Territorial behavior in humans?

Territorial behavior in humans?

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Do humans exhibit territorial behavior like other primates? I have seen people sometimes stare at others -- notably males -- and then physical fights spontaneously turn up. Is this territorial? It seems it either goes two ways: One person looks at another; the other looks back and either looks away or both look away; or they both hold a stare until one or both erupt in to physical blows and try to dominate the other or fight/assault them. Is this a display of human territorial behavior? I know some chicks do it too.

I've also read that in males more so that staring can be an "alpha" or "dominating" gesture to others -- especially if a stare is held at one in response to them either turning away or provoking a fight.

This can be seen in every area, but possibly more so in clubs, bars, or certain social settings.

From encyclopedia britannica

Territorial behaviour, in zoology, the methods by which an animal, or group of animals, protects its territory from incursions by others of its species.

Following, this definition, yes territorial behaviour exists in humans. Here are three simple examples drawn from different (western) cultures

You seem to be confusing territorial behaviour with general, aggressive behaviour. Whether or not the behaviours you describe qualify as territorial behaviour requires one to make a psychological study to determine whether the individuals had a notion of territory that they wish to defend.

I'd argue that territoriality can be observed on many scales with humans. At the bar, 1-on-1 conversations with a spouse, between homes, between cultures, between parties during war, nations, the list goes on. It is also peculiar that humans seem to extend territoriality into abstract spaces, such as thoughts and ideologies.

I once read the 2010 book Supernormal Stimuli: How Primal Urges Overran Their Evolutionary Purpose by Deirdre Barrett which argues, details and very elegantly describes our instinctual, territorial tendencies in modern humans. I do not doubt that humans today follow instincts we evolved for our time spent in the African savannahs. The book explains other vestigial instincts too, which evolved and now exist in an artificial environment.

Take a look:

Gorilla ‘territorial behaviour’ may give clues about human evolution

Gorillas have been found to show territorial behaviour – and it could reveal important clues on the social evolution of humans, scientists believe.

Researchers studying eight western lowland gorilla groups have discovered that the primates command ‘ownership’ of their home ranges, the areas in which they live and move.

But these animals can also ‘peacefully co-exist’ with their neighbouring groups while claiming “exclusive use” of areas close to the central hub of their home range.

The researchers said the findings, published in the journal Scientific Reports, contradict widely-held belief that these primates were non-territorial.

Dr Jacob Dunn, a reader in evolutionary biology at Anglia Ruskin University and one of the study authors, said: ‘This new research changes what we know about how groups of gorillas interact and has implications for what we understand about human evolution.

‘Almost all comparative research into human evolution compares us to chimpanzees, with the extreme territorial violence observed in chimpanzees used as evidence that their behaviour provides an evolutionary basis for warfare among humans.

Our research broadens this out and shows instead just how closely we compare to our next nearest relatives.

‘Gorillas’ core areas of dominance and large zones of mutual tolerance could help with our understanding of the social evolution of early human populations, showing both the capacity for violence in defending a specific territory and the between-group affiliations necessary for wider social cooperation.’

Scientists monitored the movements of 113 gorillas at the Odzala-Kokoua National Park in the Republic of Congo, with cameras across 36 feeding spots.

The team found the gorillas’ movements were strongly influenced by the location of their neighbours, suggesting these animals may avoid the central hubs of other groups’ home ranges to prevent conflict.

The authors said this behaviour is markedly different to chimpanzees, which display extreme territorial-based violence.

Lead author Dr Robin Morrison, who carried out the study during her PhD at the University of Cambridge, said: ‘Our findings indicate that there is an understanding among gorillas of ‘ownership’ of areas and the location of neighbouring groups restricts their movement.

‘Gorillas don’t impose hard boundaries like chimpanzees. Instead, gorilla groups may have regions of priority or even exclusive use close to the centre of their home range, which could feasibly be defended by physical aggression.

‘At the same time groups can overlap and even peacefully co-exist in other regions of their ranges.

‘The flexible system of defending and sharing space implies the presence of a complex social structure in gorillas.’

Animal Models for Examining Social Influences on Drug Addiction

6 Sex-Related Differences in Social Defeat-Induced Addiction-Like Behaviors

As described in Section 2.2 , the ethological difference between territorial and maternal aggression in rodents poses some argument that the direct comparison between brain and behavioral changes of males and females in socially defeated animals may be inadequate, except for some species or strains. One such exception is the use of California mice. Studies using California mice have shown that females but not males showed social withdrawal, that is, a decrease in interacting time with a novel mouse, after exposure to repeated social defeat ( Trainor et al., 2011, 2013 ). A recent study showed that DA-D1 receptors were particularly necessary for mediating defeat-induced social withdrawal in females but not in males ( Campi, Greenberg, Kapoor, Ziegler, & Trainor, 2014 ). Furthermore, these socially withdrawn females showed an increase in BDNF protein levels in the anterior part of BNST that could be ameliorated by blocking the BDNF receptor, TrKB ( Greenberg, Howerton, & Trainor, 2014 ). When Long–Evans rats were exposed to intermittent social defeat due to either territorial or maternal aggression, however, sex-related differences were seen in cross-sensitization, DA response in the NAc, and duration of the “binge” phase ( Holly et al., 2012 ). Furthermore, stressed females showed increased locomotor activity compared to both non-stressed females and respective stressed males, particularly during the first 5 min after cocaine injection. This locomotor activity was independent of their estrous phase. Also, these females showed prolonged DA accumulation in the NAc followed by an extended “binge” period, suggesting that intermittent social defeat produced profound sex differences in cocaine consumption and DA response. In this particular series of study, the authors did not see any difference in latency to the first bite, total number of bites received, or duration of defeat encounter between males and females ( Holly et al., 2012 ). In line with these studies, my laboratory has not observed any differences in anhedonia-like responses between males and females when exposed to chronic social defeat ( Rappeneau et al., 2016 ).


Dollard et al. (1939) proposed that aggression was due to frustration, which was described as an unpleasant emotion resulting from any interference with achieving a rewarding goal. [9] Berkowitz [10] extended this frustration–aggression hypothesis and proposed that it is not so much the frustration as the unpleasant emotion that evokes aggressive tendencies, and that all aversive events produce negative affect and thereby aggressive tendencies, as well as fear tendencies. Besides conditioned stimuli, Archer categorized aggression-evoking (as well as fear-evoking) stimuli into three groups namely, pain, novelty, and frustration, although he also described "looming," which refers to an object rapidly moving towards the visual sensors of a subject, and can be categorized as "intensity." [11]

Aggression can have adaptive benefits or negative effects. Aggressive behavior is an individual or collective social interaction that is a hostile behavior with the intention of inflicting damage or harm. [2] [3] Two broad categories of aggression are commonly distinguished. One includes affective (emotional) and hostile, reactive, or retaliatory aggression that is a response to provocation, and the other includes instrumental, goal-oriented or predatory, in which aggression is used as a means to achieve a goal. [12] An example of hostile aggression would be a person who punches someone who insulted him or her. An instrumental form of aggression would be armed robbery. Research on violence from a range of disciplines lend some support to a distinction between affective and predatory aggression. [13] However, some researchers question the usefulness of a hostile versus instrumental distinction in humans, despite its ubiquity in research, because most real-life cases involve mixed motives and interacting causes. [14]

A number of classifications and dimensions of aggression have been suggested. These depend on such things as whether the aggression is verbal or physical whether or not it involves relational aggression such as covert bullying and social manipulation [15] whether harm to others is intended or not whether it is carried out actively or expressed passively and whether the aggression is aimed directly or indirectly. Classification may also encompass aggression-related emotions (e.g. anger) and mental states (e.g. impulsivity, hostility). [16] Aggression may occur in response to non-social as well as social factors, and can have a close relationship with stress coping style. [17] Aggression may be displayed in order to intimidate.

The operative definition of aggression may be affected by moral or political views. Examples are the axiomatic moral view called the non-aggression principle and the political rules governing the behavior of one country toward another. [18] Likewise in competitive sports, or in the workplace, some forms of aggression may be sanctioned and others not (see Workplace aggression). [19] Aggressive behaviors are associated with adjustment problems and several psychopathological symptoms such as Antisocial Personality Disorder, Borderline Personality Disorder, and Intermittent Explosive Disorder. [20]

Biological approaches conceptualize aggression as an internal energy released by external stimuli, a product of evolution through natural selection, part of genetics, a product of hormonal fluctuations. Psychological approaches conceptualize aggression as a destructive instinct, a response to frustration, an affect excited by a negative stimulus, a result of observed learning of society and diversified reinforcement, a resultant of variables that affect personal and situational environments. [21] [22]

The term aggression comes from the Latin word aggressio, meaning attack. The Latin was itself a joining of ad- and gradi-, which meant step at. The first known use dates back to 1611, in the sense of an unprovoked attack. [23] A psychological sense of "hostile or destructive behavior" dates back to a 1912 English translation of Sigmund Freud's writing. [24] Alfred Adler theorized about an "aggressive drive" in 1908. Child raising experts began to refer to aggression, rather than anger, from the 1930s. [25]

Ethologists study aggression as it relates to the interaction and evolution of animals in natural settings. In such settings aggression can involve bodily contact such as biting, hitting or pushing, but most conflicts are settled by threat displays and intimidating thrusts that cause no physical harm. This form of aggression may include the display of body size, antlers, claws or teeth stereotyped signals including facial expressions vocalizations such as bird song the release of chemicals and changes in coloration. [26] The term agonistic behaviour is sometimes used to refer to these forms of behavior.

Most ethologists believe that aggression confers biological advantages. Aggression may help an animal secure territory, including resources such as food and water. Aggression between males often occurs to secure mating opportunities, and results in selection of the healthier/more vigorous animal. Aggression may also occur for self-protection or to protect offspring. [27] Aggression between groups of animals may also confer advantage for example, hostile behavior may force a population of animals into a new territory, where the need to adapt to a new environment may lead to an increase in genetic flexibility. [28]

Between species and groups Edit

The most apparent type of interspecific aggression is that observed in the interaction between a predator and its prey. However, according to many researchers, predation is not aggression. A cat does not hiss or arch its back when pursuing a rat, and the active areas in its hypothalamus resemble those that reflect hunger rather than those that reflect aggression. [29] However, others refer to this behavior as predatory aggression, and point out cases that resemble hostile behavior, such as mouse-killing by rats. [30] In aggressive mimicry a predator has the appearance of a harmless organism or object attractive to the prey when the prey approaches, the predator attacks.

