Transcript Evolution-and

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Evolutionary explanations
of human aggression
•Aggression is adaptive
• Discuss reasons for this statement
• Survival
• Increase chances of procreation
• The evolutionary approach to
explaining aggression sees
aggression in terms of its ability to
increase survival chances therefore
to enhance reproductive success.
• How can aggression improve survival
chances?
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Aggressive behaviour has
evolved to serve adaptive
problems of social living
Gain territory and resources i.e.
children bullying others for money or
toys, adults mugging and warfare.
Defending against attacks: aggression
to prevent loss of resources and status
necessary for reproductive fitness i.e.
“stick up for yourself.
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Inflicting cost on same sex-rivals:
aggression between same sex members
to aid in the competition for resources
and mates i.e. men fighting over women.
Negotiating status and power
hierarchies: aggression to gain prestige
and dominance among same-sex
members i.e. gang violence to “prove
oneself” to aid sexual selection by
opposite sex members i.e. women
attracted to dominant and powerful men.
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Deterring rivals from future
aggression: aggression to maintain
dominance and fear in others i.e. making
threatening gestures, reinforcing
aggressive reputation, maintaining an
aggressive appearance
Deterring mates from infidelity:
aggression against opposite-sex
members to maintain fidelity of desired
long-term mates and ensuring paternity
i.e. wife-battering
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Evolutionary explanations
of human aggression
• Jealousy is an adaptive response
• Why?
• To deal with the threat of paternal
uncertainty from acts of infidelity
Jealousy and aggression
Jealousy:
Emotional response to anticipated loss of
affection and/or status
Infidelity:
Unfaithfulness of sexual
partners.
Sexual infidelity:
Any behaviour
involving sexual
contact i.e. kissing,
touching, sexual
intercourse
99% of married people
expect spouses to be
faithful however 11% of
women and 21% of men
admit to extramarital sex.
Emotional infidelity:
Formation of affectional
attachment to another
person, can involve
flirting, intimate
conversations
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Why do men and women
express jealousy differently?
Need to compete with other males for
access to choosy females
If the female is unfaithful the
man faces paternity
uncertainly
Lower status men are willing to take
greater risks by using aggression or face
genetic extinction.What about
reconstituted
families, adoption
and fostering?
Human males cannot risk wasting investment on offspring who are
not their own so they should show more jealous violent aggression
relating to female fidelity- both towards the male competitors and
their long-term female mates if infidelity is suspected especially if the
female is young and reproductively valuable
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Infidelity and jealousy
• Cuckoldry and sexual jealousy:
• As fertilisation is hidden from men as it
happens inside the woman, men are
always at risk of cuckoldry.
• The consequence of cuckoldry is that the
man might unwittingly invest his resource
in offspring that are not his own.
• Jealousy, therefore deters the female
partner from sexual infidelity.
Mate retention and violence
• Buss (1988) suggests that men have
evolved a number of strategies to keep
their partners.
• ‘direct guarding’ (vigilance) of the female
which restricts access to other males to
their partners. E.g. unexpectedly arriving
home to see what she is up to.
• ‘negative inducements’ (violence) which
act as deterrent of sexual infidelity.
Dobash and Dobash (1984) Battered
women cite jealously as key cause.
If a male is unfaithful the female
partner risks losing his time,
resources, energy, protection and
commitment to her children.
Human females can always guarantee that
their offspring are their own and compete
with other females for the quality of men
40% of domestic violence
rather than for the availability.
victims are men in 2009
according to the British
Crime Survey .
Women take fewer risk with violence and
use more indirect form of aggression.
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Research evidence
Male-male aggression
Cross-culturally, human violent
aggression and homicide is far more
common in males, against other males
(Daly and Wilson, 1988).
Homicide is more common in poor and
unmarried men than richer, married ones
(Wilson and Daly, 1985).
Female-female aggression
Sexual jealousy produces more male- Female aggression is more verbal against
male homicides than female-female. other women to maintain status and reduce
the attractiveness of competitors,
especially by using verbal criticism of the
physical unattractiveness of other females
and their promiscuity (for men looking for
long-term mates with sexual fidelity) to
lower their appeal in the eyes of men
(Buss and Dedden, 1990).
