1.1 Human uniqueness

Human uniqueness has always been one of the most fascinating and fundamental issues for scientists and philosophers. Behavioral, cultural, and biological accounts of human uniqueness, however, have started to converge only recently (Boyd & Richerson, 2005; Hill et al., 2009). While all species are unique, only humans have been able to control energy and their environment, and to develop complex tools and technology to ease and extend life substantially (Bingham, 1999; Laland & Seed, 2021). Although humans gained large-scale ecological dominance only in recent historical times, an exceptional total biomass, tool use, and social cognition had already been achieved in prehistoric hunter-gatherer societies (Vitousek et al., 1997; Hill et al., 2009).

Humans extensively rely on social learning that results in cumulative adaptive change and extra-somatic storage of information (Hill et al., 2009) that allow for the rapid accumulation of knowledge and skills across generations (Boyd & Richerson, 1985). Tools, technology, social learning, and cumulative culture made our innovations sustainable and resulted in rapid development in the recent evolutionary period (Boyd et al., 2011). But how did humans attain and sustain tools, technology, and cumulative culture? Anthropologists have been speculating about this question for some time (e.g., Schick & Toth, 1994) and are brought back to the fundamental search for key features that made humans uniquely capable to achieve this development.

Following multiple lines of literature that arrive at this position (Richerson & Boyd, 1998; Gintis, 2000; Potts, 2004; Tomasello, 2014, 2020; Levinson & Enfield 2020), we consider that human uniqueness lies in exceptional human sociality. The essential features of exceptional human sociality have been and will remain debated. The list of behaviors, cultural and social characteristics that are human universals and are less likely to be found in other species (Brown, 2000, 2004), could be longer or shorter as new findings in studies of animal behavior might eliminate certain elements from this list (e.g., in Høgh-Olesen, 2010).

We identify cooperation, a high level of social order, language, exceptional social cognition, and a high level of social complexity built on social norms as essential characteristics of exceptional human sociality. The first crucial element of unique success of human societies is the ability to solve the problem of cooperation between non-closely related individuals (Bingham, 1999; Fehr & Gächter, 2000; Ostrom, 2000; Okada & Bingham, 2008). Another problem that appears with an increased amount of competitive and other interdependencies in group life is the maintenance of social order, for which humans developed two distinct solutions: formal and informal hierarchies. Furthermore, in line with other perspectives, we acknowledge that the use of language as an advanced form of communication, the acquisition of advanced social cognition, and social complexity in the organization of social life that is built on social norms that prescribe what is good and bad behavior and how should others be treated are essential parts of human uniqueness. They are, however, partly consequences and partly catalysts of unique human solutions to the problems of coordination, cooperation, and social order.

During this theoretical speculation, we take it as granted that new insights for human uniqueness can only be gained if human social life is scrutinized in a comparative perspective with non-human social life (Hill et al., 2009; Tomasello, 2009).

1.2 Reputation is key to explaining exceptional human sociality

Human uniqueness is certainly a complex question and various attempts have tried to attribute its origins to a single social characteristic. Cumulative culture has been proposed as an explanation (e.g., by Boyd & Richerson, 1985; and Henrich & McElreath, 2003). Culture is information, tools, material goods, and regulations of behavior, that is transmitted socially (Hill et al. 2009). Although culture is present in several animal species as they transmit behavioral patterns, including tool use, food extraction and storage techniques, and social behaviors (Whiten et al., 1999; Vale et al., 2017), humans have an extraordinary capacity for cumulative culture and imitation (Boyd & Richerson, 1996; Mesoudi & Thornton, 2018). The unique accumulation and development of human culture has largely been catalyzed by new institutions of inheritance (Cavalli-Sforza & Feldman, 1973; Boyd & Richerson, 1985; Henrich & McElreath, 2003).

Coalitional enforcement has been suggested as another candidate that has enabled cooperative social adaptations and sustained social order (Bingham, 1999). Coalitional enforcement is present in chimpanzees that spend a significant amount of time with coalition formation, management, and policing, and use joint enforcement (de Waal, 1998). Such behavior has also been observed in other primates, dolphins, social carnivores, and elephants (Bissonnette et al., 2015; Redhead & von Rueden, 2021). Human groups and societies coordinate on severe punishment of their members, including ostracism, and the death penalty, although some might have moral objections against these (de Waal, 1996, 2006; Wrangham, 2019).

In the current paper, we argue that reputation is a central organizer of our social life and is a device for unique human sociality (Conte & Paolucci, 2002; Garfield et al., 2021) as it is fundamental for the emergence of cooperation, social order, language, social cognition, and social complexity. This claim implies that reputation could have been one of the key avenues through which human uniqueness has developed.

