Plasma insulin and glucagon concentrations and biochemical variables in regularly menstruating females with ovulatory and anovulatory menstrual cycles.

Ovarian hormones are known to affect endocrine pancreas function. However, data concerning the effects of anovulatory menstrual cycles in regularly menstruating women on endocrine pancreas and blood metabolites are lacking. We examined plasma insulin, glucagon, glucose, lactate, urea and glycerol concentrations in reproductive-age, regularly menstruating females classified as ovulating or non-ovulating on the basis of basal body temperature measurements and plasma 17beta-estradiol and progesterone determinations. All measurements were performed twice--in the follicular and again in the luteal phases of the menstrual cycle. There were no differences in plasma lactate and glycerol concentrations between the two groups of subjects. Plasma insulin concentrations tended to be lower in non-ovulating than in ovulating women. In addition, plasma glucagon did not differ in the follicular (33.2 pmol/l) or luteal phase of the menstrual cycle in females with disturbed ovarian hormone secretion (34.1 pmol/l). In contrast, plasma glucagon concentrations in the luteal phase (32.8 pmol/l) were significantly higher than in the follicular phase (24.9 pmol/l) of the menstrual cycle in ovulating women. Plasma glucose concentrations in the follicular phase of the menstrual cycle in non-ovulating women (4.1 mmol/l) were slightly but significantly lower than in their ovulating counterparts (5.3 mmol/l). Furthermore, no correlations were noted between plasma glucose and insulin-to-glucagon molar ratio in non-ovulating subjects. Plasma urea concentrations in non-ovulating women were markedly lower than in ovulating women in both follicular and luteal phases of the menstrual cycle (4.1 and 3.9 mmol/l vs. 5.3 and 5.4 mmol/l in non-ovulating and ovulating women, respectively). In ovulating women, plasma urea levels in both cycle phases were significantly correlated with plasma glucagon concentrations, but no such correlation was found in non-ovulating women. In conclusion, anovulatory menstrual cycles in premenopausal females slightly altered pancreatic hormone plasma levels but markedly impaired their action on plasma glucose and urea concentrations.     

Menstrual cycle, trait estrogen level, and masculinity preferences in the human voice

Men with low testosterone (feminine men) invest in relationships and offspring more than men with high testosterone (masculine men). Women's attraction to testosterone dependent traits (e.g. masculine face shape) is enhanced during the late-follicular, fertile phase of the menstrual cycle. Attractive, feminine women have stronger preferences for masculine men as possible long-term partners than less attractive, masculine women. We manipulated 2 testosterone related vocal traits (voice pitch and apparent vocal-tract length) in voices to test if women prefer masculinized men's voices to feminized men's voices; masculinity preferences are enhanced at the fertile (late-follicular) menstrual cycle phase; the amount that masculinity preferences shift cyclically relates to average estrone-3-glucuronide concentration (the primary urinary metabolite of estrone, E3G). We found women displayed general masculinity preferences for men's voices; masculinity preferences were greater in the fertile (late-follicular) phase of the cycle than the non-fertile (early-follicular and luteal) phase; and this effect was most pronounced for women with low average E3G concentration. As feminine women (i.e. those with high average E3G levels) are most able to obtain investment even from masculine men, these women may not need to change their mating preference or strategy during the menstrual cycle as much as masculine women.     

Menstrual cycle variation in women's preferences for the scent of symmetrical men.

Evidence suggests that female sexual preferences change across the menstrual cycle. Women''s extra-pair copulations tend to occur in their most fertile period, whereas their intra-pair copulations tend to be more evenly spread out across the cycle. This pattern is consistent with women preferentially seeking men who evidence phenotypic markers of genetic benefits just before and during ovulation. This study examined whether women''s olfactory preferences for men''s scent would tend to favour the scent of more symmetrical men, most notably during the women''s fertile period. College women sniffed and rated the attractiveness of the scent of 41 T-shirts worn over a period of two nights by different men. Results indicated that normally cycling (non-pill using) women near the peak fertility of their cycle tended to prefer the scent of shirts worn by symmetrical men. Normally ovulating women at low fertility within their cycle, and women using a contraceptive pill, showed no significant preference for either symmetrical or asymmetrical men''s scent. A separate analysis revealed that, within the set of normally cycling women, individual women''s preference for symmetry correlated with their probability of conception, given the actuarial value associated with the day of the cycle they reported at the time they smelled the shirts. Potential sexual selection processes and proximate mechanisms accounting for these findings are discussed.     