An animal defending against a predator may engage in either "fight or flight" or "tend and befriend" in response to predator attack or threat of attack, depending on its estimate of the predator's strength relative to its own. Alternative defenses include a range of antipredator adaptations, including alarm signals. An example of an alarm signal is nerol, a chemical which is found in the mandibular glands of Trigona fulviventris individuals. [31] Release of nerol by T. fulviventris individuals in the nest has been shown to decrease the number of individuals leaving the nest by fifty percent, as well as increasing aggressive behaviors like biting. [31] Alarm signals like nerol can also act as attraction signals in T. fulviventris, individuals that have been captured by a predator may release nerol to attract nestmates, who will proceed to attack or bite the predator. [31]

Aggression between groups is determined partly by willingness to fight, which depends on a number of factors including numerical advantage, distance from home territories, how often the groups encounter each other, competitive abilities, differences in body size, and whose territory is being invaded. [32] Also, an individual is more likely to become aggressive if other aggressive group members are nearby. [33] One particular phenomenon – the formation of coordinated coalitions that raid neighbouring territories to kill conspecifics – has only been documented in two species in the animal kingdom: 'common' chimpanzees and humans. [34]

Within a group Edit

Aggression between conspecifics in a group typically involves access to resources and breeding opportunities. One of its most common functions is to establish a dominance hierarchy. This occurs in many species by aggressive encounters between contending males when they are first together in a common environment. [35] Usually the more aggressive animals become the more dominant. [36] [37] In test situations, most of the conspecific aggression ceases about 24 hours after the group of animals is brought together. [35] [38] Aggression has been defined from this viewpoint as "behavior which is intended to increase the social dominance of the organism relative to the dominance position of other organisms". [39] Losing confrontations may be called social defeat, and winning or losing is associated with a range of practical and psychological consequences. [40]

Conflicts between animals occur in many contexts, such as between potential mating partners, between parents and offspring, between siblings and between competitors for resources. Group-living animals may dispute over the direction of travel or the allocation of time to joint activities. Various factors limit the escalation of aggression, including communicative displays, conventions, and routines. In addition, following aggressive incidents, various forms of conflict resolution have been observed in mammalian species, particularly in gregarious primates. These can mitigate or repair possible adverse consequences, especially for the recipient of aggression who may become vulnerable to attacks by other members of a group. Conciliatory acts vary by species and may involve specific gestures or simply more proximity and interaction between the individuals involved. However, conflicts over food are rarely followed by post conflict reunions, even though they are the most frequent type in foraging primates. [41]

Other questions that have been considered in the study of primate aggression, including in humans, is how aggression affects the organization of a group, what costs are incurred by aggression, and why some primates avoid aggressive behavior. [42] For example, bonobo chimpanzee groups are known for low levels of aggression within a partially matriarchal society. Captive animals including primates may show abnormal levels of social aggression and self-harm that are related to aspects of the physical or social environment this depends on the species and individual factors such as gender, age and background (e.g. raised wild or captive). [43]

Aggression, fear and curiosity Edit

Within ethology, it has long been recognized that there is a relation between aggression, fear, and curiosity. [44] A cognitive approach to this relationship puts aggression in the broader context of inconsistency reduction, and proposes that aggressive behavior is caused by an inconsistency between a desired, or expected, situation and the actually perceived situation (e.g., "frustration"), and functions to forcefully manipulate the perception into matching the expected situation. [45] [11] [46] In this approach, when the inconsistency between perception and expectancy is small, learning as a result of curiosity reduces inconsistency by updating expectancy to match perception. If the inconsistency is larger, fear or aggressive behavior may be employed to alter the perception in order to make it match expectancy, depending on the size of the inconsistency as well as the specific context. Uninhibited fear results in fleeing, thereby removing the inconsistent stimulus from the perceptual field and resolving the inconsistency. In some cases thwarted escape may trigger aggressive behavior in an attempt to remove the thwarting stimulus. [46]

Like many behaviors, aggression can be examined in terms of its ability to help an animal itself survive and reproduce, or alternatively to risk survival and reproduction. This cost-benefit analysis can be looked at in terms of evolution. However, there are profound differences in the extent of acceptance of a biological or evolutionary basis for human aggression. [47]

According to the male warrior hypothesis, intergroup aggression represents an opportunity for men to gain access to mates, territory, resources and increased status. As such, conflicts may have created selection evolutionary pressures for psychological mechanisms in men to initiate intergroup aggression. [48] [49]

Violence and conflict Edit

Aggression can involve violence that may be adaptive under certain circumstances in terms of natural selection. This is most obviously the case in terms of attacking prey to obtain food, or in anti-predatory defense. It may also be the case in competition between members of the same species or subgroup, if the average reward (e.g. status, access to resources, protection of self or kin) outweighs average costs (e.g. injury, exclusion from the group, death). There are some hypotheses of specific adaptions for violence in humans under certain circumstances, including for homicide, but it is often unclear what behaviors may have been selected for and what may have been a byproduct, as in the case of collective violence. [50] [51] [52] [53]

Although aggressive encounters are ubiquitous in the animal kingdom, with often high stakes, most encounters that involve aggression may be resolved through posturing, or displaying and trial of strength. Game theory is used to understand how such behaviors might spread by natural selection within a population, and potentially become 'Evolutionary Stable Strategies'. An initial model of resolution of conflicts is the hawk-dove game. Others include the Sequential assessment model and the Energetic war of attrition. These try to understand not just one-off encounters but protracted stand-offs, and mainly differ in the criteria by which an individual decides to give up rather than risk loss and harm in physical conflict (such as through estimates of resource holding potential). [54]

Gender Edit

General Edit

Gender plays an important role in human aggression. [55] There are multiple theories that seek to explain findings that males and females of the same species can have differing aggressive behaviors. One review concluded that male aggression tended to produce pain or physical injury whereas female aggression tended towards psychological or social harm. [56]

In general, sexual dimorphism can be attributed to greater intraspecific competition in one sex, either between rivals for access to mates and/or to be chosen by mates. [57] [58] This may stem from the other gender being constrained by providing greater parental investment, in terms of factors such as gamete production, gestation, lactation, or upbringing of young. Although there is much variation in species, generally the more physically aggressive sex is the male, particularly in mammals. [59] In species where parental care by both sexes is required, there tends to be less of a difference. When the female can leave the male to care for the offspring, then females may be the larger and more physically aggressive. Competitiveness despite parental investment has also been observed in some species. [60] A related factor is the rate at which males and females are able to mate again after producing offspring, and the basic principles of sexual selection are also influenced by ecological factors affecting the ways or extent to which one sex can compete for the other. The role of such factors in human evolution is controversial.

The pattern of male and female aggression is argued to be consistent with evolved sexually-selected behavioral differences, [57] while alternative or complementary views emphasize conventional social roles stemming from physical evolved differences. [61] Aggression in women may have evolved to be, on average, less physically dangerous and more covert or indirect. [62] [63] However, there are critiques for using animal behavior to explain human behavior. Especially in the application of evolutionary explanations to contemporary human behavior, including differences between the genders. [64]

According to the 2015 International Encyclopedia of the Social & Behavioral Sciences, sex differences in aggression is one of the most robust and oldest findings in psychology. [65] Past meta-analyses in the encyclopedia found males regardless of age engaged in more physical and verbal aggression while small effect for females engaging in more indirect aggression such as rumor spreading or gossiping. [65] It also found males tend to engage in more unprovoked aggression at higher frequency than females. [65] This analysis also conforms with the Oxford Handbook of Evolutionary Psychology which reviewed past analysis which found men to use more verbal and physical aggression with the difference being greater in the physical type. [66] There are more recent findings that show that differences in male and female aggression appear at about two years of age, though the differences in aggression are more consistent in middle-aged children and adolescence. Tremblay, Japel and Pérusse (1999) asserted that physically aggressive behaviors such as kicking, biting and hitting are age-typical expressions of innate and spontaneous reactions to biological drives such as anger, hunger, and affiliation. [67] Girls' relational aggression, meaning non-physical or indirect, tends to increase after age two while physical aggression decreases. There was no significant difference in aggression between males and females before two years of age. [68] A possible explanation for this could be that girls develop language skills more quickly than boys, and therefore have better ways of verbalizing their wants and needs. They are more likely to use communication when trying to retrieve a toy with the words "Ask nicely" or "Say please." [69]

According to the journal of Aggressive Behaviour, an analysis across 9 countries found boys reported more in the use of physical aggression. [68] At the same time no consistent sex differences emerged within relational aggression. [68] It has been found that girls are more likely than boys to use reactive aggression and then retract, but boys are more likely to increase rather than to retract their aggression after their first reaction. Studies show girls' aggressive tactics included gossip, ostracism, breaking confidences, and criticism of a victim's clothing, appearance, or personality, whereas boys engage in aggression that involves a direct physical and/or verbal assault. [70] This could be due to the fact that girls' frontal lobes develop earlier than boys, allowing them to self-restrain. [69]

One factor that shows insignificant differences between male and female aggression is in sports. In sports, the rate of aggression in both contact and non-contact sports is relatively equal. Since the establishment of Title IX, female sports have increased in competitiveness and importance, which could contribute to the evening of aggression and the "need to win" attitude between both genders. Among sex differences found in adult sports were that females have a higher scale of indirect hostility while men have a higher scale of assault. [71] Another difference found is that men have up to 20 times higher levels of testosterone than women.

In intimate relationships Edit

Some studies suggest that romantic involvement in adolescence decreases aggression in males and females, but decreases at a higher rate in females. Females will seem more desirable to their mate if they fit in with society and females that are aggressive do not usually fit well in society, they can often be viewed as antisocial. Female aggression is not considered the norm in society and going against the norm can sometimes prevent one from getting a mate. [72] However, studies have shown that an increasing number of women are getting arrested for domestic violence charges. In many states, women now account for a quarter to a third of all domestic violence arrests, up from less than 10 percent a decade ago. The new statistics reflect a reality documented in research: women are perpetrators as well as victims of family violence. [73] However, another equally possible explanation is a case of improved diagnostics: it has become more acceptable for men to report female domestic violence to the authorities while at the same time actual female domestic violence has not increased at all. This can be the case when men have become less ashamed of reporting female violence against them, therefore an increasing number of women are arrested, although the actual number of violent women remains the same.

