How can we best discover the ultimate, evolved functions of endocrine signals within the field of human behavioral endocrinology? Two related premises will guide my proposed answer. First, hormones ...typically have multiple, simultaneous effects distributed throughout the brain and body, such that in an abstract sense their prototypical function is the coordination of diverse outcomes. Second, coordinated output effects are often evolved, functional responses to specific eliciting conditions that cause increases or decreases in the relevant hormones. If we accept these premises, then a natural way to study hormones is to hypothesize and test how multiple eliciting conditions are mapped into coordinated output effects via hormonal signals. I will call these input–output mappings “theoretical frameworks.” As examples, partial theoretical frameworks for gonadal hormones will be proposed, focusing on the signaling roles of testosterone in men and on estradiol and progesterone in women. Recent research on oxytocin in humans will also be considered as an example in which application of the theoretical framework approach could be especially helpful in making functional sense of the diverse array of findings associated with this hormone. The theoretical framework approach is not especially common in the current literature, with many theories having eschewed explicit consideration of input–output mappings in favor of parsimony-based arguments that attempt to find the one main thing that a hormone does with respect to psychology or behavior. I will argue that these parsimony-based models have many shortcomings, and conclude that the construction and testing of theoretical frameworks provides a better means of discovering the evolved functions of human endocrine signals.
•Theoretical frameworks are ways of organizing findings about hormones.•Such frameworks directly specify input–output relationships mediated by hormones.•Productive frameworks should explain multiple, coordinating effects of hormones.•Example theoretical frameworks are proposed for gonadal hormones in humans.•Possible elements of a theoretical framework for oxytocin are also discussed.
Why are physically formidable men willingly allocated higher social status by others in cooperative groups? Ancestrally, physically formidable males would have been differentially equipped to ...generate benefits for groups by providing leadership services of within-group enforcement (e.g., implementing punishment of free riders) and between-group representation (e.g., negotiating with other coalitions). Therefore, we hypothesize that adaptations for social status allocation are designed to interpret men's physical formidability as a cue to these leadership abilities, and to allocate greater status to formidable men on this basis. These hypotheses were supported in 4 empirical studies wherein young adults rated standardized photos of subjects (targets) who were described as being part of a white-collar business consultancy. In Studies 1 and 2, male targets' physical strength positively predicted ratings of their projected status within the organization, and this effect was mediated by perceptions that stronger men possessed greater leadership abilities of within-group enforcement and between-group representation. Moreover, (a) these same patterns held whether status was conceptualized as overall ascendancy, prestige-based status, or dominance-based status, and (b) strong men who were perceived as aggressively self-interested were not allocated greater status. Finally, 2 experiments established the causality of physical formidability's effects on status-related perceptions by manipulating targets' relative strength (Study 3) and height (Study 4). In interpreting our findings, we argue that adaptations for formidability-based status allocation may have facilitated the evolution of group cooperation in humans and other primates.
Tests of whether women's psychology or behavior shifts during the fertile window vs. other cycle phase regions often employ a design in which fertile window test sessions are scheduled after a ...positive urinary luteinizing hormone (LH) test result. Lobmaier and Bachofner (2018) point out that this design will schedule high fecundity test sessions at the very end of the fertile window, if not later, when fecundity is not at its highest. I agree with their arguments, and here argue that the problems with this scheduling technique appear even more severe if one considers the hormonal mechanisms that are the likely regulators of cycle phase shifts. Test sessions scheduled after positive LH tests will occur at a time of rapid transitions in hormone production and will often systematically exclude periovulatory days with the highest concentrations of important hormones, such as estradiol. In doing so, this method may often fail to detect cycle phase shifts that are regulated by changes in these hormones. Hypothesis testing in cycle phase research can be improved via a transition from thinking of “fertility” as a discrete and monolithic variable, to instead thinking about the predicted effects of more continuous hormonal signals. I conclude with some general thoughts about how LH tests may be used more productively in studies of cycle phase shifts in psychology and behavior.
