Short-term Mating Overview of the Day Definitions Evidence Costs and benefits Individual differences

What is Short-Term Mating? Sexual intercourse with: little prior acquaintance with partner, and/or little commitment to future relationship with partner and/or little commitment to be sexually faithful to partner

Some Questions What are ultimate and proximate causes of ST mating? Is ST mating an evolved mating strategy, culturally determined, or due to individual differences? Are there differences between male and female ST mating strategies and why?

Evidence for ST Mating as an Evolved Strategy in Men Kamikaze sperm Larger sperm counts after separation from mate (712 mil. Vs 389 mil) Across species, testicle size is correlated with frequency of multiple matings testicle size as a percentage of body weight: (.018, gorilla; .079, human, .269, chimp)

Evidence for ST Mating as an Evolved Strategy in Men Male preference for sexual variety Estimates that 50% of men have had an extra-marital affair Prostitution (exists over time and culture; prostitutes are primarily female; their clients are primarily male) Male sexual fantasies often involve sexual variety (e.g., multiple female partners)

Benefits to Males More offspring By ST partner A hypothesis to be tested : By LT partner (by enhancing sexual interest, testosterone level, and self-esteem)

Costs to Males STD Sullied reputation Being physically attacked (e.g., by ST partner’s husband or boyfriend) Economic, occupational, legal losses Retaliation (sexual and other) and divorce by wife Lower quality care and outcomes for children fathered in ST relationships

Evidence for ST Mating as an Evolved Strategy among Women Orgasms and affairs Timing of affairs with ovulation Evidence of affairs in all cultures Evidence of number of children fathered by male other than LT partner

Benefits to Females Resources and protection Genetic benefits (fertility, quality, diversity) Mate switching

Costs to Females STD Sullied reputation Abuse (ST partner, LT partner) Loss of investment from LT partner Unwanted pregnancy Sole support of children Hostility by LT partner and other offspring toward children fathered by ST partner

Individual Differences in Frequency of ST Mating Women with the following characteristics tend to engage in more ST relationships higher testosterone levels more masculine self image Girls raised in homes where father is absent reach puberty earlier are at higher risk for promiscuous sexual behavior and teenage pregnancy

Individual Differences in Frequency of ST Mating Males and females are more likely to engage in ST mating when they perceive that they have high mate value have anxious personalities

Summary ST Mating: definition and evidence Costs and benefits Individual differences