Our perspective finds support in reputation being a human universal. Anthropological accounts have identified that striving for reputation is part of human nature (Buss, 2001). From a social science perspective, reputation has been considered as one of the ultimate individual goals that indicates social integration and approval (e.g., Smith, 1976). Individuals strive for and are concerned about their reputation as it brings them social benefits in the form of social comfort, feelings of acceptance, and popularity in partner selection, and direct material benefits such as possession of and access to resources (Lindenberg, 1996; Smith & Bliege Bird, 2005; Romano et al., 2021, 2022; Nieper et al., 2022).

Our perspective is supported also by the multidimensional character and multi-method construction of reputation in humans. Other species evaluate each other as well, because this is essential, for instance, for partner choice. Evaluation could take place also based on interactions that do not directly involve the observer (Subiaul et al., 2008; Herrmann et al., 2013). This happens, for instance, when fights for dominance are observed by bystanders. Reputation in humans as a complex evaluation device has its origins probably in these more elementary forms of evaluations.

Next, we will discuss what is meant by reputation, how it is linked with individual actions and behavior, and how it is constructed. This scrutiny is necessary to differentiate reputation from evaluation of other individuals that is present also in other species. This discussion is organized to illustrate the role of reputation in the struggle for individual survival, in partner choice, in experiencing more complex forms of interdependencies in group life, and in large-scale societies.

1.3 What is reputation?

Reputation is an evaluation of other individuals based on their skills and past actions (Számadó et al., 2021). Reputations also include the beliefs and perceptions we form about others (Wu et al., 2016a; Romano et al., 2021). The collective aspect of reputations is often emphasized in definitions indicating that evaluations of other individuals are discussed, shared, and collectively formed (Giardini & Wittek, 2019b). In our complex social world, reputation provides guidance, helps partner selection, and assists to condition our actions towards others. The universal currency that helps to inform group members about good and bad actions of others is the reputation (Milinski, 2016) that is shared and debated in private and public discussions.

Individuals are motivated to gain and maintain a good reputation, because with good reputation one can harvest and accumulate private gains, such as sex, food, territory use, resources, and social favors (Næss et al., 2010; Redhead & von Rueden, 2021). Individuals can turn their good reputation into power, influence, control over redistribution, and privileges (Farley, 2019). Once reputation is valued this way and provides such advantages, it becomes an important asset that individuals will strive for. In fact, people very much would like to appear in a favorable light for others (Goffman, 1959).

How can people earn their reputation? Even in the hominid past, reputation has not been determined purely by a single skill, but has been based on a complex assessment of multiple qualities (Henrich & Gil-White, 2001; Garfield et al., 2021). Although hunting-competence has been important (Smith & Wishnie, 2000), prosociality and sharing knowledge about the environment also directly assisted group-beneficial cooperation and hence have likely been valued dimensions. The ability to settle disputes and the capacity of leadership for the group in need have also likely been esteemed dimensions in hominid group life. Also today, reputation can be earned with group-beneficial traits and actions that contribute to solving problems of co-existence, conflict, inequality, and cooperation. It is important to notice that many positively valued traits directly relate to other-regarding behavior, group-beneficial actions, leadership skills, and conflict resolution potential, and indirectly to problems of coordination and cooperation that the group needs to solve (Hoyt, 1994; Romano et al., 2021).

A discussion about what do people evaluate in others can be paralleled with the use and accumulation of reputation. Reputation largely depends on perceptions of other individuals and on cognitive simplifications, as objective records of skills and attributes are difficult to obtain.

Although the collective aspect of reputation must be emphasized and our assessment is never independent of that of others, we evaluate others privately. We often assign reputations to others based on experience from direct encounters and direct observation. In addition to interactions and observation, the assessment of the target can be based on receiving communication and marketing of qualities directly from the target or from others, collecting information about the target, and gathering information about the evaluations made by others about the target. These imply an arsenal of relevant actions and communications, including neutral observation, bystander involvement, signaling, communication, storytelling, and self-marketing. Although assigned privately, reputations are shaped in social interactions. This includes third-party communication, open discussions, public displays, and stereotype-driven processes. Table 1 summarizes some characteristics of different ways of reputation construction, ranging from evaluations after direct private involvement in dyadic interactions till learning from public display.

Next, in Section 2 we examine the essential characteristics of exceptional human sociality: large-scale cooperation between unrelated individuals, social order, language, social cognition, and complex social organization built on social norms. We elaborate on the relevance of reputation for these characteristics. In Section 3 we navigate from individual actions through partnerships and group life to large-scale societies to illustrate the central role of reputation for interdependencies that mount up to the development of features of human uniqueness. This approach enables to speculate about at which stage of social organization individual reputation reached its peak importance. Section 4 summarizes the paper and calls for subsequent inquiries of reputation-based human sociality.