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INTER-SEXUAL JEALOUSY
AGGRESSION
Most male non-sexual aggression against
women involves girlfriends and spouses
due to sexual jealousy.
Verbal aggression and non-lethal
physical violence against mates is often
similar in men and women, but spousal
homicide by women is less frequent
and often due to defense against a
jealous abusive husband (Daly and
Wilson, 1988).
In 100 cases of spousal violence, the
husbands' frustration over their
inability to control their wives and
accusations of infidelity were the most
reported causal factors (Whitehurst,
1971).
In a study of 36 Baltimore
spousal homicides, 25
were attributed to
jealousy, and the wives
were the victims in 24 of
these cases (Guttmacher,
1955).
Young wives/girlfriends are more
likely to be killed than older ones
(Daly and Wilson, 1988).
In a study of battered
women, 57 out of 60
attributed the violence to
their husband's extreme
jealousy and
possessiveness (Hilberman
and Munson, 1978).
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Task
• Pick two pieces of evidence and explain
HOW they support the role of evolution
and natural selection to explain aggression
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Evaluation
• Harris (2003) found the results from forcedchoice studies about males being more stressed
by sexual infidelity and females by emotional
infidelity to be true of imagined scenarios, but in
real instances both males and females felt
threatened by emotional fidelity. The results from
the imagined scenarios might be explained as
males being aroused by images of sexual
infidelity rather than feeling threatened.
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• Cultural differences in murder rates of
wives by husbands and in the degree of
anxiety felt in response to sexual infidelity
by males suggest that factors other than
those determined by evolution play a part.
• Cultural differences (Brase study p.18
booklet)
Most relationships where a
partner is or has been
unfaithful continue or end
without physical violence.
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• Dreznick (2004) suggested that there may be an
alternative explanation to evolutionary theory such as a
difference in beliefs of what constitutes infidelity. If men
do not perceive emotional infidelity as infidelity, then they
would not be particularly jealous in response to a
partner’s emotional infidelity.
• .
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• Forced-choice methodology does not allow
participants to specify the level or quantity of
their agreement. In Buss et al.'s (1992) original
study, although more men were distressed than
women by sexual infidelity (49 per cent
compared to 19 per cent), 51 per cent of men
were distressed by emotional infidelity,
compared to women's 81 per cent - that is, more
men were distressed by emotional than sexual
jealousy, which goes against evolutionary theory
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• Some critics feel that evolutionary
explanations justify violence by men
against women as natural and inevitable.
on average, two women a week in
England and Wales are killed by a
violent partner or ex-partner. Killing
a partner because of infidelity “crime
passionel” is no longer accepted as a
defense in court (since 2008)
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• The evolutionary perspective offers an
explanation of how aggressive behaviour
due to suspicions of infidelity may arise as
a result of natural selection.
• Evolutionary explanations account for male and
female differences in their experiences of
infidelity and jealousy as due to different
selective pressures, and therefore are not
gender biased.
• Evolutionary theory brings explanations of
infidelity and jealousy down to the level of
genes and therefore can be perceived as being
reductionist. It is also determinist, as it
disregards any role for free will in behaviour
relating to infidelity and jealousy.
• Cultural differences
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What does this tell us?
• Compare the biological, psychodynamic
and evolutionary causes of aggression.
• Which do you think explains aggression
best? Explain your reasoning.
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Links to issues and Debates
Ethics – e.g. studying aggression and how
findings are used; in the research itself such as
issues of confidentiality and informed consent.
Reductionism – e.g. focusing specifically on
aggression when studying the brain.
Nature-nurture – e.g. brain localisation in
aggression and environmental influences on
aggression.
The use of psychological knowledge within
society – e.g. understanding causes of
aggression, in order to perhaps deal with them.
Can you spot the links to Issues and Debates in today’s lesson????
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Homework
• Read sheet ‘Evolutionary explanations for
Human Aggression’ and make notes about
the role of evolution and natural selection
as explanations of aggression.
• Be prepared to discuss this in class next
lesson.
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