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chapter 15

G ossip, R epu tation,

a n d Fr i en dship i n
W ithi n- grou p
Com petition
An Evolutionary Perspective

Nicole H. Hess and Edward H. Hagen

Introduction

Men and boys are substantially more aggressive than girls and women, according to
early findings by aggression researchers. When developmental and social psychologists
began to study nonphysical forms of aggression, however (e.g., those that did not involve
hitting, pushing, or yelling), they discovered a very different pattern. These harmful
nonphysical forms of aggression, such as gossip, ostracism, breaking confidences, and
criticism (Owens, Shute, & Slee, 2000a, b), appeared to be more often used by females
than males, at least in children and adolescents (e.g., Bjorkqvist & Niemela, 1992; Galen
& Underwood, 1997; Lagerspetz, Bjorkqvist, & Peltonen, 1998.) In this chapter we review
theories of human nonphysical aggression, where gossip and reputation play central
roles. We then address aggression among non-human primates, where between-group
physical defense of territories and within-group physical competition for resources
like food and mates are key. Under certain social and ecological conditions, resource
competition involves within-group coalitions and alliances. Whereas human between-
group competition over territory mainly involves physical aggression among coalitions
of men, we propose that within-group competition over material and social resources
mainly involves nonphysical aggression among both men and women, sometimes in
coalitions (cliques). Because access to resources often depends on having a good rep-
utation, within-group aggression frequently utilizes gossip to harm the reputations of

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competitors. We propose that human friendships are analogous (and probably homolo-
gous) to within-group alliances in non-human primates, and similarly serve to increase
successful competition for within-group resources by enhancing the effectiveness of
gossip and reputational attacks, a strategy we term informational warfare. We conclude
by offering testable hypotheses for this model.

Three Terms for Non-Physical

Aggression: Indirect, Relational,
and Social Aggression

Over the past few decades, developmental and social psychologists and other researchers
have developed three theoretical constructs to characterize the suite of behaviors and
psychological phenomena that are aggressive—that is, executed in order to harm
another—but that do not involve the use of physical force, such as hitting or the use
of weapons, to inflict bodily damage. These constructs include indirect aggression,
relational aggression, and social aggression.
Indirect aggression, coined by Feshbach (1969), was adopted and elaborated by
researchers in the late 1980s who sought to compare overt physical aggression, typical of
boys, to forms of aggression that seemed to be more apparent in girls. The distinction
between physical aggression and indirect aggression was confirmed by factor analysis.
Items loading on the indirect aggression factor described various types of social manip-
ulation in which aggressors would harm victims by, for example, lying about them
behind their backs, calling them names, or attempting to exclude them from friendship
groups (Lagerspetz, Bjorkqvist, & Peltonen, 1988). These researchers emphasized that
the indirectness or covertness of the aggression is aimed at separating the perpetrator
from the aggressive act, where the aggressor does not want the victim to know the aggres-
sor’s identity, perhaps with the intent of avoiding retaliation (Bjorkqvist, Lagerspetz, &
Kaukianian, 1992; Lagerspetz, Bjorkqvist, & Peltonen, 1988; Bjorkqvist, 2001).
Relational aggression, introduced by Crick and colleagues in the 1990’s, includes
behaviors whose intent is to damage a peer’s relationships and standing within the social
group. As in indirect aggression, these behaviors could be covert, but they also include
direct confrontations. Other examples of relational aggression include ostracism and
ending a friendship. In their review, Voulgaridou & Kokkinos (2015) summarize rela-
tional aggression (p. 2):

Relational aggression . . . includes behaviors that damage or threaten to harm

relationships, acceptance and inclusion through manipulation of peer relationships
(Crick,  1996; Crick, Ostrov, & Kawabata,  2007). Relationally aggressive behavior
primarily involves the direct manipulation of peer relationships and does not
include negative facial expressions or gestures (Crick and Grotpeter, 1995). These

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behaviors may be confrontational (e.g., excluding a peer from the social group) or
non-confrontational (e.g., character denigration) and may or may not involve
members of the social community.  (Archer & Coyne, 2005)

Social aggression is a broad construct for nonphysical aggression that includes all the
phenomena that fall under indirect aggression and relational aggression, such as the
manipulation of group acceptance through alienation, ostracism, character defama-
tion, and rejection. It also includes phenomena that are nonverbal, like negative facial
expressions and gestures, which were explicitly excluded from relational aggression
(Crick & Grotpeter, 1995), as well as direct social confrontations that would be excluded
from indirect aggression (Cairns et al., 1989; Galen & Underwood, 1997; for reviews,
see Heilbron & Prinstein, 2008; Card et al., 2008; Voulgaridou & Kokkinos, 2015).

Three terms, one phenomenon?

Reviews of the literature on indirect, relational, and social aggression (e.g., Archer, 2004;
Card et al., 2008; Heilbron and Prinstein, 2008; and Voulgaridou and Kokkinos, 2015)
concur that the three constructs overlap to a considerable degree, and that there is no
consensus about which term should be used.
In his meta-analysis, Archer (2004) prefers the term indirect aggression to describe
nonphysical aggression among humans, as historically it was the first construct that was
explored. Card et  al. (2008) argued that indirect aggression excludes nonphysical
aggression: “The term indirect aggression is also limited in that it excludes more direct
attacks on social well-being.” (p. 1186). But like Archer (2004), Card et al. (2008) felt that
historical precedence should be honored. In their 2008 meta-analysis on direct and
indirect aggression, Card et al. use indirect aggression to include indirect aggression,
relational aggression, social aggression, and covert aggression; direct aggression
includes physical aggression and direct, overt, verbally aggressive behaviors like yell-
ing, taunting, and threatening. Factor analysis studies cited by Card et al. support these
categorizations (Card, 2008, p. 1186).
Heilbron and Prinstein’s, 2008 review, which summarizes research on the develop-
ment these nonphysical forms of aggression, favors the term social aggression, arguing
that it is most all-encompassing of the behaviors that make up nonphysical aggression.
Bjorkqvist (2001), however, pointed out that the term social aggression includes physical
aggression, as any physically aggressive act involves at least two actors: a perpetrator
and a victim.
In their recent review of relational aggression in adolescents, Voulgaridou and
Kokkinos (2015) prefer the term relational aggression because it describes nonphysical
forms of aggression that include behaviors and phenomena where the act is direct and
where the victim can easily identify the perpetrator, like verbal confrontations, which
would seem to be excluded by the indirect aggression construct.