2.1 Cooperation

The great extent of large-scale cooperation between non-closely related individuals seems to be one key puzzle of human uniqueness. By cooperative action, individuals take substantial cost to themselves in order to provide substantial benefits to strangers or other group members (Henrich, 2004; Rand & Nowak, 2013). Cooperation has already been the likely feature when humans lived in smaller subsistence communities, illustrated by the frequency of cooperation in current small-scale societies (Glowacki & Lew-Levy, 2022). Unlike humans, other species show very limited cooperation between non-kin individuals (Dugatkin, 1997a; Bingham, 1999).

Once group members face cooperation problems repeatedly, reciprocal help can develop (Wilkinson, 1984; Kettler et al., 2021). Reciprocity offers a straightforward solution to the problem of cooperation in repeated interactions (Axelrod, 1984). Reciprocal help requires patience for delayed exchange, individual discrimination, and memories concerning past behavior (Clutton-Brock, 2009; Hauser et al., 2009). These are cognitively demanding conditions and are based on subjective evaluation of past behavior of the interaction partner (Stevens & Hauser, 2004).

Indirect reciprocity extends the notion of direct reciprocity (Nowak & Sigmund, 1998, 2005; Panchanathan & Boyd, 2004). Through direct reciprocity, help provided is returned directly by the interaction partner in the future. Through indirect reciprocity, help is reciprocated by someone else, and reputation is the simplifying device that is used to evaluate who is worthy of receiving help and who is not.

Reputation-based mechanisms can provide an answer to widely observed cooperation in small-scale and larger human societies (Nowak, 2006; Wu et al., 2016a, 2016b; Számadó et al., 2021; Romano et al., 2021; Giardini et al., 2022). The relevance of reputation for trust and cooperation has been demonstrated by a wide range of experimental studies (e.g., those of Sommerfeld et al., 2008; Boero et al., 2009; Samu et al., 2020; and Samu & Takács, 2021). Reputation can either be a device to govern the choice of interaction partners or it can instruct how to behave in a given interaction against a specific interaction partner. There are different kinds of theoretical accounts that are built on emphasizing the relevance of reputation-based mechanisms for human cooperation (Roberts et al., 2021).

Costly help to another individual can signal social preferences and care for other group members (Barclay et al., 2021). In general, we would like to be seen as helpful to others and we appreciate generosity of others also if we are not direct beneficiaries (Samu et al., 2020). Hence, reputation is not only earned in direct encounters. Good reputation is attributed to somebody who has helped others in the past, but it could also be more complexly determined and being ascribed only to those who has helped good partners in the past, depending on the prevalent social norm in the society. In addition to informal rules that prescribe what one ought to or ought not to do (Bicchieri, 2005; Andrighetto & Vriens, 2022), social norms prescribe also who is entitled to have good or bad reputation in the society (Ohtsuki & Iwasa, 2004, 2006). Only a limited set of social norms can establish and sustain cooperation (Ohtsuki & Iwasa, 2004, 2006; Okada, 2020; Samu et al., 2020; Podder et al., 2021b). While rewarding good actions and punishing bad behavior seem to be straightforward responses, some guidelines can be controversial or easily misinterpreted. An example is the handling of justified defection in which someone is supposed to reward defections against badly reputed others (Yamamoto et al., 2020).

Models of competitive altruism emphasize that as reputation has direct benefits for partner selection and can be obtained by helpful behavior, hence individuals are willing to help each other, and costly cooperation escalates (Roberts, 1998; Barclay, 2004; Roberts et al., 2021; Giardini et al., 2021). Once over-commitment can bring reputational benefits to the individual, a solution by equal contributions becomes a shaky equilibrium, because individuals would like to help more than others. Competitive altruism is further enhanced once there are further advantages of high reputation in the society beyond partner choice, such as access to resources or power. Competitive altruism can explain cooperation in human groups and the general appreciation of individuals who make sacrifices for their group (Roberts, 1998; Barclay, 2004; Fehr & Schurtenberger, 2018; Roberts et al., 2021).

Reputation might be gained also by sacrifices in intergroup competition (Handley & Mathew, 2020; De Dreu et al., 2020; Takács et al., 2021). Bounded generalized reciprocity theory (Yamagishi et al., 1999; Yamagishi & Kiyonari, 2000; Yamagishi & Mifune, 2009) and parochial altruism describe how out-group threat, mobilization for collective resources, and identity formation triggers altruistic actions benefiting the in-group because group-beneficial acts are recognized with good reputation (Rusch, 2014; Balliet et al., 2014; De Dreu et al., 2014, 2022).

2.2 Social order

Orderly living and the management of internal disputes and conflicts is a typical characteristic of small human groups and societies. Humans live a harmonized group life with a limited number of conflicts despite the large number of interdependencies that they face when living and acting closely together. In current human societies, social norms and institutions safeguard and enforce social order, although they are constantly challenged and change (Bicchieri & Mercier, 2014; Bicchieri, 2016), might be local, or support social order only within group boundaries at the expense of being hostile to out-group members (Gambetta, 2011).

