Evolutionary explanations of human aggression (2)Presentation Transcript
Aggression as an Adaptive ResponseDescribe + Evaluate 2 evolutionary explanations of aggression: 1.Infidelity & jealousy 2.The Evolution of murder
Infidelity and jealousy• Daly + Wilson claim men evolved mate-retention strategies to deter their mate from leaving or cheating b/c W/o a mate, the chance of passing his genes on is reduced.• So these strategies enhance reproductive fitness (surviving + passing genes).
Mate retention strategiesRange from: - vigilance (e.g.mate ‘guarding’) and violence todeter infidelity.1 strategy is ‘direct guarding’-restricting her freedom toprevent males gaining access.E.g. stopping partnersspeaking/interacting withw/other men.Other forms might includesnooping through personalbelongings to look for signs ofinfidelity
OTHER STRATEGIES• Different vigilance strategies are used in diff cultures e.g. veiling of women / female circumcision [infibulation] / chastity belts / popping home unexpectedly
Cuckoldry and sexual jealousy• Cuckoldry occurs when a woman deceives her partner into investing in another man’s offspring.• Why are the risks of cuckoldry even higher for men than women?
• Cuckolded men risk losing invested resources & reproductive opportunity.(Platek and Shackleford- 2006)• Males evolved mate-retention strategies to prevent being cuckolded.• These are driven by sexual jealousy, an adaptation evolved in males to deal w/paternal uncertainty.• Sexual jealousy prevents the female mating w/others, so it is an adaptive response.•
The ‘cuckoldry risk hypothesis’ (Camilleri 2004)• predicts males may use sexually coercive tactics• e.g. partner rape when risk of cuckoldry is high e.g. suspecting infidelity.• Lalumiere et al (2005) argues some men carry out partner rape to decrease paternal uncertainty.• Thornhill + Thornhill (1992) argue a woman who resists sex w/her partner may signal infidelity, thus increasing the male’s sexual jealousy and fear of cuckoldry.
Mate retention and violence• Buss & Shackleton (1997) examined mate- retention tactics in married couples + found:• men used more debasement (e.g. giving in to her every wish) + intra-sexual threats (threatening to beat other man).• But women used verbal possession “he’s taken” & threats of punishing infidelity ‘leaving her man if unfaithful’.
Read key research: Shackleford et al (2005) p149• What were the findings?• Do they support the Mate retention and violence hypothesis?• What were the limitations of this study?
Mate retention + violence against women• Shackelford studied 461 men and 560 women from US unis – all Ps in committed, heterosexual relationships.
They found in study 1 that:• men’s 2 types of mate- retention strategies positively correlated w/their violence scores.• ‘intersexual negative inducements’ (e.g. shouting at her for looking at another man)• ‘direct guarding’ (e.g. controlling her time at a party)
In study 2 they found that:• results confirmed the validity of findings from study 1, w/reports of ‘intersexual -ive inducements’ + ‘direct guarding’ associated w/female-directed violence.• - women also stated partners who used emotional manipulation were more likely to have used violence against them.•
A02-Evaluation• A limitation is data was correlational, they did not establish a causal link between the use of mate-retention strategies and violence against women.• Lack of information – another limitation of research is it does not control for actual relationship threats (e.g. a man’s suspicion or knowledge of his partner’s infidelities).
A02-Evaluation of infidelity + jealousy as explanations for aggression• Use of mate-retention tactics• Research on sexual coercion• Practical applications of research
A02-Use of mate-retention tactics Sexual jealousy issupported by studies ofbattered women, wherevictims cite extremesexual jealousy ofpartners as the majorcause of violence againstthem.(Dobash & Dobash‘84)
AO2• Wilson’s study found evidence of direct guarding as mate- retention: in women reporting partners used this tactic (e.g. not allowing to talk to other men) 72% required medical attention after an assault by their partner.
AO2 Research supports sexual coercion• Of females by male partners -is an adaptive response to the risk of infidelity.• Camilleri ‘04 found: the risk of a partner’s infidelity predicted the chance of sexual coercion in men but not women.• Does this support the adaptive explanation and why?
• Supports the adaptive explanation, as it is men at risk of cuckoldry, not women.