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Disagreements about precedent versus accuracy versus generality still exist. As all
constructs intend to exclude physical aggression, these forms of aggression could also
be described as nonphysical aggression. Here, we use these terms interchangeably to
refer to all forms of nonphysical aggression.

Major Findings about

Nonphysical Aggression

We will now review the most important findings about nonphysical aggression with the
aim of linking them to the ongoing debate about gossip.

The Lack of an Important Sex Difference

In his meta-analysis of 124 studies of physical aggression, Archer (2004) found a very
consistent, large male bias across cultures, a bias that appears at or before the age of 2, and
that does not increase with age during childhood. He also found that the maximum sex
differences in physical aggression occur well after puberty, between 18 and 30 years of age.
In his meta-analysis of sixty-one studies of nonphysical aggression, Archer (2004)
found that a female bias increased with age from 6 to 17 years, reaching a peak between
11 and 17 years. He found little evidence of a sex bias in indirect among adults, however,
and in the few cross-cultural studies of indirect aggression, there was either no sex bias,
or a female bias. Archer also found that there were no sex differences in the experience
of anger.
Card et al. (2008) conducted another meta-analysis of nonphysical aggression to clar-
ify whether sex differences in aggression types were present, to see if physical and indi-
rect were correlated, and to see what types of maladjustment were associated with each
type of aggression (discussed under the next two subheadings). This meta-analysis
included more studies than were available to Archer, focused on children and adoles-
cents, included studies involving a wider range of aggression measurement methods,
and used different statistical methods. They also explored variables that might be related
to sex differences, but for which there were not necessarily any clear directional predic-
tions, such as social norms, first author gender, the proportion of ethnic minorities
included in the studies, and so on.
With regard to sex differences, Card et al.’s analysis corroborated Archer’s (2004)
conclusion: boys clearly use physical aggression more than girls, and girls use slightly
more indirect aggression than boys, with the female bias in indirect aggression being
statistically significant but trivial in effect size. The slight female bias was consistent
across age, ethnicity, and country in which the data were collected. The authors

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c­ onclude, “indirect aggression is not a ‘female form’ of aggression.” (2008, p. 1209,

emphasis in the original)

Nonphysical and Physical Aggression

Are Strongly Correlated in Both Sexes
Card, et al. (2008) found that across ninety-eight studies, the average corrected correla-
tion between the two aggression types was 0.76, meaning that about half (58%) of the
variance in these two forms overlaps. The authors argue that the constructs are separate
despite this considerable overlap. They also point out that accurately measuring indirectly
aggressive behaviors is inherently more challenging because covert actions are more
difficult to observe. Interestingly, the Card et al. also report a somewhat greater overlap
for boys than girls.

No Strong or Consistent Association

between Nonphysical Aggression and Maladjustment
High levels of physical aggression in childhood are associated with adult maladjust-
ment, that is, with a high risk of being violent in adolescence and adulthood as well as
a higher risk of substance abuse, accidents, depression, and suicide attempts; these
associations are particularly clear for boys (Tremblay et al., 2004; Broidy et al., 2003).
Influential early studies of nonphysical aggression paralleled studies of physical
aggression by investigating potential links between childhood nonphysical aggression
and poor social and mental health outcomes in adolescence and adulthood; these
studies are particularly associated with the term relational aggression (e.g., Crick and
Grotpeter,  1995). Unlike physical aggression, however, nonphysical aggression in
childhood is not consistently associated with poor outcomes at any age for either sex,
probably because successful nonphysical aggression against one person requires good
social relationships with other people (Card et al., 2008).

Evolutionary Approaches to Human

Physical Aggression and Dominance

Evolutionary theorists of human physical aggression unanimously view it as an evolved

strategy to successfully compete for the social and material resources that increased bio-
logical fitness in our human and nonhuman ancestors (e.g., Archer, 2009; Burbank, 1987;

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Buss and Shackelford, 1997; Campbell, 1999; Chagnon, 1988; Hawley, 1999; Manson and