Social order in many group-living species is established with the help of dominance hierarchies. Dominance is based on the actual capacity to threaten, injure, or kill other group members. In a dominance ranking based on a single dimension of physical strength, the assessment of strength is relatively straightforward. Leadership is determined and occasionally challenged in fights and dominance is disambiguated with signals, cues, and badges. Signals positively correlated with the relevant internal quality, such as body size and advanced weaponry decrease the necessity of aggressive encounters, because they reliably communicate strength to the observer (Spence, 1973, 1974; Bergstrom et al., 2002), but do not eliminate the costs and risks implied by occasional fights needed.

Dominance hierarchies specify the rights of access to mates, food, and territory, but might also imply special responsibilities in exchange for defence, decision-making, representation, and in-group punishment. Dominance hierarchies make individual sacrifices for the group possible through two different mechanisms: coercive enforcement and voluntary competition for dominant positions (Adler & Borys, 1996). Order can be established by coercion if dominance is correlated with the actual capacity to employ superior physical strength in a close-range encounter toward other group members (Clutton-Brock & Parker, 1995; Bingham, 1999). At the same time, there is less need to apply coercion because dominance hierarchies disambiguate role stress (Adler & Borys, 1996), while guiding and synchronizing group life for joint movement, physical location, and access to food and reproduction. The maintenance of monitoring, threats, and physical dominance, however, is costly and results occasionally in unwanted injuries.

Humans have advanced the hierarchical solution of in-group social order in two different ways: with the development of formalized hierarchies and institutions, and with the use of reputation as the basis of informal hierarchies (Buss, 2001; Flanagan, 1989; Grove, 2020). Both formal and informal hierarchies simplify the enforcement of orderly actions and sanction violations of order. Formalized hierarchies and institutions centralize rights and rules for applying coercion (Richerson & Boyd 1999). They enable the fine-tuning of hierarchical asymmetries and their careful consideration for conditional actions and privileges (Borgerhoff Mulder et al., 2009). Formalization and supporting institutions allow that hierarchies could operate also in larger groups. Formalization has been key to scaling up the organization of group life by size and time, because formal ranks have provided unambiguous distinctions also when dyadic monitoring of actions and dyadic enforcement of contribution have not been feasible.

Material signals to earn or communicate reputation were important to disambiguate hierarchical relations in humans. Display of success in a costly and group-beneficial hunt is considered as a signal to earn reputation (Smith & Bliege Bird, 2000, 2005). Success and reputation could be communicated with various signals, including body paint and tattoos (Jacques, 2017), durable material substances such as clothing, beads, necklaces, bracelets, or jewelry (Kuhn, 2014), and giving away possessions (Rappaport, 1979; Bliege Bird & Smith, 2005). Archeological evidence of that warriors and heroes have been buried with their possessions in ancient graves supports this argument (Hansen, 2013). A public display of signals is an efficient way to share and harmonize reputations, which could be used to organize access to resources, coordinate decisions on social integration and exclusion, and motivate members for increased cooperation. A public display largely decreases the costs involved in dyadic interactions. A public display can be arranged easily in small groups that spend their lives together. Accordingly, rituals of inauguration, ostracism, punishment, and apologies are often exercised publicly in order to publicly ascribe, demolish, or repair reputations.

Signals of earned reputation, in any case, must be credited by group members. This is difficult because reputation signals could potentially be faked, meaning that they might not be perfectly correlated with actual group-beneficial contributions. The establishment of credible formalized public signaling conventions of reputation is therefore challenging.

Even in the absence of formalized public reputation systems and supporting institutions, in our diverse contexts of social life, we develop and rely on informal rankings based on reputation — when this does not seem to be necessary (Boehm, 1999, 2019; Érdi, 2019). In our social life in various group contexts, reputation is the central organizer of action. A good reputation can be acquired by contributing to in-group social order and behaving in a manner that is in line with in-group norms and expectations. In addition, reputation can also be earned by prosocial protection of group order. Prosocial guardians might voluntarily punish free riders and take initiations for humiliation or social exclusion of norm violators and free riders. For instance, adolescents imposing sanctions on those who stand out of the group attain higher informal status (Adler & Adler, 1995; Eder, 1985).

Bad reputation is a sanction for those who disturb the in-group order and violate group norms. These norms, however, can be local and support costly actions against out-groups or against the larger society. In such cases, reputations are also considered within the group only and internal social order can be linked with external disorder (Gambetta, 2011; Meier et al., 2016). In return, reputation is the device to signal and prescribe in-group privileges. Consequently, reputation rewards and sanctions are largely responsible for the spontaneous maintenance of emergent order within the group (Conte & Paolucci, 2002).

