Reproductive ecology and life history of the human male

Bribiescas, Richard G.

doi:10.1002/ajpa.10025

Cited by 211 publications

(130 citation statements)

References 305 publications

(315 reference statements)

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“…Consistent with data from a range of non-western populations (Bribiescas 2001;Ellison 2003), both Hadza and Datoga men maintained low levels of testosterone in comparison with North American men. Morning testosterone levels averaged 151 and 170 pmol l K1 in the Hadza and the Datoga, respectively.…”

Section: Resultssupporting

confidence: 78%

Testosterone and paternal care in East African foragers and pastoralists

et al. 2008

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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.

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Section: Resultssupporting

confidence: 78%

Testosterone and paternal care in East African foragers and pastoralists

et al. 2008

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“…Age is a likely factor that might account for the failure to document a relationship between male rank and testosterone at Ngogo (Table 1). Testosterone decreases with age in human males (Bribiescas 2001), and some high and middle ranking male chimpanzees in our sample were old. Further research will be necessary to investigate this possibility.…”

Section: Discussionmentioning

confidence: 59%

Female parity, male aggression, and the Challenge Hypothesis in wild chimpanzees

2012

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The Challenge Hypothesis proposes that testosterone mediates aggression during periods of heightened conflict between males, especially episodes that have important fitness consequences. Considerable evidence from seasonally breeding species provides support for this hypothesis, but few data exist in animals that mate yearround. We tested predictions generated by the Challenge Hypothesis in chimpanzees, a non-seasonally breeding primate, through a study of individuals living in an exceptionally large community at Ngogo, Kibale National Park, Uganda. Results indicated that dominance rank had no influence on testosterone levels. Instead of rank influencing testosterone production, additional analyses revealed an important role for reproductive competition. Male chimpanzees displayed more aggression when they were in the same party as parous estrous females than when reproductively active females were unavailable. Male chimpanzees competed more intensely for mating opportunities with parous females than with nulliparas, and as a consequence, males displayed more aggression around the former than the latter. When males accompanied parous estrous females, their urinary testosterone concentrations were significantly higher than baseline concentrations. In contrast, urinary testosterone concentrations did not exceed baseline when males associated with nulliparous estrous females. These differences in testosterone levels could not be attributed to mating per se because males copulated equally often with parous and nulliparous females. Furthermore, variation in testosterone concentrations were not due to males gathering together in large parties, as their levels in these situations did not exceed baseline. Taken together, these findings, derived from a relatively large sample of males and estrous females, replicate those from a prior study and furnish additional support for the Challenge Hypothesis. Our results suggest that the Challenge Hypothesis is likely to be broadly applicable to chimpanzees and increase our understanding of the physiological costs to males who compete for estrous females.

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“…Although we did not measure the behavioral or physical pathways linking T with mating success in this analysis, T has previously been shown to bolster traits related to mating effort and attractiveness, such as musculature (1,28,29), motivation to win during competition (30), and pursuit of social dominance (2,31). Men with higher T have also been shown to have physical attributes deemed attractive by females and to have more recent and lifetime sexual partners (32)(33)(34).…”

Section: Discussionmentioning

confidence: 99%

“…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)(2)(3)(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).…”

mentioning

confidence: 99%

Longitudinal evidence that fatherhood decreases testosterone in human males

Gettler

McDade

Feranil

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

434

381

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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 (7), 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.Humans have been described as serial monogamists who frequently engage in one or more long-lasting partnerships with females during reproductive life spans that last several decades (10-12). Humans are one of the few mammalian species in which paternal care is relati...

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Reproductive ecology and life history of the human male

Cited by 211 publications

References 305 publications

Testosterone and paternal care in East African foragers and pastoralists

Testosterone and paternal care in East African foragers and pastoralists

Female parity, male aggression, and the Challenge Hypothesis in wild chimpanzees

Longitudinal evidence that fatherhood decreases testosterone in human males

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