Human cooperation is highly unusual. We live in large groups composed mostly of non-relatives. Evolutionists have proposed a number of explanations for this pattern, including cultural group selection and extensions of more general processes such as reciprocity, kin selection, and multi-level selection acting on genes. Evolutionary processes are consilient; they affect several different empirical domains, such as patterns of behavior and the proximal drivers of that behavior. In this target article, we sketch the evidence from five domains that bear on (...) the explanatory adequacy of cultural group selection and competing hypotheses to explain human cooperation. Does cultural transmission constitute an inheritance system that can evolve in a Darwinian fashion? Are the norms that underpin institutions among the cultural traits so transmitted? Do we observe sufficient variation at the level of groups of considerable size for group selection to be a plausible process? Do human groups compete, and do success and failure in competition depend upon cultural variation? Do we observe adaptations for cooperation in humans that most plausibly arose by cultural group selection? If the answer to one of these questions is “no,” then we must look to other hypotheses. We present evidence, including quantitative evidence, that the answer to all of the questions is “yes” and argue that we must take the cultural group selection hypothesis seriously. If culturally transmitted systems of rules (institutions) that limit individual deviance organize cooperation in human societies, then it is not clear that any extant alternative to cultural group selection can be a complete explanation. (shrink)

This paper provides strong evidence challenging the self-interest assumption that dominates the behavioral sciences and much evolutionary thinking. The evidence indicates that many people have a tendency to voluntarily cooperate, if treated fairly, and to punish noncooperators. We call this behavioral propensity “strong reciprocity” and show empirically that it can lead to almost universal cooperation in circumstances in which purely self-interested behavior would cause a complete breakdown of cooperation. In addition, we show that people are willing to punish those who (...) behaved unfairly towards a third person or who defected in a Prisoner’s Dilemma game with a third person. This suggests that strong reciprocity is a powerful device for the enforcement of social norms involving, for example, food sharing or collective action. Strong reciprocity cannot be rationalized as an adaptive trait by the leading evolutionary theories of human cooperation (in other words, kin selection, reciprocal altruism, indirect reciprocity, and costly signaling theory). However, multilevel selection theories of cultural evolution are consistent with strong reciprocity. (shrink)

The finding that women are attracted to men older than themselves whereas men are attracted to relatively younger women has been explained by social psychologists in terms of economic exchange rooted in traditional sex-role norms. An alternative evolutionary model suggests that males and females follow different reproductive strategies, and predicts a more complex relationship between gender and age preferences. In particular, males' preferences for relatively younger females should be minimal during early mating years, but should become more pronounced as the (...) male gets older. Young females are expected to prefer somewhat older males during their early years and to change less as they age. We briefly review relevant theory and present results of six studies testing this prediction. Study 1 finds support for this gender-differentiated prediction in age preferences expressed in personal advertisements. Study 2 supports the prediction with marriage statistics from two U.S. cities. Study 3 examines the cross-generational robustness of the phenomenon, and finds the same pattern in marriage statistics from 1923. Study 4 replicates Study 1 using matrimonial advertisements from two European countries, and from India. Study 5 finds a consistent pattern in marriages recorded from 1913 through 1939 on a small island in the Philippines. Study 6 reveals the same pattern in singles advertisements placed by financially successful American women and men. We consider the limitations of previous normative and evolutionary explanations of age preferences and discuss the advantages of expanding previous models to include the life history perspective. (shrink)

Kin selection and multilevel selection are alternative approaches for studying the evolution of social behaviour, the relation between which has long been a source of controversy. Many recent theorists regard the two approaches as ultimately equivalent, on the grounds that gene frequency change can be correctly expressed using either. However, this shows only that the two are formally equivalent, not that they offer equally good causal representations of the evolutionary process. This article articulates the notion of an ‘adequate causal representation’ (...) using causal graphs, and then seeks to identify circumstances under which kin and multilevel selection do and do not satisfy the test of causal adequacy. 1 Introduction2 The KS and MLS Approaches2.1 The MLS decomposition2.2 The KS decomposition3 Equivalence and Causality4 Two Problem Cases4.1 The non-social trait case4.2 Genotypic selection with meiotic drive5 Casual Adequacy: A Graphical Approach5.1 The basic idea5.2 Graphs with individual and group variables5.3 Cases where KS is causally adequate5.4 Cases where MLS is causally adequate6 Discussion6.1 Relation to previous work. (shrink)

