Understanding Aggression: Evolutionary Insights on Female Behavior

1. The relevance of our evolutionary history for understanding aggression The case of women Marta Iglesias Julios

2. Tools to solve collective problems We often have in mind the problems that our citizens are facing such as drug addiction, suicides or various forms of crime Specific problems often demand specific policy and legislative solutions

3. Tools to solve collective problems Our social problems are all specific manifestations of a more general human nature Crime arises partly because human beings have always fought over dominance using aggression

4. To understand and prevent crime, it can be helpful to better understand the universal human desire to dominate

5. Talk overview Main objective Apply this general framework to the problems of aggression among females Breakdown of the talk • Part 1: the specific evidence regarding female-female aggression • Part 2: the general (multi-cultural) patterns • Part 3: biology and evolutionary triggers of aggressive behaviour • Part 4: conclusions

6. Is consistent across countries and regions, irrespective of the homicide typology or weapon used Source: United Nations Office on Drugs and Crime. (2013). UNODC. Part 1: the specific evidence Men are much more likely to murder, to rape, or to generally use physical violence

7. Part 1: the specific evidence Does not mean that female aggression is non-existent or harmless Women use more indirect means like bullying and reputation harming Indirect aggression creates very real problems: social isolation, bullying... Nonfatal Self-Inflicted Injury Emergency Department Visits Among Youth Aged 10 to 24 (not based on self-report studies) Rise in self-harm rate among teenage girls. No significant trends for annual percentage change for males. Source: Mercado, et al (2017). JAMA

8. Part 1: the specific evidence Does not mean that female aggression is non-existent or harmless Women use more indirect means like bullying and reputation harming Indirect aggression creates very real problems: social isolation, bullying... Adolescent girls are significantly more likely to have experienced cyberbullying in their lifetimes (36.7% vs. 30.5%) Source: Hinduja and Patchin (2016)

9. more research is necessary The most honest attitude is to say that we really don’t know much about the relationship between important issues like bullying and self-harm

10. Part 1: the specific evidence • Bullying at the workplace • In the workplace, women report experiencing more incivility from other women than from men

11. Part 1: the specific evidence • Bullying at the workplace • Females believed that other women are good managers, but the female workers did not actually want to work for them.

12. Part 1: the specific evidence • Bullying at the workplace • Women will abdicate the opportunity to support highly or moderately qualified female candidates as potential work group peers. Because often see highly qualified female candidates as “competitive threats” and lower qualified female candidates as “collective threats”

13. Part 1: the specific evidence • Violence in same sex partners • Nearly 1 in 3 lesbian women, 1 in 2 bisexual women, and 1 in 4 heterosexual women has experienced at least one form of severe physical violence by an intimate partner in her lifetime Source: Walters, M.,et al (2011). National Intimate Partner and Sexual Violence Survey 2010: Findings on Victimization by Sexual Orientation.

14. Part 1: the specific evidence • Violence in same sex partners • 4 in 10 lesbian women (43.8% of women IPV) and approximately 1 in 4 gay men (26.0% of man IPV) reported experiencing rape, physical violence, and/or stalking within the context of an intimate partner relationship at least once Source: Walters, M.,et al (2011). National Intimate Partner and Sexual Violence Survey 2010: Findings on Victimization by Sexual Orientation. Lifetime Prevalence of Rape, Physical Violence, and/or Stalking Victimization by an Intimate Partner by Sexual Orientation

15. Part 1: the specific evidence • Family Wars and cooperation • The preeminence of the ideology of combative mothering—at least in the United States—appears to make it challenging for mothers to make sense of relationships between mothers outside of a mandate to be the best, which requires being better than other mothers.

16. Part 1: the specific evidence • Family Wars and cooperation • Female groups engaged in social ostracism more than male groups did

17. Part 1: the specific evidence • Family Wars and cooperation • While 15 % of mother-in-law/son-in-law relationships have some tension, 60% percent of mother-in-law/daughter-in-law bonds are described by some strong negative term. Source: Apter, T. (2010). What do you want from me?: Learning to get along with in-laws. WW Norton & Company.

18. Part 1: the specific evidence • Family Wars and cooperation • High status women reported that they would invest less in partners than high status men. High status males intuitively evaluate sharing rewards with same sex partners as more beneficial

19. Part 1: the specific evidence • More aggressive responses • Females reported more negative reactions than males when outperformed by their same-sex peers. Further, compared with males, female participants believed that their samesex friends would have more negative reactions if they performed better than their friends

20. Part 1: the specific evidence • More aggressive responses • Females are more likely than males to respond to threats of social exclusion with exclusion. The results further suggest that females and males compete in different ways.