Informal reputations, the emergence of formalized hierarchies, and the emergence of formalized hierarchies and the development of supporting and regulating institutions could have reinforced each other. The increasing complexity of group life, however, could have resulted also in the decoupling of informal reputations from formal hierarchies. Given the multiplexity of relevant dimensions, informal and formal hierarchies could refer to different skills and traits. Prestige earned by having specialist skills and knowledge, for instance, is a distinct dimension of gaining influence over others than dominance gained by threat and fear (Brand & Mesoudi, 2019). Informal reputation could also be a correction mechanism that arises because of the rigidity of formal hierarchies and the compensation opportunities inherent in informal reputation attributions. Noble men and kings could have bad reputations, and low-ranked servicemen could enjoy high social esteem. In any of these cases, informal reputations remain to guide behavior. In an organization, for instance, the allocation of tasks and responsibilities are linked with the formal hierarchy, and personal favors are compensated with informal reputation. Most benefits accrue to the formal hierarchy, but some benefits are aligned with informal reputation.

There is also transferability between formal and informal hierarchical positions. On the one hand, individuals at the top of formal rankings might try to turn their formal position and visibility into good reputation by investment in charity, public image making, and conspicuous consumption (Veblen, 1899). On the other hand, good informal reputation can be turned into political gain and success in formal selection processes. Status differentiation of this kind is a fundamental socio-relational process. Social status is formed through informal and formal interactions and exchanges, and through alliance formation dynamics and conflicts (Emerson, 1962; Blau, 1964; Frank, 1985).

2.3 Language and gossip

Communication is a tool to solve problems of interdependence. Language is a uniquely human way of communication that enables navigation in our societies (Tomasello, 2008). Language is a human universal; it exists in all known human cultures and there is an innate capacity of humans to learn any language (Brown, 2000). Hence, language is part of the puzzle of human uniqueness, but it is a tool or a solution rather than a problem itself. In humans, language has enabled the accumulation of knowledge and culture, and largely assisted the negotiated division of labor and the establishment of large-scale cooperation (Gärdenfors, 2004; Számadó & Szathmáry, 2006). In turn, the development of complex language has likely been helped by the need of solving the puzzle of cooperation. Language can be used to talk somebody into cooperation and share who has made sacrifices for the group.

How and why we have attained this master tool of communication is an open and complex question. Given the amazing power and uniqueness of human language, there is a wide range of theories that speculate about early language evolution (Számadó & Szathmáry, 2006). Dunbar (1996, 1998a, 2021) finds an answer in how we talk. Most of our informal conversations are intimate and mutually enjoyed. Such activities create or maintain social bonds between the partners involved in the communication. Informal conversations are less demanding and more time-efficient than physical grooming, and hence “grooming” conversations could have replaced physical grooming in the hominid lineage.

Gossip, talk about third parties who are not present (Dores Cruz et al., 2021b), is an informal conversation (Dunbar, 1996); it is often intimate, mutually enjoyed, and creates or maintains social bonds between the communication partners. Hence, it can indeed be a form of social grooming (Torres, 2019). Gossip constitutes a major part of our informal conversations (Emler, 1992, 1994; Dunbar et al., 1997; Dunbar, 2004; Pápay et al., 2022). Gossip is uniquely human (Bloom, 2004). Talking about others in an evaluative way implies that the reputation of others is discussed, questioned, and influenced in gossip. This is how we can construct reputations in any human social context (Dores Cruz et al., 2021a; Giardini et al., 2022). Hence, gossip is more than social grooming and the important role of who is targeted by gossip should not be underestimated. The focus on the absent target brings complexity into the communication. Gossip is certainly the most important tool for building reputations socially. As a precondition of gossip, identification of third-party individuals who are not present is necessary, which imposes a complex cognitive requirement.

But why is it so necessary to talk about third parties who are not present, especially if it requires high cognitive effort? Social bonding and trust between the sender and the receiver do not necessitate the cognitive investment because social grooming can also be obtained by chit-chat talk, touching, and smiling (Dunbar, 2021). There is also little need of exchanging information about targets if the group lives a compact life and individual actions are to a large extent observed by everyone. Once the group life includes a temporary absence or separation of its members, division of labor, or a larger size in which direct observation of all actions is not feasible, gossip becomes an important tool to share relevant information that is used to update reputations of known third parties. The value of talking about absent third parties is therefore primarily associated with in-group relations. In a small group, the need for third-party information occurs, for instance, if activities are done separately (for instance, due to the development of division of labor). If group members separate temporarily, then direct control, for instance of partners, becomes inaccessible. This is typical of the hunter-gatherer lifestyle. Efforts and contributions in hunt can only be assessed by those who are present, and hence they might be asked to share this information.