Wrangham, 1991, Sell et al., 2009; Van Vugt, 2009; Wilson and Daly, 1985; Wrangham
and Glowacki, 2012; Wrangham and Peterson, 1996). They are also unanimous that it is
physical injury, or the threat of it, that serves to deter or eliminate competitors.
High upper body strength appears to afford an advantage in physical fights (Sell
et al., 2009). Most adult men have higher upper body strength than most adult women
(Pheasant, 1983), and there is a large male bias in physical aggression that is present by
about age 2 and persists throughout the lifespan, with male violence peaking during
early adulthood (Archer,  2009). Evolutionary scholars largely agree that intrasexual
selection resulted in the male-bias in physical formidability and physical aggression:
due to their lower investment in offspring, males, more than females, benefit reproduc-
tively by competing with members of the same sex for access to members of the opposite
sex (Trivers, 1972). In most mammals, including humans, this involves physical aggression
directed toward male competitors. Males might also benefit by physically intimidating
or coercing females (for review, see Archer, 2009).
Females, in contrast, due to their higher investment in offspring (e.g., pregnancy,
lactation) are expected to compete with other females over access to resources. Unlike
males in most other primate species, human males do provide resources to females.
Hence, females might compete for access to males that are able to provide resources.
Across cultures, physical fights among adult women are often over the means of
­subsistence (e.g., gardens, crops, money), and co-wives and other sexual competitors, as
well as physical defense of their offspring (Burbank, 1987; Campbell, 1999).
The costs of physical fights (i.e., injuries) can be high for both winners and losers.
Dominance hierarchies are thought to have evolved for the mutual benefit of avoiding
the costs of a fight: when two animals are in competition over a resource, the one with
higher rank in the hierarchy almost always obtains the resource without a fight
(Maynard Smith & Parker, 1976; Drews, 1993). Dominance rank is often based on an
individual’s reputation for fighting ability, and it can also be inherited (e.g., Holekamp &
Smale, 1991). In social species1 that physically compete for material resources (e.g., food)
and social resources (e.g., mates), dominance hierarchies are common (Schjelderup-
Ebbe, 1922; Bernstein, 1981; Silk, 2007a,b).
In many primate species, dominance hierarchies are solidified, or challenged, via alli-
ances with other group members (Harcourt & de Waal, 1992). For example, to maintain
her rank, an alpha female might need to cooperate with a lower-ranking female in an
alliance against the alpha’s challengers. Thus, in species with complex social relation-
ships, dominance hierarchies might involve intricate combinations of conflict and
cooperation.
There is increasing evidence that humans, like many other social species, form
dominance hierarchies, and that these are based on intricate combinations of agonism
and prosociality (e.g., Hawley, 1999, 7). If so, this implies that human evolution was
also characterized by potentially costly contests over material and social resources
among within-group alliances, which in humans are termed “cliques.” We return to
this theme later.

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Evolutionary Approaches
to Nonphysical Aggression

Evolutionary theorists focusing on nonphysical aggression agree that it, too, is likely
an  evolved strategy to successfully compete for resources. (e.g., Campbell,  1999;
Archer, 2009; Ingram, 2014; Hess, 1999, 2006, 2017; Hess and Hagen, 2002, 2003, 2006a,b;
Hawley, 1999; Hawley, Little, and Card, 2008; Geary, 1998; and Buss and Dedden, 1990).
These theorists have offered different accounts of why nonphysical aggression evolved
as an alternative to physical aggression, and how, exactly, nonphysical aggression inflicts
harm on competitors. Sex differences emerge as an important component in many of
these accounts because there is a large sex difference in physical aggression (Archer, 2009)
and early studies seemed to indicate that nonphysical aggression was more common in
females than males (a view that is now known to be incorrect).
Campbell (1999) argued that indirect aggression evolved as an alternative to physical
aggression because maternal care is more important to infant survival than paternal care
is. Mothers with young children cannot risk the bodily harm that is associated with physi-
cal aggression, and engage in nonphysical aggression as a safer alternative. Further, indi-
rectly aggressive strategies like gossip can separate the attacker from the victim, decreasing
the likelihood of retaliation, and reducing the risk of physical harm, and idea endorsed by
Archer (2004, 2009) and Ingram (2014), among others. (Presumably, males would also
benefit from the reduced risk of physical harm afforded by indirect aggression.)
Geary (1998) and Buss & Dedden (1990) put forward theories to explain how indirect
aggression harms competitors. Geary (1998, p. 250) argued that indirect aggression
harms adversaries by “disrupt[ing]” the reciprocal relationships of unrelated female
competitors, thereby inducing stress in female competitors. Disrupted relationships and
stress indeed reduce fertility in other primates (Abbott, 1993; Smuts & Nicolson, 1989;
cited in Geary, 1998). Geary suggested this might be a form of reproductive competition
(1998, pp. 137–138,) where sex differences in hormonal responses to stress make indirect
aggression an effective weapon against female reproductive competitors.
Buss & Dedden (1990, p. 398) suggested that, for example, using derogatory terms,
makes “intrasexual competitors less attractive or appealing to members of the opposite
sex,” and explored sex differences in the content of the information. Schmitt & Buss
(1996) further investigated the perceived effectiveness of these tactics in short-term and
long-term mating competition.
Ingram (2014) argued that chimpanzee-like dominance hierarchies could not effec-
tively regulate access to resources in the larger groups that characterize human societies.
Instead, systems of indirect reciprocity (Alexander, 1987), in which a group member’s
cooperative and non-cooperative acts positively and negatively influence others’ pro-
pensities to cooperate with her, leading to extended dominance hierarchies mediated by
gossip and other nonphysical forms of aggression rather than physical aggression
(Ingram, 2014).

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Critique of Current Evolutionary

Approaches to Nonphysical
Aggression

Although each of these evolutionary theories offers important insights into indirect
aggression and its relationship to physical aggression, each can be questioned on evolu-
tionary grounds. Regarding Campbell and Archer’s early arguments that sex differences
in the costs of physical aggression explain the evolution of indirect aggression, we now
know that males use indirect aggression as frequently as females. Thus, sex differences
in the costs of physical fights might explain women’s avoidance of physical aggression,
but do not clearly explain the evolution of indirect aggression. Moreover, non-human
female mammals all face the same high costs that human mothers face, and yet they still
often engage in physical aggression, and consequently form female dominance hierar-
chies that help reduce the costs of physical fighting (Chapais & Schulman, 1980).
With regard to female physical aggression, it is important to distinguish intra- from
inter-sexual conflict. Most anthropoid primate species, including humans, are sexually
dimorphic, with a male advantage in body and canine size (Plavcan, 2001; Plavcan, 2012).
Although human body dimorphism is modest—men weigh about 15% more than
women—human upper body strength is highly sexually dimorphic, and in over 90% of
chance encounters between an adult man and woman, the man would have higher
upper body strength (Pheasant,  1983). Hence, in most anthropoid species, including
humans, males would have the advantage over females in intersexual physical conflicts,
which would select for female avoidance of physical conflicts with males.
Sexual body dimorphism says little, however, about the nature of intrasexual conflict.
Females in many primate species have formidable canines, and it is increasingly recog-
nized that there are many selection pressures on both male and female body sizes and
fighting abilities. These can include male-male physical contests over mates and female-
female physical contests over resources, but can also include, for example, benefits of
higher or lower reproductive rates that select for smaller and larger female body size,
respectively (Plavcan, 2001; Plavcan, 2012).
In summary, in species in which males have clear advantages in physical formidability
over females, such as humans, females should avoid physical conflicts with males, but
should not necessarily avoid physical conflicts with other females. In fact, physical fights
among girls and women are not unknown, and when they do occur, fights are often over
the means of subsistence and access to male resources (Burbank, 1987; Campbell, 1999).
Campbell, Archer, and others have failed to explain why in human females the costs of
female-female physical contests generally outweigh the benefits, but in other species the
benefits often outweigh the costs.
Regarding the “indirectness” of indirect aggression, it is not clear how indirect it
actually is, and the extent to which its putative indirectness protects attackers from