Fertility and race perception predict voter preference for Barack Obama

Research shows that women more positively evaluate targets evincing cues of high male genetic quality as a function of fertility across the menstrual cycle. Recently, a link between fertility and anti-black race bias has also been documented, an effect that is argued to serve a sexual coercion avoidance function. Here we demonstrate that both effects can be operative toward the same male target depending on inter-individual differences in race perception of the target. Across two studies, we found that the intention to vote for Barack Obama in the months preceding the 2008 election increased as a function of conception risk across the menstrual cycle. In the second study, we found that the effect is greatest among women who perceived him as more white than black, whereas the opposite was true among women who perceived him as mostly black. Our findings tie together separate conceptual research threads on positive and negative evaluations of men by women across the menstrual cycle — integrating them to shed light on women's voting preferences.     

Preferences for masculinity in male bodies change across the menstrual cycle

In human females cyclic shifts in preference have been documented for odour and physical and behavioral male traits. Women prefer the smell of dominant males, more masculine male faces and men behaving more dominantly when at peak fertility than at other times in their menstrual cycle. Here we examine variation in preferences for body sexual dimorphism. Across two studies, both between- and within-participant, we show that women prefer greater masculinity in male bodies at times when their fertility is likely highest, in the follicular phase of their cycle. Shifts were seen when rating for a short-term but not when rating for a long-term relationship. In line with studies showing similar effects for facial sexual dimorphism, we also show that women prefer greater masculinity when they think themselves attractive than when they think themselves less attractive. These results indicate that women's preferences for sexual dimorphism in male bodies follow a similar pattern as found for sexual dimorphism and dominance in other domains and such differences in preference may serve a similar function. Cyclic preferences could influence women to select partners when most likely to become pregnant that possess traits that may be most likely to maximize their offspring's quality via attraction to masculinity or serve to help acquire investment via attraction to femininity.     

State Dependent Valuation: The Effect of Deprivation on Risk Preferences

The internal state of an organism affects its choices. Previous studies in various non-human animals have demonstrated a complex, and in some cases non-monotonic, interaction between internal state and risk preferences. Our aim was to examine the systematic effects of deprivation on human decision-making across various reward types. Using both a non-parametric approach and a classical economic analysis, we asked whether the risk attitudes of human subjects towards money, food and water rewards would change as a function of their internal metabolic state. Our findings replicate some previous work suggesting that, on average, humans become more risk tolerant in their monetary decisions, as they get hungry. However, our specific approach allowed us to make two novel observations about the complex interaction between internal state and risk preferences. First, we found that the change in risk attitude induced by food deprivation is a general phenomenon, affecting attitudes towards both monetary and consumable rewards. But much more importantly, our data indicate that rather than each subject becoming more risk tolerant as previously hypothesized based on averaging across subjects, we found that as a population of human subjects becomes food deprived the heterogeneity of their risk attitudes collapses towards a fixed point. Thus subjects who show high-risk aversion while satiated shift towards moderate risk aversion when deprived but subjects who are risk tolerant become more risk averse. These findings demonstrate a more complicated interaction between internal state and risk preferences and raise some interesting implications for both day-to-day decisions and financial market structures.     

The Scent of Symmetry: A Human Sex Pheromone that Signals Fitness?

