In men, high levels of endogenous testosterone (T) seem to encourage behavior intended to dominate other people. Sometimes dominant behavior is aggressive, its apparent intent being to inflict harm on another person, but often dominance is expressed nonaggressively. Sometimes dominant behavior takes the form of antisocial behavior, including rebellion against authority and law breaking. Measurement of T at a single point in time, presumably indicative of a man's basal T level, predicts many of these dominant or antisocial behaviors. T (...) not only affects behavior but also responds to it. The act of competing for dominant status affects male T levels in two ways. First, T rises in the face of a challenge, as if it were an anticipatory response to impending competition. Second, after the competition, T rises in winners and declines in losers. Thus, there is a reciprocity between T and dominance behavior, each affecting the other. We contrast a reciprocal model, in which T level is variable, acting as both a cause and effect of behavior, with a basal model, in which T level is assumed to be a persistent trait that influences behavior. An unusual data set on Air Force veterans, in which data were collected four times over a decade, enables us to compare the basal and reciprocal models as explanations for the relationship between T and divorce. We discuss sociological implications of these models. (shrink)

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. (shrink)

In my work I argue that sexual differences in the brain seem to shape the ideological gulf between the respective social groups each side represents. And most significantly, it is the male sex hormone testosterone that is the primary hormone affecting our sexual evolution. Not only does testosterone fuel the passion for reproduction and play a critical role in the length of human lives, it is an integral component to the mechanism of human civilization—its triumphs and its tragedies. (...) In order to understand the forces that drive the life cycles of human cultures and form the engine of history, it is important to look at the most fundamental building blocks of human neuroscience. Our hormones are the impetus for our history. Hormones regulate and control the way the human mind perceives the world and forms social organizations and political order accordingly. Hormones drive waves of social mood, shaping the evolution of our social life, the fluctuations of religious doctrines, cultural crusades, and sexual norms. (shrink)

This paper investigates relationships between men’s testosterone and family life in a sample of approximately 350 Jamaican fathers of children 18–24 months of age. The study recognizes the role of testosterone as a proximate mechanism coordinating and reflecting male life history allocations within specific family and cultural contexts. A sample of Jamaican fathers and/or father figures reported to an assessment center for an interview based on a standardized questionnaire and provided a saliva sample for measuring testosterone level. (...) Outcomes measured include subject demographics such as age and relationship status as well as partnership quality and sexuality and paternal attitudes and behavior. The variation in these fathers’ relationship status was not associated with men’s testosterone. Too few stepfathers participated to enable a direct test of the prediction that stepfathers would have higher testosterone than biological fathers, although fathers who reported living with partners’ children did not have higher testosterone than fathers not reporting residing with a non-biological child. Fathers’ relationship quality was negatively related to their testosterone. Measures of paternal attitudes and behavior were not related to fathers’ testosterone. Consistent with previous ethnography, this sample of Jamaican fathers exhibited variable life history profiles, including residential status. We discuss why fathers’ relationship quality was found to be negatively related to their testosterone level, but other predictions were not upheld. (shrink)

Testosterone is related to dominance, but in a broader sense than Mazur & Booth suggest. Dominance need not be competitive. It can arise from strong personal characteristics that produce admiration and deference in others. To understand the testosterone–dominance relationship fully, we must examine behaviors that affect ordinary social encounters. Baseline testosterone levels may be more important than testosterone changes in predicting everyday dominance.

Mazur & Booth's (1998) target article concerns basal and reciprocal relations between testosterone and dominance, and has its roots in Mazur's (1985; 1994) model of primate dominance-submissiveness interactions. Threats are exchanged in these interactions and a psychological stress-manipulation mechanism is suggested to operate, making sure that face-to-face dominance contests are usually resolved without aggression. In this commentary, a recent line of evidence from human research on the relation between testosterone, cortisol, and vigilant (dominant) and avoidant (submissive) responses to (...) threatening “angry” faces is discussed. Findings, to a certain extent, converge with Mazur & Booth's theorizing. However, the strongest relations have been found in subliminal exposure conditions, suggesting that biological instead of psychological mechanisms are involved. (shrink)

There is substantial evidence that psychological factors influence human testosterone levels, but little support if any for an influence of circulating testosterone on dominance in men. Persistent interest in testosterone as an explanation of behaviors such as dominance and aggression might reflect the influence of cognitive schemas regarding race and sex rather than empirical evidence.