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retaliation. After all, retaliation could occur at a later time, which would be difficult for
researchers to detect. A physically strong male victim of indirect aggression could inflict
serious physical harm on his antagonist should he discover his or her identity (and in
the small hunter-gatherer bands in which we evolved, would identifying the perpetrator
be that difficult?). The putative ability of indirect aggression to avoid retaliation requires
more investigation.
Regarding the ways in which nonphysical aggression inflicts harm, Geary’s (1998)
hypothesis that stress-induced endocrine disruption suppresses fertility provides a
possible proximate mechanism by which indirect aggression could harm competitors.
It does not provide an ultimate evolutionary explanation, however, because victims
should have evolved endocrine systems that resisted disruption by verbal threats and
harassment that did not actually reduce access to resources or cause injury. Why do
victims remain vulnerable to stress-induced fertility reduction?
Buss & Dedden (1990) astutely pointed out that derogation of competitors might
make them less attractive as mates (thus increasing one’s own access to mates). But here,
too, it is not clear why potential mates should avoid an individual simply because he or
she was derogated by a competitor. If the derogations were baseless, the potential mates
would erroneously pass up valuable mating opportunities, and should therefore have
evolved to ignore derogations by competitors.
In our view, although there is widespread agreement that physical and nonphysical
aggression are evolved strategies to gain access to contested material and social
resources, several outstanding questions remain, including, (1) Why is physical
aggression among women exceptionally infrequent? (2) Why did nonphysical forms of
aggression evolve that are commonly used by both sexes? (3) Over human evolution,
how did nonphysical forms of aggression harm competitors?
Drawing on the work of many others, we now sketch our evolutionary account of the
evolution of physical and non-physical aggression in humans (Hess, 2006, 2017; Hess
& Hagen, 2003, 2006a) that explains the rarity of physical aggression among women, the
widespread use of non-physical forms of aggression by both sexes, and how the latter
harms competitors.

The Evolution of Aggression

over Resources in Humans and
Other Species

Physical and nonphysical aggression appear to be human universals (Archer,  2004;

Card et al., 2008). We therefore sketch one scenario by which both forms of aggression
could have evolved, drawing heavily on comparisons with our primate relatives and also

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with social carnivores, which probably occupied an ecological niche similar to our
hunter-gatherer ancestors (e.g., Stiner, 2002; Smith et al., 2012).
Humans are one of about 400 primate species, which diverged from other mammals
about 65 million years ago (MYA; Fleagle, 2013). Whereas most mammals are solitary
as adults, most primates are gregarious, that is, they live permanently as members of
social groups.
The human lineage split from that of our closest relative, the chimpanzee, sometime
between 6 and 13 MYA (Langergraber et al., 2012). Until about 2 MYA, this lineage com-
prised species that were bipedal but had ape-sized brains and appear to have subsisted
mostly on plant foods. The first notable increase in brain size occurred with the appear-
ance of the genus Homo some 2–2.5 MYA, around the beginning of the Pleistocene
(Antón et al., 2014). Although there is little agreement about the social organization and
diet of early members of our genus, most anthropologists would agree that they proba-
bly lived in multi-female multi-male groups and that meat was a valuable and increas-
ingly important component of the diet (e.g., Antón et al., 2014).
The role of aggression in human evolution is particularly contentious. Our theory
relies heavily on distinguishing between-group aggression, which we discuss first, from
within-group aggression, which we discuss second.

Between-Group Competition
for Territory

Most primate species are social. Many such species are territorial and vigorously defend
their territories with physical aggression toward outsiders, but many others do not.
Territorial defense among non-human primates (and other social animals) could be an
analogy for human warfare (Crofoot & Wrangham, 2010).
Some anthropologists have argued that lethal competition between groups—warfare—
was important throughout human evolution, basing their case on similar patterns of
behavior in one of our sister species, the chimpanzee, on pervasive evidence of warfare
in almost all modern human societies, and on clear evidence of warfare in the archaeo-
logical record of the last 10,000 years (e.g., Wrangham, 1999; Bowles, 2009).
Others vehemently deny any role for warfare in human evolution, basing their case
on the putative rarity of warfare among contemporary band-level foragers, absence of
archaeological evidence for warfare prior to about 10,000 years ago, on the apparent
lack of warfare among our other sister species, the bonobo, and the rarity of lethal
between-group conflict in other animals (Ferguson, 1997; Fry & Söderberg, 2013). For a
recent overview of the ethnographic and archaeological evidence for warfare among
hunter-gatherers, see Allen & Jones (2014). For a comparative analysis of lethal violence
(not necessarily warfare) in humans and human ancestors relative to other primates and
mammals, see Gómez et al. (2016).

