Men in committed, romantic relationships have lower testosterone

Variation in human male testosterone levels may reflect, and effect, differential behavioral allocation to mating and parenting effort. This proposition leads to the hypothesis that, among North American men, those involved in committed, romantic relationships will have lower testosterone levels than men not involved in such relationships. Our study is the first to examine whether being in such a relationship (rather than being married) is the meaningful predictor of male testosterone levels. To test this hypothesis, 122 male Harvard Business School students filled out a questionnaire and collected one saliva sample (from which testosterone level was measured). Results revealed that men in committed, romantic relationships had 21% lower testosterone levels than men not involved in such relationships. Furthermore, the testosterone levels of married men and unmarried men who were involved in committed, romantic relationships did not differ, suggesting that, at least for this sample, male pair bonding status is the more significant predictor of testosterone levels than is marital status.     

Male-female differences in effects of parental absence on glucocorticoid stress response

This study examines the family environments and hormone profiles of 316 individuals aged 2 months-58 years residing in a rural village on the east coast of Dominica, a former British colony in the West Indies. Fieldwork was conducted over an eight-year period (1988–1995). Research methods and techniques include radioimmunoassay of cortisol and testosterone from saliva samples (N=22,340), residence histories, behavioral observations of family interactions, extensive ethnographic interview and participant observation, psychological questionnaires, and medical examinations. Analyses of data indicate complex, sex-specific effects of family environment on endocrine function. Male endocrine profiles exhibit greater sensitivity to presence of father than do female endocrine profiles. Father-absent males tend to have (a) low cortisol levels during infancy, (b) high or abnormal cortisol profiles during childhood and adolescence, and (c) high cortisol and low testosterone levels during adulthood compared with those of males raised with a resident father. These results indicate that early family environment has significant effects on endocrine response throughout male life histories. Mark V. Flinn is an Associate Professor of Anthropology at the University of Missouri, Columbia. He studies family relationships, endocrine stress response, and child health from a mix of evolutionary and developmental psychology perspectives. Robert J. Quinlan is a graduate student in the Department of Anthropology at the University of Missouri, Columbia. His interests include time allocation, family relationships, and medical anthropology. He is planning a long-term ethnographic study of cross-cousin marriage among the E’nyepa of Venezuela. Mark T. Turner is a graduate student in the Department of Anthropology at Northwestern University. He studies covariance of mother and infant hormone and immune function in naturalistic settings using assays from saliva and breast milk samples and ethnographic observations. Seamus A. Decker is a graduate student in the Department of Anthropology at Emory University. He has studied social factors associated with daily variations of salivary cortisol and testosterone levels among males in a Caribbean village. He is currently investigating levels of stress in rural and urban populations in Botswana. Barry G. England is an Associate Professor of Pathology and director of the ligand assay laboratories of the University of Michigan Hospitals. His primary interests concern reproductive endocrinology.     

Testosterone and paternal care in East African foragers and pastoralists

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.     

The presence of a woman increases testosterone in aggressive dominant men

In line with the challenge hypothesis, this study investigated the effects of the presence of a woman on the testosterone (T) levels of young men. An informal contact with a woman of approximately 5 min resulted in an increase in salivary T among men. These effects occurred particularly in men with an aggressive dominant personality. In addition, higher salivary T levels were related to a more aggressively dominant personality, being sexual inactive for a month or more, and not being involved in a committed, romantic relationship. The most important findings of this study are that the short presence of a woman induces specific hormonal reactions in men, and that these effects are stronger for aggressively dominant men.     

The presence of a woman increases testosterone in aggressive dominant men

In line with the challenge hypothesis, this study investigated the effects of the presence of a woman on the testosterone (T) levels of young men. An informal contact with a woman of approximately 5 min resulted in an increase in salivary T among men. These effects occurred particularly in men with an aggressive dominant personality. In addition, higher salivary T levels were related to a more aggressively dominant personality, being sexual inactive for a month or more, and not being involved in a committed, romantic relationship. The most important findings of this study are that the short presence of a woman induces specific hormonal reactions in men, and that these effects are stronger for aggressively dominant men.     

Sensation seeking in fathers: the impact on testosterone and paternal investment

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.     