Unlike condemnation in front of a large public, the privacy of the gossip situation offers a safer place to be critical about a third party. This is an important distinction because many scholars question the honesty of gossip, while critical gossip can actually be more honest than the public sharing of personal information that is constrained by social desirability and a risk of conflict and retaliation (Giardini, 2012). Emotions related to reputational dynamics can be expressed in this private setting easier than publicly. Unlike public communication, gossip can undoubtedly be related to coalitions, alliance formation, and power dynamics; it can be about social relationships, enemies, or the exclusion and integration of others. Furthermore, while condemnation in the public could ruin the sender’s relationship with the target, negative gossip does not directly have such consequences.

Voluntary disclosure of private and sensitive information in gossip implies indebting the communication partner with the promise of returning important information in the future. Gossip is also the tool to improve perceptions about the perspectives of others, including their motivations, beliefs, and expectations. Accordingly, the language of gossip is highly complex and contains much more than just adjectives describing the skills and past actions of the target (Vincze et al., 2021).

2.4 Social cognition

Humans have distinctive cognition, and their cognitive uniqueness contains several elements, including memory of the past and imagining the future, the design of complex tools and technology, exceptional exploration and problem-solving capacities, and complex social cognition. Social cognition in particular is central to human cognitive uniqueness (Laland & Seed, 2021). A large number of interdependent situations continuously require remembering, learning from, and conditionally adjusting behavior. Furthermore, carrying out action conditional on the interaction partner requires the use of social information and advanced social cognition. Information that concerns whom to trust, whom to follow, and whom to punish has to be accessed, analyzed, and utilized to make appropriate decisions in interactions with others. Reputation is a shortcut developed exactly for such a purpose.

In turn, the communication of reputations and its interpretation requires advanced social cognition. We continuously attempt to impress others with our own qualities, our prosocial intentions, and care for others (Barclay & Barker, 2020). Skills, qualities, and behavior that are relevant to reputation are signaled intentionally. Evidence of helping behavior, for instance, is displayed or told in stories. Knowledge, wisdom, humor, and management skills are showcased in conversations.

Direct interaction experience or visual inspection of an interaction might be sufficient to draw conclusions about the qualities of an individual. Direct experience can be of various kinds, including aggressive fights, mutually beneficial encounters, and neutral meetings. Interaction can include information sharing, threats, and could be self-marketing, storytelling, or motivated by social bonding. It could include signals of abilities, capacities, dominance, submission, and future actions, but also of current need.

Bystander observations are also the sources to evaluate others. The presence of observers implies the use of complex signals targeting the outside observers with the action. As bystander observations are used to learn important social information, the presence of bystanders modifies the actions of interaction partners (Bateson et al., 2006; Manesi et al., 2016).

Most interaction situations lack the incentives to lie, especially to trusted interaction partners or to the public. This is because communication of reputations is cheap, benefits to the receiver are substantial, and the receiver could immediately reciprocate with other information, social acknowledgment, social bonding, or other rewards. Still, given the competition for reputation, reputational signals are not necessarily honest. Strategic investments in reputation construction and deconstruction are beneficial individually. So, it is a fundamental question what are the mechanisms that can ensure the credibility of reputations and reduce problems with imperfect of incorrect information (Giardini et al., 2022).

Strategic intentions behind some of these signals drive receivers to devote efforts to figure out the true intentions and motives of their senders, which is labelled as epistemic vigilance (Kraus & Fussell, 1991; Mascaro & Sperber, 2009; Sperber et al., 2010). Attention of receivers to the intentions of senders increases the risk of disseminating dishonest information and hence decreases the expected gain from lying (Sperber et al., 2010). Clarification of the intentions of others and disambiguation of their reputations takes place in communication about others (Estévez et al., 2022). The huge amount of time we spend in gossip (Emler, 1992, 1994; Dunbar et al., 1997; Foster, 2004; Besnier, 2009; Pápay et al., 2022) is not just an exchange of reputation assessments. Gossip contains communication about the perspectives of others to anticipate their behavior in interdependent situations correctly (Righi & Takács 2022). Humans are exceptional in their ability to represent the mental states of oneself and others, including beliefs, desires, and intentions, which is also summarized as the theory of mind (Premack & Woodruff, 1978; Laland & Seed, 2021).

Language and the management of cooperation and of hierarchical relations are all related to the emergence of advanced cognitive skills, increased brain and neocortex size. The social brain hypothesis (Dunbar 1998b, 2021) could also be referenced here, as with increasing social complexity we need to use more of our brain to carry out, interpret, and influence actions. At the same time, our increased brain and neocortex size enables us to deal with problems of coordination, cooperation, and social order. Although advanced social cognition and our complex brain are somewhat costly solutions, they could still be considered as efficient tools that help solve fundamental problems of our life.

2.5 Social complexity, social norms, and the interrelation of characteristic features of unique human sociality and reputation

We argue that the essential features of human uniqueness are interrelated, and a perspective centered on reputation helps the explanation of their development. These features are present in every human culture, as all human societies exhibit large-scale cooperation, social order, have spoken language, gossip, and advanced social cognition.

