Transcript Anti-Rape Powers! BAM! POW!

Rape : It is not always this cute…
Holly Herrick and Ryan Schmidt
Background of EP
Key Premises:
- Human behavior can only be understood by taking into account evolutionary
history as well as natural selection
- Behavior depends on evolved psychological mechanisms
- Mechanisms are functionally specialized to perform specific tasks/problems
related to reproductive success
- Human brain is made of specific psychological mechanisms to produce behavior
Evolved Psychological Mechanisms:
Information processing mechanisms housed in the brain that register and process
specific information and generate as output specific behaviors, physiological
activity, or input relayed to other psychological mechanisms
Adaptations of Rape with Animals
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Physical adaptations to increase capability of forced copulation
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Male Scorpion Fly
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Orangutan
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Some beetle species (see below)
Rape in Humans
Rape: The use of force or threat of force to achieve penile-vaginal
penetration of a woman without her consent
Rape results from adaptations formed from natural/sexual selection
Rape adaptations in Humans are psychological, not physical
Behavioral and learned factors increase the likely hood of the physical aspect
of rape but do not fully explain the complex organized behavior of rape
Favored Explanations:
- Rape is a product of specialized psychological adaptations
- Rape is a by-product of other adaptations in the male brain
Evidence of Human Adaptations for Sexual
Coercion and Rape
Rape must have been reproductively advantageous for human ancestors
Adapted features:
- Recognition of highly fertile women (young age – peak fertility)
However, studies show that men prefer younger women in general
Rape is a possible reproductive strategy for all human males (not just low
status/disadvantaged males)
McKibbin et al propose the existence of five types/contexts of rape
Disadvantaged Males/ Mate Deprivation
Hypothesis
Males with no other means to copulate
Rape committed by men with low socioeconomic status and lower facial symmetry
(indicators of low genetic quality)
Not necessarily indicator of strategic rape but rather higher propensity for risk taking
in general.
Specialized Rapists
Males that are sexually aroused by violent sexual stimuli
- More likely to rape fertile women (again, may not be specific to rape)
Because costs of rape may be high – it favors a rapist with the ability to have quicker
arousal and ejaculation during rape situations
Known that men can unconsciously adjust sperm count, meaning that rapists might
have this to increase odds of insemination during the single copulation
Adaptive advantage in rapid ejaculation during rape (minimizes costs to male)
Studies show 6% of rapes result in pregnancy vs. 3% in consensual mating
Opportunistic Rapists
Males who seek out receptive women, but willing to shift to force if the woman
becomes non receptive. Tend to rape when cost is low and victim is vulnerable
Low evidence for this type of rapist
Support however is seen in how rape is less common for females with family members
in the proximity
High-Mating-Effort Rapists
Males seem to be more sexually experienced, aggressive, with higher self-esteem
(commonly believed to be psychopathic)
A male who believes that he has successfully mated in the past and has a long history
of casual sexual relations is more likely to have incidents of sexual coercion in his
past.
Belief of higher need/right for sexual encounters leads to increased sexually coercive
behaviors (may result from high self-esteem)
Partner Rapists
Males motivated to rape due to increased sperm competition
Situation: husband finds out of possible infidelity of his long term partner
Due to internal fertilization makes paternity uncertain
Males who spend more time away from partners overall believe their partners are
more interested in copulating with them
Positive relation between partners infidelities and sexually coercive behavior
Women’s Defenses
Bodyguard Hypothesis: women’s mate preferences reflect stronger/socially dominant
men who possess Anti-Rape Powers!
BAM! POW!
Preeclampsia and spontaneous abortion may be a result of adaptations
Psychological pain – telling you to avoid rape next time (according to Thornhill and
Thornhill . . . )
Reproductive age women are found to be more traumatized by rape
Strength (hand grip) varies during a woman’s menstrual cycle
Women in fertile phase of cycle perform fewer high risk behaviors; more attuned to
detecting sexually coercive males
Summary
More research into psychological adaptations for rape in males, and into the
preventative measures in females needs to be completed
surprise