In addition, males in competitive sports are often advised by their coaches not to be in intimate relationships based on the premises that they become more docile and less aggressive during an athletic event. The circumstances in which males and females experience aggression are also different. A study showed that social anxiety and stress was positively correlated with aggression in males, meaning as stress and social anxiety increases so does aggression. Furthermore, a male with higher social skills has a lower rate of aggressive behavior than a male with lower social skills. In females, higher rates of aggression were only correlated with higher rates of stress. Other than biological factors that contribute to aggression there are physical factors are well. [74]

Physiological factors Edit

Regarding sexual dimorphism, humans fall into an intermediate group with moderate sex differences in body size but relatively large testes. This is a typical pattern of primates where several males and females live together in a group and the male faces an intermediate number of challenges from other males compared to exclusive polygyny and monogamy but frequent sperm competition. [75]

Evolutionary psychology and sociobiology have also discussed and produced theories for some specific forms of male aggression such as sociobiological theories of rape and theories regarding the Cinderella effect. Another evolutionary theory explaining gender differences in aggression is the Male Warrior hypothesis, which explains that males have psychologically evolved for intergroup aggression in order to gain access to mates, resources, territory and status. [48] [49]

Brain pathways Edit

Many researchers focus on the brain to explain aggression. Numerous circuits within both neocortical and subcortical structures play a central role in controlling aggressive behavior, depending on the species, and the exact role of pathways may vary depending on the type of trigger or intention. [76] [3]

In mammals, the hypothalamus and periaqueductal gray of the midbrain are critical areas, as shown in studies on cats, rats, and monkeys. These brain areas control the expression of both behavioral and autonomic components of aggression in these species, including vocalization. Electrical stimulation of the hypothalamus causes aggressive behavior [77] and the hypothalamus has receptors that help determine aggression levels based on their interactions with serotonin and vasopressin. [78] In rodents, activation of estrogen receptor-expressing neurons in the ventrolateral portion of the ventromedial hypothalamus (VMHvl) was found to be sufficient to initiate aggression in both males and females. [79] [80] Midbrain areas involved in aggression have direct connections with both the brainstem nuclei controlling these functions, and with structures such as the amygdala and prefrontal cortex.

Stimulation of the amygdala results in augmented aggressive behavior in hamsters, [81] [82] while lesions of an evolutionarily homologous area in the lizard greatly reduce competitive drive and aggression (Bauman et al. 2006). [83] In rhesus monkeys, neonatal lesions in the amygdala or hippocampus results in reduced expression of social dominance, related to the regulation of aggression and fear. [84] Several experiments in attack-primed Syrian golden hamsters, for example, support the claim of circuity within the amygdala being involved in control of aggression. [82] The role of the amygdala is less clear in primates and appears to depend more on situational context, with lesions leading to increases in either social affiliatory or aggressive responses. Amygdalotomy, which involves removing or destroying parts of the amygdala, has been performed on people to reduce their violent behaviour.

The broad area of the cortex known as the prefrontal cortex (PFC) is crucial for self-control and inhibition of impulses, including inhibition of aggression and emotions. Reduced activity of the prefrontal cortex, in particular its medial and orbitofrontal portions, has been associated with violent/antisocial aggression. [85] In addition, reduced response inhibition has been found in violent offenders, compared to non-violent offenders. [76]

The role of the chemicals in the brain, particularly neurotransmitters, in aggression has also been examined. This varies depending on the pathway, the context and other factors such as gender. A deficit in serotonin has been theorized to have a primary role in causing impulsivity and aggression. At least one epigenetic study supports this supposition. [86] Nevertheless, low levels of serotonin transmission may explain a vulnerability to impulsiveness, potential aggression, and may have an effect through interactions with other neurochemical systems. These include dopamine systems which are generally associated with attention and motivation toward rewards, and operate at various levels. Norepinephrine, also known as noradrenaline, may influence aggression responses both directly and indirectly through the hormonal system, the sympathetic nervous system or the central nervous system (including the brain). It appears to have different effects depending on the type of triggering stimulus, for example social isolation/rank versus shock/chemical agitation which appears not to have a linear relationship with aggression. Similarly, GABA, although associated with inhibitory functions at many CNS synapses, sometimes shows a positive correlation with aggression, including when potentiated by alcohol. [87] [88]

The hormonal neuropeptides vasopressin and oxytocin play a key role in complex social behaviours in many mammals such as regulating attachment, social recognition, and aggression. Vasopressin has been implicated in male-typical social behaviors which includes aggression. Oxytocin may have a particular role in regulating female bonds with offspring and mates, including the use of protective aggression. Initial studies in humans suggest some similar effects. [89] [90]

In human, aggressive behavior has been associated with abnormalities in three principal regulatory systems in the body serotonin systems, catecholamine systems, and the hypothalamic–pituitary–adrenal axis. Abnormalities in these systems also are known to be induced by stress, either severe, acute stress or chronic low-grade stress [91]

Testosterone Edit

Early androgenization has an organizational effect on the developing brains of both males and females, making more neural circuits that control sexual behavior as well as intermale and interfemale aggression become more sensitive to testosterone. [92] There are noticeable sex differences in aggression. Testosterone is present to a lesser extent in females, who may be more sensitive to its effects. Animal studies have also indicated a link between incidents of aggression and the individual level of circulating testosterone. However, results in relation to primates, particularly humans, are less clear cut and are at best only suggestive of a positive association in some contexts. [93]

In humans, there is a seasonal variation in aggression associated with changes in testosterone. [94] For example, in some primate species, such as rhesus monkeys and baboons, females are more likely to engage in fights around the time of ovulation as well as right before menstruation. [92] If the results were the same in humans as they are in rhesus monkeys and baboons, then the increase in aggressive behaviors during ovulation is explained by the decline in estrogen levels. This makes normal testosterone levels more effective. [95] Castrated mice and rats exhibit lower levels of aggression. Males castrated as neonates exhibit low levels of aggression even when given testosterone throughout their development.

Challenge hypothesis Edit

The challenge hypothesis outlines the dynamic relationship between plasma testosterone levels and aggression in mating contexts in many species. It proposes that testosterone is linked to aggression when it is beneficial for reproduction, such as in mate guarding and preventing the encroachment of intrasexual rivals. The challenge hypothesis predicts that seasonal patterns in testosterone levels in a species are a function of mating system (monogamy versus polygyny), paternal care, and male-male aggression in seasonal breeders. This pattern between testosterone and aggression was first observed in seasonally breeding birds, such as the song sparrow, where testosterone levels rise modestly with the onset of the breeding season to support basic reproductive functions. [96] The hypothesis has been subsequently expanded and modified to predict relationships between testosterone and aggression in other species. For example, chimpanzees, which are continuous breeders, show significantly raised testosterone levels and aggressive male-male interactions when receptive and fertile females are present. [97] Currently, no research has specified a relationship between the modified challenge hypothesis and human behavior, or the human nature of concealed ovulation, although some suggest it may apply. [94]

Effects on the nervous system Edit

Another line of research has focused on the proximate effects of circulating testosterone on the nervous system, as mediated by local metabolism within the brain. Testosterone can be metabolized to estradiol by the enzyme aromatase, or to dihydrotestosterone (DHT) by 5α-reductase. [98]

Aromatase is highly expressed in regions involved in the regulation of aggressive behavior, such as the amygdala and hypothalamus. In studies using genetic knockout techniques in inbred mice, male mice that lacked a functional aromatase enzyme displayed a marked reduction in aggression. Long-term treatment with estradiol partially restored aggressive behavior, suggesting that the neural conversion of circulating testosterone to estradiol and its effect on estrogen receptors influences inter-male aggression. In addition, two different estrogen receptors, ERα and ERβ, have been identified as having the ability to exert different effects on aggression in mice. However, the effect of estradiol appears to vary depending on the strain of mouse, and in some strains it reduces aggression during long days (16 h of light), while during short days (8 h of light) estradiol rapidly increases aggression. [98]

Another hypothesis is that testosterone influences brain areas that control behavioral reactions. Studies in animal models indicate that aggression is affected by several interconnected cortical and subcortical structures within the so-called social behavior network. A study involving lesions and electrical-chemical stimulation in rodents and cats revealed that such a neural network consists of the medial amygdala, medial hypothalamus and periaqueductal grey (PAG), and it positively modulates reactive aggression. [99] Moreover, a study done in human subjects showed that prefrontal-amygdala connectivity is modulated by endogenous testosterone during social emotional behavior. [100]

In human studies, testosterone-aggression research has also focused on the role of the orbitofrontal cortex (OFC). This brain area is strongly associated with impulse control and self-regulation systems that integrate emotion, motivation, and cognition to guide context-appropriate behavior. [101] Patients with localized lesions to the OFC engage in heightened reactive aggression. [102] Aggressive behavior may be regulated by testosterone via reduced medial OFC engagement following social provocation. [101] When measuring participants' salivary testosterone, higher levels can predict subsequent aggressive behavioral reactions to unfairness faced during a task. Moreover, brain scanning with fMRI shows reduced activity in the medial OFC during such reactions. Such findings may suggest that a specific brain region, the OFC, is a key factor in understanding reactive aggression.

General associations with behavior Edit

Scientists have for a long time been interested in the relationship between testosterone and aggressive behavior. In most species, males are more aggressive than females. Castration of males usually has a pacifying effect on aggressive behavior in males. In humans, males engage in crime and especially violent crime more than females. The involvement in crime usually rises in the early teens to mid teens which happen at the same time as testosterone levels rise. Research on the relationship between testosterone and aggression is difficult since the only reliable measurement of brain testosterone is by a lumbar puncture which is not done for research purposes. Studies therefore have often instead used more unreliable measurements from blood or saliva. [103]

The Handbook of Crime Correlates, a review of crime studies, states most studies support a link between adult criminality and testosterone although the relationship is modest if examined separately for each sex. However, nearly all studies of juvenile delinquency and testosterone are not significant. Most studies have also found testosterone to be associated with behaviors or personality traits linked with criminality such as antisocial behavior and alcoholism. Many studies have also been done on the relationship between more general aggressive behavior/feelings and testosterone. About half the studies have found a relationship and about half no relationship. [103]

Studies of testosterone levels of male athletes before and after a competition revealed that testosterone levels rise shortly before their matches, as if in anticipation of the competition, and are dependent on the outcome of the event: testosterone levels of winners are high relative to those of losers. No specific response of testosterone levels to competition was observed in female athletes, although a mood difference was noted. [104] In addition, some experiments have failed to find a relationship between testosterone levels and aggression in humans. [105] [20] [106]

The possible correlation between testosterone and aggression could explain the "roid rage" that can result from anabolic steroid use, [107] [108] although an effect of abnormally high levels of steroids does not prove an effect at physiological levels.

