Evolutionary explanations of human aggression

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Evolutionary explanations of human aggression
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Learning objectives

• Understand how evolutionary psychology explains
  aggression
• Explain how jealousy and infidelity can influence
  aggressive behaviour
• Understand how to evaluate evolutionary
  explanations of behaviour

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On Aggression by Lorenz (1966)

• Humans are animals and therefore show similar
  patterns of behaviour.

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4 main motivators

• For all types of animal
• Fear
• Reproduction
• Hunger
• Aggression

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Functions of aggression

• Ensures that the fittest and strongest are
  selected (females select the best males)
• Ensure survival of the young (parents can fight
  off predators)
• Helps to distribute a species in a balanced way
  as animals have their own territories

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Types of social organisation and relationships

• Family and social life
• Tribes and rat packs (gang)
• Anonymous crowds
• Love and friendship
• In each type, the aggression (if shown) is very
  different.

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Ritualised aggression

• Often results in little damage done e.g. stags
• Compare with Craig (1921) animals fight but not
  to destroy - just to get rid of.

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• Morris (1990) animal disputes show a lot of
  restraint.
• Gross (1998) refers to jackdaw behaviour. One
  often uses an appeasement tactic showing the
  nape of its neck.

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Lehrman (1953)

• Questions the correctness of making comparisons
  between species.
• Two behaviours may seem similar but the
  underlying mechanisms may be different.

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Human aggression

• Fromm (1973) also questions Lorenzs view
• Benign aggression
• Malignant aggression

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Nelson (1974)

• Lorenz should have considered 3 basic factors
  that can affect aggression
• 1. Banduras social learning theory
• 2. Structural causes the nature of social life
  and its norms.
• 3. Psychological causes personal feelings e.g.,
  mood and feelings or situational factors such as
  heat or overcrowding.

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Humans and animals

• Significant differences between the two.
• Generalisation is impossible
• Humans use weapons
• Humans label others as the enemy even objects
  Rapoport (1965)
• Tinbergen (1968) humans are the only species in
  which aggression is not part of elaborate system
  of ritual (for mating) but is rooted in a deep
  desire to hurt another.

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Evolutionary explanations

• Aggression is the result of sexual competition.
• In males aggression ensures reproductive success.
• The dominant man is a provider of valuable
  resources.

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Mass killings and genocide

• Waller (2002) - us and them groups result in
  aggression.
• Tingenberg (1968) appeasement gestures no
  longer appropriate with todays technology.
• Easier to kill from a distance (role of buffers).

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Buss (1999)

• Aggression in females is often verbal
• It is aimed at reducing the attractiveness of
  competitors in the eyes of males.

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Influence of infidelity

• Infidelity perceived as a threat
• triggers emotional states
• Buss et al. (1992) - infidelity leads to violent
  and aggressive actions
• Different in males and females
• Males uncertainty of paternity
• Females insecurity about resources

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Influence of jealousy

• Cascardi and Vivian (1995) found
• Jealousy is the most common factor in aggression
  in a relationship.
• Reliable finding in several studies.
• Although non violent ways of responding can be
  effective.
• Causes of jealousy can be complex.

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Issues and debates

• Evolutionary psychologists state jealousy can be
  explained adaptively through mate retention
  (survival of the species)
• Any trait with survival value is passed on.

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Differences in men and women

• Haden and Hojjat (2006)
• Men more likely to consider aggressive action
  when jealous.
• Women more emotionally and behaviourally
  reactive.

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Key points

• Craig (1921) attempted to apply the principles of
  ethology to explain aggressive behaviour.
• Lorenz (1966) advanced the notion of ritualised
  aggression to encompass aggressive animal
  behaviour (e.g. stags rutting). Other ethologists
  have furthered this by stating that animals know
  when to stopfew kill their enemy.

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Key points continued

• Lorenz generalised from animals to humans and was
  criticised for this.
• Nelson (1974) provides a well-structured
  criticism of Lorenz. He argues that Lorenz misses
  3 fundamental issues that can affect human
  behaviour, (a) processes of learning, b)
  structural causes and c) psychological factors.

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Key points continued

• Jealousy has a basis of explanation that links
  with evolutionary theory.
• Harvey et al. (2004) show support for the
  assertion that jealousy is a motivator for
  violence and suggest that the causes of jealousy
  are complex.