A previous study by the authors showed that the body scent of men who have greater body bilateral symmetry is rated as more attractive by normally ovulating (non-pill-using) women during the period of highest fertility based on day within the menstrual cycle. Women in low-fertility phases of the cycle and women using hormone-based contraceptives do not show this pattern. The current study replicated these findings with a larger sample and statistically controlled for men's hygiene and other factors that were not controlled in the first study. The current study also examined women's scent attractiveness to men and found no evidence that men prefer the scent of symmetric women. We propose that the scent of symmetry is an honest signal of phenotypic and genetic quality in the human male, and chemical candidates are discussed. In both sexes, facial attractiveness (as judged from photos) appears to predict body scent attractiveness to the opposite sex. Women's preference for the scent associated with men's facial attractiveness is greatest when their fertility is highest across the menstrual cycle. The results overall suggest that women have an evolved preference for sires with good genes.     

Commitment to relationships and preferences for femininity and apparent health in faces are strongest on days of the menstrual cycle when progesterone level is high

Previous studies of changes in women's behavior during the menstrual cycle have offered insight into the motivations underpinning women's preferences for social cues associated with possible direct benefits (e.g., investment, low risk of infection) and indirect benefits (e.g., offspring viability). Here we sought to extend this work by testing for systematic variation in women's preferences for male and female faces and in their attitudes to their romantic relationship during the menstrual cycle. In Study 1, we found partnered women's reported commitment to their romantic relationship and preferences for femininity in male and female faces were strongest on days of the menstrual cycle when progesterone levels are increased (and fertility is low). Happiness in relationships did not change across the cycle. In Study 2, we found that the effect of cycle phase on women's preference for feminine faces was independent of increased attraction to apparent health in faces during the luteal phase. Collectively, these findings are further evidence that women's preferences for social cues associated with possible direct benefits and commitment to relationships are strongest during conditions characterized by raised progesterone level, while attraction to men displaying cues associated with possible indirect benefits is strongest when women are most fertile.     

Women's preferences for men's scents associated with testosterone and cortisol levels: Patterns across the ovulatory cycle

Women in the fertile phase of their menstrual cycle show an enhanced sexual preference for masculine expressions in behavioral, morphological and scent traits. These masculinity preferences may be associated with testosterone (T) levels in males and hence connote male quality as a sire. Thus, a scent preference of fertile-phase women for T is predicted. A recent study, however, found no evidence for this, but reported that women prefer the scent of men with high cortisol (C). That study had low power to detect the predicted effect, as well as other methodological limitations. We tested women's preferences across their ovulatory cycle for the body scent of men who varied in T and C, using a larger sample of men and methods used in research on cycle preferences for symmetry-related male body scent. Conception risk in the cycle positively predicted women's scent ratings of men's T; scent ratings of C or T × C interaction were not robustly related to conception risk. Conception risk is related positively to a preference for scent of men's symmetry. This preference is distinct from that arising from a preference for the scent of T. The male-emitted chemical(s) responsible for these preferences shifts across women's cycle remain unknown.     

Resting States Are Resting Traits – An fMRI Study of Sex Differences and Menstrual Cycle Effects in Resting State Cognitive Control Networks

To what degree resting state fMRI is stable or susceptible to internal mind states of the individual is currently an issue of debate. To address this issue, the present study focuses on sex differences and investigates whether resting state fMRI is stable in men and women or changes within relative short-term periods (i.e., across the menstrual cycle). Due to the fact that we recently reported menstrual cycle effects on cognitive control based on data collected during the same sessions, the current study is particularly interested in fronto-parietal resting state networks. Resting state fMRI was measured in sixteen women during three different cycle phases (menstrual, follicular, and luteal). Fifteen men underwent three sessions in corresponding time intervals. We used independent component analysis to identify four fronto-parietal networks. The results showed sex differences in two of these networks with women exhibiting higher functional connectivity in general, including the prefrontal cortex. Menstrual cycle effects on resting states were non-existent. It is concluded that sex differences in resting state fMRI might reflect sexual dimorphisms in the brain rather than transitory activating effects of sex hormones on the functional connectivity in the resting brain.     

Does the response to cocaine differ as a function of sex or hormonal status in human and non-human primates?

