Testosterone levels correlate with the number of children in human males, but the direction of the relationship depends on paternal education (original) (raw)
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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.
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, 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.
Hormones and Behavior, 2020
Male testosterone (T) decreases in response to childbirth. Longitudinal support for this has come from samples across cultures. In this study, we look at individual differences in this phenomenon. Utilizing a sample of U.S. fathers, we employ life history theory to investigate the influence of a father's early experience on his neuroendocrine response to fatherhood. We conducted three home visits (n = 226 fathers) from the third trimester of pregnancy to when infants were 10 months old. In this sample, T declined from the third trimester of (a partner's) pregnancy to the early months of the postnatal period. T recovered to pre-birth levels by the time infants reached 10 months old. We did not find any evidence that one's subjective experience of their early environment could account for any meaningful variability in T calibration. Objective, "event" measures of early harshness (i.e., death of a sibling/friend) and unpredictability (i.e., parent upheaval) each uniquely predicted a younger age of sexual debut. Neither harshness nor unpredictability had any (direct or indirect) effects on T calibration. Age of sexual debut did predict the rate of T recovery from 3 to 10 months postnatal. The younger one's sexual debut, the more accelerated their T ascent during this period. We discuss the potential reasons for, and implications of our mixed results.
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.
… of the Royal …, 2006
A growing body of evidence, almost entirely from North America, has found that male testosterone levels are positively associated with mating effort (male–male competition and mate-seeking behaviour), while lower testosterone levels have been associated with affiliative pair bonding and paternal care. To expand the cross-cultural scope of this research, here we investigate variation in salivary testosterone levels among Chinese men in relation to marital and parenting variables. One hundred and twenty-six men drawn from a Beijing university setting between the ages of 21 and 38 completed a questionnaire and provided both morning and late afternoon saliva samples from which testosterone levels were measured. The 66 unmarried men had slightly higher levels of testosterone than the 30 married non-fathers, but this difference was not statistically significant. However, the 30 fathers exhibited significantly lower testosterone levels than both unmarried men and married non-fathers. Among married non-fathers, marital relationship quality was not significantly related to testosterone levels. Among married fathers, men with children aged less than 4 years of age did not have lower testosterone levels than men with older children. These data are the first outside of North America to show lower testosterone levels among fathers, and lend support to the theoretical view that male testosterone levels differ according to mating and parenting effort.
Adaptive Human Behavior and Physiology, 2014
Past paternal psychobiology research has focused almost exclusively on biological, residential fathers and the role of fathers as direct caregivers. Here, drawing on a large sample of Filipino men, we help to expand this research area by testing for relationships between fathers' testosterone, prolactin, and weekly hours in work, childcare, and recreation. Using longitudinal data collected when men were an average of 21.5 and 26.0 years old, we tested whether changes in fathers' investments in childcare and work interrelated with testosterone changes. We also assessed whether fathers' residence status affected paternal testosterone changes. Cross-sectionally, we did not find evidence that fathers' testosterone or prolactin varied based on work effort or weekly hours of childcare (all p>0.1). Fathers who increased their weekly involvement in childcare between baseline and follow-up experienced declines in testosterone, on average (p<0.05). Men who transitioned from being non-fathers (baseline) to being new fathers residing with their children (follow-up) experienced significantly larger declines in both waking and evening testosterone, compared to men who were residential fathers at both time points (both p≤0.0001). Men who became new fathers but were not residing with their children also showed significantly greater declines in evening testosterone, relative to the comparison group (p<0.05). Our results add confirmation and expansion of the notion that low paternal testosterone is linked to heightened father-child interaction and proximity, but leave open the possibility that Adaptive Human Behavior and Physiology fatherhood can also affect men's testosterone independent of whether they reside with their children.
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.
2020
In human males, testosterone (T) decreases in the period following the birth of offspring. This decline has been widely interpreted as a facultative neuroendocrine response that facilitates parenting effort. Conversely, research on if (or when) this decline in T would be followed by an eventual recovery and subsequent shift away from parenting effort is lacking. In a U.S. community sample of 225 males transitioning to first-time fatherhood, we measured T at three occasions: third trimester, infant 3 months postnatal, and infant 9-10 months postnatal. Using a piecewise latent growth curve model (GCM), we detected a T rebound from when infants were 3 months old to when infants were 9-10 months old. The slope of this rebound was able to predict paternal care using two distinct measures: (a) an experience sampling method (ESM) that gathered data on paternal time allocation over the course of the study period and (b) independent coders rating fathers for the quality of paternal care duri...
Sensation seeking in fathers: The impact on testosterone and paternal investment
Hormones and Behavior, 2012
Paternal care is associated with a reduced likelihood of engaging in competitive or mating behavior and an increased likelihood of providing protection when necessary. Over recent years, there has been increasing evidence to assume that the steroid testosterone (T) in men might reflect the degree of mating effort. In line with this, decreased T levels were shown in fathers compared to non-fathers and it was suggested that paternal care, and most behavior positively associated with T, might be incompatible with each other. Independently, the personality trait sensation seeking (SS) has been related to mating behavior and also to elevated T in men. Aiming to integrate these different lines of research in a longitudinal approach, we explored the impact of SS on T levels in the context of the transition to fatherhood. Thirty-seven fathers and 38 men without children but in committed, romantic relationships (controls) were recruited. At two time points (for fathers: four weeks prior to (t1) and eight weeks after birth (t2)), all subjects repeatedly collected saliva samples for T measurement, filled in a protocol of activities during the course of these days and completed an online questionnaire. In line with our hypotheses, the results show significantly lower aggregated (AUC-T) T levels in fathers compared with non-fathers. Furthermore, moderation analyses revealed a significant interaction between group and SS at t2, with the lowest T levels in low SS fathers. These data suggest that adaptation processes of the transition to fatherhood are influenced by individual differences in personality traits.