Award Date


Degree Type


Degree Name

Doctor of Philosophy (PhD)



First Committee Member

Peter B. Gray

Second Committee Member

Daniel Benyshek

Third Committee Member

William Jankowiak

Fourth Committee Member

Marta Meana

Number of Pages



This project investigates the influence of lactation on female sociosexuality and mate preferences in urban Manila, a population with long-term breastfeeding, low contraceptive use, and quick return to ovulatory cycling. Physiological and evolutionary considerations suggest that lactating women face important life history allocation trade-offs between mating and parenting effort that may be manifest in their sociosexual behavior and mate preferences. Breastfeeding (n=155) and control (n=105) women were recruited to provide a saliva sample (for testosterone and estradiol analyses), complete a questionnaire, and complete a face and voice preference task to determine preferences for masculinity. Breastfeeding women reported differences in commitment to their relationship, jealousy levels, and sexual functioning. Breastfeeding women reported feeling more committed to their relationship and less jealousy than regularly cycling women. Breastfeeding women reported higher sexual functioning, including higher sexual satisfaction and more orgasms than regularly cycling women. Breastfeeding women also had a higher preference for higher-pitched voices than the regularly cycling women. Cultural and life history factors are discussed and aid interpretation of the findings. This study benefits from an empirically-based quantification of women's negotiations between mating and parenting efforts, and culturally-relevant information regarding maternal health, long-term breastfeeding, and evolutionary-based ideas of women's sexuality and trait preferences.


Breastfeeding; Estrogen; Mate selection; Maternal health; Mothers – Health and hygiene; Philippines – Manila; Sexuality; Testosterone


Gender and Sexuality | Hormones, Hormone Substitutes, and Hormone Antagonists | Women's Studies

File Format


Degree Grantor

University of Nevada, Las Vegas




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