Social complexity could be added to this list of unique human sociality. A complex organization of group life, however, is featured also in some other species. For instance, eusocial species live in large and complex societies with extensive cooperation and division of labor. These species have developed advanced forms of communication (such as communication with dance in honeybees or with pheromones in ants), but as cooperation is kinship-based, there is no need for reputations and gossip. Social complexity in humans involves methods and rules for the transmission of knowledge and social information, ways of interpreting the intentions and actions of others, management of action in increasing and volatile groups, ways to keep records and memory of past actions, imagination and plans for the collective future, the practical organization of the division of labor, exploration and joint problem solving, and the creation of the social self and social identity (Laland & Seed, 2021).

Social complexity in humans is largely governed by socially learned and transmitted social norms. Social norms provide guidance about who is entitled to have a good reputation. Moreover, social norms could also provide guidelines for reputation misinterpretation and repair. They are so complex that their transmission requires the use of language and active teaching (Tomasello, 2009). Social norms are often internalized and become implicit social prescriptions (Conte & Paolucci, 2002). Internal representations of rules, and beliefs about their general acceptance, provide the basis for social control. These norm-based systems generate complexity in social cognition, social interactions, and in the social organization of life.

Social complexity and the social network organization of human groups are enriched also because the reliability of reputational information needs to be checked. Receivers of third-party information often purposively inquire after the original source of information in order to evaluate the content of communication properly, especially after hearing something surprising or that is against their prior beliefs. People also regularly cross-check information with trusted contacts. Hence, reputation is shaped carefully through extending communication. As a result, reputational information exchange might also be responsible for social network dynamics (Redhead et al., 2019; Takács et al., 2021).

As a result of cross-checks, information might turn out to be fake or strategically manipulated. In this case, receivers might downgrade the reputation of the sender. Consequently, honesty of communication is also a valued dimension for the construction of reputations. People in general are more willing to trust others who do not lie, and do not intend to manipulate others. Thanks to these supporting mechanisms and the additional complexity they imply, reputations can be reliably used to guide social behavior.

We argue that increasing complexity is a consequence of reputation-based human solutions to fundamental problems, but social complexity is also a catalyst of the development of sophisticated tools for maintaining social order and cooperation in larger societies. In order to get a better understanding of the essential features of human uniqueness, in the next section, we guide the reader through levels of emerging complexity of human life that are calling for an increasing guidance by reputation.

3.1 Individual struggles

In this section, we take account of an increased complexity of social life from the individual pursuit for survival and reproduction up to the integration into large-scale societies. This review is aimed at showing the origins and the role of reputation in solving increasingly difficult problems of interdependencies. We start from the individual struggle for survival and reproduction. The assessment of problems subsequently moves towards the formation and maintenance of stable partnerships. It is followed by the discussion of small group contexts, intra-group competition, and intergroup relations. We finally arrive at life in large-scale societies (Figure 1).

The essential elements of life are individual struggle for survival and reproduction. Individuals competing for survival and reproduction are in conflict of interest with each other. The conflict of interest is most severe when there is a shortage of food, possible mates, or breeding sites. In such circumstances, physical fighting might occur with the likely success of the stronger, larger, more experienced, better equipped, more motivated individual. But injuries can occur for both sides, and therefore physical fights are better avoided (e.g., Hess & Hagen, 2019). This is possible, for instance, if mating competition is organized openly. Observation of fights of others is supplemented with threat, dominance, submission, and walk-by signals that assist keeping of physical fights at minimum (Bradbury & Vehrenkamp, 2011). The assessment of previous encounters enables the ranking of individuals based on their wins, losses, and retreats and can support the establishment of dominance hierarchies that determine access to mating (Chase, 1982, 1986; Dugatkin, 1997b, 2001). Hence, hierarchies exist also in species living a solitary life but are able to recognize each other. The ranks are based on fighting ability and dominance signals, and assessments are made based on direct experience and bystander observation (Dugatkin 2001; Dugatkin & Earley 2003).

While human individuals, just as other animals, are in conflict of interest with each other for limited resources, the existence of language, successful cooperation, and social norms significantly alter and pacify how we compete with each other for our elementary needs.