Testosterone levels among Aché hunter-gatherer men

Salivary testosterone levels were measured in a population of New World indigenous adult hunter-gatherer males in order to compare circulating levels of free unbound bioactive steroid with those previously reported among Boston and nonwestern males. The study population consisted of adult Aché hunter-gatherer males (n=45) living in eastern Paraguay. Morning and evening salivary testosterone levels (TsalA.M.; TsalP.M.) among the Aché were considerably lower than western values (Boston) and even lower than other previously reported nonwestern populations (Efe, Lese, Nepalese). No association was observed between height, weight, or age and salivary testosterone levels within the Aché group, although older men (ages>40) were poorly represented in the study sample. Nevertheless, a mild correlation was observed between Aché TsalA.M. levels and BMI (r=0.133,p=0.0725). Comparison of Aché values with those for other populations confirms the prevalence of significant interpopulational variation in testosterone levels among adult males. Interpopulational variation in male testosterone is not as great, however, as has been documented for ovarian steroids among females, nor is it likely that such variation reflects differences in male fecundity. Nevertheless, such interpopulational variation in salivary testosterone levels may have a functional significance in the regulation of protein anabolism in skeletal muscle, thereby affecting the overall energy budget of the organism. It is suggested that relative suppression of average testosterone may be adaptive under conditions of chronic energy shortage. This research was funded by the National Science Foundation, the Mellon Foundation, Sigma Xi, and Harvard University. The author is a doctoral candidate in biological anthropology at Harvard University. He received his B.A. in anthropology and psychology from UCLA in 1988 and his M.A. in anthropology from Harvard in 1994. His research interests include male reproductive ecology, male hormone function, foraging societies, evolutionary biology, and behavioral evolution.     

Girl helpers and time allocation of nursing women among the Toba of Argentina

In this paper we outline the activities of young girls in a Toba community of northern Argentina and examine the effect of girl helpers on time allocation of nursing women. Activity budgets were obtained for 41 girls aged 3 to 15 using spot observations. Girls spent substantial portions of observations engaged in helping behaviors. Individual values varied with age, anthropometric characteristics, and birth order. Activity budgets of 21 nursing women were obtained through focal observation sessions. Women living in households with girls aged 7 to 15 allocated 17% less time to domestic work and 9% more time to socializing during afternoon observation sessions. For nursing women in this community, direct childcare (provided by the infant’s own mother) seemed to be a priority. Living with a girl helper did not have any measurable effect on the frequency or duration of nursing, or on the time that women spent caring for their infants. Based on these findings, hypotheses are outlined for future work on the effect of girl helpers on women’s fertility. Research for this project was funded by the Nestlé Foundation, the Harvard Anthropology Goelet Fund, and the Harvard College Research Program. Eduardo Fernandez-Duque commented on an early draft of this paper. Riley Bove (A.B., Harvard, 1998) is a research associate in the Department of Anthropology at Harvard University with research interests in intergenerational female networks and polygyny as a social mediator of women’s health (esp. urban, African). Claudia Valeggia (Ph.D., U.C. Davis, 1996) is a postdoctoral fellow in the Department of Anthropology at Harvard University with research interests in reproductive ecology and ethnopediatry. Peter Ellison (Ph.D., Harvard, 1983) is a professor of anthropology and director of the Reproductive Ecology Laboratory at Harvard University. He is the author of On Fertile Ground: Ecology, Evolution and Human Reproduction (Harvard University Press, 2001).     

Multiple partners are associated with higher testosterone in North American men and women

Previous research has shown that being partnered is associated with lower testosterone (T) in men and women. To address how multiple partners may be associated with T, we examined 47 men and 48 women who were single, monoamorously partnered (partnered), polyamorous (having multiple committed relationships), or in a polyamorous lifestyle but not currently multipartnered. Men who were partnered had lower T than all other men, and polyamorous men had higher T than single men. Polyamorous women had higher T than all other women. Measures of sociosexual orientation (SOI) and sexual desire differed in women by relationship type, but not in men. Findings are interpreted in light of 'competitive' and 'bond-maintenance' relationship orientations and statuses.     

The influence of social cues on the reproductive endocrinology of male brown-headed cowbirds: field and laboratory studies

Captive male brown-headed cowbirds exposed to long days exhibit gonadal growth and have elevated plasma testosterone (T) levels. This photoperiodic response is enhanced if males are housed with female cowbirds: Photostimulated males with females increase plasma testosterone levels sooner than do individually housed photostimulated males. Peak plasma T levels are similar in both groups, although peak levels are maintained longer in males housed with females. The gonadal cycle is similarly affected; males in the presence of females have earlier gonadal recrudescence and maintain mature gonads longer than do photostimulated males without females. Plasma corticosterone levels increase in the unpaired males, suggesting that removal of social cues is stressful for these birds. Free-living paired males have significantly higher plasma testosterone levels than do unpaired/unknown males early in the season, when social relationships are being established; the levels are similar thereafter. There is no difference between the two groups in testicular maturation rates; nor do they differ in plasma corticosterone levels at any time of the season. These results suggest that social stimuli are important in modulating the secretion of testosterone in males early in the season when pairing occurs, and possibly late in the season as well, probably to prevent termination of breeding prior to that of females.     