Stimulant abuse continues to be a growing problem among women. Over the last 10-15 years, an increasing number of studies have focused on factors that may be implicated in stimulant abuse in women as compared to men, including the role of hormonal fluctuations across the menstrual cycle. Numerous preclinical studies have documented that female rodents are more sensitive than male rodents to the behavioral effects of stimulant administration and the hormone estradiol is involved in the enhanced response to stimulants observed in females. In contrast, fewer studies have been conducted in humans and non-human primates addressing the role of sex and gonadal hormones on the effects of cocaine. This review paper presents a recent update on data collected in our Human Cocaine Challenge Laboratory and our Non-human Primate Laboratory, including analysis of cocaine pharmacokinetics, sex differences, the menstrual cycle, and the role of progesterone in modulating the response to cocaine. Our studies indicate that there is minimal evidence that the response to intranasal cocaine varies across the menstrual cycle or between men and women. In contrast, the response to smoked cocaine is greater in the follicular phase than the luteal phase and differences between men and women generally only emerge when men are compared to women in the luteal phase. In terms of potential hormonal mechanisms for these differences, the hormone progesterone attenuates the subjective response to cocaine. With respect to cocaine self-administration, there are minimal changes across the menstrual cycle in both humans and non-human primates. Thus, there is converging evidence across a range of species that the behavioral effects of cocaine (1) differ between males and females, (2) differ in relation to hormonal fluctuations, (3) can be attenuated by progesterone (at least in females), and (4) do not appear to be related to differences in cocaine pharmacokinetics.     

What people prefer and what they think they prefer in short- and long-term partners. The effects of the phase of the menstrual cycle,hormonal contraception,pregnancy, and the marital and the parenthood status on partner preferences

The issue with most studies concerned with mate selection preferences in humans is that they rely on declarations and rational actions of experimental subjects, which are affected by their pre-conceived opinions and prejudices. Moreover, current research suggests that subcortical structures and processes, rather than the neocortex, play the principal role in actual partner choice behaviour. Consequently, we have only limited information on how relevant our current knowledge is in relation to real-life human ethology. To address these issues, we surveyed 2718 women and 4073 men between the ages of 16–50 and compared their declared and observed preferences for various properties in short-term and long-term partners. We found differences between what the subjects declared to prefer and what they preferred in reality: for example, men declared that wealth was the second least desirable property out of eleven in short-term partners, but we observed that in reality, they considered wealth the third most important factor after charisma and sense of humour. Similarly, while women declared that dominance and masculinity were desirable properties in short-term partners, in the observational part of the study, they showed little preference for these traits. Furthermore, we investigated the effects of the phase of the menstrual cycle, hormonal contraception, pregnancy, and partnership and parenthood status on these preferences. We found some support for the good parents hypothesis and no support for the good genes and the immunocompetence handicap hypotheses when observed, rather than declared preferences were considered. We also detected that hormonal contraception, and parenthood and partnership status influenced declared preferences in considerable ways, but had only a small, if any, impact on observed preferences. We suggest interpreting the results of studies reliant on declarations and rational actions of experimental subjects with great caution.     

Menstrual cycle phase affects discrimination of infant cuteness

Recent studies have shown that women are more sensitive than men to subtle cuteness differences in infant faces. It has been suggested that raised levels in estradiol and progesterone may be responsible for this advantage. We compared young women's sensitivity to computer-manipulated baby faces varying in cuteness. Thirty-six women were tested once during ovulation and once during the luteal phase of their menstrual cycle. In a two alternative forced-choice experiment, participants chose the baby which they thought was cuter (Task 1), younger (Task 2), or the baby that they would prefer to babysit (Task 3). Saliva samples to assess levels of estradiol, progesterone and testosterone were collected at each test session. During ovulation, women were more likely to choose the cuter baby than during the luteal phase, in all three tasks. These results suggest that cuteness discrimination may be driven by cyclic hormonal shifts. However none of the measured hormones were related to increased cuteness sensitivity. We speculate that other hormones than the ones measured here might be responsible for the increased sensitivity to subtle cuteness differences during ovulation.     