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We take a middle ground. There are solid theoretical and empirical grounds to
suppose that human ancestors were territorial and were physically agonistic toward
intruders, but physical defense of territories might or might not have involved
lethal attacks.
According to some researchers, between-group agonism among non-human pri-
mates appears to depend on the presence or absence of collective action problems.
Although territory is a valuable resource, defending it with physical aggression can be
costly due to the risk of injury and death. If some members of a group pay the price of
territorial defense but others do not, natural selection will favor the latter, and coopera-
tive defense cannot evolve. In primates, the species that exhibit high levels of between-
group agonism are those that appear to have solved the collective action problem by
some combination of high degrees of relatedness among the dominant sex, small group
size, and cooperative breeding, which all tend to align the interests of group members
relative to outsiders (Willems & van Schaik, 2015). Modern humans often live in rela-
tively small social groups with male philopatry and cooperative breeding, and accord-
ing to this model should therefore aggressively defend territories (Willems & van
Schaik, 2015), which they do (Dyson & Smith, 1978).
If meat were an increasingly important part of the diet in Homo, as it appears it was,
then early humans could also be compared to social carnivores like lions, hyenas,
African wild dogs, and wolves. These species also vigorously defend territories (for brief
review, see Hagen & Hammerstein, 2009).
Thus, as both philopatric, cooperatively breeding primates, and as social hunters,
human ancestors were probably territorial and defended their territories with coali-
tional physical aggression toward outsiders. This does not necessarily mean that human
evolution involved much, or any, warfare. Lethal between-group aggression is rare even
in territorial primates (Crofoot & Wrangham, 2010), and in social carnivores, although
lethal inter-group aggression is common in wolves, it is rare in lions (Hagen &
Hammerstein,  2009). In addition, human groups commonly cooperate with other
groups, often forming alliances by marriage that play important roles in defense of large
regions (Rodseth et al., 1991).
Thus, in our model, the male bias in physical aggression is explained, at least in part,
by an evolutionary history during which closely related male human ancestors (but not
female ancestors) collectively defended hunting territories with physically agonistic
behaviors toward outsiders; these behaviors might or might not have involved lethal
aggression (warfare).
Women, we propose, mostly avoided direct participation in territorial defense
because it would have brought them into physical fights with men, whose advantages
in upper body strength would have posed severe threats to female fitness. Similar views
about the evolutionary importance of human male intergroup aggression have been
expressed by many others, including Tooby & Cosmides (1998), Sell et  al. (2009),
Wrangham & Glowacki,  2012, and Bowles (2009). Male-biased agonism between
groups does not, however, explain why women rarely physically fight other women
within groups.

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The Impact of Within-group

Resource Competition on Social
Behaviors in Non-human Primates

In the 1970s, biologists realized that social living would generally decrease biological
fitness because it increased competition for resources and exposure to parasites (e.g.,
Alexander,  1974). Thus, gregariousness must have some valuable fitness benefit that
compensated for these fitness costs. For primates, this benefit is thought to be either
improved defense against predators (van Schaik, 1983) and/or a competitive advantage
in competition over defensible resources (Wrangham, 1980).
Despite the benefits of group living, such as better protection from predators, within-
group competition for resources still has a profound impact on primate social relation-
ships. Primate social relationships can vary widely among different species, and even
among the same species living in different ecologies. According to the socioecological
models of primate sociality, the distribution and value of food resources plays a central
role in determining the intensity of within-group competition, and thus patterns of
social relationships.

Frugivores Have Complex

Social Relationships that Provide
Advantages in Within-group
Competition over Food

When resources are scarce, valuable, and clumped, and thus monopolizable, primates
will compete aggressively or contest over them. These patterns characterize frugivores—
primate species that rely mostly on fruit, which is a nutrient-rich food that is patchily
distributed, and which is also only seasonably available. In frugivores and other pri-
mate species that rely on valuable, clumped food resources, within-group aggression
is higher, and aggression tends to involve more complex aggressive strategies
than  just one-on-one physical fighting over monopolizable foods. Dominance is
one such strategy.
Alliances and coalitions are also more common when food is monopolizable, because
coalitions increase physical formidability in fights (e.g., Barrett and Henzi,  2002;
Boinski, Sughrue, Selvaggi, Quatrone, Henry, & Cropp, 2002; Harcourt & de Waal, 1992;
Isbell & Young, 2002; Kappeler & van Schaik, 2002; Koenig, 2002; Silk, 2002; Sterck,
Watts, & van Schaik, 1997; Wrangham, 1980; cf. Janson, 2000). The term coalition refers
to a temporary group of two or more individuals that forms to attack one or more

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gossip, reputation, and friendship   287

i­ndividuals (Pandit & van Schaik,  2003). The term alliance refers to long-lasting
­relationships. Social relationships among frugivorous primates are characterized by
dominance hierarchies, coalitions, and alliances.

Folivores Have Simpler Social

Relationships Reflecting
Reduced Within-group Competition
over Food

When resources are abundant, not valuable, and dispersed, on the other hand, and thus
not monopolizable, primates will not engage in aggressive competition for them. These
patterns characterize folivores—primate species that rely mostly on leaves, which are
low in nutrients, high in toxins, abundant, and relatively evenly distributed. The benefits
of winning physically competitive bouts over such resources are small. Relationships of
dominance and subordinance are less apparent, aggression and displacement are lower,
and aggression is less likely to involve complex strategies such as dominance hierarchies,
coalitions, and alliances. When resources are nonmonopolizable, instead of engaging in
high-stakes contest competition, primates engage in low-stakes scramble competition.
Socioecological models also include factors other than food monopolizability versus
nonmonopolizability, such as protection from infanticide and the defense and acquisi-
tion of mates by males (van Schaik, Pandit, & Vogel, 2006).