Allocation tradeoffs with the immune system can enforce honesty on sexual signals that act as indicators of individual quality. Such tradeoffs can be brought about by (1) the dual action of testosterone, which stimulates sexual signals but also suppresses immune functions, and/or (2) competition for carotenoids, which can be deposited as ornamental pigments or used as antioxidants in support of immune functions. Recent studies1-3 integrate these two mechanisms by showing that testosterone treatment in male birds upregulates circulating lipoproteins, (...) plasma carriers for carotenoids, and increases bio-availability of carotenoids, which enhances carotenoid-based sexual coloration and immune responsiveness. BioEssays 29:427–430, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

The testosterone–dominance model is noteworthy but should incorporate the ecological factors that often underlie variability in basal testosterone. This is evident in the ethnic testosterone differences discussed in the target article (sect. 8). The significance of acute changes in testosterone levels in response to competition is also poorly understood. Significant metabolic effects have been reported, suggesting that other physiological explanations should be explored, independent of potential behavioral or social factors.

Testosterone's connection to sex differences and key evolutionary processes arouses controversy. Effects on humans and other species, though, are not robotically deterministic but are parts of complex interactions. We discuss the societal implications of these findings and consider how the naturalistic fallacy and the person–situation dichotomy contribute to misunderstandings here.

Mazur & Booth have shown an association between testosterone and dominance behavior, but the strength of the relationship is not given. In addition to being statistically significant, it is also necessary that testosterone account for a meaningful proportion of the variance; a multivariate model is probably necessary. A cautionary tale from the animal literature is related.

Using testosterone alone as a measure of dominance presents problems, especially when dominance is loosely defined to include a range of behaviors that may arise from multiple causes. Testosterone should be examined in relation to other hormonal and neurotransmitter factors, such as serotonin. Various hypotheses about the relationship between high and low levels of testosterone with serotonin and with impulse control are suggested for future study.

There is increasing interest in the role played by testosterone in economic decision-making and social cognition. However, despite the growing body of findings in this field of research, no empirical study to date has tested whether testosterone modulates decision-making when an asymmetrically dominated decoy option is introduced in a choice set. Within a choice set that comprises two options, an asymmetrically dominated decoy option is a third option that, when introduced in the choice set, is much worse than (...) one of the existing options, but comparable to the other existing option. Introduction of a decoy option leads to a preference toward the dominating option (i.e., decoy effect). Healthy male participants (n = 63) received a single-dose of 150 mg testosterone gel in a double-blind, placebo-controlled, between-subjects design. At 180 min post-administration, participants took part in a decision-making task to elicit decoy effect. Results showed that participants in the testosterone group made less consistent choices and more target choices (i.e., decoy effect) than participants in the placebo group. These findings are interpreted in light of the dual-process theory and are in line with existing evidence suggesting that testosterone promotes more intuitive and automatic judgments in human decision-making. (shrink)

Because the reciprocal theory of Mazur & Booth dominates the static basal model, given the evidence they present, it is worth considering the implications for women's equality, supposing it true. Testosterone might well give males a competitive edge, and hence higher status, creating an inequality that mere social legislation would be ill-suited to address. Further research on the role of testosterone is needed.

Prenatal exposure to high levels of testosterone may lead to increased probability of left-handedness. Extrapolating from arguments by Mazur & Booth leads to a prediction of increased incidence of antisocial behavior among left-handers. Six hundred ninety-four males were tested for seven indicators of delinquency in high school. Left-handers were more likely to display such behaviors, providing indirect evidence for the hypothesized behavioral effects of testosterone.

