# 22 - Stress and aggression among primates

# Stress and aggression among primates

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1. High arousal 
2. Disinhibition – ‘this is happening everywhere; it is not uncommon.' 
3. Imitation: e.g. copycat crimes and suicides – Shannon Matthews incident in UK (2008) is 
speculated to be akin to a channel 4 drama episode (Shameless). 
4. Desensitisation: due to repeated showing 
5. Priming- enhancing automatic associations of certain stimuli with a crime. 
 
Family background and aggression: Aggressive children tend to commit violent and non-violent 
offences in adulthood. Antisocial behavior is much more common in men. Harsh and inconsistent 
discipline and an absence of positive parenting may be an aetiological factor in aggression. 
Note that cultural differences exist in expression of aggression; it is said to be much more 
common in individualist than in collectivist cultures (Oatley, 1993) 
Stress and aggression among primates 
 In most species, dominance ranks influence the extent of sustaining stressors. It is too 
simplistic to say higher / lower ranking individuals have the highest stress or aggression 
levels. The actual amount of stress and aggression depends very much on group’s social 
structure and dynamics. 
 Ability to avoid confronting dominant individuals will reduce stress levels. When this is 
lost in captivity (artificial environments) the subordinates show high-stress hormones. For 
example dominant wolves have more cortisol in the wild; subordinates have higher levels 
in captivity. 
 The most frequent context in which aggression is seen is in defense of status. But the best 
fighter does not become the highest-ranking individual in a group all the time (ability to 
form coalition and source social support are important). 
 In some species, aggression is a primary cause of mortality. 
 The most important modulating influence on aggression is social dominance; once it is 
established the rate of aggression drops substantially. 
 Aggressive encounters are highest among adolescent males during group migrations. 
Aggression is also higher under conditions of crowding. 
 Males are generally more aggressive than females, but once dominance is stabilized, males 
have a substantial drop leading to females showing higher aggression than or as high as 
males. 
 Mating competition can increase male-to-male aggression. The presence of children can 
act as agonistic buffers to reduce aggression among both males and females in some 
species.

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 Socially living primates learn social cues of aggression and restraint from the early period 
of development by observing their parents and older individuals; they later practice these 
skills with their peers. In fact, parental control is essential for the development of cortical 
areas involved in impulse control. 
 Coping outlets for stress include social support (grooming, coalition formation and 
physical contact). Reconcilative behaviour immediately after a competition may help the 
loser to cope. Poor availability of this support with low presence of kin will increase stress 
among subordinates.