AO2 Goetz also found :• men who sexually coerced their partners were more likely to report thinking partners were unfaithful.• women reporting coercion were more likely to admit infidelity.
AO2 Practical applications of research• Mate-retention tactics may be early indicators of potential violence against a partner.• The use of tactics can alert friends + family of potential future violence in relationships.• So relationship counselling may be used before the situation escalates into physical violence. Dobash & Dobash (1984)•
AO2: However: the link between jealousy & violence is probably a complex one• Holtzworth–Monroe & Anglin (1991) – suggest that violence in males may not be directly due to jealousy• But it may be that violent males lack ways of mediating & responding effectively in situations of jealousy compared to non-violent males.
IDA -Gender Bias:• Majority of studies have focused on male mate retention strategies BUT women also engage in tactics to retain their mate. Archer (2002) studied family conflict & found equal rates of assault by men & women
The evolution of murder.• The UK defines murder as:• ‘Taking a life with the intention to kill or do serious harm.’• Recent murder statistics are as follows: 1 in 15000 are murdered in the US (Stolinksy & Stolinksy 2000).• This equates to 1 in 200 chance of being murdered in our lifetime (75 year lifespan).• Risk- less in UK- 1:100 000• Other countries- SA and Columbia- 1:20
Murder as an adaptive responseBuss & Duntley propose:•humans have adaptations (i.e. characs for survival)that evolved by natural selection to produce murder.•The activation of these evolved adaptations isdetermined by factors such as:1. degree of genetic relatedness between killer and victim2. relative status of killer and victim3. sex of killer and victim4. size and strength of ‘killers’ and ‘victims’ families and socialallies
Buss & Duntley ‘06• Claim that for our ancestors, murder solved adaptive problems such as:• preventing harm – e.g. injury, rape or killing of the person, their family, mates by others.• Reputation management – e.g. avoiding being seen as easily injured, raped or killed.• Protecting resources – e.g. shelter + food
Predisposing factors for murder• Daly + Wilson noted males + females murder for diff reasons.• What are these?
• Men more likely to kill men seen as sexual rivals or who challenge their position in the dominance hierarchy.• But women are likelier to kill in self-defence e.g. murdering abusive male sexual partners.• They also found that murders were age related, peaking for males early 20s – peak years of reproductive competition.
Predisposing factors for murder. Daly & Wilson (1988).Nature of murder FrequencyMale offender/male 65.3%victimMale offender/female 22.7%victimFemale offender/male 9.6%victimFemale 2.4%offender/female victimSource: FBI supplementary homicide reports 1976-2005
Research suggests there are common factors inthe competition for reproductive status: Sexual jealousy – cause of same-sex aggression+ murder.• B/c of infidelity and cuckoldry, men are both killers + victims.• Daly + Wilson got data from 8 studies of same-sex killings involving ‘love triangles’• They found 92% of murders involved males killing males & only 8% of females killing another female.
Lack of resources –• (research on sexual selection shows females prefer males w/resources.)• Daly + Wilson suggest• a lack of resources increases male-male competition and risk of murder.• They cite murder statistics in Detroit, showing 43% of male victims and 41% male killers were unemployed, although the overall unemployment rate for adult males was 11%.•
Threats to male status –• the biggest factor related to murder is maleness, second is youth.• In addition to sexual jealousy and lack of resources, threats to status appear an important determinant of murder among young men.• Daly + Wilson argue females prefer males who are dominant over others, so men are shaped by evolution to seek status. During competition for scarce resources (e.g. territory, mates) this status is more likely to be threatened.. they cite a strong correlation between degree of income inadequacy + murder rates – countries w/more income inequality tend to have higher murder rates.• According to evolution, loss of male status harmed survival + reproduction of our ancestors, & mechanisms to prevent loss of status still operate today when triggered by threatening events.
Evaluation of evolutionary explanation of murder
Comparative evidence –• The ‘murder as adaptation’ hypothesis is supported by studies of other species.• Many cases of mammals killing other mammals-conspecific.• E.g. Male lions + cheetahs kill offspring of rival males (Ghiglieri).• This benefits the killer’s reproductive fitness, as the mothers of killed infants will go into oestrus sooner, allowing the killer to impregnate them w/his own offspring.• Among primates, the killing of rival adult males also documented among mountain gorillas (Fossey ‘84) and chimpanzees (Wrangham & Peterson ‘96).
