Evolutionary Explanations
Evolution of Aggression:
The evolutionary explanation of human aggression derives from the changes in species over millions of years. These changes work to increase their chances of survival and reproduction, these changes also known as characteristics, these are what are naturally selected to be passed onto offspring
Evolutionary Explanations say Aggression is an Adaptive Response:
Evolutionary psychology explains aggression as a strategy that has evolved as an adaptive response to problems.
The argument is that using aggression helped individuals to survive and reproduce in the past — so aggression is a trait that modern humans have inherited
Evolutionary psychologists have outlined various adaptive functions which aggression may have served in the past:
To gain status or dominance in a group.
To gain resources from others (eg. territory, mates).
In defence (against losing resources or status, or being injured or killed).
To deter infidelity in long-term mates.
Evolutionary explanations have been criticised because they don't explain cross-cultural or individual differences in aggression or take social factors into account.
The Brain:
Evolutionary psychologists believe that the human brain comprises a number of adaptions to cope with various challenges associated with group living
Aggression is a strategy that would have been effective for solving adaptive problems such as intimidating or eliminating male rivals
Solving these problems enhances the survival and reproductive success of the individual and as a result, this mental model would have spread through the Gene pool
Sex Differences in Aggression May Have Evolved:
Wilson and Daly (1985) studied murders in Detroit and found that the majority of perpetrators and victims were young men. 29 of the cases they looked at were murders that had resulted from 'escalated showing off disputes', and only one of these murders resulted from a dispute between women.
Evolutionary psychologists argue that men (and young men in particular) are more aggressive because they faced the most competition for mates in the past. The main limit on men's reproduction was access to fertile mates, so competing successfully for mates was important.
Women, however, were mainly limited by their access to resources. Evolutionary psychologists argue that these different pressures have led to different psychological responses evolving in men and women.
Sexual Competition:
Puts (2010) argues that various male traits seem to imply that competition with other males did take place among ancestral males
For example:
Have thicker jawbones than women (Puts, 2010)
More robust skulls and brow ridges
75% more muscle mass than women (Lassek and Gaulin, 2009)
Are more likely to die violently than women (Buss, 2005)
Ancestry of Sexual Competition:
Ancestral males seeking access to females would have to compete with other males (sexual competition). One way of eliminating this would have been through aggression
Successful males would acquire mates and pass on their genes. This would then lead to the development of a genetically transmitted tendency for males to be aggressive towards other males
Various male traits support this explanation such as 75% more muscle mass than women. Anthropological evidence shows that universally males have thicker jaw bones, more robust skulls and brow ridges than women.
What is Cuckoldry:
In biology, a cuckold is a male who unwittingly invests parental effort in juveniles who are not genetically his offspring.
Sexual Jealously:
Unlike women, a man can never be totally sure about whether he has truly fathered a child
This paternity uncertainty results in a fear of cuckoldry. Perhaps demonstrated by the males than in females
Therefore, aggression displayed by men towards female partners may serve the adaptive response of preventing them from ‘straying’
Evaluation:
One strength of evolutionary theory is that there is research that supports it.
Shackeford et al (2005) found that men who use. mate retention behaviours (e.g. direct guarding) were more likely to be physically violent towards their partners
These findings support the view that predicts a link between, the risk of infidelity, sexual jealousy and aggression
Buss et al (1992)- Sex differences in jealousy:
Method:
This was a cross-cultural questionnaire study. Participants were presented with the hypothetical scenario that someone they were in a serious, committed romantic relationship with had become interested in someone else. They were asked what would distress them more - imagining their partner forming a deep emotional attachment to that other person, or enjoying passionate sexual intercourse with the person.
Results:
Across all studies, more men than women reported sexual infidelity to be most upsetting. On average, 51% of the men versus 22% of the women chose this to be more distressing than emotional infidelity.
Conclusion:
Men's jealousy is innately triggered by the threat of uncertainty over the paternity of children produced within the relationship. However, women are more threatened by emotional involvement as it could mean being left for another woman, and so reducing the resources available to her children.
Evaluation:
The fact that the evidence was consistent across different cultures suggests that these different responses are innate rather than learned. However, the fact that the questionnaires were based around a hypothetical situation, and the responses available to the participants were multiple choice, means that the validity of the results is questionable - they may not accurately reflect what participants would actually do if they found themselves in that situation.
Evolutionary theories are very difficult to provide evidence for (or against) — they re effectively impossible to test on humans.
