Marital Status and Sleeping Arrangements Predict Salivary Testosterone Levels in Rural Gambian Men (original) (raw)
Related papers
Marriage, parenting, and testosterone variation among Kenyan Swahili men
American journal of physical anthropology, 2003
Male variation in testosterone (T) levels may, in part, reflect a differential behavioral allocation to mating and parenting effort. This research tests whether demographic indicators of pair bonding and parenting were associated with salivary T levels among Kenyan Swahili men. Men in the sample were either unmarried (N = 17), monogamously married (N = 57), or polygynously married (N = 14), and between ages 29–52. In contrast with earlier findings among North American men, monogamously married men did not have lower T levels than unmarried men. However, among all married men, men with younger genetic children tended to have marginally lower T levels. Polygynously married men, all of whom had two wives, had higher T levels than all other Swahili men. Possible explanations of higher T levels among polygynously married men are explored.
Testosterone and paternal care in East African foragers and pastoralists
Proceedings of The Royal Society B: Biological Sciences, 2009
The 'challenge hypothesis' posits that testosterone facilitates reproductive effort (investment in male-male competition and mate-seeking) at the expense of parenting effort (investment in offspring and mates). Multiple studies, primarily in North America, have shown that men in committed relationships, fathers, or both maintain lower levels of testosterone than unpaired men. Data from non-western populations, however, show inconsistent results. We hypothesized that much of this cross-cultural variation can be attributed to differential investment in mating versus parenting effort, even among married fathers. Here, we directly test this idea by comparing two neighbouring Tanzanian groups that exhibit divergent styles of paternal involvement: Hadza foragers and Datoga pastoralists. We predicted that high levels of paternal care by Hadza fathers would be associated with decreased testosterone in comparison with non-fathers, and that no such difference between fathers and non-fathers would be evident in Datoga men, who provide minimal direct paternal care. Twenty-seven Hadza men and 80 Datoga men between the ages of 17 and 60 provided morning and afternoon saliva samples from which testosterone was assayed. Measurements in both populations confirmed these predictions, adding further support to the hypothesis that paternal care is associated with decreased testosterone production in men.
Hormones and behavior, 2009
Recent evidence suggests that, in humans, variations in testosterone (T) levels between men reflect their differential allocation in mating versus parenting efforts.However, most studies have been conducted inurbanized, monogamous populations, making generalizations from them questionable. This study addressesthe question of whether indicators of male reproductive effort are associated with variations in salivary Tlevels in a polygynous population of agriculturists in rural Senegal. We first show that pair-bonding and/ortransition to fatherhood is associated with T profiles: married fathers (N =53) have lower morning andafternoon T levels than unmarried non-fathers (N =28). Second, among fathers, individual differences inparenting effort, as well as variations in mating effort, predict morning T levels. Indeed, men highly investing in parental care show lower morning T levels. Moreover, among men under 50, polygynous men show highermorning T levels than monogamous men. Taken together with previous results in monogamous settings,these findings suggest that the endocrine regulation of reproductive effort is probably a general feature of human populations.
Testosterone and Marriage among Ariaal Men of Northern Kenya
Recent studies suggest that differential human male investment in mating (male-male competition and mate-seeking behavior) and parenting effort may be associated with variation in testosterone levels. The Ariaal present an interesting test case because marital relations tend to be aloof and direct paternal care minimal by cross-cultural standards. Polygyny is prevalent and increases with age, and the age-set system highly structures the transition to marriage. A test of the effect of marital status on testosterone levels among the Ariaal involved 205 men aged 20 and older from a settled agropastoral community and nomadic populations. Each participant provided morning and afternoon saliva samples in which testosterone levels were measured, provided demographic background during interviews, and had anthropometrics taken. As predicted, during the dynamic ages (20-39) of transition from life as a bachelor and warrior to monogamous marriage, men with one wife had significantly lower testosterone levels than unmarried men. Contrary to prediction, however, polygynously married men did not have higher testosterone levels than their monogamously married counterparts. While variation in testosterone may be associated with mating effort in young Ariaal men, political networks and wealth may be better predictors of marital status in older men.
Marriage and fatherhood are associated with lower testosterone in males
Evolution and Human …, 2002
In order to study the hormonal correlates of the tradeoff between mating and parenting effort in human males, we examined the salivary testosterone (T) levels of 58 Boston-area men who were either unmarried (n=29), married without children (n=14), or married with children (n=15). Additionally, we asked participants to complete a questionnaire that surveyed their demographic, marital, and parenting backgrounds. We tested the hypotheses that (1) T levels will be lower in married than in unmarried men and (2) married men with children will have lower T levels than unmarried men and married men without children. We also tested a series of hypotheses relating variation in parenting and spousal relationships to T. We found that married men with and without children had significantly lower evening T than unmarried men. No significant differences in T were found among the groups in morning samples. Among married men without children, higher scores on a “spousal investment” measure and more hours spent with a man's wife on his last day off work were both associated with lower T levels. We suggest that lower T levels during the day among fathers may facilitate paternal care in humans by decreasing the likelihood that a father will engage in competitive and/or mating behavior.
Fatherhood, pairbonding and testosterone in the Philippines
Hormones and Behavior, 2009
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.