Dehydroepiandrosterone Edit

Dehydroepiandrosterone (DHEA) is the most abundant circulating androgen hormone and can be rapidly metabolized within target tissues into potent androgens and estrogens. Gonadal steroids generally regulate aggression during the breeding season, but non-gonadal steroids may regulate aggression during the non-breeding season. Castration of various species in the non-breeding season has no effect on territorial aggression. In several avian studies, circulating DHEA has been found to be elevated in birds during the non-breeding season. These data support the idea that non-breeding birds combine adrenal and/or gonadal DHEA synthesis with neural DHEA metabolism to maintain territorial behavior when gonadal testosterone secretion is low. Similar results have been found in studies involving different strains of rats, mice, and hamsters. DHEA levels also have been studied in humans and may play a role in human aggression. Circulating DHEAS (its sulfated ester) levels rise during adrenarche (≈7 years of age) while plasma testosterone levels are relatively low. This implies that aggression in pre-pubertal children with aggressive conduct disorder might be correlated with plasma DHEAS rather than plasma testosterone, suggesting an important link between DHEAS and human aggressive behavior. [98]

Glucocorticoids Edit

Glucocorticoid hormones have an important role in regulating aggressive behavior. In adult rats, acute injections of corticosterone promote aggressive behavior and acute reduction of corticosterone decreases aggression however, a chronic reduction of corticosterone levels can produce abnormally aggressive behavior. In addition, glucocorticoids affect development of aggression and establishment of social hierarchies. Adult mice with low baseline levels of corticosterone are more likely to become dominant than are mice with high baseline corticosterone levels. [98]

Glucocorticoids are released by the hypothalamic pituitary adrenal (HPA) axis in response to stress, of which cortisol is the most prominent in humans. Results in adults suggest that reduced levels of cortisol, linked to lower fear or a reduced stress response, can be associated with more aggression. However, it may be that proactive aggression is associated with low cortisol levels while reactive aggression may be accompanied by elevated levels. Differences in assessments of cortisol may also explain a diversity of results, particularly in children. [93]

The HPA axis is related to the general fight-or-flight response or acute stress reaction, and the role of catecholamines such as epinephrine, popularly known as adrenaline.

Pheromones Edit

In many animals, aggression can be linked to pheromones released between conspecifics. In mice, major urinary proteins (Mups) have been demonstrated to promote innate aggressive behavior in males, [109] [110] and can be mediated by neuromodulatory systems. [111] Mups activate olfactory sensory neurons in the vomeronasal organ (VNO), a subsystem of the nose known to detect pheromones via specific sensory receptors, of mice [110] and rats. [112] Pheremones have also been identified in fruit flies, detected by neurons in the antenna, that send a message to the brain eliciting aggression it has been noted that aggression pheremones have not been identified in humans. [113]

In general, differences in a continuous phenotype such as aggression are likely to result from the action of a large number of genes each of small effect, which interact with each other and the environment through development and life.

In a non-mammalian example of genes related to aggression, the fruitless gene in fruit flies is a critical determinant of certain sexually dimorphic behaviors, and its artificial alteration can result in a reversal of stereotypically male and female patterns of aggression in fighting. However, in what was thought to be a relatively clear case, inherent complexities have been reported in deciphering the connections between interacting genes in an environmental context and a social phenotype involving multiple behavioral and sensory interactions with another organism. [114]

In mice, candidate genes for differentiating aggression between the sexes are the Sry (sex determining region Y) gene, located on the Y chromosome and the Sts (steroid sulfatase) gene. The Sts gene encodes the steroid sulfatase enzyme, which is pivotal in the regulation of neurosteroid biosynthesis. It is expressed in both sexes, is correlated with levels of aggression among male mice, and increases dramatically in females after parturition and during lactation, corresponding to the onset of maternal aggression. [82] At least one study has found a possible epigenetic signature (i.e. decreased methylation at a specific CpG site on the promoter region) of the serotonin receptor 5-HT3a that is associated with maternal aggression among human subjects. [86]

Mice with experimentally elevated sensitivity to oxidative stress (through inhibition of copper-zinc superoxide dismutase, SOD1 activity) were tested for aggressive behavior. [115] Males completely deficient in SOD1 were found to be more aggressive than both wild-type males and males that express 50% of this antioxidant enzyme. They were also faster to attack another male. The causal connection between SOD1 deficiency and increased aggression is not yet understood.

In humans, there is good evidence that the basic human neural architecture underpinning the potential for flexible aggressive responses is influenced by genes as well as environment. In terms of variation between individual people, more than 100 twin and adoption studies have been conducted in recent decades examining the genetic basis of aggressive behavior and related constructs such as conduct disorders. According to a meta-analysis published in 2002, approximately 40% of variation between individuals is explained by differences in genes, and 60% by differences in environment (mainly non-shared environmental influences rather than those that would be shared by being raised together). However, such studies have depended on self-report or observation by others including parents, which complicates interpretation of the results. The few laboratory-based analyses have not found significant amounts of individual variation in aggression explicable by genetic variation in the human population. Furthermore, linkage and association studies that seek to identify specific genes, for example that influence neurotransmitter or hormone levels, have generally resulted in contradictory findings characterized by failed attempts at replication. One possible factor is an allele (variant) of the MAO-A gene which, in interaction with certain life events such as childhood maltreatment (which may show a main effect on its own), can influence development of brain regions such as the amygdala and as a result some types of behavioral response may be more likely. The generally unclear picture has been compared to equally difficult findings obtained in regard to other complex behavioral phenotypes. [116] [117] For example, both 7R and 5R, ADHD-linked VNTR alleles of dopamine receptor D4 gene are directly associated with the incidence of proactive aggression in the men with no history of ADHD. [118]

Humans share aspects of aggression with non-human animals, and have specific aspects and complexity related to factors such as genetics, early development, social learning and flexibility, culture and morals. Konrad Lorenz stated in his 1963 classic, On Aggression, that human behavior is shaped by four main, survival-seeking animal drives. Taken together, these drives—hunger, fear, reproduction, and aggression—achieve natural selection. [119] E. O. Wilson elaborated in On Human Nature that aggression is, typically, a means of gaining control over resources. Aggression is, thus, aggravated during times when high population densities generate resource shortages. [120] According to Richard Leakey and his colleagues, aggression in humans has also increased by becoming more interested in ownership and by defending his or her property. [121] However, UNESCO adopted the Seville Statement of Violence in 1989 that refuted claims, by evolutionary scientists, that genetics by itself was the sole cause of aggression. [122] [123]

Social and cultural aspects may significantly interfere with the distinct expression of aggressiveness. For example, a high population density, when associated with a decrease of available resources, might be a significant intervening variable for the occurrence of violent acts. [124]

Culture Edit

Culture is one factor that plays a role in aggression. Tribal or band societies existing before or outside of modern states have sometimes been depicted as peaceful 'noble savages'. The ǃKung people were described as 'The Harmless People' in a popular work by Elizabeth Marshall Thomas in 1958, [125] while Lawrence Keeley's 1996 War Before Civilization suggested that regular warfare without modern technology was conducted by most groups throughout human history, including most Native American tribes. [126] Studies of hunter-gatherers show a range of different societies. In general, aggression, conflict and violence sometimes occur, but direct confrontation is generally avoided and conflict is socially managed by a variety of verbal and non-verbal methods. Different rates of aggression or violence, currently or in the past, within or between groups, have been linked to the structuring of societies and environmental conditions influencing factors such as resource or property acquisition, land and subsistence techniques, and population change. [127]

American psychologist Peter Gray hypothesizes that band hunter-gatherer societies are able to reduce aggression while maintaining relatively peaceful, egalitarian relations between members through various methods, such as fostering a playful spirit in all areas of life, the use of humor to counter the tendency of any one person to dominate the group, and non-coercive or "indulgent" child-rearing practices. Gray likens hunter-gatherer bands to social play groups, while stressing that such play is not frivolous or even easy at all times. [128] According to Gray, "Social play—that is, play involving more than one player—is necessarily egalitarian. It always requires a suspension of aggression and dominance along with a heightened sensitivity to the needs and desires of the other players". [129]

Joan Durrant at the University of Manitoba writes that a number of studies have found physical punishment to be associated with "higher levels of aggression against parents, siblings, peers and spouses", even when controlling for other factors. [130] According to Elizabeth Gershoff at the University of Texas at Austin, the more that children are physically punished, the more likely they are as adults to act violently towards family members, including intimate partners. [131] In countries where physical punishment of children is perceived as being more culturally accepted, it is less strongly associated with increased aggression however, physical punishment has been found to predict some increase in child aggression regardless of culture. [132] While these associations do not prove causality, a number of longitudinal studies suggest that the experience of physical punishment has a direct causal effect on later aggressive behaviors. [130] In examining several longitudinal studies that investigated the path from disciplinary spanking to aggression in children from preschool age through adolescence, Gershoff concluded: "Spanking consistently predicted increases in children's aggression over time, regardless of how aggressive children were when the spanking occurred". [133] similar results were found by Catherine Taylor at Tulane University in 2010. [134] Family violence researcher Murray A. Straus argues, "There are many reasons this evidence has been ignored. One of the most important is the belief that spanking is more effective than nonviolent discipline and is, therefore, sometimes necessary, despite the risk of harmful side effects". [135]

Analyzing aggression culturally or politically is complicated by the fact that the label 'aggressive' can itself be used as a way of asserting a judgement from a particular point of view. [ according to whom? ] Whether a coercive or violent method of social control is perceived as aggression – or as legitimate versus illegitimate aggression – depends on the position of the relevant parties in relation to the social order of their culture. This in turn can relate to factors such as: norms for coordinating actions and dividing resources what is considered self-defense or provocation attitudes towards 'outsiders', attitudes towards specific groups such as women, the disabled or the lower status the availability of alternative conflict resolution strategies trade interdependence and collective security pacts fears and impulses and ultimate goals regarding material and social outcomes. [124]

Cross-cultural research has found differences in attitudes towards aggression in different cultures. In one questionnaire study of university students, in addition to men overall justifying some types of aggression more than women, United States respondents justified defensive physical aggression more readily than Japanese or Spanish respondents, whereas Japanese students preferred direct verbal aggression (but not indirect) more than their American and Spanish counterparts. [136] Within American culture, southern men were shown in a study on university students to be more affected and to respond more aggressively than northerners when randomly insulted after being bumped into, which was theoretically related to a traditional culture of honor in the Southern United States, or "saving face". [137] Other cultural themes sometimes applied to the study of aggression include individualistic versus collectivist styles, which may relate, for example, to whether disputes are responded to with open competition or by accommodating and avoiding conflicts. In a study including 62 countries school principals reported aggressive student behavior more often the more individualist, and hence less collectivist, their country's culture. [138] Other comparisons made in relation to aggression or war include democratic versus authoritarian political systems and egalitarian versus stratified societies. [124] The economic system known as capitalism has been viewed by some as reliant on the leveraging of human competitiveness and aggression in pursuit of resources and trade, which has been considered in both positive and negative terms. [139] Attitudes about the social acceptability of particular acts or targets of aggression are also important factors. This can be highly controversial, as for example in disputes between religions or nation states, for example in regard to the Arab–Israeli conflict. [140] [141]

Media Edit

Some scholars believe that behaviors like aggression may be partially learned by watching and imitating people's behavior, while other researchers have concluded that the media may have some small effects on aggression. [142] There is also research questioning this view. [143] For instance, a long-term outcome study of youth found no long-term relationship between playing violent video games and youth violence or bullying. [144] One study suggested there is a smaller effect of violent video games on aggression than has been found with television violence on aggression. This effect is positively associated with type of game violence and negatively associated to time spent playing the games. [145] The author concluded that insufficient evidence exists to link video game violence with aggression. However, another study suggested links to aggressive behavior. [146]

Fear-induced aggression Edit

According to philosopher and neuroscientist Nayef Al-Rodhan, "fear(survival)-induced pre-emptive aggression" is a human reaction to injustices that are perceived to threaten survival. It is often the root of the unthinkable brutality and injustice perpetuated by human beings. It may occur at any time, even in situations that appear to be calm and under control. Where there is injustice that is perceived as posing a threat to survival, "fear(survival)-induced pre-emptive aggression" will result in individuals taking whatever action necessary to be free from that threat.

