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

2. 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

3. 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?

4. 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)

5. 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)

6. 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)

7. 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

8. 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

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

10. 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

11. 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

12. 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

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