An alternative explanation –• Evolved Goal Hypothesis – of murder argues humans evolved motivations for certain GOALS (e.g. strive for status, or ‘acquire a mate’) that were, among our ancestors, associated w/greater reproductive success.• Goals could be reached by using evolved problem-solving mechanisms.
• Hrdy (‘99)claims early ancestors calculated costs + benefits + future consequences, of actions, which may conclude murder as the best solution to achieve a certain goal.• Read Implications of an evolved adaptation for murder p153
Evaluation of evolutionaryexplanations of aggression
Limitations• an evolutionary approach for aggression does not explain why people react in diff ways to the same adaptive problem.• Buss + Shackelford show diff men react v. differently about wife’s infidelity,• e.g. violence (toward other man) - debasement (e.g. granting her every wish to keep her) or avoiding the issue, by getting drunk.
IDA: Cultural differences –• Also, an evolutionary view doesn’t explain why some cultures (e.g. in south America) require male violence to attain social status, whereas in others (peaceful !Kung San of Kalahari) aggression damages the aggressors reputation.
IDA: REDUCTIONIST• Evolutionary theories are also reductionist as they fail to offer a complete explanation of displays of aggression in human reproductive behaviour; it reduces it to simple predisposition (nature). Aggression could be determined by other factors (previous relationship history, the availability of alternatives, the role of social learning (nurture).
Deterministic• Evolutionary explanations are also Deterministic, as they imply that we are slaves to our inborn aggressive instincts and unable to exercise free will
POST HOC• Another problem is that evolutionary theory is post-hoc (after the fact) theory. This means that it only explains aggressive behaviour after it has happened rather than making predictions about what is going to happen via testing. Evolutionary theory could only be tested if we isolated a large number of humans and for a very long time to see if particular genes persisted in the populations (never going to happen.....ETHICS!!!!).
Research into infidelity is gender biased• The evolutionary argument for infidelity states that it is something a man must prevent a woman from doing, and does not really acknowledge the fact that men may be just as unfaithful as women. This is heavily gender biased and does not reveal the true nature of male and female infidelity.
Nature nurture debate• Evolutionary explanations argue that behaviour has evolved through gene selection and is therefore biological. If jealousy and uxoricide were really evolved responses to female infidelity and determined by genes, then we would expect all men to behave violently to women, but clearly they do not.• There must, therefore, be an alternative explanation that takes into account the fact that men may have naturally aggressive responses to female infidelity, but that also explains why many men do not behave violently and others do.• Social learning theory may account for this as violent men may have grown up with violent role models, and have learned to be violent by observing them.
AO3: Much research makes use of questionnaires and surveys to collect data• Surveys are a self report method and therefore has inherent difficulties with collecting reliable and valid data. If a man is asked to complete a questionnaire asking how violent he is towards his partner, then it is most likely that he will distort the truth due to his desire to appear more socially desirable than he actually is (social desirability bias).• Similarly, a woman may be less likely to accurately report her partner as abusive if she fears recriminations from him, or she may even choose to deny the truth about his behaviour because acknowledging it could mean the end of her relationship with him.• Questionnaires and surveys may not therefore reveal the true extent and nature of male jealousy
Answering exam questions (PSYA3 AQA A specification)• Outline and evaluate research into sexual jealousy and infidelity as a cause of human aggression (24 marks)
• 8 AO1 marks come from outlining the evolutionary debate in terms of men never being able to be certain that they are the father of a child, and needing to ensure that they are not subject to cuckoldry. Outline male behaviours to control women. Outline uxoricide as an accidental killing when control has gone too far. Also explain that men may kill other men because of social competition including competition for a mate. 16 AO2 marks come from evaluating and discussing the research. Describe studies supporting the argument that men need to control women and the sort of behaviours they use to do so. Illustrate the link between male jealousy, mate retention and violence using research studies (e.g. Shackleton et al). Discuss the alternative argument to the accidental nature of uxoricide and state why it may be an intentional act. Discuss the problem for the evolutionary argument in that not all men act the same way in the same situation. Remember to build in synoptic links including the problem with questionnaire and survey research, and the gender biased nature of research into infidelity.•
Explanations of group display in humans• Describe and evaluate at least two evolutionary reasons for displays of aggressive group behaviour1) lynch mobs – a group illegally kill a person for a presumed offence.2) Self-directed aggression during religious + cultural displays – signals commitment in a gp.