The complexity of human societies of the past few thousand years rivals that of social insect societies. We hypothesize that two sets of social “instincts” underpin and constrain the evolution of complex societies. One set is ancient and shared with other social primate species, and one is derived and unique to our lineage. The latter evolved by the late Pleistocene, and led to the evolution of institutions of intermediate complexity in acephalous societies. The institutions of complex societies often conflict with (...) our social instincts. The complex societies of the last few thousand years can function only because cultural evolution has created effective “work-arounds” to manage such instincts. We describe a series of work-arounds and use the data on the relative effectiveness of WWII armies to test the work-around hypothesis. (shrink)

What contribution can the empirical sciences make to metaethics? This paper outlines an argument to a particular metaethical conclusion - that moral judgments are epistemically unjustified - that depends in large part on a posteriori premises.

What motivates grandparents to their altruism? We review answers from evolutionary theory, sociology, and economics. Sometimes in direct conflict with each other, these accounts of grandparental investment exist side-by-side, with little or no theoretical integration. They all account for some of the data, and none account for all of it. We call for a more comprehensive theoretical framework of grandparental investment that addresses its proximate and ultimate causes, and its variability due to lineage, values, norms, institutions (e.g., inheritance laws), and (...) social welfare regimes. This framework needs to take into account that the demographic shift to low fecundity and mortality in economically developed countries has profoundly altered basic parameters of grandparental investment. We then turn to the possible impact of grandparental acts of altruism, and examine whether benefits of grandparental care in industrialized societies may manifest in terms of less tangible dimensions, such as the grandchildren's cognitive and verbal ability, mental health, and well-being. Although grandparents in industrialized societies continue to invest substantial amounts of time and money in their grandchildren, we find a paucity of studies investigating the influence that this investment has on grandchildren in low-risk family contexts. Under circumstances of duress there is converging evidence that grandparents can provide support that helps to safeguard their children and grandchildren against adverse risks. We conclude by discussing the role that grandparents could play in what has been referred to as Europe's demographic suicide. (shrink)

In a passage in A Theory of Justice, which has become increasingly influential in recent years, John Rawls (1971) noted an analogy between moral phi- losophy and grammar. Moral philosophy, or at least the first stage of moral philosophy, Rawls maintained, can be thought of as the attempt to describe our moral capacity – the capacity which underlies “the poten- tially infinite number and variety of [moral] judgments we are prepared..

Mindreading capacity has been widely understood as the human ability to gain knowledge about the inner processes and states of others that bring about the behavior of these agents. This paper argues against this epistemic view of mindreading on the basis of different empirical studies in linguistics and social and developmental psychology: we are systematically biased in attributing mental states, and many everyday uses of mental ascription sentences do not reflect an epistemic function in our social interactions. We introduce an (...) alternative view of mental ascriptions, the social cover view, which is consistent with the evidence. The social cover view holds that the main function of mental ascriptions is to cover the social status and reputation of an agent rather than to gain knowledge about her inner processes and states. Finally, we discuss two possible objections to our proposal. (shrink)

Moral licensing theory posits that individuals who initially behave morally may later display behaviors that are immoral, unethical, or otherwise problematic. While previous literature mainly focused on individual moral licensing, the influences from the social environment have barely been investigated. To address this issue, the present paper develops a conceptual framework of social moral licensing and outlines two main avenues for future research via six propositions. The first avenue entitled “the conspicuousness of moral licensing” considers moral licensing that comes into (...) play when people are observed by others. The second avenue entitled “the relativity of moral licensing” focusses on social comparisons between individuals, their ingroups and outgroups. Specific and testable social moral licensing effects are derived in both avenues. By doing so, this paper outlines promising directions for future studies in this new research stream. (shrink)