Testosterone levels in women and men who are single, in long-distance relationships, or same-city relationships

Research points to an association between testosterone (T) and partnering in some women and men, and this association has been interpreted as an effect of either relationship status (i.e. differences in relationship status lead to differences in T) or relationship orientation (i.e. T is associated with the likelihood of entering relationships). To address whether physical partner presence was associated with decreased T, we examined T levels in people (72 women; 49 men) who were single, in long-distance relationships, or in same-city relationships. No participants were using exogenous hormones, including hormonal contraceptives. Participants provided a saliva sample and responded to questions about their relationship status. Single men had higher T than long-distance and same-city partnered men, which supports the relationship orientation interpretation. In contrast, same-city partnered women had lower T than single women and women in long-distance relationships, which supports the relationship status interpretation. We conclude that physical partner presence is not necessary to see an association between partnering and hormones in men (since same-city and long-distance partnered men had similar T levels), but may be necessary in women (since same-city partnered women had lower T than long-distance partnered women).     

Aromatase activity after a short-course of letrozole administration in adult men at sea level and at high altitude (with or without excessive erythrocytosis)

Men living at high altitudes in Peru compared to sea level counterparts have erythrocytosis (hemoglobin 16-21?g/dl) or excessive erythrocytosis (hemoglobin>21?g/dl). High testosterone (T) levels in men at high altitude (HA) were associated with excessive erythrocytosis. High androgen levels could be due to a low aromatase activity or to an elevated rate of conversion from precursors to testosterone. The aim of this study was to evaluate aromatase activity and rate of conversion from precursors to testosterone before and after administration of the aromatase enzyme inhibitor letrozole (5?mg/day) for a 5-day period to men at HA and at sea level (SL). The response to short term aromatase inhibition was assessed in 30 adult men living at sea level, 31 native men at HA with erythrocytosis (Hb 16-21?g/dl), and 35 men at HA with excessive erythrocytosis (Hb>21?g/dl). Serum hormone levels, estradiol/testosterone, testosterone/androstenedione, and testosterone/dehydroepiandrosterone sulfate (DHEAS) ratios were measured. Men with erythrocytosis had lower basal serum T/androstenedione ratios than men with excessive erythrocytosis at HA and men at sea level. Men at HA with excessive erythrocytosis had higher T/DHEAS ratios than men with erythrocytosis and than those at sea level before and after letrozole administration. After letrozole administration, both groups of men at high altitude (with erythrocytosis or with excessive erythrocytosis) showed lower aromatase activities than those at sea level. In conclusion, higher serum testosterone levels in men with excessive erythrocytosis were associated with an increased rate of conversion from DHEAS to testosterone rather than to a lower aromatase activity.     

Effects of age on testosterone responses to resistance exercise and musculoskeletal variables in men

This study compared serum total testosterone (TT) and free testosterone (FT) responses of young (20-26 years, n = 8), middle-aged (38-53 years, n = 7), and older (59-72 years, n = 9) men to resistance exercise. We also examined the relationships between testosterone (T) levels and strength, bone mineral density (BMD), and body composition variables for each age group. Subjects were tested for isotonic muscular strength (1 repetition maximum [1RM]), BMD (dual-energy x-ray absorptiometry [DXA]) and body composition (DXA). Each group performed an acute exercise protocol (3 sets, 10 repetitions, 80% of 1RM, 6 exercises). Blood samples were obtained at baseline, immediately postexercise, and 15 minutes postexercise for the TT and FT assays. The older age group had significantly (p < 0.05) lower T levels than the young group, but each group exhibited an increase (p < 0.05) in TT and FT immediately postexercise. Total T and FT were significantly correlated (p < 0.05) with strength in middle-aged and older men and with bone-free lean tissue mass in older men. In conclusion, middle-aged and older men showed similar relative T responses to those of younger men to a single bout of high-intensity resistance exercise. However, T levels were related to strength and muscle mass only in middle-aged or older men. On a practical application level, older men can complete a high-intensity resistance exercise program resulting in spikes in T that may attenuate age-related muscle and BMD loss.     

2009 Society for Medical Anthropology Conference: Reflections on the Future of Anthropology

In his plenary session entitled Five Questions on the Future, Harvard anthropologist Arthur Kleinman capitalized on the 2009 Society for Medical Anthropology Conference’s theme of Medical Anthropology at the Intersections to speculate on the future of the discipline.As he reflects on the field of anthropology, which had lacked theory, ethnography, and strong ties to public health and medicine, Harvard anthropologist Arthur Kleinman celebrates the accomplishments made by his contemporaries by saying, “My generation has made medical anthropology what it is today.” However, he is now looking to the future of the discipline, saying it must re-examine itself as a field.During the 2009 Society for Medical Anthropology Conference at Yale University, Kleinman capitalized on the theme of Medical Anthropology at the Intersections in his plenary session entitled Five Questions on the Future. Casting the conference itself as a kind of intersection, Kleinman not only lauded its size and diversity, but asserted that it marked a pivotal moment in which medical anthropology must re-evaluate its central questions.     