Regulations implemented by World Athletics (WA) require female athletes with differences of sexual development to suppress their blood testosterone levels in order to participate in certain women’s sporting competitions. These regulations have been justified by reference to fairness. In this paper, we reconstruct WA’s understanding of fairness, which requires a “level playing field” where no athlete should have a significant performance advantage based on factors other than talent, dedication, and hard work over an average athlete in their category. We (...) demonstrate that by placing regulations only on testosterone levels, while ignoring physical as well as socioeconomic advantages, WA consistently fails to meet its own definition of fairness. We then discuss several ways in which this definition could be met. Our analysis shows that a categorical system, in which athletes are divided into categories based on properties leading to significant performance advantages, is best suited for meeting WA’s definition of fairness. (shrink)

Mazur & Booth provide life scientists with an example of the multilevel biopsychosocial approach. Research paradigms have to become more flexible and multidisciplinary if we are to free ourselves from the nature–nurture dichotomy that we have long agreed was simplistic and shortsighted. I point out a variety of kinds of interactions that may be the next frontier for behavioral scientists.

By integrating the entire body of research in human sexual dynamics, immune responses, and sociocultural behavior, we can conclude that the mass hysteria our society is currently experiencing originates in our evolved psychological adaptations to pandemic conditions [i]. A lack of hormonal balance [ii], due to a collapse in testosterone levels, may cause a disproportionate immune response that leads to the destruction of our cherished sociopolitical institutions—the very institutions that are design to protect human liberty and prosperity. What is (...) playing out at a societal level is similar to an excessive immune response that causes the body to attack itself: decreased testosterone causing the kind of auto-immune response that is more prevalent in females. [i] Barzilai, R.. Low Solar Activity, Winter Flu Conditions, Pandemics and Sex Wars: A Holistic View of Human Evolution. Science & Philosophy, 8. Doi: 10.23756/sp.v8i1.514 [ii] Barzilai, R.. Solar cycles, light, sex hormones and the life cycles of civilization: Toward integrated chronobiology. Science & Philosophy, 7. doi: 10.23756/sp.v7i2.483. (shrink)

There is evidence that in women high levels of testosterone are associated with more sexual partners and more permissive sexual attitudes. If a similar relationship holds true for men, the higher basal testosterone levels of divorced and unmarried men may be caused by this relationship rather than by testosterone's effect on dominance striving.

Mazur & Booth present an intriguing model of the relationship between circulating testosterone levels and dominance behaviour in man, but their review of studies on testosterone–behaviour relationships in man is selective. Much of the evidence they cite is correlational in nature. Placebo-controlled manipulations of testosterone levels are required to test their hypothesis that dominance levels are testosterone-dependent in man. The changes in testosterone level that follow behavioural experience may be a consequence of stress. Testosterone (...) levels in man are determined by a wide variety of factors, and a multivariate approach is required. (shrink)

Mazur & Booth (1998) (M&B) suggested that high testosterone (T) relates to status, dominance, and (anti-) social behaviour. However, low T also relates to status and to formal dominance. The General Trait Covariance (GTC) model predicts both relations under the assumption that high and low T modulates the genotype in ways that enforce the development of almost polar covariant patterns of body, brain, intellectual, and personality traits, irrespective of race. The precise modelling of these dose-dependent molecular body-intelligence-personality-behaviour relations requires (...) that causes, mechanisms, and effects enjoy equal operational standing. (shrink)

The expansion of human evolutionary theory into the domain of personal and environmental determinants of mating strategies is applauded. Questions are raised about the relation between fluctuating asymmetry (FA), testosterone, and body size and their effects on male behavior and outcomes. Low FA males' short-term mating pattern is considered in the context of an evolved tendency for closer and longer human relationships.

Our commentary summarises the current understanding of how testosterone can be used as a mechanism to link quality to external traits potentially used in sexual signalling, particularly female choice. Testosterone-dependent traits may reveal male's status to rivals and immunocompetence to females. We highlight some interesting unanswered questions and suggest that cross-disciplinary collaboration would help solve them.

(1) Mazur & Booth do not explain precontest rise in testosterone. Anticipatory T rise may result from fantasized dominance scenarios. (2) Mazur & Booth conclude that females do not experience the dominance–T rise effect. The data are insufficient for this judgment. (3) Mazur & Booth misstate my position on T and sexuality. I offer an emendation and correction.