Important Caveats

The tight causal links between food distribution, feeding competition, and social
structure posited by the socioecological model are increasingly challenged by studies of
species that do not conform to key predictions. Some primate species inhabiting similar
feeding ecologies exhibit marked differences in social structure, for instance, whereas
some species with similar social structures inhabit markedly different feeding ecologies
(Clutton-Brock & Janson, 2012; Silk & Kappler, 2017). It is not yet clear whether these
and other discrepancies will require only modest modifications to the theory, or aban-
donment of it altogether. Explanations for the discrepancies include the possibility that
the feeding ecology of some species has been misclassified, or that some species entering
a new feeding niche have not yet evolved the corresponding social structure (phyloge-
netic inertia).
According to one critical review (Clutton-Brock & Janson, 2012), certain tenets of
the socioecological model are fairly well established in primates and other mammals.

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288   nicole h. hess and edward h. hagen

Food value and distribution, for example, are related to the intensity of competition and
group size. Social hierarchies and coalitions, on the other hand, might not always be
related to feeding competition but instead to competition over other “resources,” such as
breeding opportunities. Inspired both by the socioecological model as well as this and
other critiques, we therefore consider the role of competition over food and other
resources in the evolution of human sociality.

Did Ancestral Humans Contest

Valuable Monopolizable Resources?

Meat, like fruit, is a valuable but scarce and patchily distributed resource, and is thus
monopolizable. Members of the genus Homo living during the late-middle Pleistocene
and later clearly hunted large game animals, bringing kills to central processing sites like
caves, where the meat was consumed by several individuals (Stiner,  2002; Stiner
et al., 2009). If the principles of the socioecological model applied, then early humans,
perhaps especially females, should have competed for meat with their fellow group
members using aggression, alliances, coalitions, and dominance hierarchies that are
associated with contest competition.
Among modern hunter-gatherers, an important part of the meat-sharing process
involves distributions that are directed by the hunter and other individuals to kin,
spouses, sex partners, and reciprocally sharing partners (for review, see Kaplan &
Gurven,  2005). Although these distributions are regulated by rules whose function
appears to be to reduce conflict, complaints over meat sharing abound (Peterson, 1993).
Items other than meat are shared in modern foragers and small-scale horticultural
societies, and, importantly, these items are also scarce, valuable, and monopolizable.
These items can include tools, weapons, medicines, scarce nutrients, status items, arti-
facts, and raw materials needed for manufacturing artifacts. Social resources like mates,
hunting partners, and exchange partners can also be valuable, limited, and monopoliz-
able. Tiger and Fox (1971) argued that in humans, social rank was equivalent, indeed
homologous, to dominance hierarchies in our primate ancestors. They emphasize
human male dominance hierarchies and access to females, similar to patterns seen
among males in non-human primates. Because humans rely on monopolizable material
and social resources, we should expect them to contest over access to them.
Evidence from the developmental literature supports the view that humans compete
over both material and social resources. Hawley summarizes what children compete for
(1999, p. 105; citations in the original omitted):

In general, resources are anything outside the individual essential for survival,
growth, and development . . . Although no one would deny that monkeys must
­compete for ecological resources in the environment (e.g., food, water), it is not

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gossip, reputation, and friendship   289

clear that children in peer groups must . . . But developmentalists are quick to

­recognize that optimal growth and development require much more than nutrients
and hydration; important resources include social contacts . . . , play partners . . . , and
cognitive stimulation . . . Thus, it should come as no surprise that developing humans
are highly motivated to seek out others for interaction opportunities (e.g., peers and
adults) and novelty for cognitive and physical stimulation (e.g., toys). Research in
diverse domains such as motivation . . . and children’s friendships . . . indicates that
children, indeed primates in general . . . , are highly motivated to access social part-
ners and novel stimuli. To the extent that novelty and peers are limited, individuals
must compete for them in various ways . . . Therefore . . . resources can be social or
material.

There is an important difference, however, between human and nonhuman contest

competition: Humans have language.

Reputation Mediates Access

to Resources

Humans often obtain contested group resources via their reputations; in other words,
they increase and defend access to resources, including food, mates, and care, by
increasing and defending their reputations. Although Tiger & Fox (1971) acknowledged
the importance of prestige in the evolution of human social rank, it was Barkow
(1975, 1989) who emphasized that in humans, within-group hierarchies were usually
established by striving for prestige within particular culture settings, rather than by
physically fighting. As in other species, human reputations can involve fighting ability
(Alexander, 1987; Chagnon, 1988; Hess, Helfrecht, Hagen, Sell, & Hewlett, 2010), but
they are usually based on a much broader range of behaviors and capabilities such
as  being able to provide valuable group benefits (Gurven, Allen-Arave, Hill, &
Hurtado, 2000; Sugiyama & Chacon, 2000), being able to take risks and come out win-
ning (the “show-off ” or “costly-signaling” models: Gintis, Smith, & Bowles,  2001;
Hawkes, 1991; Smith & Bliege Bird, 2000), being a good reciprocator of benefits received
(i.e., reciprocal altruism: Cox, Sluckin, & Steele, 1999; Enquist & Leimar, 1993; Pollock &
Dugatkin, 1992), and having been observed to give benefits to others (i.e., indirect reci-
procity: Alexander,  1987; Leimar & Hammerstein,  2001; Nowak & Sigmund,  1998).
Experimental economists, whose research involves study participants sharing real
money with other participants or keeping it for themselves, have shown that a sharing
strategy can persist in an evolving population when players establish reputations as
donors (e.g., Milinski, Semmann, Bakker, & Krambeck, 2001; Milinski, Semmann, &
Krambeck, 2002; Wedekind & Milinski, 2000).
This empirical and theoretical research demonstrates that individuals must have
­reputation for being able to provide valuable benefits to others in order to receive

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290   nicole h. hess and edward h. hagen

­ enefits from others. A reputation is based on information about one’s traits, behaviors,
b
intentions, abilities, and culturally-specific competencies, and this information can be
obtained via direct observation, or from other individuals. Reputations can be strongly
impacted by the transfer of information about these various behaviors and capabilities,
in other words, gossip.

