EVOLUTIONARY EXPLANATIONS OF AGGRESSION
Knowing the routes of aggression helps us understand it today.
Animal aggression
Craig – the aim of aggression is not to destroy the enemy but get rid of his presence. Lorenz
argued that humans are animals and therefore show similar behaviour patterns. He argued
aggression only occurred within not between species. The functions of aggression were;
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Only the fittest and strongest were selected by females – offspring more likely to
survive
Parents show aggression to protect their offspring so more likely to survive
Help distribute a species in a balanced way as animals would have their own
territories.
Lorenz’s ideas have been criticised e.g as over-simplistic, and by suggesting parallels between
human and non human animal behaviour.
Fromm - human aggression compromises 2 forms
A) Benign aggression –parent defends child
B) Malignant aggression – gang warfare, ethnic cleansing.
Nelson – states that Lorenz should have considered 3 basic factors that can affect aggression.
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Process of learning e.g. through observing others
Structural causes – nature of social life – are there norms? Rules?
Psychological causes – highlights failings of the biological approach. In the animal
kingdom action is directed towards an ‘actual enemy’ in humans aggression may be
motivated by other things e.g. mood (personal) heat (situational)
Aggression in humans may well be adaptive but not usually ritualistic (like in animals). Use of
weapons makes it more destructive.
Explanations
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Reproductive success – aggression is the result of sexual competition. Females invest heavily
in child rearing so very picky, males have to compete to be chosen and pass on genes. The
image of man is ‘a provider of valuable resources’ i.e. they need to be more assertive and
aggressive than women. Waller uses this theory to explain mass killings and genocide. We
evolved to live in groups and need to define boundaries of behaviour for the group ‘in group
– us’ and ‘out group – them’ this way of thinking is likely to lead to aggression. Xenophobia
(fear of people from other culture/countries), the need to feel socially dominant and holding
ethnocentric perspectives leads to acts of aggression and violence.
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Buss male to male aggression explains some but not all instances of aggression e.g. verbal
aggression female to female to reduce ‘attractiveness of competitor in the eyes of males’.
Giving an evolutionary advantage to the name caller.
Infidelity and jealousy
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Daly and Wilson – men have evolved different strategies to deter women from committing
adultery ranging from vigilance to violence. All fuelled by male jealousy – jealousy is an
adaptation to deal with the threat of cuckoldry. Men are never certain they are the fathers,
and cost is unwittingly investing resources in offspring not his own. The adaptive function of
sexual jealousy is to deter mate from sexual infidelity.
Support - Buss – strategies used, direct guarding e.g. chaperone, harems, and now coming
home unexpectedly and negative inducements – threats
In questionnaire women who said their husbands didn’t like them talking to other men were
twice as likely to have experienced serious violence from partner – 72% needed hospital
treatment. Studies of battered women have shown that in the majority of cases, women cite
extreme jealousy on part of their partners as key cause (sexual jealousy primary cause of
violence.)
Uxorocide – (wife killing) may be unintended outcome of evolutionary adaptation that was
designed to control rather than kill female partner.
Support -Daly and Wilson – for women sexual jealousy is due to possible lack of
resources/emotional support.
Aggression in females.
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Females generally viewed as less aggressive since the cost of such behaviour
outweighs the benefits
More important for mother to survive as more critical to survival of offspring than
father.
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A women has nothing to gain by exhibiting aggression since her aim is not to gain high
status but to secure a valuable male.
To this end females have evolved low risk and indirect strategies in disputes and
conflicts e.g. gossip and ostracism, aimed at resucing the attractiveness of competing
females
Reseach – support
Hill and Hurtado – among Ache of Paraguay, children are 5 times more likely to die if
the mother dies, and 100% likely if this happens before child is aged 1.
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Research support – Shackleford – survey method of 461 men and 560 females in US all in
committed heterosexual relationships. Males answered questions about their use of mate
retention techniques and were assessed on how often they performed each of 26 different
types of violent acts against partners. Females answered questions concerning partners use
of male retention techniques and degree they used violence against them. From males found
that negative inducements (sexual jealousy) were positively correlated with violence scores.
Results from females confirmed this trend. Buss and Shackelford also found if men suspected
wife might be unfaithful in following year exacted greater punishment for known or
suspected infidelity than those who didn’t anticipate future infidelities.
Application – Particular tactics of mate retention can be an early indicator of violence against
female partner. Alerts you/friends/family to danger signs – help can be sought before
violence.
Buss in students in US – found males had higher stress levels when viewing pictures of sexual
infidelity, females had higher levels when viewing pictures of emotional fidelity.
Does the theory justify violence by men against women as natural and inevitable?
Uxorocide
Daly and Wilson conclusion that it is an unintended consequence was challenged by
Shackelford – analysed ½ million homicides – selected 13 670 where a man had killed his wife
– found younger women at greater risk (regardless of age of partner) Evolved homicide
module theory – if women is young infidelity carries a double loss for male – loses a partner
(decreased reproductive fitness) but another man gains and increases own fitness. By killing
wife he prevents completion from gaining.
Women can also behave violently towards their partners but this needs more research.
Shackelford’s study was a survey using self report technique. Social desirability bias (as asking
about violence against spouse) how likely are they to tell the truth.
Evolutionary explanations do account for male and female differences in experiences of
infidelity and jealousy.
Evolutionary theories are reductionist and deterministic as disregards the role of free-will in
behaviour
Evolutionary approach/theories cannot be proved or disproved which means it lacks a
scientific approach/rigour. Many of the theories can be explained in other ways and if the
approach is flawed and the evidence is methodologically flawed the theory could be flawed.
EVOLUTION OF HOMICIDE.
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Majority of killers and victims are men
Acquisition of status
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Males are more motivated to acquire status since high status males have access to
mates and resources for survival
High status males are more likely to be selected by females since they will be better
able to guarantee the survival of her and her offspring.
Not engaging in conflict with other males can therefore be costly
Low status males have to engage in high risk strategies to enhance their chances of
reproduction
Research – support
Wilson –Daly – study in Detroit - 43% of male victims and 41% of male perpetrators were
unemployed (male unemployment rate in Detroit 11%) 73% of male perpetrators and 69% of
male victims also unmarried. A lack of resources and inability to attract long term mates
appears to lead to social competition and male –male homicides.
Loss of status – one of key motives in male – male homicides appears to be defence of status
in peer group. We used to live in small groups - loss of status could have been catastrophic
for survival and reproduction. So although it is maladaptive now it still occurs (genome lag)
Sexual jealousy A key motivation in same sex aggression and homicide – usually male – male.
A summary of 8 studies of same sex killings involving love triangles 92% were male – male
and only 8% female – female –Daly and Wilson.
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As humans face been killed in different ways; status conflict, jealous mate, sexual rival –
would expect evolution of anti-homicide defences e.g. reading the signs of homicidal intend,
killing in self defence. Once these evolve homicide becomes a more costly strategy. Duntley
and Buss – success rate becomes lower and attempts to kill more dangerous, so homicide
gives decreased fitness benefits to killer. Selection would therefore favour development of
deceptive strategies to conceal homicidal intent to avoid activating homicidal defences.
Limitations – cannot explain why people react in such different ways when faced with the
same problem e.g. Buss and Shackelford - 3 men confronted with wives infidelity, one results
in beating, one in a homicide and one in getting drunk. Nor can it explain why some cultures
e.g. Yonomamo of S. America seem to require male violence to attain status and in others
e.g. Kung San of Kalahari – aggression leads to irreparable reputational damage (B and S)