21. Part 1: the specific evidence • More aggressive responses • Women reported their anger would dissipate less quickly and they would take longer to reconcile. The results indicate that women are less prepared than men to resolve a conflict with a same-sex peer

22. Part 1: the specific evidence • More aggressive responses • Adolescent girls are more often victims of social exclusion by their peers

23. Part 1: the specific evidence • More aggressive responses • The victims are usually girls bullied by girls. The factors that encourage this aggression are physical attractiveness and sexual activity

24. Part 1: the specific evidence • More aggressive responses • Indirect aggression from women towards other women is about self-promotion and by disparaging the competitor’s appearance or by spreading rumours that question the fidelity or level of promiscuity of a rival

25. Part 1: the specific evidence • More aggressive responses • Women damage rivals' reputations but do not report explicitly disliking them

26. Women do exhibit systematic aggressive tendencies

27. Part 1: the specific evidence. Why is it important? Many forms of female aggression do cross the line from unpleasant to the truly damaging • Same sex spousal abuse • Child abuse • Bullying-triggered self-harm (more research needed) The possible damage from verbal forms of aggression (more research is needed) • Indirect undermining of diversity initiatives • Loss of ability to jointly understand good parenting practices • Weakening of society's capacity for cooperation

28. Part 2: The general patterns. Multicultural meta-analysis When women commit aggressive acts, they usually do so against other women and they use indirect forms of aggression Source: Archer, J. (2004). Sex differences in aggression in real-world settings: A meta-analytic review. Review of general Psychology, 8(4), 291.

29. Part 2: The general patterns. Multicultural meta-analysis The differences exist since early childhood Self-report: Source: Archer, J. 2004 Sex Differences in Aggression in Real-World Settings Archer, J. 2009 does sexual selection explains human sex differences in aggression Physical Aggression Verbal Aggression Indirect Aggression

30. Part 2: The general patterns. Multicultural meta-analysis The tendency of boys and girls to attack each other increases progressively with age Peer-report: Source: Booth, A. 2012 Choosing to compete, How different are girls and boys Niederle, M. 2011 Gender and Competition Wilson, M. and Daly, M. 1985 Competitiveness, risk taking, and violence: the young male syndrome Indirect Aggression Physical Aggression

31. Why is the female aggression type so different from the typical male method?

32. Part 3: Biology and evolutionary triggers of aggression Evolutionary game theory, evolutionary ecology and evolutionary biology All human beings have something in common: we are offspring Dobzhansky Fisher Mayr Maynard Smith

33. Part 3: Biology and evolutionary triggers of aggression An evolutionary perspective is not prescriptive It does not imply that what has evolved is morally good Explains why human behaviour is sometimes very stereotyped

34. Part 3: Biology and evolutionary triggers of aggression What evolutionary theory tells us about aggression: • Men and women have to compete to be chosen by a partner • We also compete for the help of other members of the group • Indirect aggression is often attributed to the way human reproduction works Our cultural dimension affects the way we reproduce

35. Part 3: Biology and evolutionary triggers of aggression What evolutionary theory tells us about aggression: • Men and women have to compete to be chosen by a partner • We also compete for the help of other members of the group • Indirect aggression is often attributed to the way human reproduction works Our cultural dimension affects the way we reproduce

36. Part 3: Biology and evolutionary triggers of aggression What evolutionary theory tells us about aggression: • Men and women have to compete to be chosen by a partner • We also compete for the help of other members of the group • Indirect aggression is often attributed to the way human reproduction works Our cultural dimension affects the way we reproduce

37. Part 3: Biology and evolutionary triggers of aggression Aggressivestrategies are not necessarily implemented through strategic planning Most of these impulses seem to remain subconscious within us Hormones certainly influence how likely we are to commit aggression There is also a genetic component to consider Women harm reputations of attractive, flirtatious, and provocatively dressed women Mother lion protect her child

38. Psychiatric diagnosis Criminality Antisocial behavior Aggression Source: Bouchard, T. J. 2001 Genes, evolution, and personality Rhee, S. H. 2002 Genetic and environmental influences on antisocial behavior A meta-analysis of twin and adoption studies. Part 3: Biology and evolutionary triggers of aggression Self-report Peer-report Criminal records Experimental Heritability of aggression Children Adolescents Adults additive genetic influences nonadditive genetic influences shared environmental influences nonshared environmental influences Females Males Twin studies Adoption (parents) Adoption (siblings)

39. Part 4: Conclusions • Women engage in several forms of aggressive behaviour. The primary type seems to be reputation harming which is directed mainly at other women. These behaviour changes how to cooperate in groups and in extreme cases can lead to ostracism • The female tendencies toward indirect same sex aggression seem to be explained by our evolutionary need to compete for the best mates and for the best social support, while avoiding lasting physical damage to our bodies • About 40% of the variation between tendencies towards aggressive behaviour is modulated by genes. During our lifetime, these genetic influences are implemented through the wiring of our brain and the level of hormones in our bodies • We need more research in how non-physical female aggression has an impact on society