Little is known regarding which hormonal signals may best predict within- and between-women variance in sexual motivation among naturally cycling women. To address this, we collected daily saliva ...samples across 1–2 menstrual cycles from a sample of young women; assayed samples for estradiol, progesterone, and testosterone; and also collected daily diary reports of women's sexual behavior and subjective sexual desire. With respect to within-cycle, day-to-day fluctuations in subjective desire, we found evidence for positive effects of estradiol and negative effects of progesterone. Desire exhibited a mid-cycle peak, similar to previous findings; measured progesterone concentrations statistically mediated the fall in desire from mid-cycle to the luteal phase, but no combination of hormone measures substantially mediated the follicular phase rise in desire, which suggests that other signals may be implicated in this effect. Hormonal predictors of within-cycle fluctuations in sexual behavior generally reached only trend levels of statistical significance, though the patterns again suggested positive effects of estradiol and negative effects of progesterone. Between-women and within-women, between-cycle effects of hormone concentrations were generally absent, although statistical power was more limited at these higher levels of analysis. There were no significant effects of testosterone concentrations when controlling for the effects of estradiol and progesterone, which raises questions regarding the importance of this hormone for the regulation of sexual motivation in natural cycles. Our study is among the first to identify hormonal predictors of within-cycle fluctuations in sexual motivation, and thus adds novel evidence regarding the endocrine correlates of human sexuality.
•Current and time-lagged estradiol positively predicted sexual desire and behavior.•Progesterone was a consistent negative predictor of sexual desire.•Women exhibited mid-cycle peaks in sexual desire.•Progesterone mediated the fall in desire from mid-cycle to the luteal phase.•Testosterone did not predict measures of women's sexual motivation.
Although prior evidence supports women's mating behaviors and preferences being related to ovarian hormonal levels, there is conflicting evidence about exactly which hormones predict sexual function ...best, which specific psychosexual facets are affected and how between-individual and within-individual differences relate to this question. In this study levels of estradiol and progesterone were measured (once daily for 15 days for each participant) for 97 women, who attended two testing sessions, in times of the cycle varying in conception probability (based on the luteinizing hormone (LH) test result). Women completed surveys on their sexual desire, arousal, sexual activity frequency and initiation. There was a significant difference between peri-ovulatory and luteal values for all sexual function variables. Between-subject progesterone negatively predicted sexual activity frequency only. Within-subject estradiol positively and progesterone negatively predicted sexual desire. The findings provide support for hormonal underpinnings of sexual desire and sexual activity frequency fluctuations during the menstrual cycle. The findings did not yield support for hormonal influences on sexual arousal and initiation of sexual encounters. The main findings are consistent with the excitatory and inhibitory effects of estradiol and progesterone, respectively, on measures of women's sexual motivation.
Grebe et al. (2016) argued that women's sexual interest in their own partners may be under different hormonal regulation than their sexual desire for other men. They measured partnered women's ...salivary hormones and reports of attraction to different categories of men at two time points separated by one week. Change in progesterone positively predicted change in women's desire for their own partners, whereas change in estradiol was a negative predictor. These results are opposite to those we previously reported for the hormonal prediction of general sexual desire in a study that employed frequent hormone sampling across multiple menstrual cycles (Roney and Simmons, 2013). Here, to test replication of the Grebe et al. findings, we assessed hormonal predictors of targeted in-pair and extra-pair desire among the subset of the sample from our 2013 paper who reported being in romantic relationships. Contrary to Grebe et al. (2016), we found that within-cycle fluctuations in progesterone were negatively correlated with changes in women's desire for both their own partners and other men. In addition, both in-pair and extra-pair desire were elevated within the fertile window and lowest during the luteal phase. Our findings contradict the idea that partner-specific desire has a unique form of hormonal regulation, and instead support a general elevation of sexual motivation associated with hormonal indices of fecundity. Discussion focuses on possible reasons for the discrepancies in findings between our study and that of Grebe et al. (2016), and on the evolved functions of women's sexual motivation.
•Tested hormonal predictors of in-pair and extra-pair desire in partnered women•Progesterone was a negative predictor of both in-pair and extra-pair sexual desire.•Both types of desire exhibited mid-cycle peaks and luteal phase drops.•Findings contradict recent claims that progesterone promotes in-pair desire.•Discussion addresses hormonal and non-hormonal influences on sexual desire.
