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Evolutionary forensic psychology perspectives

Evolutionary forensic psychology perspectives. Presented By: Joseph A. Camilleri Evolutionary Psychology November 8 th , 2002. Definitions. Homicide Killing of one human being by another Neonaticide Killing of an infant within 24 hours after his/her birth Infanticide

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Evolutionary forensic psychology perspectives

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  1. Evolutionary forensic psychology perspectives Presented By: Joseph A. Camilleri Evolutionary Psychology November 8th, 2002

  2. Definitions • Homicide • Killing of one human being by another • Neonaticide • Killing of an infant within 24 hours after his/her birth • Infanticide • Killing of an infant within 1 year after his/her birth • Filicide • Killing of a son/daughter over the age of 1 • Uxoricide • Killing of the wife by a husband • Parricide • Killing one’s parent

  3. Why study homicide? • Conflict assay (Daly & Wilson) • Window on evolved motivations that are rarely lethal • Severe and genuine conflict • Unlike self-report • Minimal biases of detection & reporting

  4. Adaptive or Non-Adaptive Byproduct? • Homicide is rare • Non-Adaptive Byproduct 1. Male competition 2. Discriminative parental solicitude 3. Sexual jealousy/proprietariness

  5. Who are the victims of homicide? 13th Century England Homicide Data Victims are rarely related to the offender Co-offenders are more likely to be genetically related (Daly & Wilson, 1988)

  6. Cross-cultural data Daly & Wilson (1988) Homicide

  7. Who does the killing? Daly & Wilson (1990) Human Nature 1: 83-109

  8. Most common situation… Men killing men Motives… • Majority of all homicides (37%) are “altercations of relatively trivial origin; insult, curse, jostling etc” (Wolfgang, 1958) • “Altercations appeared to be the primary motivating forces… usually trivial, indicating that many homicides are spontaneous acts of passion” (Mulvihill, Tumin & Curtis, 1969)

  9. Most common situation continued… Maladaptive By-product #1: Competition • Females are choosey • Look for dominant male • Insults focus on one’s dominance (weak, poor…) • Violence is an adaptive way of deterring/resolving Examples… • Movie • Duels • Men willing to die for honour • ‘Chicken’ • Car race to edge of cliff

  10. Most common situation continued… • Generally, violent behaviour is related to fitness and lethality may be governed by situation • Less secure society, homicide may be seen as ‘adaptive’ eg Dani Tribe, ‘kepu’ • Some groups, killing is a primary method of survival eg Mafia • Variance of income

  11. Familicide All homicides: Detroit 1972 Killing relatives: Detroit 1972 * 75% of all familial homicides were directed against non-genetic kin

  12. Uxoricide Two possible theories • Risk increases with age -Due to less value • Risk decreases with age -Younger, more valuable mate increases jealousy/proprietary

  13. Uxoricide continued… The winner is… • Risk decreases with age Wilson & Daly (1998) in Rethinking Violence against Women (Dobash & Dobash, eds.)

  14. Uxoricide continued… Maladaptive By-product #2: Sexual Proprietariness (Daly & Wilson) • Males guard and control a valuable mate • Males will change efforts due to… • Factors affecting her mate value (youth, health) • Factors affecting his mate value (status, resources) • Competition (sex ratio and qualities of rivals)

  15. Uxoricide continued… • Factors affecting his mate value & competition • Study by Dijkstra & Buunk (1998) • Males are influenced by a rival’s dominance • More dominant rivals evoke greater sense of jealousy • These types of responses may be adaptive, but lethal consequences are not

  16. Uxoricide continued… Potential confound #1? • Coincides with age of males that murder more often… • NO: Risk is elevated with older husbands Age specific rates of killing same sex unrelated persons Uxoricide rates for wives aged 15-24 years Homicides per million Daly & Wilson (1999) Scientific American Presents 10(2): 8-14

  17. Uxoricides (1974-1995) Genetic Mixed Step only only Daly et al. 1997 Homicide Studies 1: 61-71 Uxoricide continued… • Does presence of step children increase uxoricide risk? • YES: Evidence for greater shelter admissions and uxoricides with presence of step-children (Daly & Wilson) Shelter admissions (1986-1987) per 1000 per annum Genetic Mixed Step only only

  18. Neonaticide, Infanticide & Filicide Homicides per million • Who is at most risk? 1. Stepchildren: Child’s age (years) Canada 1974 - 1990

  19. Filicide continued… Maladaptive by-product #3: Discriminative Parental Solicitude • *Remember, step-parental homicide is RARE, however, presence of a step-parent increases a child’s risk by over 100% • Makes sense to invest more with children who are genetically related • Spend less $ per child on food • Less financial support for college

  20. Filicide continued… Per capita rates of validated child abuse reports to the American Humane Association, 1976 • Who is at most risk? • Younger children Wilson et al (1980) J Biosocial Science 12: 333 - 340

  21. Filicide continued… • Who is at most risk? • 3. Children with younger mothers England & Wales 1977-1990 Ayoreo: Mid- 20th Centruy Canada: 1974-1990

  22. Filicide continued… • Maladaptive by-product #4: Residual reproductive value • - the older the mother the lower the opportunity cost

  23. Summary • Definitions • Conflict assay • Adaptive vs Non-adaptive byproduct • Male competition • Sexual proprietariness • Discriminative parental solicitude • Residual reproductive value • Homicide perpetrators/victims • Homicide, uxoricide, filicide

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