Endotoxin induced TNF and IL-10 mRNA production is higher in male than female donors: correlation with elevated expression of TLR4

Modification of cytokine production by gender hormones has been postulated to affect disease susceptibility and outcome. Here we investigate the effect of gender and the menstrual cycle on production of cytokines. Mononuclear cells were isolated every week for 10 consecutive weeks from healthy pre-menopausal women and men. TNF and IL-10 mRNA and protein levels were measured as well as membrane CD14 and intracellular TLR4 protein. Endotoxin stimulation of mononuclear cells from men produced more TNF and IL10 mRNA than cells from women. TLR4 expression was also significantly higher in cells from men. These gender differences in the immune response may help to elucidate the sexual dimorphism observed in infectious diseases.     

Risk Preferences and Prenatal Exposure to Sex Hormones for Ladinos

Risk preferences drive much of human decision making including investment, career and health choices and many more. Thus, understanding the determinants of risk preferences refines our understanding of choice in a broad array of environments. We assess the relationship between risk preferences, prenatal exposure to sex hormones and gender for a sample of Ladinos, which is an ethnic group comprising 62.86% of the population of Guatemala. Prenatal exposure to sex hormones has organizational effects on brain development, and has been shown to partially explain risk preferences for Caucasians. We measure prenatal exposure to sex hormones using the ratio of the length of the index finger to the length of the ring finger (2D:4D), which is negatively (positively) correlated with prenatal exposure to testosterone (estrogen). We find that Ladino males are less risk averse than Ladino females, and that Ladino males have lower 2D:4D ratios than Ladino females on both hands. We find that the 2D:4D ratio does not explain risk preferences for Ladinos. This is true for both genders, and both hands. Our results highlight the importance of exploring the behavioral significance of 2D:4D in non-Caucasian racial groups.     

The influence of hormonal changes during menstrual cycle on serum adiponectin concentrations in healthy women

Adiponectin is an adipocyte-derived hormone involved in the regulation of carbohydrate and lipid metabolism. Its concentrations are decreased in patients with obesity, type 2 diabetes and atherosclerosis and are higher in females than in males. Gender differences of adiponectin levels raise the possibility that sex hormones directly regulate its serum concentrations, which may in turn influence insulin sensitivity in different phases of the menstrual cycle. To test this hypothesis we measured serum adiponectin, estradiol, progesterone, luteinizing hormone and follicle-stimulating hormone concentrations daily throughout the menstrual cycle in six healthy women. Mean adiponectin levels strongly positively correlated with serum cortisol concentrations [R=0.94286; p=0.0048 (Spearman correlation test)], but were not significantly related to other anthropometric, biochemical and hormonal characteristics of the subjects (BMI, blood glucose, insulin, testosterone, prolactin, cholesterol, HDL cholesterol, LDL cholesterol, triglycerides concentrations, or atherogenic index). Furthermore, no significant changes of serum adiponectin levels were found throughout the menstrual cycle. We conclude that changes in sex hormones during the menstrual cycle do not affect total circulating adiponectin levels in healthy women. Therefore, the differences in insulin sensitivity in various phases of the menstrual cycle are not due to changes of circulating adiponectin levels.     

Menstrual Cycle Phase Does Not Predict Political Conservatism

Recent authors have reported a relationship between women''s fertility status, as indexed by menstrual cycle phase, and conservatism in moral, social and political values. We conducted a survey to test for the existence of a relationship between menstrual cycle day and conservatism.2213 women reporting regular menstrual cycles provided data about their political views. Of these women, 2208 provided information about their cycle date, 1260 provided additional evidence of reliability in self-reported cycle date, and of these, 750 also indicated an absence of hormonal disruptors such as recent hormonal contraception use, breastfeeding or pregnancy. Cycle day was used to estimate day-specific fertility rate (probability of conception); political conservatism was measured via direct self-report and via responses to the "Moral Foundations” questionnaire. We also recorded relationship status, which has been reported to interact with menstrual cycle phase in determining political preferences.We found no evidence of a relationship between estimated cyclical fertility changes and conservatism, and no evidence of an interaction between relationship status and cyclical fertility in determining political attitudes. Our findings were robust to multiple inclusion/exclusion criteria and to different methods of estimating fertility and measuring conservatism. In summary, the relationship between cycle-linked reproductive parameters and conservatism may be weaker or less reliable than previously thought.     