Adaptive explanations for lynch mobs• At least 2805 lynched from 1882 – 1930 in US southern states by a hate-driven white mob (Tolnay + Beck).• Most African-American males.• Obscure reasons included ‘demanding respect’ & ‘being disreputable.’
Evolutionary explanations for the behaviour of lynch mobs are:• the power-threat hypothesis• dehumanization of the victim
The power-threat hypothesis• Blalock suggests as minority groups grow, majority gps try harder to maintain dominance.• ‘Power-threat’ is a fear of the minority’s POLITICAL power, E.g. Tolnay + Beck found reasons for lynchings included ‘trying to vote’ & ‘voting wrong party’.• This fear of ‘Negro’ power meant White mobs used ‘LYNCH LAW’ as social control, E.g. after slavery was abolished, when the social transition left the White community feeling at risk.• Ridley suggests group displays of discrimination against outsiders are more likely when groups feel at risk.
Lynch mobs and dehumanization• Hyatt argues that by defiling the Black body in lynching + burnings, the mob reduced it to a form unrecognizable as a human.
• Tolnay suggested PROPOGANDA reduced Blacks to simplistic animalistic stereotypes to whites, that dehumanized victims to a worthless hated object.• encouraging lynch mob’s actions b/c they were ‘defending their community from black brutality’.• So lynching can be seen as an evolved adaptation to perceived threats
Lynch mobs & deindividuation• However, Mullen analysed 60 newspaper reports of lynchings + found:• As the mob size increased, lynchers became more violent.• Consistent w/deindividuation, the increases in mob size broke down normal self- regulation processes, increasing violence against the victim.
Evaluation of adaptive explanations for lynch mobs• The power-threat hypothesis –• Clark studied lynch mob murders in Brazil, evidence contradicted power-threat hypothesis.• Main victim Afro-Brazilians, were NOT SEEN as threats, political or economic, to the dominant community.• Consequently, ‘fear of minority’ was not a causal factor in these ritual murders.
Reductionist• The power-threat hypothesis itself can be argued to be a reductionist approach and not fully consider other possibilities for such behaviour beyond fear and feeling threatened.• Clark et al found evidence suggesting the power- threat hypothesis may not provide a complete picture and be universal; Victims of lynching’s in Sao Paulo were majority Afro-Caribbean but posed no threat politically or economically.• This suggests other possible reasons behind group aggression that the Power-Threat hypothesis cannot explain.
Evidence of Dehumanization• In Guatemala, lynch mob violence became common in recent yrs.• Rothenberg observes although most cases are for crimes like murder, some are for minor offences like stealing chickens/pickpocketing.
• Consistent w/dehumanization, enraged crowds burn corpses, further degrading a dead victim.• makes it easier to kill by removing moral constraints on killing humans.• By reducing victims to status of animals, killing rivals becomes easier, ultimately beneficial to group members –by allowing for the elimination of rivals which is consistent with the evolutionary theory of group aggression.
• Evolutionary approach – increased intragroup solidarity may lead to increased intergroup confl ict.
The role of deindividuation• There’s support for claim that lynching: may be a group display of extreme discrimination made more likely through deindividuation.• Rothenberg says however, although some lynchings were - at night, (where violence obscured by darkness) most occurred in the day.• In some cases only a few angry citizens present, whereas in others there were 1000s.• Although some aspects of deindividuation (e.g. large mob size) in the majority of cases, there appears to be no clear relationship between deindividuating factors + the ferocity of violence.• By reducing the status of potential threats to the status of animals; killing itself becomes easier and
IDA-Cultural Diffs• Evolutionary theory-not all cultures display such forms of aggression- Not universal• The Kung San tribe of the Kalahari view aggression in a completely negative light and therefore aggressive behaviour in any form is extremely rare.• Suggests such behaviour may in fact be learnt rather than an evolutionary response
Free will/determinism• It is also unclear whether such group behaviour is unconscious and deterministic as evolutionary theories propose or whether it is regulated by the individuals own free will.