Nayef Al-Rodhan argues that humans' strong tendency towards "fear(survival)-induced pre-emptive aggression" means that situations of anarchy or near anarchy should be prevented at all costs. This is because anarchy provokes fear, which in turn results in aggression, brutality, and injustice. Even in non-anarchic situations, survival instincts and fear can be very powerful forces, and they may be incited instantaneously. "Fear(survival)-induced pre-emptive aggression" is one of the key factors that may push naturally amoral humans to behave in immoral ways. [147] Knowing this, Al-Rodhan maintains that we must prepare for the circumstances that may arise from humans' aggressive behavior. According to Al-Rodhan, the risk of this aggression and its ensuing brutality should be minimized through confidence-building measures and policies that promote inclusiveness and prevent anarchy. [148]

Children Edit

The frequency of physical aggression in humans peaks at around 2–3 years of age. It then declines gradually on average. [149] [150] These observations suggest that physical aggression is not only a learned behavior but that development provides opportunities for the learning and biological development of self-regulation. However, a small subset of children fail to acquire all the necessary self-regulatory abilities and tend to show atypical levels of physical aggression across development. These may be at risk for later violent behavior or, conversely, lack of aggression that may be considered necessary within society. Some findings suggest that early aggression does not necessarily lead to aggression later on, however, although the course through early childhood is an important predictor of outcomes in middle childhood. In addition, physical aggression that continues is likely occurring in the context of family adversity, including socioeconomic factors. Moreover, 'opposition' and 'status violations' in childhood appear to be more strongly linked to social problems in adulthood than simply aggressive antisocial behavior. [151] [152] Social learning through interactions in early childhood has been seen as a building block for levels of aggression which play a crucial role in the development of peer relationships in middle childhood. [153] Overall, an interplay of biological, social and environmental factors can be considered. [154] Some research indicates that changes in the weather can increase the likelihood of children exhibiting deviant behavior. [155]

Typical expectations Edit

  • Young children preparing to enter kindergarten need to develop the socially important skill of being assertive. Examples of assertiveness include asking others for information, initiating conversation, or being able to respond to peer pressure.
  • In contrast, some young children use aggressive behavior, such as hitting or biting, as a form of communication.
  • Aggressive behavior can impede learning as a skill deficit, while assertive behavior can facilitate learning. However, with young children, aggressive behavior is developmentally appropriate and can lead to opportunities of building conflict resolution and communication skills.
  • By school age, children should learn more socially appropriate forms of communicating such as expressing themselves through verbal or written language if they have not, this behavior may signify a disability or developmental delay.

Aggression triggers Edit

The Bobo doll experiment was conducted by Albert Bandura in 1961. In this work, Bandura found that children exposed to an aggressive adult model acted more aggressively than those who were exposed to a nonaggressive adult model. This experiment suggests that anyone who comes in contact with and interacts with children can affect the way they react and handle situations. [156]

    (2011): "The best way to prevent aggressive behavior is to give your child a stable, secure home life with firm, loving discipline and full-time supervision during the toddler and preschool years. Everyone who cares for your child should be a good role model and agree on the rules he's expected to observe as well as the response to use if he disobeys." [157] (2008): "Proactive aggression is typically reasoned, unemotional, and focused on acquiring some goal. For example, a bully wants peer approval and victim submission, and gang members want status and control. In contrast, reactive aggression is frequently highly emotional and is often the result of biased or deficient cognitive processing on the part of the student." [158]

Gender Edit

Gender is a factor that plays a role in both human and animal aggression. Males are historically believed to be generally more physically aggressive than females from an early age, [159] [160] and men commit the vast majority of murders (Buss 2005). This is one of the most robust and reliable behavioral sex differences, and it has been found across many different age groups and cultures. However, some empirical studies have found the discrepancy in male and female aggression to be more pronounced in childhood and the gender difference in adults to be modest when studied in an experimental context. [56] Still, there is evidence that males are quicker to aggression (Frey et al. 2003) and more likely than females to express their aggression physically. [161] When considering indirect forms of non-violent aggression, such as relational aggression and social rejection, some scientists argue that females can be quite aggressive, although female aggression is rarely expressed physically. [162] [163] [164] An exception is intimate partner violence that occurs among couples who are engaged, married, or in some other form of intimate relationship.

Although females are less likely than males to initiate physical violence, they can express aggression by using a variety of non-physical means. Exactly which method women use to express aggression is something that varies from culture to culture. On Bellona Island, a culture based on male dominance and physical violence, women tend to get into conflicts with other women more frequently than with men. When in conflict with males, instead of using physical means, they make up songs mocking the man, which spread across the island and humiliate him. If a woman wanted to kill a man, she would either convince her male relatives to kill him or hire an assassin. Although these two methods involve physical violence, both are forms of indirect aggression, since the aggressor herself avoids getting directly involved or putting herself in immediate physical danger. [165]

See also the sections on testosterone and evolutionary explanations for gender differences above.

Situational factors Edit

There has been some links between those prone to violence and their alcohol use. Those who are prone to violence and use alcohol are more likely to carry out violent acts. [166] Alcohol impairs judgment, making people much less cautious than they usually are (MacDonald et al. 1996). It also disrupts the way information is processed (Bushman 1993, 1997 Bushman & Cooper 1990).

Pain and discomfort also increase aggression. Even the simple act of placing one's hands in hot water can cause an aggressive response. Hot temperatures have been implicated as a factor in a number of studies. One study completed in the midst of the civil rights movement found that riots were more likely on hotter days than cooler ones (Carlsmith & Anderson 1979). Students were found to be more aggressive and irritable after taking a test in a hot classroom (Anderson et al. 1996, Rule, et al. 1987). Drivers in cars without air conditioning were also found to be more likely to honk their horns (Kenrick & MacFarlane 1986), which is used as a measure of aggression and has shown links to other factors such as generic symbols of aggression or the visibility of other drivers. [167]

Frustration is another major cause of aggression. The Frustration aggression theory states that aggression increases if a person feels that he or she is being blocked from achieving a goal (Aronson et al. 2005). One study found that the closeness to the goal makes a difference. The study examined people waiting in line and concluded that the 2nd person was more aggressive than the 12th one when someone cut in line (Harris 1974). Unexpected frustration may be another factor. In a separate study to demonstrate how unexpected frustration leads to increased aggression, Kulik & Brown (1979) selected a group of students as volunteers to make calls for charity donations. One group was told that the people they would call would be generous and the collection would be very successful. The other group was given no expectations. The group that expected success was more upset when no one was pledging than the group who did not expect success (everyone actually had horrible success). This research suggests that when an expectation does not materialize (successful collections), unexpected frustration arises which increases aggression.

There is some evidence to suggest that the presence of violent objects such as a gun can trigger aggression. In a study done by Leonard Berkowitz and Anthony Le Page (1967), college students were made angry and then left in the presence of a gun or badminton racket. They were then led to believe they were delivering electric shocks to another student, as in the Milgram experiment. Those who had been in the presence of the gun administered more shocks. It is possible that a violence-related stimulus increases the likelihood of aggressive cognitions by activating the semantic network.

A new proposal links military experience to anger and aggression, developing aggressive reactions and investigating these effects on those possessing the traits of a serial killer. Castle and Hensley state, "The military provides the social context where servicemen learn aggression, violence, and murder." [168] Post-traumatic stress disorder (PTSD) is also a serious issue in the military, also believed to sometimes lead to aggression in soldiers who are suffering from what they witnessed in battle. They come back to the civilian world and may still be haunted by flashbacks and nightmares, causing severe stress. In addition, it has been claimed that in the rare minority who are claimed to be inclined toward serial killing, violent impulses may be reinforced and refined in war, possibly creating more effective murderers. [169]

As a positive adaptation theory Edit

Some recent scholarship has questioned traditional psychological conceptualizations of aggression as universally negative. [39] Most traditional psychological definitions of aggression focus on the harm to the recipient of the aggression, implying this is the intent of the aggressor however this may not always be the case. [170] From this alternate view, although the recipient may or may not be harmed, the perceived intent is to increase the status of the aggressor, not necessarily to harm the recipient. [171] Such scholars contend that traditional definitions of aggression have no validity because of how challenging it is to study directly. [172]

From this view, rather than concepts such as assertiveness, aggression, violence and criminal violence existing as distinct constructs, they exist instead along a continuum with moderate levels of aggression being most adaptive. [39] Such scholars do not consider this a trivial difference, noting that many traditional researchers' aggression measurements may measure outcomes lower down in the continuum, at levels which are adaptive, yet they generalize their findings to non-adaptive levels of aggression, thus losing precision. [173]

Defending Your Territory: Is Peeing on the Wall Just for the Dogs?

It seems that everyone becomes an amateur animal behaviorist while walking their dogs. They notice that their dogs tend to pee on, well, just about everything, and infer that Fido is marking his territory.

Welcome to Territoriality Week! Every day this week, I'll have a post about some aspect of animal or human territoriality. How do animals mark and control their territories? What determines the size or shape of an animal's territory? What can an animal's territory tell us about neuroanatomy? Today, I begin by asking two questions: first, what is the functional purpose of establishing territories? Second, to what extent can we apply findings from research on animal territorial behavior to understanding human territorial behavior?

