title: Fatherhood, pairbonding and testosterone in the Philippines.
abstract: In species with a high level of paternal care, including humans, testosterone (T) is believed to help mediate the trade-off between parenting and mating effort. This hypothesis is supported by the observation of lower T in pairbonded men or fathers compared to single, non-fathers; however, prior work has highlighted population variation in the association between T and pairbonding or fatherhood status. Here we evaluate this hypothesis in a large (n=890), representative birth cohort of young men (age range 20.5-22.5 years) living in Cebu City, the Philippines. Bioavailable T was measured in saliva collected prior to bed and immediately upon waking the following morning. Plasma T and luteinizing hormone (LH) were measured in morning plasma samples. In this sample, 20% of men were pairbonded, defined as living with a partner or married, 13% were fathers, and roughly half of fathers reported involvement in childcare. Pairbonded men had significantly lower T at both times of day. Unlike in other populations, this relationship was accounted for entirely by fatherhood status: among the large sub-sample of non-fathers, mean T was nearly identical among pairbonded and single men. There was a strong association between self-reported involvement in childcare and lower evening T, supporting the idea that the evening nadir in T is related to social interactions across the day. Similar relationships were found for total plasma T and LH, suggesting that these relationships are coordinated by centrally-mediated changes in LH secretion. The relatively modest T difference in relation to fatherhood at Cebu, in comparison to other studies, may reflect a lower level of paternal involvement in childcare activities in this population. Our findings using a large, well-characterized birth cohort support the hypothesized role of T as a mediator of mating and parenting effort in humans, while contributing evidence for cultural variation in the relative importance of pairbonding and fathering to these relationships.
authors: Northwestern University, Department of Anthropology, Evanston, IL 60208, USA. kuzawa@northwestern.edu
authors: Christopher W
authors: CW
authors: Kuzawa
authors: Lee T
authors: LT
authors: Gettler
authors: Martin N
authors: MN
authors: Muller
authors: Thomas W
authors: TW
authors: McDade
authors: Alan B
authors: AB
authors: Feranil
mesh_terms: D015331:Cohort Studies; D005219:Father-Child Relations; D005220:Fathers; D006801:Humans; D007398:Interpersonal Relations; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008393:Marriage; D010679:Philippines; D017440:Photoperiod; D012044:Regression Analysis; D012463:Saliva / Q000378:metabolism; D013739:Testosterone / Q000097:blood / Q000378:metabolism*; D013997:Time Factors; D055815:Young Adult
chemical_list: D013739:Testosterone; D007986:Luteinizing Hormone