasiveness of the latter, we argue that the role of altruistic mechanisms in the evolution of multicellularity is limited and that our understanding of this evolution must be enriched through the consideration of coercion mechanisms. (shrink)

At one level, this paper is a lament and a warning. I lament biologists borrowing well-known terms and then drastically and awkwardly changing their meanings, and I warn about the mischief this does. Biology''s public image is at stake, as is its general usefulness. At another level, I attempt to clarify the misnamed concepts, beyond what has been achieved in recent philosophical writings. This helps to account for the mischief, and to see how it might be avoidable. But the most (...) important thing about the paper is that, at a third level, it is an argument against physicalism and materialism, especially those variants which deny the autonomy of organisms and the existence of intrinsic goods. Interpreting biology from the point of view of those denials leads to unsatisfactory and even bizarre results. (shrink)

What explains the distinctive features of human behavior? In this book, Stewart-Williams aims to answer this ambitious question. This book is an engaging addition to the already long list of recent attempts to provide an evolutionary explanation of human uniqueness. It is organized into six chapters, plus two appendices. These chapters address several key topics in evolutionary theory, sex differences and sexual behavior, altruism, and cultural evolution, albeit with varying degrees of detail and depth. These topics include sexual selection, (...) kin selection, Hamilton’s rule, reciprocal altruism, costly signaling theory, group selection, gene-centered views of evolution, inclusive fitness, proximate and ultimate evolutionary explanations, inbreeding avoidance, the Westermarck effect, jealousy, sperm competition, mating and parenting effort, cumulative cultural evolution, imitation and learning biases, evolutionary mismatch theories, and more. (shrink)

Stove's article, 'So you think you are a Darwinian?'[ 1] was essentially an advertisement for his book, Darwinian Fairytales.[ 2] The central argument of the book is that Darwin's theory, in both Darwin's and recent sociobiological versions, asserts many things about the human and other species that are known to be false, but protects itself from refutation by its logical complexity. A great number of ad hoc devices, he claims, are used to protect the theory. If co operation is observed (...) where the theory predicts competition, then competition is referred to the time of the cavemen, or is reinterpreted as competition between some hidden entities like genes or abstract entities like populations. In a characteristic sally, Stove writes of the sociobiologists' oscillation on the meaning of kin altruism: Any discussion of altruism with an inclusive fitness theorist is, in fact, exactly like dealing with a pair of balloons connected by a tube, one balloon being the belief that kin altruism is an illusion, the other being the belief that kin altruism is caused by shared genes. If a critic puts pressure on the illusion balloon - perhaps by ridiculing the selfish theory of human nature - air is forced into the causal balloon. There is then an increased production of earnest causal explanations of why we love our children, why hymenopteran workers look after their sisters, etc., etc. Then, if the critic puts pressure on the causal balloon - perhaps about the weakness of sibling altruism compared with parental, or the absence of sibling altruism in bacteria - then the illusion balloon is forced to expand. There will now be an increased production of cynical scurrilities about parents manipulating their babies for their own advantage, and vice versa, and in general, about the Hobbesian bad times that are had by all. In this way critical pressure, applied to the theory of inclusive fitness at one point, can always be easily absorbed at another point, and the theory as a whole is never endangered.[ 3] Now, it is uncontroversial to assert that Darwinism is a logically complex theory, and that its relation to empirical evidence is distant and multi faceted. One does not directly observe chance genetic variations leading to the development of new species, or even continuous variations in the fossil record, but must rely on subtle arguments to the best explanation, scaling up from varieties to species, and so on.. (shrink)

Many of the most important properties of human groups – including properties that may give one group an evolutionary advantage over another – are properly defined only at the level of group organization. Yet at present, most work on the evolution of culture has focused solely on the transmission of individual-level traits. I propose a conceptual extension of the theory of cultural evolution, particularly related to the evolutionary competition between cultural groups. The key concept in this extension is the emergent (...) group-level trait. This type of trait is characterized by the structured organization of differentiated individuals and constitutes a unit of selection that is qualitatively different from selection on groups as defined by traditional multilevel selection theory. As a corollary, I argue that the traditional focus on cooperation as the defining feature of human societies has missed an essential feature of cooperative groups. Traditional models of cooperation assume that interacting with one cooperator is equivalent to interacting with any other. However, human groups involve differential roles, meaning that receiving aid from one individual is often preferred to receiving aid from another. In this target article, I discuss the emergence and evolution of group-level traits and the implications for the theory of cultural evolution, including ramifications for the evolution of human cooperation, technology, and cultural institutions, and for the equivalency of multilevel selection and inclusive fitness approaches. (shrink)

The group selection controversy largely focuses on altruism (e.g., Wilson 1983; Lloyd 2001; Shavit 2004; Okasha 2006, 173ff; Borrello 2010; Leigh 2010; Rosas 2010; Hamilton and Dimond in press). Multilevel selection theory is a resolution of this controversy. Whereas kin selection partitions inclusive fitness into direct and indirect components (via influencing the replication of copies of genes in other individuals), multilevel selection considers within-group and between-group components of fitness (Gardner et al. 2011; Lion et al. 2011). (...) Two scenarios of multilevel selection are often distinguished (Damuth and Heisler 1988; Okasha 2006; Pigliucci 2010): (1) group structure only divides individual fitnesses into within- and between-group components (MLS1); and, (2) groups get their own component of fitness and also, in most definitions, a group-level adaptation (MLS2). (shrink)