It is argued that the question of whether or not one is required to be or become a strict vegetarian depends, not upon a rule or ideal that endorses vegetarianism on moral grounds, but rather upon whether one's own physical, biological nature is adapted to maintaining health and well-being on a vegetarian diet. Even if we accept the view that animals have rights, we still have no duty to make ourselves substantially worse off for the sake of other rights-holders. Moreover, (...) duties to others, such as fetuses and infants, may require one to consume meat or animal products. Seven classes of individuals who are not required to be or become vegetarians are identified and their examption is related to nutritional facts; these classes comprise most of the earth's population. The rule of vegetarianism defines a special or provisional duty rather than any general or universal rule, since its observance it based upon the biological capacities of individual humans whose genetic constitution and environment makes them suitably herbivorous. It is also argued that generalizing the vegetarian ideal as a social goal for all would be wrongful because it fails to consider the individual nutritional needs of humans at various stages of life, according to biological differences between the sexes, and because it would have the eugenic effect of limiting the adaptability of the human species. The appeal to the natural interests of omnivores will not justify any claim that humans may eat amounts of meat or animal products in excess of a reasonable safety margin since animals have rights-claims against us. (shrink)

Strong adaptationists explore complex organic design as taskspecific adaptations to ancestral environments. This strategy seems best when there is evidence of homology. Weak adaptationists don't assume that complex organic (including cognitive and linguistic) functioning necessarily or primarily represents taskspecific adaptation. This approach to cognition resembles physicists' attempts to deductively explain the most facts with fewest hypotheses. For certain domainspecific competencies (folkbiology) strong adaptationism is useful but not necessary to research. With grouplevel belief systems (religion) strong adaptationism degenerates into spurious notions (...) of social function and cultural selection. In other cases (language, especially universal grammar) weak adaptationism's 'minimalist' approach seems productive. (shrink)

Human cooperation is a key driving force behind the evolutionary success of our hominin lineage. At the proximate level, biologists and social scientists have identified other-regarding preferences – such as fairness based on egalitarian motives, and altruism – as likely candidates for fostering large-scale cooperation. A critical question concerns the ontogenetic origins of these constituents of cooperative behavior, as well as whether they emerge independently or in an interrelated fashion. The answer to this question will shed light on the interdisciplinary (...) debate regarding the significance of such preferences for explaining how humans become such cooperative beings. We investigated 15-month-old infants' sensitivity to fairness, and their altruistic behavior, assessed via infants' reactions to a third-party resource distribution task, and via a sharing task. Our results challenge current models of the development of fairness and altruism in two ways. First, in contrast to past work suggesting that fairness and altruism may not emerge until early to mid-childhood, 15-month-old infants are sensitive to fairness and can engage in altruistic sharing. Second, infants' degree of sensitivity to fairness as a third-party observer was related to whether they shared toys altruistically or selfishly, indicating that moral evaluations and prosocial behavior are heavily interconnected from early in development. Our results present the first evidence that the roots of a basic sense of fairness and altruism can be found in infancy, and that these other-regarding preferences develop in a parallel and interwoven fashion. These findings support arguments for an evolutionary basis – most likely in dialectical manner including both biological and cultural mechanisms – of human egalitarianism given the rapidly developing nature of other-regarding preferences and their role in the evolution of human-specific forms of cooperation. Future work of this kind will help determine to what extent uniquely human sociality and morality depend on other-regarding preferences emerging early in life. (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)

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)

An increasing number of scholars argue that moral judgements are adaptations, i.e., that they have been shaped by natural selection. Is this hypothesis true? In this paper I shall not attempt to answer this important question. Rather, I pursue the more modest aim of pointing out three difficulties that anybody who sets out to determine the adaptedness of moral judgments should be aware of (though some so far have not been aware of). First, the hypothesis that moral judgements are adaptations (...) has been advocated in various different specificities and scopes, and on various different levels. Second, the three kinds of evidence that have most often been appealed to by discussants of this hypothesis require additional arguments. And third, there is significant reasonable disagreement about what moral judgements essentially are. (shrink)