Gossip as a Strategy to Manipulate

Reputation

Several theories have been put forward for the evolution of gossip, including “cultural
learning” (e.g., Baumeister, Vohs, & Zhang, 2004), “social learning,” such as learning
norms or one’s place in a group (e.g., Eckert, 1990; Fine, 1977; Fine & Rosnow, 1978;
Gottman & Mettetal, 1986; Suls, 1977) or acquiring new and important knowledge (e.g.,
Watkins & Danzi, 1995), strategy learning (DeBacker, 2005), social comparison (e.g.,
Wert & Salovey, 2004), a mechanism for showing off one’s social skill and connections,
and therefore one’s mate value (Miller, 2000), norm learning and enforcement, sanc-
tioning, social control, or “policing” (e.g., Wilson, Wilczynski, Wells, & Weisner, 2000,
Villatoro, Giardini, & Conte, 2011; Giardini & Conte, 2012), a means to maintain the
good reputations of allies (e.g., Brenneis, 1984), and a means to maintain the unity,
morals, and values of social groups (e.g., Gluckman, 1963). Dunbar (1996, 2004) pro-
posed that gossip (and language more generally) evolved to facilitate social bonding
and social cohesion in the very large groups that characterize human primates, but
recent research by Grueter, Bissonnette, Isler, & van Schaik (2016) failed to find support
for this hypothesis.
The importance of gossip for the evolution of human cooperation, especially via
indirect reciprocity, has recently received considerable attention (e.g., Leimar &
Hammerstein, 2001; Giardini & Vilone, 2016a, b; Wu, Baillet & van Lange, 2016a, b, c.).
Gossip has been demonstrated to increase cooperation via indirect reciprocity in exper-
imental economics games (e.g., Milinski, this volume; Sommerfeld et al., 2007), where
reputational information impacts contributions to a shared pool of resources (e.g.,
Beersma & van Kleef, 2011), or where information about the past behaviors of coopera-
tive partners impacts participants’ inclinations to engage in future cooperation (e.g.,
Feinberg, Willer, & Schultz, 2014.) Recent research has also explored how varying the
quantity and quality (i.e., noisiness) of gossip impacts cooperation in experimental eco-
nomics games, such as the Public Goods Game (Giardini & Vilone, 2016a)
Despite numerous theories of the evolution of gossip, it is unclear how gossip differs
from any other use of language (about gossip and language, see Mangardich and Fitneva,
this volume). For reasons that are still obscure, human language evolved to permit one
person to communicate detailed information about themselves and their environment,

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gossip, reputation, and friendship   291

including their social and nonsocial environment, to another person. “Gossip” is the
exchange of information about the doings of others. It is therefore probably fruitless to
consider the evolution of gossip independently of the evolution of language. Indeed,
Bloom (2004) opines, “[i]t is tempting to ask about the origins and functions of gossip,
but this temptation should be resisted. From a psychological perspective, gossip is likely
to be an arbitrary and unnatural category . . . it is a domain where the most interesting
aspects of mental life are laid bare.” We agree. Gossip, defined as the communication of
information about others, is therefore informative, and not necessarily aggressive, com-
petitive, cooperative, or pedagogical.
Nevertheless, we and many others have proposed that socially competitive strate-
gies evolved that use gossip (language) as one tool. If one’s reputation impacted his or
her access to scarce, contested material and social resources in ancestral environ-
ments, as reputation does todays’ small scale and large scale societies, selection should
have favored psychological adaptations for the strategic manipulation of reputations
in ways that benefitted oneself. Attack would involve transmitting negative informa-
tion about the behaviors and traits of one’s competitor(s) to resource providers, and
withholding positive information about the behaviors and traits of competitors from
resource providers. Strategies would also include transmitting positive information
about oneself to resource providers (i.e., bragging), preventing the spread of negative
information about oneself (e.g., punishing disseminators of such information), or
challenging the veracity of negative information about oneself (e.g., providing alibis).
In this process, the reputation of the attacker would improve relative to the reputation
of the attacked, thereby increasing the attacker’s access to contested group resources
(Barkow, 1989, 1992; Buss & Dedden, 1990; Emler, 1990; Leimar & Hammerstein, 2001;
McAndrew & Milenkovic, 2002; Paine,1967; Radin, 1927; Hess, 2006, 2017; Hess &
Hagen, 2006a). On this view, one way that indirect aggression harms adversaries is by
harming their reputations.

Indirect Aggression Is Better

than Physical Aggression for
Within-group Competition

We argue that when it comes to within-group competition, indirect aggression is usually

better than physical aggression. Members of one’s local group provide valuable repro-
ductive, kinship, political, economic, military, and other benefits to fellow group mem-
bers. Within-group physical aggression involves injuring a fellow group member.
Although this physical harm might increase the aggressor’s access to a contested
resource, it also reduces the victim’s ability to provide benefits to other group members.
Physical aggression within groups can also reduce the group’s ability to compete with

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292   nicole h. hess and edward h. hagen