The following three points are made. One must consider not only the levels of circulating hormone but the target tissue upon which the hormone acts. Increased testosterone levels alone do not account for differences in displayed intermale aggression, because testosterone and social environment interact in complex ways to influence behavior. A given behavior can be triggered by multiple motivational systems.

Culture and social structure may affect the testosterone–behavior link by shaping the way we construe events; by muting, channelling, or amplifying the drives that testosterone produces; and by affecting the distribution and level of testosterone in various parts of the population. Research on testosterone, culture, and social class has produced suggestive results, opening broad areas for research.

Previous research in North America has supported the view that male involvement in committed, romantic relationships is associated with lower testosterone (T) levels. Here, we test the prediction that undergraduate men involved in committed, romantic relationships (paired) will have lower T levels than men not involved in such relationships (unpaired). Further, we also test whether these differences are more apparent in samples collected later, rather than earlier, in the day. For this study, 107 undergraduate men filled out a questionnaire (...) and collected one saliva sample (from which a subject’s T level was measured) at various times across the day. As in previous studies, men involved in committed, romantic relationships had lower salivary T levels, though only during later times of the day. Furthermore, additional analysis of the variation among unpaired subjects indicated that men without prior relationship experience had lower T levels than experienced men. Finally, while paired men as a group had lower T levels than unpaired men, those men at the earliest stage (less than six months) of a current relationship had higher T levels than unpaired men as well as men in longer-term relationships. These results suggest that variation in male testosterone levels may reflect differential behavioral allocation to mating effort. (shrink)

In April 2018, the International Association of Athletics Federations released new regulations placing a ceiling on women athletes’ natural testosterone levels to “ensure fair and meaningful competition.” The regulations revise previous ones with the same intent. They require women with higher natural levels of testosterone and androgen sensitivity who compete in a set of “restricted” events to lower their testosterone levels to below a designated threshold. If they do not lower their testosterone, women may compete in (...) the male category, in an intersex category, at the national level, or in unrestricted events. Women may also challenge the regulation, whether or not they have lowered their testosterone, or quit sport. Irrespective of IAAF’s stated aims, the options forced by the new regulations are impossible choices. They violate dignity, threaten privacy, and mete out both suspicion and judgement on the sex and gender identity of the athletes regulated. (shrink)

Mazur & Booth fail to consider the conceptual complexities of dominance; it is unlikely that there is a motive to dominate in animals. Also, the lack of empirical evidence for a causal link between testosterone and dominance is obscured by the narrative reviewing procedure, which is prone to bias.

The negative co‐variation of life‐history traits such as fecundity and lifespan across species suggests the existence of ubiquitous trade‐offs. Mechanistically, trade‐offs result from the need to differentially allocate limited resources to traits like reproduction versus self‐maintenance, with selection favoring the evolution of optimal allocation mechanism. Here I discuss the physiological (endocrine) mechanisms that underlie optimal allocation rules and how such rules evolve. The hormone testosterone may mediate life‐history trade‐offs due to its pleiotropic actions in male vertebrates. Conservation in the (...) actions of testosterone in vertebrates has prompted the ‘evolutionary constraint hypothesis,’ which assumes that testosterone signaling mechanisms and male traits evolve as a unit. This hypothesis implies that the actions of testosterone are similar across sexes and species, and only the levels of circulating testosterone concentrations change during evolution. In contrast, the ‘evolutionary potential hypothesis’ proposes that testosterone signaling mechanisms and male traits evolve independently. In the latter scenario, the linkage between hormone and traits itself can be shaped by selection, leading to variation in trade‐off functions. I will review recent case studies supporting the evolutionary potential hypothesis and suggest micro‐evolutionary experiments to unravel the mechanistic basis of life‐history evolution. BioEssays 29: 133–144, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

Approach–avoidance generally describes appetitive motivation and fear of punishment. In a social context approach motivation is, however, also expressed as social aggression and dominance. We therefore link approach–avoidance to dominance–submissiveness, and provide a neural framework that describes how the steroid hormone testosterone shifts reflexive as well as deliberate behaviors towards dominance and promotion of social status. Testosterone inhibits acute fear at the level of the basolateral amygdala and hypothalamus and promotes reactive dominance through upregulation of vasopressin gene expression (...) in the central-medial amygdala. Finally, the hormone can, depending on social context and prenatal hormone exposure, promote both pro- and antisocial behaviors and decisions through its effects on prefrontal–amygdala interactions. All these effects of testosterone, however, serve to increase and maintain social status. (shrink)