The finding that women are attracted to men older than themselves whereas men are attracted to relatively younger women has been explained by social psychologists in terms of economic exchange rooted in traditional sex-role norms. An alternative evolutionary model suggests that males and females follow different reproductive strategies, and predicts a more complex relationship between gender and age preferences. In particular, males' preferences for relatively younger females should be minimal during early mating years, but should become more pronounced as the (...) male gets older. Young females are expected to prefer somewhat older males during their early years and to change less as they age. We briefly review relevant theory and present results of six studies testing this prediction. Study 1 finds support for this gender-differentiated prediction in age preferences expressed in personal advertisements. Study 2 supports the prediction with marriage statistics from two U.S. cities. Study 3 examines the cross-generational robustness of the phenomenon, and finds the same pattern in marriage statistics from 1923. Study 4 replicates Study 1 using matrimonial advertisements from two European countries, and from India. Study 5 finds a consistent pattern in marriages recorded from 1913 through 1939 on a small island in the Philippines. Study 6 reveals the same pattern in singles advertisements placed by financially successful American women and men. We consider the limitations of previous normative and evolutionary explanations of age preferences and discuss the advantages of expanding previous models to include the life history perspective. (shrink)

Naive physics beliefs can be systematically mistaken. They provide a useful test-bed because they are common, and also because their existence must rely on some adaptive advantage, within a given context. In the second part of the commentary we also ask questions about when a whole family of misbeliefs should be considered together as a single phenomenon.

Relatively short Dutch introduction to an evolutionary approach to morality. A synthesis is given of various models of moral evolution. Some remarks are made on a way to look at the evolution of a compatibilistic 'free will' and a model is given of a way in which the 'good' can be understood as the results of shared interests (which, of course, gives an incomplete model, but at the same time throws a lot of light on the way in which we (...) have to resolve ethical issues). (shrink)

Most current modeling for evolution of communication still underplays or ignores the role of local action in spatialized environments: the fact that it is immediate neighbors with which one tends to communicate, and from whom one learns strategies or conventions of communication. Only now are the lessons of spatialization being learned in a related field: game-theoretic models for cooperation. In work on altruism, on the other hand, the role of spatial organization has long been recognized under the term ‘viscosity’.Here we (...) offer some simple simulations that dramatize the importance of spatialization for studies of both cooperation and communication, in each case contrasting a model dynamics in which strategy change proceeds globally, and a spatialized model dynamics in which interaction and strategy change both operate purely locally. Local action in a spatialized model clearly favors the emergence of cooperation. In the case of communication, spatialized models allow communication to arise and flourish where the global dynamics more typical in the literature make it impossible.Simulations make a dramatic case for spatialized modeling, but analysis proves difficult. In a final section we outline some of the surprises of spatial dynamics but also some of the complexity facing attempts at deeper analysis. (shrink)

In the article it is argued that contemporary evolutionary ethics – to the extent it accepts sociobiological strategies of naturalizing human morality – faces some serious conceptual and explanatory difficulties. Conceptual difficulty consists in recognizing that “morality” is not the same as “altruism”, but rather comprises several specific elements which distinguish it from both evolutionary and psychological altruism. Explanatory difficulty consists in recognizing that the phenomenon of morality appropriately conceptualized cannot be incorporated into standard sociobiological explanations without endangering some basic (...) assumptions of those explanations, primarily the assumption of “gene selectionism”, as well as the assumption of “evolutionarily stable strategies”. The basic argument is that one cannot retain both the appropriate concept of human morality and key assumptions of sociobiological explanations. (shrink)

This response outlines more reasons why we need the integrative framework of grandparental investments and intergenerational transfers that we advocated in the target article. We discusses obstacles that stand in the way of such a framework and of a better understanding of the effects of grandparenting in the developed world. We highlight new research directions that have emerged from the commentaries, and we end by discussing some of the things in our target article about which we may have been wrong.