Parental Investment Theory:
Robert Trivers parental investment theory (1972)
This approach argues that differences between males and females have their origins in the different amounts of parental investment made by males and females
Sexually Selected Mate Retention Strategies:
These are two such sexually selected mate retention strategies (Wilson and Daly, 1996):
Direct guarding: A man may monitor his partner’s behaviours and actively prevent her from meeting other men. This could involve him using physical violence
Negative inducements: A man may issue threats of violence or other consequences of infidelity (I'll kill you if you leave me)
Investments:
The human male investments in offspring are relatively small. He has large amounts of sperm and remains fertile throughout his life.
He is also capable of many matings, and the only limit on the number of offspring he can produce is in the number of available female partners
Each takes little in terms of time and energy. The best way to maximise his reproductive success is to have many matings with multiple fertile partners
In contrast, the human female’s investment in each offspring is substantial. Her reproductive life is around 30 yrs., The Gamete she supplies, (the ova) is around one hundred times larger than the sperm, and she has a limited supply of these. •
Following conception, her prenatal investment continues – she carries the growing foetus for around 40 weeks feeding it from her own supplies of nourishment. Then she must give birth and continue to invest in the baby ie breastfeeding.
Her investment is substantial, and her best chance of reproductive feeding_baby success is to ensure the survival of her few precious offspring.
Parental Investment Theory Evaluation:
Parental investment theory helps us to understand mate preference.
As a woman invests heavily in each child, she should seek a man with good genes, a man who shows commitment also if he has material resources, her offspring will be more likely to survive.
This helps explain Buss’s finding that women valued material resources and industriousness
In contrast, males who make less parental investment will be more reproductively successful if they have multiple matings with young fertile females. This helps us to understand why youth is universally important to men.
Buss 1988:
Male strategies evolved specifically for the purpose of keeping a mate. Including the use of violence or threats of violence to prevent the female straying, and violence towards a perceived love rival.
Sexual jealousy is a primary cause of violence against women. For example, Studies of battered women cite extreme jealousy as the key cause
Aggression in warfare:
Displays of aggressiveness and bravery are attractive to females. For example, male warriors in traditional societies tend to have more sexual partners and more children suggesting a direct a direct reproductive benefit.
Aggression in combat can also increase the status of individual warriors. This would leave peers to respect them more and so strengthen the bond between them and other males in the group.
Displays of aggression and bravery in battle mean that individuals are more likely to share the benefits associated with status
Socialisation:
Perceived parental disapproval of violence was associated with more prosocial attitudes and less use of physical violence among adolescents, whereas, adolescents who were more likely to engage in fighting, bullying, and victimization of others reported that their parents engaged in corporal punishment as a disciplining method.
These findings suggest that perceived parental disapproval of violence may serve as a protective factor against violent behaviour among adolescents. Alternatively, parental use of corporal punishment may pose a risk for violent behaviours among youth.
Smetana (1989) found parents are more likely to physically punish boys but explains why it is wrong for girls
Status:
Anthropological evidence suggests that many tribal societies bestow increased status and honour to men who have committed murder.
Cambell (1993) – the most violent gang members in the states have the highest status among their peers. They also show a high sensitivity to perceived affronts to their status and reputation leading to many male-on-male assaults (Buss 2005)
Cruelty:
Evolutionary explanations are based on mating success but fail to explain the astonishing levels of cruelty that are often found in human conflicts but not in non-human species.
For example wide-scale slaughter of whole groups (genocide) Nor do they tell us why humans torture or mutilate their defeated opponents who no longer pose a threat
Gender Bias:
Evolutionary explanations do not adequately reflect the behaviour of women. Adams (1983) claimed that the idea of the women warrior is almost unheard of within most societies. Even within those societies that do it is rare. Women have considerably less to gain and more to lose (ie loss of reproductive capacity.
Seh-Dong-Hong-Beh (meaning, “God Speaks true”) was a leader of the Dahomey Amazons. In 1851, she led an all-female army consisting of 6,000 warriors against the Egba fortress of Abeokuta.
Evaluation- Gender Differences:
The common observation is that men engage in more aggressive acts (physical aggression.
Evolutionary theory can explain this
Campell (1996) - females with offspring are less likely to be aggressive as it will jeopardise her and babies' safety.
Adaptive strategy is verbal aggression to retain a partner who provides.
Buss and Shackelford (1997) - to avoid life-threatening situations with physical violence.
Explains why females are more likely to use non-aggressive methods to resolve conflicts.
Evaluation- Methodological Issues:
Difficult to test hypotheses about the evolution of behaviours to solve problems of adaptation in our evolutionary past.
Most research is therefore correlational o e.g. finding associations between mate retention behaviours and aggression.
Doesn't allow us to draw cause-and-effect conclusions