Though historical myths may foster cooperation because they provide cues of fitness interdependence through identity fusion, we suggest that, when effective in promoting cooperation, they also create affective feelings of security, trust, and intimacy. Sijilmassi et al. posit that historical myths increase cooperation because they create a “mental representation that cooperation within a given coalition constitutes a mutually beneficial cooperative arrangement” (sect. 3.2, para. 7). In this commentary, we discuss why the authors’ explanation may need to be supplemented with an account of the affective states of the recipients of the myths.

To begin, note that not all perceptions of mutual benefits “manifests as a feeling of moral duty.” Consider the case of individuals working together on dangerous technologies, who are cooperating in a scientific coalition but who still have doubts about the morality of their project. We agree that a “sense of should” (Theriault, Young, & Feldman Barrett, Reference Theriault, Young and Feldman Barrett2021) will be an important part of the power of myths, and this requirement suggests to us that more attention can be given to the affective power of myths.

In addition, consider that even in population structures supported by shared myths, cooperators face a challenge: They must be sure that their partner is motivated enough to gain benefits from cooperating; and honest enough to share the benefits fairly, without deception, exploitation, or flawed self-perception. Given this challenge of selecting good cooperators from a pool of individuals with their own motivations, personality traits, energy levels, and capabilities, we need to look beyond population structure to person-level cues of honesty, ability, and integrity.

For an example, consider this case: I am journeying in unfamiliar territory and spot an opportunity to spear a bison if I can recruit a member of a nearby camp to help me. I incentivize assistance by offering a share in the spoils. Simulating one-shot cooperative incentives like this, laboratory games have shown that people use systematic heuristics to decide how cooperative to be with unfamiliar individuals: Physical markers of strength, attractiveness, health, and social status all strongly predict the extent to which individuals are chosen for cooperative partnerships (Eisenbruch, Grillot, Maestripieri, & Roney, Reference Eisenbruch, Grillot, Maestripieri and Roney2016). Given our sensitivity to these physical characteristics when choosing cooperative partners, we should expect historical narratives which portray fellow group members in these lights to incentivize cooperation. This can explain the tendency of historical myths to showcase the physical traits, personal attributes, and life legacies of valued and respected legendary group members (living and nonliving), portraying these legends as intricately connected to the group's kinship and social networks (Wiessner, Reference Wiessner2014). Reporting on the stories told by firelight in small-scale hunter gatherer communities, Wiessner notes that the ritual of retelling stories by firelight engenders “more accurate understanding of the thoughts and emotions of others, particularly those not immediately present” which generates “the regularity of behaviour so essential for cooperation” (p. 14027).

While we thus agree that myths can increase cooperation among group members by inculcating beliefs about the group, we suggest that an affective feeling of security can have these effects on cooperation without the need for any particular belief. Consider that the successful coalitions seen in nonhuman animals function without myths, and arguably without any cognitive representations of what makes the group a group. Positive affect toward others as fellow travelers, or at least high levels of toleration, permits the cooperative arrangement.

Returning to the human case, a sense of security versus discomfort with another person explains willingness or reluctance to invest resources and time in partnerships, without the need to form an explicit representation of the features that constitute a good cooperative arrangement. Sharing a historical myth about one's group can provide a feeling of similarity to our partners, who share a part of our identity that we feel strongly about (e.g., a Canadian, a Sikh, a socialist, etc.). This can motivate us to help them and trust them, by creating a sense of intimacy which may otherwise be absent, rather than by creating a belief about how we become a community. The affective account can explain why historical myths would be more prevalent in larger populations, without which, intimacy among average members is lower, members tend to be less like each other, and individuals’ goals are more varied. Also, in places where people have more coalitional opportunities, the incentives are higher to display these desirable traits and foster cooperative relationships.

Sharing myths about a group's defining characteristics, historical developments, and legendary members also enable us to set observable standards on what it means to do things “the way I would,” or “as a self-respecting Canadian would” given the values showcased in the myths, and the behaviors proscribed and promoted. By marking out contexts in which cooperation is expected from all members of a group, for example, religious activities like rituals, holiday celebrations, and offerings to deities; seasonal agricultural activities; and environmental calamities, the myths have the additional feature of making free riders or noncooperators easily identifiable – by failing to cooperate in the contexts featured in myths as defining of the group, the sense of intimacy and similarity is missing. This causes feelings of discomfort which have constraining effects on altruism, cooperation, and trust. This feature of exposing untrustworthy or incapable individuals explains the prevalence of historical myths when coalitions require more costly investments – in these cases it is more important to detect and avoid disingenuous or unreliable cooperative partners, with whom these investments are unlikely to pay off.

In summary, since coalescing in groups that have stood the test of time provided such significant fitness advantages for our ancestors, we predict that humans evolved an emotional affinity for cues of longstanding groups, and displaying these cues in our interpersonal interactions cause us to feel more comfortable and safer with each other. These feelings can independently serve as a motivation to trust each other, and to invest more of our time, our resources, and our energy in cooperative ventures.