The kin selection hypothesis posits that male androphilia (male sexual attraction to adult males) evolved because androphilic males invest more in kin, thereby enhancing inclusive fitness. Increased kin-directed altruism has been repeatedly documented among a population of transgendered androphilic males, but never among androphilic males in other cultures who adopt gender identities as men. Thus, the kin selection hypothesis may be viable if male androphilia was expressed in the transgendered form in the ancestral past. Using the Standard (...) Cross-Cultural Sample (SCCS), we examined 46 societies in which male androphilia was expressed in the transgendered form (transgendered societies) and 146 comparison societies (non-transgendered societies). We analyzed SCCS variables pertaining to ancestral sociocultural conditions, access to kin, and societal reactions to homosexuality. Our results show that ancestral sociocultural conditions and bilateral and double descent systems were more common in transgendered than in non-transgendered societies. Across the entire sample, descent systems and residence patterns that would presumably facilitate increased access to kin were associated with the presence of ancestral sociocultural conditions. Among transgendered societies, negative societal attitudes toward homosexuality were unlikely. We conclude that the ancestral human sociocultural environment was likely conducive to the expression of the transgendered form of male androphilia. Descent systems, residence patterns, and societal reactions to homosexuality likely facilitated investments in kin by transgendered males. Given that contemporary transgendered male androphiles appear to exhibit elevated kin-directed altruism, these findings further indicate the viability of the kin selection hypothesis. (shrink)

Social dilemmas occur when the pursuit of self-interest by individuals in a group leads to less than optimal collective outcomes for everyone in the group. A critical assumption in the human sciences is that people's choices in such dilemmas are individualistic, selfish, and rational. Hence, cooperation in the support of group welfare will only occur if there are selfish incentives that convert the social dilemma into a nondilemma. In recent years, inclusive fitness theories have lent weight to such (...) traditional views of rational selfishness on Darwinian grounds. To show that cooperation is based on selfish incentives, however, one must provide evidence that people donotcooperatewithoutsuch incentives. In a series of experimental social dilemmas, subjects were instructed to make single, anonymous choices about whether or not to contribute money for a shared “bonus” that would be provided only if enough other people in the group also contributed their money. Noncontributors cited selfish reasons for their choices; contributors did not. If people are allowed to engage in discussion, they will contribute resources at high rates, frequently on irrational grounds, to promote group welfare. These findings are consistent with previous research on ingroup biasing effects that cannot be explained by “economic man” or “selfish gene” theories. An alternative explanation is that sociality was a primary factor shaping the evolution ofHomo sapiens. The cognitive and affective mechanisms underlying such choices evolved under selection pressures on small groups for developing and maintaining group membership and for predicting and controlling the behavior of other group members. This sociality hypothesis organizes previously inexplicable and disparate phenomena in a Darwinian framework and makes novel predictions about human choice. (shrink)

Humans spend large portions of their time and energy talking to one another, yet it remains unclear whether this activity is primarily selfish or altruistic. Here, it is shown how parent‐of‐origin specific gene expression—or “genomic imprinting”—may provide an answer to this question. First, it is shown why, regarding language, only altruistic or selfish scenarios are expected. Second, it is pointed out that an individual's maternal‐origin and paternal‐origin genes may have different evolutionary interests regarding investment into language, and that this intragenomic (...) conflict may drive genomic imprinting which—as the direction of imprint depends upon whether investment into language is relatively selfish or altruistic—may be used to discriminate between these two possibilities. Third, predictions concerning the impact of various mutations and epimutations at imprinted loci on language pathologies are derived. In doing so, a framework is developed that highlights avenues for using intragenomic conflicts to investigate the evolutionary drivers of language. (shrink)

The effective altruism movement (EA) is one of the most influential philosophically savvy movements to emerge in recent years. Effective Altruism has historically been dedicated to finding out what charitable giving is the most overall-effective, that is, the most effective at promoting or maximizing the impartial good. But some members of EA want the movement to be more inclusive, allowing its members to give in the way that most effectively promotes their values, even when doing so isn’t (...) overall-effective. When we examine what it means to give according to one’s values, I argue, we will see that this is both inconsistent with what EA is like now and inconsistent with its central philosophical commitment to an objective standard that can be used to critically analyze one’s giving. While EA is not merely synonymous with act utilitarianism, it cannot be much more inclusive than it is right now. (shrink)

It has become common to distinguish between altruistic and commercial contract motherhood (or ‘surrogacy’). Altruistic arrangements are based on the ‘gift relationship’: a woman is motivated by altruism to have a baby for an infertile couple, who are free to reciprocate as they see fit. By contrast, in commercial arrangements both parties are motivated by personal gain to enter a legally enforceable agreement, which stipulates that the contract mother or ‘surrogate’ is to bear a child for the intending parents (...) in exchange for a fee. She is required to undergo medical examinations and to refrain from behaviour that could harm the foetus. The intending parents are the child's legal parents from the outset. The parties to the contract can, but are not expected to, maintain contact after the transaction is completed. We argue that contract motherhood should not be organized according to the norms of the gift relationship, and that contract mothers should be compensated for their labour. However, we accept that there are good reasons for rejecting the commercial model as a suitable framework for contract pregnancy, and argue, instead, in favour of viewing it as a profession. (shrink)

Unlike Sober and Wilson, I suggest that in all cases of benefits conferred on others the direct fitness of the altruist increases. The benefit to others created by the altruistic act is only a consequence of the altruistic adaptation, and not the evolutionary mechanism that created it. In many cases the investment in the altruistic act, like handicaps required for signalling in general, attests to the social prestige of the altruist and thus increases its fitness. In other cases (...) the ‘altruist’ is a phenotype that has only minute chances to reproduce, and what seems to be an altruistic act actually increases somewhat these meagre chances. It is easy to overlook this marginal benefit to the ‘altruist'. Still, if that selfish benefit to the altruist -- i.e., an increase in its direct fitness -- did not exist, the altruistic acts that benefit the group could not have evolved. (shrink)