It seems that everyone becomes an amateur animal behaviorist while walking their dogs. They notice that their dogs tend to pee on - well - just about everything, and infer that Fido is marking his territory. That most people are familiar with at least the basic principles of animal territoriality would suggest that the study of animal territoriality is fairly well established. Indeed, behavioral biologists and ethologists have been interested in animal territoriality since at least the 1920s. The main purpose of animal territoriality, it would appear, is excluding others from certain geographical areas through the use of auditory, visual or olfactory signals or by the threat of aggression. While there are certainly variations, territoriality seems to exist throughout the vertebrate phylum. While many of the early studies of territoriality focused on birds, later researchers investigated territorial behaviors in fish, rodents, reptiles, ungulates (hoofed animals, like cows), and primates. Territories may be held by individuals, by pairs, or by groups. They may be defended against anyone, against only members of the same species, or against only members of the same sex.

Why would territoriality be so widespread in the animal kingdom (at least among vertebrates)?

Dozens of reasons have been offered, including increasing security and defense, reducing the spread of disease, reinforcing dominance structures, and even localizing waste disposal. But an English zoologist named Vero Copner Wynne-Edwards suggested that territoriality operates in order to control population size. Julian Edney, a psychologist from Arizona State University, described Wynne-Edwards's hypothesis in this way:

In other words, the size of the population, and therefore the availability of resources for individuals within the population, is controlled by virtue of the fact that territory winners are generally the only lucky individuals who get to breed and pass their genes on to subsequent generations. Edney notes that Wynne-Edwards's theory is particularly attractive because, at least on some level, it applies to humans as well. It isn't much of a stretch to note that there is an observable relationship between territory ownership and social status, or between territory size and social status, in humans. For example, for much of modern history, one had to be a land-owner (not to mention white and male) in order to participate in government or even to vote. The corner office is so highly prized in business buildings partly because it is bigger than other offices.

It should come as no surprise to the frequent reader of this blog that I would argue that since humans are just another species from among many, a theory regarding animal behavior more likely than not ought to apply to human behavior as well.

I find Edney's description of the origins of human territorial behavior quite interesting, especially considering the historical context in which he was writing. While he seems content to use animal behavior as an analogy for human behavior, Edney is quick to note that territorial behavior in humans, while similar in appearance to animal territoriality, may have different origins. He objects to the practice by which some other researchers would "beastopomorphize" humans. He writes,

He offers the following as evidence that human territoriality is different from animal territoriality, and in particular, is not derived from biology:

    (a) Human use of space is very variable and not like the stereotypic spatial expressions of animals. This suggests a learned, rather than a genetic, basis.

Have the distinctions between humans and animals that Edney laid out (above) in 1974 held up in the face of empirical research? Do you think that human territoriality is qualitatively distinct from animal territoriality, or only quantitatively so? Do you think that human territoriality is purely the result of learning, experience, and/or culture? Or is human territorial behavior built upon evolutionarily ancient mechanisms, subsequently modified or shaped by culture?

Please jump in with your thoughts in the comments! Subsequent posts this week will address some of these, and other, questions about territorial behavior in humans and non-human animals.

Edney, J. (1974). Human territoriality. Psychological Bulletin, 81 (12), 959-975 DOI: 10.1037/h0037444

Dog statue image via Flickr/THEfunkyman. Whitehall Estate image via Flickr/Steven_M61.

The views expressed are those of the author(s) and are not necessarily those of Scientific American.


Jason G. Goldman is a science journalist based in Los Angeles. He has written about animal behavior, wildlife biology, conservation, and ecology for Scientific American, Los Angeles magazine, the Washington Post, the Guardian, the BBC, Conservation magazine, and elsewhere. He contributes to Scientific American's "60-Second Science" podcast, and is co-editor of Science Blogging: The Essential Guide (Yale University Press). He enjoys sharing his wildlife knowledge on television and on the radio, and often speaks to the public about wildlife and science communication.

The Evolution of Human Aggression

Everyone has experienced anger at one point in their lives and some of us — males mostly, going by statistics — have channeled that anger into violence, perhaps by throwing a punch during a hockey game or after too many beers at the bar.

Then there's aggression on a much more sinister scale, in the form of murder, wars and genocide. Trying to understand what fuels the different levels of human aggression, from fisticuffs to nation-on-nation battle, has long preoccupied human biologists.

Is there evolutionary reasoning that explains our aggressive tendencies?

This is the central question that anthropologists are now asking as they meet this week at the University of Utah to discuss violence and human evolution. Speakers at the conference, "The Evolution of Human Aggression: Lessons for Today's Conflicts," intend to explore how the long process of human evolution has shaped the various ways we display aggression in modern society.

Though it may seem easier to divide the debate into two camps — those who think evolution has made humans naturally peaceful and those who think we're more naturally prone to violence, the real answer probably lies somewhere in between, said conference organizer Elizabeth Cashdan, professor of anthropology at the University of Utah.

"There is plenty of evidence to support both claims: violence, reconciliation, and cooperation are all part of human nature," said Cashdan, who thinks these wide-ranging emotions all evolved because they benefitted humans in some way in the past.

Animal instincts Evolution can explain why humans exhibit aggression because it is a primal emotion like any other, experts say.

"Emotions (including revenge, spite, happiness, anger) must have evolved because most of the time they motivate fitness-enhancing behaviors, and that is surely true for humans as for other animals," said Cashdan.

Just as compassion for your offspring increases your genes' chance of survival, violent tendencies may have been similarly useful for some species, agreed biologist David Carrier, also of the University of Utah.

"Aggressive behavior has evolved in species in which it increases an individual's survival or reproduction and this depends on the specific environmental, social, reproductive, and historical circumstances of a species. Humans certainly rank among the most violent of species," Carrier said, adding that we also rank among the most altruistic and empathetic. In true nature-nurture fashion, though some kind of genetic preprogramming for violence may exist in humans as a result of our evolution, it is the specific environment that decides how, or whether, that biological determination is triggered, scientists say.

"Biologists speak of 'norms of reaction,' which are patterned responses to environmental circumstances. For example, some male insects are more likely to guard their mates when there are fewer females in the population, hence fewer other mating opportunities. Natural selection didn't just shape a fixed behavior, it shaped the norm of reaction — the nature of the response," said Cashdan.

In other words, though aggression for aggression's sake is rare, an intricate set of conditions could, conceivably, drive most people to violence.

Instead of competing for food, which has become relatively easy to attain in most parts of the world, today we compete for material resources, said Cashdan, and some individuals lack or lose that switch that tells us when enough is enough. Gang violence is a good example of competition for resources gone haywire, though while a gang member's desire for more things, money or partners causes problems now, it may have been the key to their survival 100,000 years ago.

Our emotions make us unique While human aggression is a naturally evolved phenomenon we have in common with other animals, the difference between human and animal violence comes down to the complexity of the emotion driving it, said Cashdan.

"Humans are unique in the complexity of their social relationships and their highly developed social intelligence. Revenge and spite are quintessential social emotions and so are not likely to be found in many, if any, other species," she said. Aggression in few animals goes beyond protecting one's territory, mates, offspring and food — there is some evidence that domestic dogs and chimpanzees do hold grudges, said Carrier — but human violence has evolved to stem from less typical sources.

"For example revenge killings, and the cultural institutions that support and restrain it, shape human aggression in new ways," said Cashdan. The intelligent reasoning that lets most of us override any innate desire to be violent also makes some people, such as parents that kill their children, as well as institutions justify violence illogically, experts say.

Worry over the future An understanding of the evolutionary roots of human aggression could help institutions make better policy decisions, according to experts.

"Evolution didn't just shape us to be violent, or peaceful, it shaped us to respond flexibly, adaptively, to different circumstances, and to risk violence when it made adaptive sense to do so. We need to understand what those circumstances are if we want to change things," said Cashdan.

Though conflicts like the ones that occurred in Rwanda and the former Yugoslavia in the 1990s may seem a distant memory, the tipping point between peace and that sort of violence is a finer line than we think, said Carrier.

"My personal opinion is that Western society, as a whole, is in mass denial about the magnitude of the problem that violence represents for the future. We are peace-loving and want to believe that the violence and transgressions of the past will not return, but recent history and current events illustrate how easy it is for humans to respond with interpersonal and intergroup violence," he said.

This will be especially important in places where key natural resources are becoming scarce, said Carrier, who warned that "if basic resources such as food and clean water become more limiting, as many scientists believe is likely to happen as a result of climate change and energy shortages, then the environmental and social drivers of violence may become more difficult to control."

Heather Whipps is a freelance writer with an anthropology degree from McGill University in Montreal, Canada. Her history column appears regularly on LiveScience. [History Column archive]

Study finds gorillas display territorial behavior

Photograph taken by a camera trap of a western lowland gorilla in the Odzala-Kokoua National Park, Republic of Congo Credit: Germán Illera of SPAC Scientific Field Station Network

Scientists have discovered that gorillas really are territorial—and their behaviour is very similar to our own.

Published in the journal Scientific Reports, the research shows for the first time that groups of gorillas recognise "ownership" of specific regions. They are also more likely to avoid contact with other groups the closer they are to the centre of their neighbours' home range, for fear of conflict.

The study, which was carried out by academics from the University of Cambridge, Anglia Ruskin University (ARU), the University of Barcelona, SPAC Scientific Field Station Network, and the University of Vienna, involved monitoring the movements of groups of western lowland gorillas (Gorilla gorilla gorilla).

Western lowland gorillas are difficult to track on foot because they live in dense forests. Instead, the scientists followed eight groups of gorillas using a network of cameras placed at 36 feeding "hotspots" across a 60km 2 area of the Odzala-Kokoua National Park in the Republic of Congo.

It was previously thought that gorillas were non-territorial, due to the overlap of home ranges and their tolerance of other groups. This is markedly different to chimpanzees, which display extreme territorial-based violence.

Footage taken during the research of western lowland gorillas in the Odzala-Kokoua National Park, Republic of Congo Credit: Germán Illera of SPAC Scientific Field Station Network

However, this new research discovered that gorillas display more nuanced behaviours, and their movements are strongly influenced by the location of their neighbours—they are less likely to feed at a site visited by another group that day—and the distance from the centre of their neighbours' home range.

Lead author Dr. Robin Morrison, who carried out the study during her Ph.D. at the University of Cambridge, said: "Our findings indicate that there is an understanding among gorillas of 'ownership' of areas and the location of neighbouring groups restricts their movement.

"Gorillas don't impose hard boundaries like chimpanzees. Instead, gorilla groups may have regions of priority or even exclusive use close to the centre of their home range, which could feasibly be defended by physical aggression.

"At the same time groups can overlap and even peacefully co-exist in other regions of their ranges. The flexible system of defending and sharing space implies the presence of a complex social structure in gorillas."