Group Displays: Religion/cultural displays• Aggression during religious/cultural displays.• This behaviour signals commitment to the group.• I.e. Self-flagellation VIRTUALPSYCHOLOGY.CO.UK
The human species has engaged in ritual behavior for atleast 100,000 years, and every known culture has someform of painful or uncomfortable religious ritual. It is difficultto explain how rituals resulting in harm (a form ofaggression) may be of benefit to humans. Yet manyexamples occur across the world.E.g. Australian aborigines perform a ritual operation onadolescent boys in which a bone or a stone is inserted intothe penis. Jews and Muslims submit their sons tocircumcision, and in some Muslim societies daughters arealso subject to circumcision or other forms of genitalmutilation. Initiation ceremonies are often brutal. AmongNative Americans, Apache boys were forced to bathe inicy water and Tukuna girls had their hair plucked out. ….
Religious/cultural displays• Self inflicted violence is not uncommon- self flagellation during Ashura. A recreation of the suffering of Hussein -grandson to Mohammed the prophet.• Some Shia Muslims symbolically recreate the suffering of Hussein by cutting their foreheads until blood streams from their bodies• A committed member of the group is a cooperative member. By engaging in these rituals an individual is cooperating and being committed.• Extreme displays such as this appears to contradict the principle of natural selection.• Why?
• A Pakistani Shiite Muslim performs ritual self- flagellation during a religious procession on the holy day of Ashura.
Kurdish Sufis (An Islamic sect)
Filipino Christians (Catholics)
• Because the patterns of behaviour are very similar & occur in so many racial groups, evolutionary psychologists conclude that they must have some adaptive advantage (or they would not have been passed on)
Religious displays and cooperative gains• William Irons (2001) argues that these group displays promote cooperation between members.• We have much to gain from living in gps i.e. food sharing, hunting, protection from outside threats etc & so have to earn our place in the gp.• Irons argues that the primary adaptive benefit of religion is its ability to facilitate cooperation within a group.
• Religion works like a mechanism. The key is that religious rituals are a form of communication.• By engaging in the ritual, the member effectively says, “I identify with the group and I believe in what the group stands for.”• Painful rituals show commitment to the group and a committed group member is likely to be a cooperative & successful one.
COSTLY SIGNALLING to deter free riders• The costs (e.g. to physical health) of cultural and religious displays deter potential free riders who’ll exploit gp membership w/o contributing.• Zahavi says ‘costly signalling’ rituals indicate status + breeding potential b/c they’re too costly for ‘low quality’ individuals to perform. Sosi exemplifies Ultra-Orthodox Jews (Haredim) who overdress in summer in their thick beards long black coats & heavy hats
• Haredi men spend days sweating as they sing praises to God in the desert sun.• Thus, the ‘quality’ these men signal is their level of commitment to their religious gp.• So the adaptive benefit of religious displays appears to be promoting cooperation within a gp, while deterring ‘free riders’ who may exploit the gp.
Evaluation of the adaptive explanation of religious/cultural displays• Religious displays –• Ruffle + Sosis studied Israeli communes and found religious males sig more cooperative w/gp members than females.• Perhaps b/c Males do highly visible rituals e.g. public prayer 3 times daily.• They found synagogue attendance positively correlated w/cooperative behaviour in males.
• And no correlation between s. attendance and cooperation from females, who it’s OPTIONAL for, so it is not a sign of commitment to the gp.• These RESULTS AGREE w/COSTLY SIGNALLING THEORY:• more displays of commitment positively relate w/higher cooperation within the gp.
Evaluation of the adaptive explanation of religious/cultural displaysThe evolutionary approach –• The adaptive value of religious displays explains the success of some religions.• By making membership ‘costly’, they increase intragp solidarity and deter outsiders from exploiting benefits of membership.