other groups. Within-group violence would therefore involve costs to the attacker well
beyond the simple risk of injury associated with a physical attack. Knauft (1991) notes
that in hunter-gatherers “interpersonal aggression and violence tend to be unrewarded
if not actively devalued by men and women alike.” Finally, winning a physical fight
might gain a resource today, but unless it permanently alters dominance rank or seri-
ously injures or kills the adversary, another fight with the same individual might be
necessary to gain a resource tomorrow.
In contrast, gossip, whether it has a positive or negative impact on the reputation of
the subject, can involve important information that fellow group members would want
to know. Individuals benefit from knowing accurate information about other members
of their community. Therefore, although many societies have norms against gossip,
especially negative gossip, gossip should be discouraged less than physical aggression.
Successful negative gossip against a competitor reduces the competitor’s reputation, and
thus access to material and social resources from potentially many group members and
potentially for long periods of time, thus increasing the aggressor’s access to resources,
perhaps permanently.
Gossip and physical aggression also differ in the precision with which they can be
used to strategically harm a competitor. Physically harming a competitor compromises
the victim’s ability to provide benefits to other community members in a sweeping man-
ner. Injury or death damages or destroys a victim’s ability to forage, to engage in inter-
group conflict, to provide vital care to children or the ill, to accomplish multiple, valued
tasks, and so on. Moreover, the relatives and allies of the victim might have to pay addi-
tional costs of caring for the victim while he or she heals. Gossip, in contrast, can be cus-
tomized to benefit the attacker by strategically targeting a particular aspect of the
victim’s reputation. Negative gossip can target a competitor’s reputation as a good mate,
while sparing her reputation as a caretaker. Gossip can be used to decrease a competi-
tor’s access to specific contested resources, without preventing the competitor from pro-
viding resources to other community members; this makes gossip a good weapon for
within-community competition.
Men do use physical aggression for within-group competition with other men, and to
dominate and coerce women (Smuts, 1995). Pair bonding provides an additional possi-
ble explanation for women’s avoidance of physical aggression: physical conflicts between
women could draw in their husbands and other male relatives, who could use their
advantages in physical formidability to either suppress female fighting, or to engage
with each other in proxy fights. Nevertheless, a study that compared levels of physical
violence in chimpanzees to that in humans found that whereas mortality from between-
group violence was similar in the two species, humans had much lower levels of within-
group physical aggression than chimpanzees (Wrangham et al., 2006).
According to our theory, then, there is little-to-no sex difference in nonphysical
aggression because both men and women regularly compete with fellow group members
for the good reputations that enhance access to the social and material resources that are
important to both sexes (for an alternative view, see Davis, Vaillancourt, Arnocky, Doyer,

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gossip, reputation, and friendship   293

this volume). Within groups, nonphysical aggression simply outperforms physical

aggression much of the time.

Friendships, Cliques, and

Informational Warfare: The
Coalitional Manipulation
of Reputations

Nonhuman primates form coalitions and alliances with other members of their groups
to improve their ability to contest resources. Hess (2003, 2006, 2017) proposed that alli-
ances, that is, friends and cliques, are valuable in human contests over monopolizable
resources where the “weapon” could be physical aggression, a point emphasized by De
Scioli & Kurzban (2009), but would more often be reputational manipulation via gossip.
Cooperating individuals would be more powerful than individuals in using information
to attack the reputations of their competitor(s) because of the improved abilities of
coalitions to strategically collect, analyze, and disseminate reputation-relevant informa-
tion. Allies provide more ears and eyes to collect negative information about competi-
tors, more brains to analyze this information, and more mouths to disseminate it (see
Hess, 2006 for a detailed discussion of “informational warfare theory”). In addition,
information transmitted by multiple individuals may be more believable. For example,
Hess & Hagen, 2006b ran a series of experiments and found that participants believe
gossip more, not when it is simply reiterated, but when it is transmitted by multiple,
independent sources without a clear conflict with the target of the gossip. Further, while
coalitions might be able to better attack competitors’ reputations with negative gossip,
they would also be better able to defend coalition members’ reputations by providing
alibis, withholding negative gossip, and transmitting positive gossip about allies. Finally,
coalitions might also be better able to deter negative gossip attacks by competitors
against coalition members by threatening competitors with retaliatory negative gossip.
Based on the observation that “competing through competition” (i.e., competing coali-
tionally) is so widespread in primates, Chapais (1996, pp. 19–20) suggests that coalitional
competition probably reflects a phylogenetically primitive process. Humans, Chapais
argues, pool not just physical power but also goods, services, and information to enhance
the acquisition and defense of resources. Along similar lines, Hess (1999, 2006, 2017) pro-
posed that for humans, coalitional aggression relies not just on enhanced physical capa-
bilities, but also informational capabilities, particularly those involving information
relevant to reputation. Ostracizing others and disrupting their social relationships—key
features of indirect aggression—harms competitors, in part, by depriving them of access to
information and the allies that would help them make best use of it.

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294   nicole h. hess and edward h. hagen

Concluding Remarks

Nonphysical forms of aggression prominently feature the use of negative gossip to harm
the reputations of competitors. They are commonly used by both sexes and are associ-
ated with the use of physical aggression, but unlike physical aggression, do not appear to
be linked with adult adjustment problems. Evolutionary theorists of aggression concur
that nonphysical forms of aggression probably evolved to increase access to material
and social resources in competition with others, but disagree on (1) why an alternative to
physical aggression evolved, (2) the role, if any, of sex differences, and (3) how, exactly,
nonphysical aggression harms competitors.
Using evolutionary principles and comparisons of humans with non-human pri-
mate relatives, we propose a strategic account of the aggressive use of gossip that
emphasizes within-group competition: when access to contested group material and
social resources depends on having a good reputation, individuals and cliques collect,
analyze, and disseminate information to improve their own reputations relative
to competitors. Over human evolution, gossip could have been used by either sex to
compete in multiple domains such as increasing access to food, mates, and valuable
social partners. Between-group competition for territory, in contrast, relied more
heavily on physical aggression by men because men have a substantial advantage in
upper body strength, and because men probably benefitted more from acquiring and
defending territories.
Several testable hypotheses can be derived from this model. Is gossip used more than
physical aggression in the context of within-group aggression, whereas physical aggres-
sion is used more than gossip in between-group competition? Do contestable, valuable
resources lead to more negative gossip about a competitor? Do participants allocate
resources based on reputation, giving more resources to those with better reputations
and fewer resources to those with poorer reputations? Are individual differences in
indirect/relational/social aggression better explained by differences in the experience of
within-group competition than by sex? Do allies allow better collection, analysis, and
dissemination of gossip in reputational contests? Future research may explore these and
other hypotheses.

Note
1. Social species permanently reside in groups, in contrast to solitary species in which “groups”
comprise brief dyads for mating, or mothers and infants only.

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