Footage taken during the research of western lowland gorillas in the Odzala-Kokoua National Park, Republic of Congo Credit: Germán Illera of SPAC Scientific Field Station Network

Co-author Dr. Jacob Dunn, Reader in Evolutionary Biology at Anglia Ruskin University (ARU), said: "This new research changes what we know about how groups of gorillas interact and has implications for what we understand about human evolution.

"Almost all comparative research into human evolution compares us to chimpanzees, with the extreme territorial violence observed in chimpanzees used as evidence that their behaviour provides an evolutionary basis for warfare among humans.

"Our research broadens this out and shows instead just how closely we compare to our next nearest relatives. Gorillas' core areas of dominance and large zones of mutual tolerance could help with our understanding of the social evolution of early human populations, showing both the capacity for violence in defending a specific territory and the between-group affiliations necessary for wider social cooperation."

Are Humans Innately Aggressive?

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Sigmund Freud tried to cure Viennese women of their neuroses, and Konrad Lorenz made his reputation studying birds, but the two men shared a belief that has become lodged in the popular consciousness. The belief is that we have within us, naturally and spontaneously, a reservoir of aggressive energy. This force, which builds up all by itself, must be periodically drained off — say, by participating in competitive sports — lest we explode into violence.

This is an appealing model because it is easy to visualize. It is also false. As animal behaviorist John Paul Scott, professor emeritus at Bowling Green State University, has written: “All of our present data indicate that fighting behavior among higher mammals, including man, originates in external stimulation and that there is no evidence of spontaneous internal stimulation.” Clearly, many people — and, in fact, whole cultures — manage quite well without behaving aggressively, and there is no evidence of the inexorable build-up of pressure that this “hydraulic” model would predict.

The theory also predicts that venting aggressive energy should make us less aggressive — an effect known as “catharsis,” following Aristotle’s idea that we can be purged of unpleasant emotions by watching tragic dramas. But one study after another has shown that we are likely to become more violent after watching or participating in such pastimes. “Engaging in aggressive play just strengthens the disposition to react aggressively,” concludes psychologist Leonard Berkowitz, who is now writing a new book on the subject to complement his classic 1962 work, Aggression: A Social Psychological Analysis.

In 1986, a group of eminent behavioral scientists met in Seville, Spain, to discuss the roots of human aggression and concluded not only that the hydraulic model is inaccurate but, more generally, that there is no scientific basis for the belief that humans are naturally aggressive and warlike (see “The Seville Statement” following this article). That belief, however, has not been easily shaken. Among the arguments one sometimes hears are these: Animals are aggressive and we cannot escape the legacy of our evolutionary ancestors human history is dominated by tales of war and cruelty and certain areas of the brain and particular hormones are linked to aggression, proving a biological basis for such behavior. Let’s deal with each of these in turn.

The first thing to be said about animals is that we should be cautious in drawing lessons from them to explain our own behavior, given the mediating force of culture and our capacity for reflection. “Our kinship with other animals does not mean that if their behavior seems often to be under the influence of instincts, this must necessarily also be the case in humans,” says anthropologist Ashley Montagu. He quotes one authority who has written: “There is no more reason to believe that man fights wars because fish or beavers are territorial than to think that man can fly because bats have wings.”

Animals are not even as aggressive as some people think — unless the term “aggression” is stretched to include killing in order to eat. Organized group aggression is rare in other species, and the aggression that does exist is typically a function of the environment in which animals find themselves. Scientists have discovered that altering their environment, or the way they are reared, can have a profound impact on the level of aggression found in virtually all species. Furthermore, animals cooperate — both within and among species — far more than many of us assume on the basis of watching nature documentaries.

When we turn to human history, we find an alarming amount of aggressive behavior, but we do not find reason to believe the problem is innate. Here are some of the points made by critics of biological determinism:

* Even if a behavior is universal, we cannot automatically conclude it is part of our biological nature. All known cultures may produce pottery, but that doesn’t mean there is a gene for pottery making. Other institutions once thought to be natural are now very difficult to find. In a century or two, says University of Missouri sociologist Donald Granberg, “it is possible that people will look back and regard war in much the same way as today we look back at the practice of slavery.”

* Aggression, in any case, is nowhere near universal. Montagu has edited a book entitled Learning Non-Aggression, which features accounts of peaceful cultures. It is true that these are hunter-gatherer societies, but the fact that any humans live without violence would seem to refute the charge that we are born aggressive. In fact, cultures that are “closer to nature” would be expected to be the most warlike if the proclivity for war were really part of that nature. Just the reverse seems to be true. The late Erich Fromm put it this way: “The most primitive men are the least warlike and . . . warlikeness grows in proportion to civilization. If destructiveness were innate in man, the trend would have to be the opposite.”

Just as impressive as peaceful cultures are those that have become peaceful. In a matter of a few centuries, Sweden has changed from a fiercely warlike society to one of the least violent among industrialized nations. This shift — like the existence of war itself — can more plausibly be explained in terms of social and political factors rather than by turning to biology.

* While it is indisputable that wars have been fought frequently, the fact that they seem to dominate our history may say more about how history is presented than about what actually happened. “We write and teach our history in terms of violent events, marking time by wars,” says Temple University psychologist Jeffrey Goldstein. “When we don’t have wars, we call it the ‘interwar years.’ It’s a matter of selective reporting.”

* Similarly, our outrage over violence can lead us to overstate its prevalence today. “Every year in the United States, 250 million people do not commit homicide,” Goldstein observes. “Even in a violent society, it’s a relatively rare event.” It is difficult to reconcile a theory of innate human aggressiveness with the simple fact that most people around us seem quite peaceful.

Many people have claimed that “human nature” is aggressive on the basis of having lumped together a wide range of emotions and behavior under the label of aggression. While cannibalism, for example, is sometimes thought of as aggression, it might represent a religious ritual rather than an expression of hostility.

The presence of some hormones or the stimulation of certain sections of the brain has been experimentally linked with aggression. But after describing these mechanisms in some detail, physiological psychologist Kenneth E. Moyer emphasizes that aggressive behavior is always linked to an external stimulus. “That is,” he says, “even though the neural system specific to a particular kind of aggression is well-activated, the behavior does not occur unless an appropriate target is available . . . [and even then] it can be inhibited.”

So important is the role of the environment that talking of an “innate” tendency to be aggressive makes little sense for animals, let alone for humans. It is as if we were to assert that because there can be no fires without oxygen, and because the Earth is blanketed by oxygen, it is in the nature of our planet for buildings to burn down.

Regardless of the evolutionary or neurological factors said to underlie aggression, “biological” simply does not mean “unavoidable.” The fact that people voluntarily fast or remain celibate shows that even hunger and sex drives can be overridden. In the case of aggression, where the existence of such a drive is dubious to begin with, our ability to choose our behavior is even clearer. Even if genes are fixed, the same does not necessarily follow for their behavioral effects. And even if “people are genetically disposed to react aggressively to unpleasant events,” says Berkowitz, “we can learn to modify and control the reaction.”

All of this concerns the matter of human aggressiveness in general. The idea that war in particular is biologically determined is even more farfetched. “When one country attacks another country, this doesn’t happen because people in the country feel aggressive toward those in the other,” explains Harvard University biologist Richard Lewontin. “If it were true, we wouldn’t need propaganda or a draft: All those aggressive people would sign up right away. State ‘aggression’ is a matter of political policy, not a matter of feeling.”

The point was put well by Jean Jacques Rousseau more than two centuries ago: “War is not a relation between man and man, but between State and State, and individuals are enemies accidentally.”

That states must “psych up” men to fight makes it even more difficult to argue for a connection between our natures and the fact of war. In the case of the nuclear arms race, this connection is still more tenuous. Says Bernard Lown, cochairman of International Physicians for the Prevention of Nuclear War, which received the Nobel Peace Prize in 1985: “The individual’s behavior, whether he’s aggressive or permissive or passive, is not the factor that makes up his outlook toward genocide. Even the person who’s aggressive won’t readily accept extinction.”

THE EVIDENCE, THEN, seems to indicate that we have the potential to be warlike or peaceful. Why, then, is the belief in a violent “human nature” so widespread? And what are the consequences of that belief?To begin with, we tend to make generalizations about the whole species on the basis of our own experience. “People in a highly warlike society are likely to overestimate the propensity toward war in human nature,” Granberg says. And the historical record shows the United States to be one of the most warlike societies on the face of the planet, having intervened militarily around the world more than 150 times since 1850. Within such a society, not surprisingly, the intellectual traditions that support the view that aggression is more a function of nature than nurture — such as the writings of Freud, Lorenz and the sociobiologists — have found a ready audience.

But there is more to it than that. We sometimes feel better, at least for a while, after acting aggressively, and this can seem to confirm the catharsis theory. The trouble is, says Berkowitz, “the fact that I reached my goal means that the behavior is reinforced, so in the long term I have an increased likelihood of behaving aggressively again” — for reasons that have more to do with learning than with instincts.

The mass media also play a significant role in perpetuating outdated views on violence, according to Goldstein. “If all one knows about aggression is what one sees on TV or reads in the newspaper,” he says, “what one knows is 19th-century biology.” Entertainment and news programming alike tend to favor Lorenz’s discredited model, confirming the notion that we human beings have a limitless supply of aggressive energy that must be discharged one way or the other.

Because it is relatively easy to describe, and because it makes for a snappier news story, reporters seem to prefer explanations of aggression that invoke biological necessity, Goldstein says. Wesleyan University psychologist David Adams, one of the Seville Statement organizers, got a taste of that bias when he tried to persuade reporters that the statement was newsworthy. Few news organizations in the United States were interested, and one reporter told him, “Call us back when you find a gene for war.”

Psychologist Leonard Eron of the International Society for Research on Aggression observes, “TV teaches people that aggressive behavior is normative, that the world around you is a jungle when it’s actually not so.” In fact, research has shown that the more television a person watches, the more likely he or she is to believe that “most people would take advantage of you if they got a chance.”

The belief that violence is unavoidable, while disturbing at first glance, actually holds a curious attraction for many people, both psychologically and ideologically. “It does have that ‘let’s face the grim reality’ flavor, which has a certain appeal to people,” says Robert Holt, a psychologist at New York University.

It also allows us to excuse our own acts of aggression by suggesting that we really have little choice. “If one is born innately aggressive, then one cannot be blamed for being so,” says Montagu. The belief, he maintains, functions as a kind of pseudoscientific version of the doctrine of original sin.

