Evolutionary theory of aggression

Including  infidelity,  war and sports events

  • Created by: ava.scott
  • Created on: 06-04-15 18:46

Evolutionary explanation of infidelity

Infidelity is being unfaithful to a partner.

Infidelity makes sens evolutionarily because

  • If your offspring have a variety of genes, they are more likely to survive.
  • Therefore, those witha gene for infidelity will have more advantageous offspring, and their offspirng will also carry the infidelity gene.
  • This makes a gene for infidelity more likely to survive in the gene pool.

Men should be more unfaithful because:

  • They can impregnate many women at once, and therefore should attempt too.
  • Women can only be pregnant with one cild, so should be selective in their partnerships.
  • Men also dont know if they are the father or not, so having many partners increases the chance of their children being born.
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Explanation of sexual jealousy

Sexual jealousy is the state of fear caused by a threat to someone's status as an exlcusive sexual partner.

Men should show greater sexual jealousy:

  • They have a question of paternity.
  • They cannot be sure if the woman is pregant with his child or someone else.
  • This would make aggression more likely, as a way to scare their partner into being faithful.

Women could be aggressive:

  • ensuring she gets all the male's resources for her child, increasing its likelyhood to survive.

Sexual jealousy is an adaptive repsonse leading to mate retentive behaviours:

  • These behaviours are used to prevent your partner from mating with soemone else
  • e.g. public displays of affection, or aggression towards competing males/females.

Retaining a mate is very importnt, as it makes sure that your genes are passed forward to offspring. THIS IS HOW IT LINKS TO AGGRESSION.

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Sexual Jealousy IDA


  • Is it logical to kill or damage your partner in fits of sexual jealousy aggression?

This would decrease your offspring's chance of survival, and theefore your genes would not be passed on. You may not be able to find another mate.

-MAYBE- a man would not wnant to waste his resources on a child he didn't think was his.

  • Evolutionary theory is impossible to prove empirically/scientifically.

This means we cannot prove the theoyr outright, and must use observations.

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Sexual jealousy research: Buss


  • Looked at 37 cultures
  • Males consistently valued chastity (not having sex with anyone else) and faithfulness (in an emotional sense)
  • Women valued faithfulness more.
  • Females found emotional infidelity more distressing than sexual infidelity, while men found sexual infidelity more.


This supports the evolutionary explanation, as its hows that across many cltures, that men want women to be sexually faithful, which gives a greater cahnce of sexual jealousy. This would eveolve across all humans, as its increases the chance of your offspring being born and raised successfully. Women need emotional commitment, as this would lead to greater resources for her and her child.

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Sexual jealousy research: Day and Wilson

Day and Wilson

  • looked at 80 murders where the victim and murderer were partners.
  • 44 of the victims were husbands and 36 were wives.
  • 29% of these conflicts had arisen out of sexual jealousy.
  • Most conflicts were judged to have been started by the male, and the woman killed in self defence.


Supports the theory as men show more aggression on account of sexual jealousy, perhapd because of the paternity issue. They wouldnit want to commit resources to a child which wasn't theirs.

However, relies on the women being honest, and the judicial system being correct and unbiased.

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Sexual jealousy research: Miller


  • studied 44 female victims of abuse, living in a womans hostel
  • 55% of the woman stated jealousy as the reason for their partners aggression.
  • 25% fo women stated their own infidelity as the reason for his aggression.
  • Some women reported their partner hadn't liked them going out with friends, or alone.


Supoorts the theory, as the majority of women stated the man's jealousy as the cause for his aggression. This makes sense evolutionarily as the man needs to be sure of his paternity of any children. The posessive behaviour is a mate retentive behaviour, used to prevent infidelity.

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Sexual jealousy research evaluation


  • Low face validity, as it didn't look at incident rates of aggression within these different cultures just the similarities in values. It could be that evolutinarily all men value chasitity, but nly in certain cultures this is expressed as aggression.
  • However has high population validity
  • Researcher effects?

Day and Wilson/Miller--

  • The women may have said they were the victims of sexual jealousy as it got them out of a prison sentence.

The research is not very scientific, and lacks conteol over variable.s This is the nature of research into evolutionary theory, but it makes the theory less compelling.

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Sexual jealousy wider evaluation

Western bias

  • Polygamous societies exist without seuxla jealousy or aggression
  • ON THE OTHER HAND- These mainly consist of men with many wives.

Deterministic/lack of practical applications

  • The thoeyr says that men will always be aggressive towards women due to the partenity question and sexual jealousy.
  • Does it try to justify male aggression to women? 
  • This isn't positive or constructive, and so the theory is less useful to us.

Nature v Nuture

  • If sexual jealousy and grression was completly evolutionary, we would see equal rates of domestic abuse around the world. This isn;t the case, so social factors must play a role too. The theory doesn't account for these, and so is less compelling.
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Evolutionary explanation of war

Group display is when a group of people act in a certain way in public, using gestures and sound. Often to intimated and threaten rather than do.