What role do ovarian hormones play in modulating day-to-day shifts in women's motivational priorities? In many nonhuman mammals, estradiol causes drops in feeding and foraging, progesterone reverses ...this effect, and the two hormones in combination produce cycle phase shifts characterized by lower food intake near ovulation when sexual receptivity is at its peak. Hormonal predictors of within-cycle shifts in women's total food intake have not been previously tested. Here, in a study with both daily hormone measures and self-reported food intake, we found that within-cycle fluctuations in estradiol negatively predicted shifts in food intake, progesterone fluctuations positively predicted them, and the two hormones together statistically mediated a significant peri-ovulatory drop in eating. These patterns are precisely opposite to those previously reported for sexual desire from this same sample (i.e. positive and negative effects of estradiol and progesterone, respectively, on desire). To more precisely test endocrine regulation of tradeoffs between sexual and eating motivation, a difference score for the daily standardized values of the sexual desire and food intake variables was created. Fluctuations in estradiol and progesterone were oppositely associated with shifts in this difference score, supporting hormone modulation of tradeoffs between alternative motivational priorities. These tradeoffs were especially pronounced during the fertile window of the menstrual cycle on days when conception was possible, consistent with the hormone effects functioning to shift motivational salience between feeding and mating depending on within-cycle changes in fecundity. The findings provide direct evidence that phylogenetically conserved endocrine signals regulate daily shifts in human motivational priorities.
•Tested hormonal predictors of daily self-reported food intake•Estradiol negatively and progesterone positively predicted food intake.•A fertile window drop in eating was mediated by the two hormones.•Hormone effects were mirror images of those found for sexual desire.•Overall patterns were highly similar to those seen in nonhuman primates.
The origins of variation in extraversion are largely mysterious. Recent theories and some findings suggest that personality variation can be orchestrated by specific genetic polymorphisms. Few ...studies, however, have examined an alternative hypothesis that personality traits are facultatively calibrated to variations in other phenotypic features, and none have considered how these distinct processes may interact in personality determination. Since physical strength and physical attractiveness likely predicted the reproductive payoffs of extraverted behavioral strategies over most of human history, it was theorized that extraversion is calibrated to variation in these characteristics. Confirming these predicted patterns, strength and attractiveness together explained a surprisingly large fraction of variance in extraversion across two studies— effects that were independent of variance explained by an androgen receptor gene polymorphism. These novel findings initially support an integrative model wherein facultative calibration and specific genetic polymorphisms operate in concert to determine personality variation.
Abstract Economists and psychologists have developed a variety of models to explain human behavior in the ultimatum game, but none can adequately account for all of the available data. Across two ...studies using a face perception paradigm, we provide evidence that people use evolved, specialized heuristics for long-term cooperative partner choice to calibrate their generosity toward ultimatum game partners. Men and women played one-shot ultimatum games for real incentives with partners represented by face photographs. Men were more generous toward partners who were stronger, and who appeared more attractive, more prosocial, more productive, healthier and higher in social status; the effect of strength was mediated by productivity, but not dangerousness, suggesting that men implemented heuristics designed for partner choice rather than the asymmetric war of attrition. Moreover, men reduced their earnings by cooperating selectively with valuable long-term partners. Women also gave better treatment to valuable-appearing partners, but appeared to prioritize partner choice less than men did, relative to game earnings and intrasexual competition. The results suggest that people treat the ultimatum game as though it were an opportunity to establish a cooperative relationship with a new partner, and implications are discussed for an evolved psychology of cooperative partner choice.
There have been mixed findings regarding whether raters judge women's natural faces more attractive when the women were photographed near ovulation relative to when photographed in other cycle ...regions. Bobst and Lobmaier (2012) isolated shape cues associated with ovulatory timing via computer morphing techniques and found that men judged face shapes characteristic of the fertile window as more attractive than those characteristic of the luteal phase. Here, we tested replication of their findings but also added stimuli from the early follicular phase. We constructed three composite faces constructed from photos of the same 23 women who had each been photographed in the early follicular phase, during the fertile window, and during the luteal phase. We next warped 20 other identity faces to the shapes of the composite faces representing each cycle phase, and asked male participants to rank order the resulting face triplets for attractiveness. Men ranked fertile window and luteal phase stimuli as more attractive than early follicular stimuli, but ranked fertile window and luteal phase faces as equally attractive. This result failed to replicate preferences for fertile window over luteal phase stimuli, and thereby argues against perceivers' ability to detect face shape cues of immediate fecundity. Because estradiol was lower in the early follicular phase relative to the other two cycle phases, our findings are consistent with the possibility that within-women increases in estradiol produce subtle increases in face shape attractiveness. Discussion addresses the overall evidence for facial cues of women's ovulatory timing.
•Tested whether women's face shapes become more attractive near ovulation•Fertile window and luteal face stimuli were judged to be equally attractive.•Early follicular stimuli were ranked the least attractive.•Effects were consistent with positive effects of estradiol on face attractiveness.•Results did not support the presence of clear facial cues of immediate fecundity.
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