Raised salivary testosterone in women is associated with increased attraction to masculine faces

Women's preferences for masculinity in men's faces, voices and behavioral displays change during the menstrual cycle and are strongest around ovulation. While previous findings suggest that change in progesterone level is an important hormonal mechanism for such variation, it is likely that changes in the levels of other hormones will also contribute to cyclic variation in masculinity preferences. Here we compared women's preferences for masculine faces at two points in the menstrual cycle where women differed in salivary testosterone, but not in salivary progesterone or estrogen. Preferences for masculinity were strongest when women's testosterone levels were relatively high. Our findings complement those from previous studies that show systematic variation in masculinity preferences during the menstrual cycle and suggest that change in testosterone level may play an important role in cyclic shifts in women's preferences for masculine traits.     

Voting Intention and Choices: Are Voters Always Rational and Deliberative?

Human rationality–the ability to behave in order to maximize the achievement of their presumed goals (i.e., their optimal choices)–is the foundation for democracy. Research evidence has suggested that voters may not make decisions after exhaustively processing relevant information; instead, our decision-making capacity may be restricted by our own biases and the environment. In this paper, we investigate the extent to which humans in a democratic society can be rational when making decisions in a serious, complex situation–voting in a local political election. We believe examining human rationality in a political election is important, because a well-functioning democracy rests largely upon the rational choices of individual voters. Previous research has shown that explicit political attitudes predict voting intention and choices (i.e., actual votes) in democratic societies, indicating that people are able to reason comprehensively when making voting decisions. Other work, though, has demonstrated that the attitudes of which we may not be aware, such as our implicit (e.g., subconscious) preferences, can predict voting choices, which may question the well-functioning democracy. In this study, we systematically examined predictors on voting intention and choices in the 2014 mayoral election in Taipei, Taiwan. Results indicate that explicit political party preferences had the largest impact on voting intention and choices. Moreover, implicit political party preferences interacted with explicit political party preferences in accounting for voting intention, and in turn predicted voting choices. Ethnic identity and perceived voting intention of significant others were found to predict voting choices, but not voting intention. In sum, to the comfort of democracy, voters appeared to engage mainly explicit, controlled processes in making their decisions; but findings on ethnic identity and perceived voting intention of significant others may suggest otherwise.     

Metabolic State Alters Economic Decision Making under Risk in Humans

Background

Animals'' attitudes to risk are profoundly influenced by metabolic state (hunger and baseline energy stores). Specifically, animals often express a preference for risky (more variable) food sources when below a metabolic reference point (hungry), and safe (less variable) food sources when sated. Circulating hormones report the status of energy reserves and acute nutrient intake to widespread targets in the central nervous system that regulate feeding behaviour, including brain regions strongly implicated in risk and reward based decision-making in humans. Despite this, physiological influences per se have not been considered previously to influence economic decisions in humans. We hypothesised that baseline metabolic reserves and alterations in metabolic state would systematically modulate decision-making and financial risk-taking in humans.

Methodology/Principal Findings

We used a controlled feeding manipulation and assayed decision-making preferences across different metabolic states following a meal. To elicit risk-preference, we presented a sequence of 200 paired lotteries, subjects'' task being to select their preferred option from each pair. We also measured prandial suppression of circulating acyl-ghrelin (a centrally-acting orexigenic hormone signalling acute nutrient intake), and circulating leptin levels (providing an assay of energy reserves). We show both immediate and delayed effects on risky decision-making following a meal, and that these changes correlate with an individual''s baseline leptin and changes in acyl-ghrelin levels respectively.

Conclusions/Significance

We show that human risk preferences are exquisitely sensitive to current metabolic state, in a direction consistent with ecological models of feeding behaviour but not predicted by normative economic theory. These substantive effects of state changes on economic decisions perhaps reflect shared evolutionarily conserved neurobiological mechanisms. We suggest that this sensitivity in human risk-preference to current metabolic state has significant implications for both real-world economic transactions and for aberrant decision-making in eating disorders and obesity.