The interrelationships of disease and culture in a primitive New Guinea community

This article explores links between disease and social standing in a primitive New Guinea community. Social and cultural events have modified the incidence of certain diseases. Furthermore, the changing patterns of disease may have influenced the development and form of social distinctions.This work is based on data collected as a predoctoral fellow in the Department of Anthropology at Columbia University. Fieldwork in New Guinea was done with NIH support under Training Grant 1 T01-MH11775-01 (related to 2 F1 MH301640-02), with Dr. Margaret Mead as the sponsor. Additional funding for analysis of data was obtained from the Harvard School of Public Health, the Department of Preventive Medicine of the Harvard Medical School, and the Institute for Transcultural Studies in New York.     

Marriage and fatherhood are associated with lower testosterone in males

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.     

Nepotistic nosiness: inclusive fitness and vigilance of kin members' romantic relationships

The logic of inclusive fitness suggests that people should be attentive to the mating relationships of their kin—especially their genetically closest kin. This logic further suggests that people will be especially attentive to close kin members' relationships when a greater indirect fitness benefit is at stake. Three studies tested implications of this analysis. The primary results were that (a) people maintain greater vigilance over (and attempt greater influence on) the romantic relationships of genetically closer kin; (b) this effect is largely mediated by feelings of emotional closeness and perceptions of physical similarity; (c) women are more vigilant than men over their kin members' relationships; (d) people are more vigilant over the relationships of female kin, as compared to male kin, but only under conditions with especially clear implications for indirect fitness; and (e) people are more vigilant over kin members' long-term committed relationships, as compared to their casual relationships. These results indicate that a subtle form of nepotism is manifest in people's concern with their kin members' romantic relationships.     

Testosterone and partnering are linked via relationship status for women and ‘relationship orientation’ for men

Cross-cultural evidence links pair bonding and testosterone (T). We investigated what factors account for this link, how casual relationships are implicated, and whether gender/sex moderates these patterns in a North American sample. We gathered saliva samples for radioimmunoassay of T and self-report data on background, health, and social/relational variables from 115 women and 120 men to test our predictions, most of which were supported. Our results show that singles have higher T than long-term (LT) partnered individuals, and that casual relationships without serious romantic commitment are more like singlehood for men and LT relationships for women–in terms of T. We were also able to demonstrate what factors mediate the association between partnering and T: in women, frequency of partnered sexual activity mediated the effect in men, interest in more/new partners mediated the effect. This supported our prediction of relationship status interpretations in women, but relationship orientation in men. Results replicated past findings that neither sexual desire nor extrapair sexuality underlie the T-partnering link. We were able to rule out a large number of viable alternative explanations ranging from the lifestyle (e.g., sleep) to the social (e.g., social support). Our data thus demonstrate pattern and mediators for the development of T-pair bonding associations, and emphasize the importance of neither under- nor overstating the importance of gender/sex in research about the evolution of intimacy.     

Testosterone and partnering are linked via relationship status for women and ‘relationship orientation’ for men

Cross-cultural evidence links pair bonding and testosterone (T). We investigated what factors account for this link, how casual relationships are implicated, and whether gender/sex moderates these patterns in a North American sample. We gathered saliva samples for radioimmunoassay of T and self-report data on background, health, and social/relational variables from 115 women and 120 men to test our predictions, most of which were supported. Our results show that singles have higher T than long-term (LT) partnered individuals, and that casual relationships without serious romantic commitment are more like singlehood for men and LT relationships for women–in terms of T. We were also able to demonstrate what factors mediate the association between partnering and T: in women, frequency of partnered sexual activity mediated the effect in men, interest in more/new partners mediated the effect. This supported our prediction of relationship status interpretations in women, but relationship orientation in men. Results replicated past findings that neither sexual desire nor extrapair sexuality underlie the T-partnering link. We were able to rule out a large number of viable alternative explanations ranging from the lifestyle (e.g., sleep) to the social (e.g., social support). Our data thus demonstrate pattern and mediators for the development of T-pair bonding associations, and emphasize the importance of neither under- nor overstating the importance of gender/sex in research about the evolution of intimacy.     

Handsome wants as handsome does: physical attractiveness and gender differences in revealed sexual preferences

In this article I evaluate the effect of physical attractiveness on young adults' sexual and romantic outcomes to reveal gender differences in acted preferences. Using data from the National Longitudinal Study of Adolescent Health (Add Health), a probability sample of young adults (n = 14,276), I investigate gender differences in desired sexual partner accumulation, relationship status, and timing of sexual intercourse. I find gender differences in sexual and romantic strategies consistent with those predicted by the double standard of sexuality and evolutionary theory. Specifically, compared to men, women pursue more committed relationships, fewer sexual partners, and delayed sexual intercourse.