Our species-unique capacity for cumulative culture relies on a complex interplay between social and cognitive motivations. Attempting to understand much of human behaviour will be incomplete if one of these motivations is the focus at the expense of the other. Anchored in gene-culture co-evolution theory, we stake a claim for the importance of social drivers in determining why shamans exist.

The target article advances several original concepts about shamanism, including prospective explanations for how shamanism could express itself in different cultural settings. Although the potential for “innate psychological tendencies” is acknowledged, the target article prematurely dismisses one such hard-wired feature of shamanism: psychosis.

Individual-specific predispositions may precede the cultural evolution of shamanism and may be linked to it via principles of predictive coding. We have used these principles to identify commonalities between clinical and shaman-like non-clinical voice-hearers. The author may find this approach helpful in relating the experiences of shamans to those of their clients.

Singh's cultural evolutionary theory of shamanism is impressive, but it does not explain why some people become shamans while others do not. We propose that individual differences in where people lie on a “psychosis continuum” could play an important causal role.

Shamans deal with events that involve the threat of death. They help buffer death anxiety because, through their claimed supernatural abilities, they can provide both hope for averting death and evidence for existence of a spirit world offering continuance beyond death. Thus, managing the threat of mortality probably played a major role in the development and maintenance of shamanism.

Singh's analysis of shamanism is regarded as a contribution to the evolutionary study of healing encounters and evolutionary medicine. Shamans must create convincing healing spectacles, while sick individuals must convincingly express symptoms and suffering to motivate community care. Both have a shared interest in convincing onlookers. This is not restricted to shamanic treatment, but is still true in modern medical care.

Singh's cultural evolutionary theory posits that methods of inducing shamanic altered states of consciousness differ, resulting in profoundly different cognitive states. We argue that, despite different methods of induction, altered states of consciousness share neurophysiological features and cause shared cognitive and behavioral effects. This common foundation enables further cross-cultural comparison of shamanic activities that is currently left out of Singh's theory.

Cultural evolutionary accounts of shamanism must explain the cross-cultural recurrence and variation in associated practices. We suggest that Singh's account of shamanism would be strengthened by considering the social functions of shamanism in groups. Shamanism increases social group cohesion, making it distinct from other magico-religious practices.

A complete picture of shamanism's cultural evolution requires an understanding of how the professionalization of shamanism affects the distribution of knowledge within societies. We suggest that limiting knowledge to fewer people could impede the accumulation of functional knowledge within shamanism. On this basis, we make further predictions about how the domain of shamanism could change and collapse.

Singh conflates diverse religious statuses into a single category that includes practitioners with roles that differ significantly from empirical characteristics of shamans. The rejection of biological models of trance and conspicuous display models misses the evolutionary roots of shamanism involving the social functions of ritual in producing psychological and social integration and ritual healing.

Singh deploys cultural evolution to explain recurrent features of shamanistic trance forms, but fails to substantively address important distinctions between these forms. Possession trance (vs. trance without possession) is disproportionately female-dominated and found in complex societies. The effects of cultural conditions on shamanism thus extend beyond its presence or absence and are vital for modeling its professionalization and spread.

The commentators endorse the conceptual and ethnographic synthesis presented in the target article, suggest extensions and elaborations of the theory, and generalize its logic to explain apparently similar specializations. They also demand clarity about psychological mechanisms, argue against conclusions drawn about empirical phenomena, and propose alternative accounts for why shamanism develops. Here, I respond.

A range of empirical findings is first used to more precisely characterize our distinctive tendency to objectify or externalize moral demands and obligations, and it is then argued that this salient feature of our moral cognition represents a profound puzzle for evolutionary approaches to human moral psychology that existing proposals do not help resolve. It is then proposed that such externalization facilitated a broader shift to a vastly more cooperative form of social life by establishing and maintaining a connection between the extent to which an agent is herself motivated by a given moral norm and the extent to which she uses conformity to that same norm as a criterion in evaluating candidate partners in social interaction generally. This connection ensures the correlated interaction necessary to protect those prepared to adopt increasingly cooperative, altruistic, and other prosocial norms of interaction from exploitation, especially as such norms were applied in novel ways and/or to novel circumstances and as the rapid establishment of new norms allowed us to reap still greater rewards from hypercooperation. A wide range of empirical findings is then used to support this hypothesis, showing why the status we ascribe to moral demands and considerations exhibits the otherwise puzzling combination of objective and subjective elements that it does, as well as showing how the need to effectively advertise our externalization of particular moral commitments generates features of our social interaction so familiar that they rarely strike us as standing in need of any explanation in the first place.

People want to form impressions of others based on their moral behaviours, but the most diagnostic behaviours are rarely seen. Therefore, societies develop symbolic forms of moral behaviour such as conventional rituals and games, which are used to predict how others are likely to act in more serious moral situations. This framework helps explain why everyday behaviours are often moralized.

We should distinguish between the apparent source of a norm and the scope of the norm's satisfaction conditions. Wide-scope social norms need not be externalised, and externalised social norms need not be wide in scope. Attending to this distinction leads to a problem for Stanford: The adaptive advantages he attributes to externalised norms are actually advantages of wide-scope norms.

We argue that, in addition to the positive effects and functionality of morality for interactions among in-group members as outlined in the target article, morality may also fuel aggression and conflict in interactions between morality-based out-groups. We summarize empirical evidence showing that negative cognitions, emotions, and behaviors are particularly likely to appear between out-groups with opposing moral convictions.

I argue that the set of moralized norms and beliefs is more expansive than Stanford appears to suggest. In particular, I contend that norms governing behavior in conflictual coordination problems are likely to be moralized.

We argue that Stanford's picture of the evolution of externalised norms is plausible mostly because of the idealisations implicit in his defence of it. Once we take into account plausible amounts of normative disagreement, plausible amounts of error and misunderstanding, and the knock-on consequences of shunning, it is plausible that Stanford under-counts the costs of externalisation.