Wra is the formation of groups to attacks others within the same species.

Evolutionarily war makes sense:

  • Individual attack more often ends in death, whereas attacking in agroup increases chance of survival.
  • Groups are more powerful and more protetcted, so group display is adaptive.
  • Success in war can give better access to resources, higher status and more mates and chance of reproducing.
  • e.g. mass **** is often used as wart tactic- threat of **** cause epople to flea terriotry, and actual raoe means the war genes are passed on.
  • Those who are more aggressive win wars, and so aggressive genes are passed onto offspring.
  • In modern societies, sporting events have replaced tribal warfare.
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War: IDA


The theory suggest that war is a innate human characteristic and it is inevitable. This is very negative and socially sensitive.

It suggests that people and governemnts vannot do anything to stop war. This prevents progress, and even tries to justify war and its atrocities.

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War Research Evidence: Chagnon


  • observed fighting in the Amazon region between branches of the Yanomamo people
  • Nearly always concerning access to women and raising status of one grouo over another.
  • The successful warriors would have more wives and children.


This supports the theory as it displays how a tendency and ability in war leads to more children, and then more successful warriors in the next generation. The ability to fight leads to an evolutionary advantage.



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War Research Evidence: Bosnian war

  • Systematic **** of women often occurs in war
  • In the 1990's, the Bosnian war was estimated to have resulted in the **** of 50,000 muslim women by Serbians.
  • This was to may women flee the land, but also to ensure their children had Serbian blood, increasing loyalty and numbers.

This supports the theory because sexual aggression in war would lead to a more loyal and secure genetation for the population and individual. Therefore, mass **** is an adaptive war tactic.

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War research evidence evaluation

Chagnon and Bosnian War

  • Very low populational validity- one brazilian tribe cannot be used to account for all war and conflict. not generalisable.
  • Low control- observations of war and conflict have low control. The mass **** may have other causes and effects that were unnoticed or recorded.

The research is unreliable and unscientific, and therefore the theory cannot be positively justified.

However, it does highlight that war isn;t just a western phenomenon, and makes us question the real need for war.

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Evolutionary approach wider evaluation

Practical applications

  • Very few practical applications, suggesting that war will always be inevitable.
  • This is quite a dangerous idea, as it justfies war and could stop attempts to reduce war.

Poor scientific value

  • very difficult to test empirically


  • would the children from **** receive the same level of care and be more likely to survive?
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Group display and sport events

  • Some psychologists argue that sporting events have replaced war as a mean of group display. 
  • It is a ritualised for if aggression with all the benefits of aggression with less risk of physical harm--adaptive behaviour. 
  • Hooliganism is a human equivalent of ceremonial conflict-the hooligans are exclusively male who need to prove strength and territory,  whilst maintaining health. 
  • A winning team holds high status and the individual members are desirable as mates. Aggression shown in the game is similar to hunting and athleticism = potential provider. 
  • Victory brings status to players and fans alike. 
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Sporting events :IDA


Sporting events and hooliganism obviously exists but we can't prove that is an evolutionary approach. Its impossible to to test experimentally. 

The theory is logical  but  there may be flaws :does supporting a winning team increase your reproductive success? Women typically don't care about a man's football team and its success rates. 

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Sporting events research: Cialdini


  • 1976
  • Found that after a university football team had won,  more students  wore team clothes and identification.
  • Students were also more likely to use 'we won'  and 'they lost' respectively when their team won/lost. 


Supports the theory as it shows how the students use the group display as a way to increase their own status - - they have won something without putting themselves at any risk at all. 

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Sporting events research: Marsh


  • 1978
  • Football fans appear ultra violent but on the whole displayed violence did not become physical. 

Grounding :

Shows that hooliganism is an adaptive response as risk to wellbeing is very minimised whilst still attracting mates and increasing status by showing potential aggression and hunting ability. This behaviour could increase reproduction and therefore,  is an evolutionary behaviour. 

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Sporting events research evaluation

High external validity as they investigated real life opinions and behaviour based around sporting events.  This makes generalisation more possible. 

However,  temporal validity is low (around 30 years ago) football attitudes may have changed. Also alot of Western bias-sportinh events  may be a more or less source of aggression in other cultures. 

Also, not experimental evidence means a lack of control and internal validity. No cause and effect can be established, so the evolutionary approach is not justified 

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Sporting events wider evaluation

Other approaches: social learning theory 

Group display could be learnt from role models and then encouraged through vicarious reinforcement,  as a winning team gets money,  and high status. 

Practical application 

This theory isn't useful to us,  as it suggests that group display is an inevitable part of human culture and cannot be avoided. This is deterministic and makes the theory more socially sensitive and even dangerous, as progress may be stopped. 

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