22 - Stress and aggression among primates

Stress and aggression among primates

© SPMM Course

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.

© SPMM Course  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.