Mothers have lower testosterone than non-mothers: Evidence from the Philippines
Hormones and Behavior, 2010
Testosterone (T) is lower among fathers and men in committed relationships, suggesting that the hormone mediates the trade-off between mating and parenting effort. The function of T in women and responses of the hormone to relationships or motherhood are less well understood. Here we report relationships between T and pairbonding and motherhood in a random sample of 67 women (20.9 to 22.4 years old) participating in a population-based birth cohort study in the Philippines. Testosterone was measured in saliva collected at bedtime and at waking the following morning to capture circadian dynamics. Compared to non-mothers and non-pairbonded women, mothers and pairbonded women had 32% (p b 0.0001) and 23% (p b 0.004) lower waking T, respectively, but similar evening T. The lower waking T in mothers largely reflected reduced T in mothers of young offspring (b 2 years), with mothers of older offspring (2+ years) having intermediate T.
Longitudinal evidence that fatherhood decreases testosterone in human males
Proceedings of the National Academy of Sciences, 2011
In species in which males care for young, testosterone (T) is often high during mating periods but then declines to allow for caregiving of resulting offspring. This model may apply to human males, but past human studies of T and fatherhood have been cross-sectional, making it unclear whether fatherhood suppresses T or if men with lower T are more likely to become fathers. Here, we use a large representative study in the Philippines (n = 624) to show that among single nonfathers at baseline (2005) (21.5 ± 0.3 y), men with high waking T were more likely to become partnered fathers by the time of follow-up 4.5 y later (P < 0.05). Men who became partnered fathers then experienced large declines in waking (median: −26%) and evening (median: −34%) T, which were significantly greater than declines in single nonfathers (P < 0.001). Consistent with the hypothesis that child interaction suppresses T, fathers reporting 3 h or more of daily childcare had lower T at follow-up compared with fathers not involved in care (P < 0.05). Using longitudinal data, these findings show that T and reproductive strategy have bidirectional relationships in human males, with high T predicting subsequent mating success but then declining rapidly after men become fathers. Our findings suggest that T mediates tradeoffs between mating and parenting in humans, as seen in other species in which fathers care for young. They also highlight one likely explanation for previously observed health disparities between partnered fathers and single men. challenge hypothesis | human evolution | hormones and behavior | paternal care | reproductive ecology I n male mammals, testosterone (T) stimulates the development and maintenance of traits and behaviors that contribute to male mating effort, including musculature, libido, conspecific aggressivity, and courtship (1-4). Although these T-driven traits factor into mating success, male reproductive fitness in some avian and mammalian species also depends on contributions to offspring care (5, 6). Because time and energy are finite , males in these species often face tradeoffs between conflicting behaviors related to mating and parenting. Adjustment of T production has been proposed as a physiological mechanism underlying this tradeoff, with males who focus on mating effort predicted to maintain elevated T, whereas males who cooperate with a female partner and invest in parental care should reduce T production (6, 8). This model is well supported by data from a variety of avian species (6, 8), but evidence for its applicability to mammalian species in which males provide direct care is mixed (9). It is presently unclear whether T mediates the tradeoff between mating and parenting effort in human males, who often express paternal care facultatively.
Hormones and Behavior, 2013
Testosterone (T) is thought to help facilitate trade-offs between mating and parenting in humans. Across diverse cultural settings married men and fathers have lower T than other men and couples' sexual activity often declines during the first years of marriage and after having children. It is unknown whether these behavioral and hormonal changes are related. Here we use longitudinal data from a large study in the Philippines (n = 433) to test this model. We show that among unmarried non-fathers at baseline (n = 153; age: 21.5 ± 0.3 years) who became newly married new fathers by follow-up (4.5 years later), those who experienced less pronounced longitudinal declines in T reported more frequent intercourse with their partners at follow-up (p b 0.01) compared to men with larger declines in T. Controlling for duration of marriage, findings were similar for men transitioning from unmarried to married (without children) (p b 0.05). Men who remained unmarried and childless throughout the study period did not show similar T-sexual activity outcomes. Among newly married new fathers, subjects who had frequent intercourse both before and after the transition to married fatherhood had more modest declines in T compared to peers who had less frequent sex (p b 0.001). Our findings are generally consistent with theoretical expectations and cross-species empirical observations regarding the role of T in male life history trade-offs, particularly in species with bi-parental care, and add to evidence that T and sexual activity have bidirectional relationships in human males.
Does Cosleeping Contribute to Lower Testosterone Levels in Fathers? Evidence from the Philippines
PLoS ONE, 2012
Because cross-species evidence suggests that high testosterone (T) may interfere with paternal investment, the relationships between men's transition to parenting and changes in their T are of growing interest. Studies of human males suggest that fathers who provide childcare often have lower T than uninvolved fathers, but no studies to date have evaluated how nighttime sleep proximity between fathers and their offspring may affect T. Using data collected in 2005 and 2009 from a sample of men (n = 362; age 26.0 6 0.3 years in 2009) residing in metropolitan Cebu, Philippines, we evaluated fathers' T based on whether they slept on the same surface as their children (same surface cosleepers), slept on a different surface but in the same room (roomsharers), or slept separately from their children (solitary sleepers). A large majority (92%) of fathers in this sample reported practicing same surface cosleeping. Compared to fathers who slept solitarily, same surface cosleeping fathers had significantly lower evening (PM) T and also showed a greater diurnal decline in T from waking to evening (both p,0.05). Among men who were not fathers at baseline , fathers who were cosleepers at follow-up (2009) experienced a significantly greater longitudinal decline in PM T over the 4.5-year study period (p,0.01) compared to solitary sleeping fathers. Among these same men, baseline T did not predict fathers' sleeping arrangements at follow-up (p.0.2). These results are consistent with previous findings indicating that daytime father-child interaction contributes to lower T among fathers. Our findings specifically suggest that close sleep proximity between fathers and their offspring results in greater longitudinal decreases in T as men transition to fatherhood and lower PM T overall compared to solitary sleeping fathers.