• However, this view also suggests a disadvantage is it accentuates intergroup conflict.• Sosis claims the big benefit of intragroup solidarity is:• unified gps can defend & compete against other gps.• E.g. societies w/stricter religious displays endure more intergroup conflict. (Roes & Raymond).
Cultural rituals –• Sosis had data from 60 diff societies on costs of gp rituals and frequency of warfare.• freq. of warfare was the strongest predictor of the costliness of the society’s male ritual displays.• & type of displays favoured, depended on the warfare common in the society.
• In societies where extreme warfare was more common (i.e. war against other societies) gps focused on uniting males into the largest combat gp possible.• For these societies, permanent, costly displays of gp commitment (e.g. scars, tattoos) reduce the chance of males escaping to another group.
AN EVOLUTIONARY APPROACH•An analysis of the adaptive advantages of religious ritual and commitment toreligious practices helps us to understand the success of religion from apurely evolutionary perspective.•However, there is also a dark side to this understanding. If the intragroupsolidarity that religion promotes is its significant adaptive advantage,then itsdisadvantage for a peaceful world must be its role in intergroup conflict.•As Sosis (2000) points out, one of the benefits of intragroup solidarity is theability of unified groups to defend and compete against other groups.• Roes and Raymond (2003) found that societies with stricter religiouspractices tend to have higher levels of intergroup conflict.•They argued that societies only attained large size if they were boundtogether by a religiously inspired morality, reducing internal conflict andpromoting group cooperation in the face of external enemies.
•IDA : Nature / Nurture debate•(P)The evolutionary approach focuses on the ‘nature’side of the debate only and does not consider the roleof other factors•(E)Social psychologists would probably focus on theeffects of ‘nurture’ and of conformity. They wouldexplain the behaviour in terms of conformity to groupnorms in order to be accepted by the group (i.e.normative conformity)•(E) A more ‘rounded’ explanation would take accountof both inherited / evolved factors as well as the socialinfluences which are likely to affect how an individualbehaves
Explanations of Group Display in Humans 1.WAR• Men only willing to fight aspart of coalition if confidentof victory.• In Yanomamo of Amazonrainforest, frequent fightingbetween villages overabduction of women.(Chagnon 1968)• Success in battle > highstatus• Successful warriors hadmore wives and children• Young men who had notkilled were rarely married.
• Pinker (1997) – In WW2, Germans raped women in concentration camps.• More than 20,000 Muslim girls and women raped as part of genocide programme in Bosnia.• Aim was to make the women pregnant and raise the children as Serbs, or terrorise them into fleeing the land (Allen 1996)
• Evolutionary theory can explain tribal warfare where casualties are few and rewards, great.• But in recent human history, prolonged warfare results in significant losses on both sides.• Wrangham (1999) – military incompetence is result of adaptive self-deception.• Positive illusions about winning will improve cohesion and co-operation and may bluff the opposition BUT may also lead to inaccurate assessment of own and opponents’ abilities.
Explanations of Group Display in Humans 2. SPORTS EVENTS• http://www.youtube.com/watch? v=tdMCAV6Yd0Y&NR=1• Ritualised form of aggression – benefits of success available to competitors with reduced risk of physical harm / death.• Winning team hold high status , team members seen as desirable mates.
• In certain games (eg, rugby union) a level of aggression is sanctioned but some players still break the rules.• Maxwell & Viscek (2009) – questioned 144 rugby union players about their aggression in the game.• Those high in professionalism placed more emphasis on winning and were more likely to use unsanctioned aggression.• Cheating (and not getting caught) is adaptive. What’s wrong with self report as a method ?
• Victory in matches also brings status to fans• Cialdini et al (1976) ‘basking in reflected glory’ – after a university football team had performed well, students more likely to wear university scarves and sweaters.
Football hooliganism• Marsh (1978) – football hooliganism is human equivalent of ‘ceremonial conflict’ in animals.• Exclusively male, ritualised symbolic aggression restrained by desire to minimise harm and death.• Intention is to humiliate opposition and secure submission. Is this a realistic For A02 marks, you interpretation though? could offer Research instances of football hooliganism to criticise this deindividuation theory as view. an alternative explanation for both types of group display.