3.2 Partnership

An additional complexity can be attributed to the consequences of sexual competition. Qualities and skills of possible partners matter for reproduction, which implies monitoring and evaluation of a larger set of individuals. Furthermore, at the moment of partner selection, no information is available on actual parenting qualities. Individuals communicate and rely on signals to arrive at their choice. In some species, particularly in those with stable partnerships, females have the freedom to actively make a choice and males need to court and impress their potential partner. This is possible in species where the female is able to escape from coercive mating attempts (e.g., females are strong enough or quick enough). Mate attraction and courtship are therefore sources of development of complex forms of animal communication (Bradbury & Vehrenkamp, 2011, ch. 12). In simple cases, only body size and strength are displayed. Coloration is often used to impress the potential partner and, more importantly, it is shown in a movement such that the best impressions can be formed. In some species, males compete with impression-making and by creating artwork. These artworks could represent shelter and the creative capacity of nest building and could be made from stones, bones, shells, or other material. In other species, courting takes place with visual movement displays (dancing) or advanced vocalizations (singing). These forms of behavioral displays are performed often for long periods and repeatedly, in an energetically costly way, to create the best impression for the potential partner. The potential partner is assessing the performance quality of the complex display and makes a quality-dependent partner choice.

These elements of costly impression making, evaluation, and partner choice based on perceived quality are also parts of more complex reputation systems. Humans make significant investments in courtship in multiple dimensions. In addition to body size, shape, and decoration, showing off resources (cars, clothes, diplomas), and complex behavioral displays, including dancing, music, poetry, storytelling, and humor, are used to make a good impression for potential partners. These skills and qualities are often discussed through the uniquely human tool of gossip to shape reputations in dimensions relevant to partner choice (Hess & Hagen, 2006; Davis et al., 2019; Wyckoff et al., 2019). When partner choice is taking place, third-party channels are the greatest source to obtain credible information on the attractiveness, qualities, and behavior of potential partners. Furthermore, as human partnerships are not strictly monogamous (de Waal & Gavrilets 2013), infidelities also open opportunities for reputational discussions.

3.3 Small group life

3.4 Intragroup coalitions and competition

Competition and advanced cognitive capacities enable the emergence of fissions, coalitions, and alliances within the group. It has been argued that the relevance of alliances and coalitions increase when resources are not abundant and dispersed (Kappeler & van Schaik, 2002; Hess & Hagen, 2019). Coalitions to monopolize resources are formed and coalition-based competition takes place also in other species (Bissonnette et al., 2015; Redhead & von Rueden, 2021), including chimpanzees (de Waal, 1998). For humans, most social events that concern us happen around these coalitions and not in large-scale intergroup relations. The small group is a familiar environment for us in which we can confidently assess the intentions of others and predict their behavior. In the small group setting, we are aware of relative reputations, relationships, and conflicts with high certainty. Accurate perceptions about group members enable us to properly evaluate the veracity of information we receive (Dores Cruz et al., 2021a). Accordingly, we are cautious about whom we are talking about with our interaction partners, considering also the relationship between the receiver and the target (Dores Cruz et al., 2021a; Estévez et al., 2022). Hence, we select with whom we share information, we filter about whom we share information, and we take into account the expected reactions from the other side (Burt, 2001; Giardini & Wittek, 2019c).

When group size increases, single leaders alone cannot efficiently direct the entire group. They need supporting allies, and they rule jointly, often against overt opposition. Coalitions can act together to enforce action of their own members or isolate outsiders (Bingham, 1999). Politics becomes essential in group governance in which individual reputations for leadership is largely supplemented with the relative strength of supporting alliance. Social networking in the form of maintaining or constructing certain ties or joining alliances are elements of strategic individual reputation building. Skills that assist the ability of forming strong coalitions are therefore essential in gaining a leadership position in the group. These skills include persuasion, bargaining, organization, and management. Once a leadership position is acquired, charismatic leaders talented in self-marketing and representation will be able to preserve their positions.

Coalitions that are able to acquire the ruling positions might be able to harvest the benefits that are accrued to leaders and turn them into private gains. These benefits might be large enough that some actors collaborate and jointly become political entrepreneurs. Given the complexity of human social organization, their potential benefits are well beyond access to food and mating; they include the accumulation of wealth and inheritance of possessions and political influence.

Once individuals alone are unable to secure leadership positions, individual reputations lose some relevance. Individual reputation becomes less important for formal group leadership due to the increased importance of coalition-formation. The central role of coalitional enforcement in human uniqueness could even be considered as appearing at a higher level of complexity with intragroup cleavages than individual reputation.

Still, individual reputation remains important also with more complex informal group structures. First, with group cleavages, reputation becomes less consensual and often becomes localized (Okada et al., 2017; Podder et al., 2021b). This means that reputations of certain individuals are not universally shared, debated, or consensual in the local social network only. Still, it is likely that individual reputation remains highly relevant, but potentially will not be agreed upon across cleavages. Second, coalitions could also develop collective or group reputation (Székely et al., 2020). Good collective reputation is important to consolidate and attract group membership.

While coalitions compete for leadership and could accept the circulation of power, group fission might also occur. Separation is natural also with the increase of group size. Humans, however, are able to manage intra-group conflict also without group separation. In such a development, leadership requires skills of conflict resolution and bargaining, and is assisted with a more sophisticated organization including institutions and norms of conflict resolution.

3.5 Inter-group relations