“In order to justify, accept and live with war, we’ve created a psychology that makes it inevitable,” Lown says. “It’s a rationalization for accepting war as a system of resolving human conflict.” To accept this explanation for the war-is-inevitable belief is simultaneously to realize its consequences. Treating any behavior as inevitable sets up a self-fulfilling prophecy: By assuming we are bound to be aggressive, we are more likely to act that way and provide evidence for the assumption.

People who believe that humans are naturally aggressive may also be relatively unlikely to oppose particular wars or get involved in the peace movement. Some observers insist that this belief functions only as an excuse for their unwillingness to become active. But others attribute some effect to the attitude itself. “The belief that war is inevitable leads people to rely on armament rather than working for disarmament,” says M. Brewster Smith, professor of psychology at the University of California, Santa Cruz.

There is some empirical support for this position. In a 1985 Finnish study of 375 young people, Riitta Wahlstrom found that those who considered war to be part of human nature were less inclined to support the idea of teaching peace or of personally working for it. David Adams and Sarah Bosch got similar results with a smaller study of U.S. college students. Forty percent said they thought war was “intrinsic to human nature,” and those students were slightly less likely than others to have worked on a peace-related activity.

Based on his own research during the Vietnam War, Granberg says, “If a war broke out tomorrow, the people protesting it would probably be those who did not believe that war is inevitable and rooted in human nature.” Those who do believe this are “more likely to accept the idea [of war] or at least unlikely to protest when a particular war occurs.”

The evidence suggests, then, that we do have a choice with respect to aggression and war. To an extent, such destructiveness is due precisely to the mistaken assumption that we are helpless to control an essentially violent nature. “We live in a time,” Lown says, “when accepting this as inevitable is no longer possible without courting extinction.”


PEACE ACTIVISTS can tell when it’s coming: Tipped off by a helpless shrug or a patronizing smile, they brace themselves to hear the phrase yet again. “Sure, I’m all in favor of stopping the arms race. But aren’t you being idealistic? After all, aggression is just” — here it comes — “part of human nature.”

Like the animals – “red in tooth and claw,” as Tennyson put it – human beings are thought to be unavoidably violent creatures. Surveys of adults, undergraduates and high school students have found that 60 percent agree with the statement, “Human nature being what it is, there will always be war.”

It may be part of our society’s folk wisdom, but it sets most of the expert’s heads to shaking. A number of researchers who have spent their lives working on the problem of aggression have concluded that violence, like selfishness, is “in human nature in the same way that David was in the marble before Michelangelo touched it,” in the words of psychologist Barry Schwartz of Tulane Medical School.

The problem is that most people are unaware of this scientific consensus. So two years ago, 20 scientists from 12 nations gathered in Seville, Spain, to hammer out a statement on the issue. The resulting declaration represents the wisdom of some of the world’s leading psychologists, neurophysiologists, ethologists and others from the natural and social sciences. It has since been endorsed by the American Psychological Association and the American Anthropological Association, among other organizations. The following are excerpts from the Seville Statement:

* It is scientifically incorrect to say we have inherited a tendency to make war from our animal ancestors. Warfare is a peculiarly human phenomenon and does not occur in other animals. War is biologically possible, but it is not inevitable, as evidenced by its variation in occurrence and nature over time and space.

* It is scientifically incorrect to say that war or any other violent behavior is genetically programmed into our human nature. Except for rare pathologies the genes do not produce individuals necessarily predisposed to violence. Neither do they determine the opposite.

* It is scientifically incorrect to say that in the course of human evolution there has been a selection for aggressive behavior more than for other kinds of behavior. In all well-studied species, status within the group is achieved by the ability to cooperate and to fulfill social functions relevant to the structure of that group.

* It is scientifically incorrect to say that humans have a “violent brain.” While we do have the neural apparatus to act violently, there is nothing in our neurophysiology that compels us to [do so].

* It is scientifically incorrect to say that war is caused by “instinct” or any single motivation. The technology of modern war has exaggerated traits associated with violence both in the training of actual combatants and in the preparation of support for war in the general population.

* We conclude that biology does not condemn humanity to war, and that humanity can be freed from the bondage of biological pessimism. Violence is neither in our evolutionary legacy nor in our genes. The same species [that] invented war is capable of inventing peace.

Territorial behavior in humans? - Biology

M any birds attempt to exclude other birds from all or part of their home range -- the area they occupy in the course of their normal daily activities. When they do, we say they are defending a "territory." Most often this behavior occurs during the breeding season and is directed toward members of the same species. Territoriality appears, in most cases, to be an attempt to monopolize resources, especially food resources or access to mates. But territoriality may also serve, in part, as a predator defense mechanism.

Some birds defend their entire home range. Others defend only their food supply, a place to mate, or the site of their nest. Some tropical hummingbirds chase most other hummingbirds and other nectar-feeding birds (and some butterflies) away from favorite patches of nectar-bearing flowers. On their leks (patches of ground traditionally used for communal mating displays) grouse, some sandpipers, and some other birds defend small territories. Most colonial-nesting seabirds simply defend the immediate vicinity of their nests -- presumably to protect their eggs and, at least in the case of some penguins, the pebbles from which the nest is constructed.

Territoriality tends to space some species of camouflaged birds and their nests rather evenly throughout their habitat it prevents them from occurring in flocks or clusters while breeding. This, in turn, may reduce the danger from predation, since many predators will concentrate on one kind of prey after one or a few individuals of that prey type are discovered (that is, the predator forms a "search image"). Clustering can promote the formation of a search image by predators and thus reduce the security of each individual prey (birds that are not cryptic, however, may gain protection in clustering).

To minimize the need for actual physical contact in order to defend territories, animals have evolved "keep-out" signals to warn away potential intruders. In birds, of course, the most prominent are the songs of males. Far from being beautiful bits of music intended to enliven the human environment (as was long assumed), bird songs are, in large part, announcements of ownership and threats of possible violent defense of an area. If, of course, the aural warning is ineffective, the territory owner will often escalate its activities to include visual displays, chases, and even combat. This territorial behavior is typically quite stereotyped, and can usually be elicited experimentally with the use of recorded songs or with stuffed taxidermy mounts.

Territory size varies enormously from species to species, and even within species, from individual to individual. Golden Eagles have territories of some 35 square miles Least Flycatchers' territories are about 700 square yards and sea gulls have territories of only a few square feet in the immediate vicinity of the nest. Territory size often varies in the same species from habitat to habitat. In relatively resource-poor Ohio shrublands, Song Sparrows have territories several thousand square yards in extent. In the resource-rich salt marshes of the San Francisco baylands they are about one-fifth to one-tenth as large. The San Francisco birds need to defend much less area to assure an adequate food supply.

Copyright ® 1988 by Paul R. Ehrlich, David S. Dobkin, and Darryl Wheye.

The troll under the bridge is, literally and figuratively, a collaboration roadblock. He doesn’t care what you do on your own time, but anything that comes near his gate is going to be held up until the toll is paid. Even worse, sometimes there is no toll, just an endless series of deflections, delays, and barriers.

Collaboration is too important for turf war interference. Understand the territorial mindset and you can find a way not just to avoid the toll but to include the troll in your plans. Start by understanding that territory isn’t chosen by accident or chance—there are some very strong, primal motives that guide a territorial mindset, and they need to be carefully unraveled.

“A territorial person, or one who shifts into that mode, is thinking about power, control, influence, and status,” says Michael Lee Stallard, president of E Pluribus Partners.

Toll ahead: how to spot the territorial collabohater

The good news is that you don’t have to work very hard to spot a territorial type. They’re the ones telling you to get off their lawns.

We kid. (A little.) Although the territorial can be aggressive about defending what they see as theirs, the signs can be much more subtle. The signs aren’t always overtly negative. The very act of carving out a corner of the universe and protecting it reflects a passion for excellence and a strong tendency to take ownership.

“Taking ownership is a positive trait, it’s what we want people to do, but when taken to an extreme, it can be seen as territorial,” says Matt Poepsel, VP of product management at PI Worldwide.

And those extremes are where the problems occur. Territorial types can be resistant to change—any change—because they believe defending the status quo and defending their turf are one and the same. They can be reluctant to delegate, share, and cede authority for fear of appearing less than indispensable.

How to work with the territorial

Although territorial drives can manifest themselves in subtle ways, often this collabohater type will be very upfront about their resistance, and lay out in no uncertain terms what their boundaries for collaboration will be. The trick, as in dealing with any collabohater, is not to take “no” for an answer, but also to find the right path to “yes.” That begins with recognizing that every stone wall protects a weakness. That weakness is typically one driven by fear—the fear of losing status, authority, and position.

“It helps to understand that typically behind the facade of strength they project lies insecurity,” Stallard says.

Fear of change is also a paramount concern for the territorial. “If someone is behaving territorially, you need to get them information about their role and why it’s changing, and why collaboration is important,” Poepsel says.

Don’t micromanage the territorial. Be proactive about recognizing and acknowledging that they are experts in their domain, without going so far as to endorse their excessive ownership. Territorial types are impressed by competence and dedication, two characteristics they prize in themselves. Take proactive steps to demonstrate those traits, and smoother collaboration will follow.

“Getting their cooperation in short order is not easy, so it’s wise to take the initiative and connect with them,” Stallard says. “They value people doing what’s right and being responsive and reliable.”

Soup for the troll under the bridge

Feeling a bit anxious about your own bailiwick? It’s very easy to slip from being a dedicated team player to an obsessive border guard. If you’re worried that your own tendencies have strayed towards the territorial, ask yourself when you last praised and recognized a collaborator. If it’s been so long that you can’t quite remember, you have probably slipped into a bridge-troll mask. Start finding ways to recognize competence and dedication in others. Giving and receiving praise is an excellent elixir against territorial behavior.

“It’s good to be generous about giving credit,” Stallard says.

Your fellow collaborators and leaders may not fully understand your need to understand how tasks, projects, and changes affect the things you care very deeply about. Start being open about communicating those needs.

“Trust-building with the territorial starts with being very transparent about motives and rationales,” says Michael Sanger, consultant with Hogan Assessment Systems. “They may have a need to hear the rationale but nobody is sharing it with them.”

Territorial types tend to let doubts about the validity of change and outside interference guide too much of their thinking. “Territorial behavior is rooted in deeply ingrained skepticism,” Sanger says.

This skepticism, once validated, leads to grudges, which the territorial have a particularly hard time letting go of. Find ways to move past old offenses—to forgive unpaid tolls, if you will—and let your collaborators help you create a shared vision.

Post by Jason Compton

Jason Compton is a writer with over 15 years of experience covering marketing, sales, and service. Based in Madison, WI, he is a regular contributor to Direct Marketing News, previously served as executive editor of CRM Magazine, and has been published in over 50 outlets.


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