Campbell's analysis of the evolution of human sex differences to include selection pressures on the female is generally welcomed. This commentary raises some specific issues about the evidence cited: the impact of paternal death on survival prospects; a possible mechanism underlying a sex difference in fear; the selective advantage of dominance hierarchies; and the absence of evidence that testosterone causes human aggression.

Two specific aspects of Mealey's model are questioned: (1) the application of the concept of Evolutionarily Stable Strategy to all alternative strategies, including those that involve reduced lifetime reproductive success; and (2) the evidence for the dual role of testosterone, which is based mainly on studies of a modulating effect on aggression.

A test of a biosocial model is reported in which we found no impact of circulating testosterone on either status-seeking or aggression. The fact that sex differences in competitiveness and aggression appear in childhood strongly suggests that the major impact of testosterone is organisational. Whereas dominance and resources are linked among males, female aggression may be a function of pure resource competition, with no element of status-seeking.

The relation between testosterone levels and aggressive behavior is well established. From an evolutionary viewpoint, testosterone can explain at least part of the sex differences found in aggressive behavior. This explanation, however, is mediated by factors such as prenatal testosterone levels and basal levels of cortisol. Especially regarding sex differences in aggression during adolescence, these mediators have great influence. Based on developmental brain structure research we argue that sex differences in aggression have a pre-pubertal origin and are (...) maintained during adolescence. Evidence of prenatal, adolescent, and adult levels of testosterone in relation to aggression taken together, support Archer's argument for sexual selection as the driver of sex differences in aggression. (shrink)

Testosterone fluctuates in response to competitive social interactions, with the direction of change typically depending on factors such as contest outcome. Watching a competition may be sufficient to activate T among fans and others who are invested in the outcome. This study explores the change in T associated with vicarious experiences of competition among combat sport athletes viewing a teammate win or lose and assesses how individual differences in social identification with one’s team relates to these patterns of T (...) reactivity. Twenty-six male combat athletes completed a social identity questionnaire on a neutral day. Later, salivary samples were obtained before and after athletes viewed a video of a teammate engaged in a formal contest. T reactivity to viewing a teammate compete varied among participants in both the magnitude and direction of change, independent of contest outcome. Individual differences in cognitive centrality, a core feature of social identification, showed a strong positive relationship with T reactivity, particularly if their teammate won. Initial findings suggest that dominance-linked androgen responses associated with watching a teammate win a competition might depend on the belief that team membership is central to one’s own identity. These exploratory results in a small sample of combat athletes should be interpreted with caution. Uncovering the role of social group dynamics in influencing T responses to competition is particularly important in light of the evolutionary history of coalitional combat in humans. (shrink)

The endogenous opioid system has received attention and extensive research for its effects on reward, pleasure, and pain. However, relative to other neurochemicals, such as oxytocin, vasopressin and dopamine, the function of opioids in regulating human attachment, sociosexuality, and other aspects of human sociality has not received much consideration. For example, nonapeptides have been extensively studied in animals and humans for their possible roles in mother-offspring attachment, romantic attachment, fatherhood, and social cognition. Likewise, others have proposed models wherein oxytocin and (...) vasopressin are moderators of the relationship between steroid hormones and human social behaviors. Recently, opioids have generated renewed interest in relation to social pain, and importantly, the brain opioid hypothesis of social attachment, which suggests that endogenous opioids are a key implementer in primate and human bonding, has received some support. Here we focus on romantic bonds by proposing that endogenous opioids are an important mechanism mediating reproductive trade-offs through their inhibitory effects on testosterone production. (shrink)

This Response focuses on the strength of the testosterone (T) dominance relationship, the circumstances under which aggression accompanies dominance, the viability of the basal model, mediators and moderators of the T-dominance relationship, and the research that is needed.