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Adaptations to Ovulation
Abstract
This chapter discusses the theory and research on sexually antagonistic coevolution, considers human sexuality in light of major sexual conflicts, and describes recent research on psychological changes across women's cycles. The selective pressures that led to concealed ovulation and extended female sexuality in humans have been debated for more than two decades. Two major theories explain them in terms of sexual conflicts, but different ones. The chapter also discusses male adaptations sensitive partners' ovulatory status. The extra-pair copulation (EPC) theory argues that women have adaptations to seek, under certain conditions, a sire other than a primary partner through multiple mating. On occasion, women may have mated with multiple men within a single cycle or consecutive cycles. In this context, cryptic choice mechanisms, adaptations that affect choice of a sire during mating or postmating, may have evolved. These mechanisms should be designed to vary across the cycle.
... Estrus is a phase of increased female sexual receptivity, proceptivity, selectivity, and attractiveness. It is common across mammalian species (Lange, Hartel, & Meyer, 2002;Lombardi, 1998), including primates (Dixson, 1998;Nelson, 2000), and seems functionally designed to obtain sires of superior genetic quality (Gangestad, Thornhill, & Garver-Apgar, 2005;Thornhill, 2006). However, the conventional wisdom holds that human female estrus became uniquely "lost" or "hidden" over evolutionary time (e.g., Burt, 1992), perhaps to promote male provisioning and paternal care in long-term pair-bonded relationships (Strassmann, 1981;Turke, 1984). ...
... By contrast, the pill users had no midcycle peak in tip earnings. As in other previous research, the pill eliminates peakfertility effects on the female body and behavior by putting the body in a state of hormonal pseudopregnancy (e.g., Gangestad, Simpson, Cousins, Garver-Apgar, & Christensen, 2004;Gangestad et al., 2005;Macrae, Alnwick, Milne, & Schloerscheidt, 2002). This also results in pill users making only US$193 per shift compared to normally cycling women making US$276 per shift-a loss of more than US $80 per shift. ...
... These results argue against the view that human estrus evolved to be lost or hidden from males (e.g., Strassmann, 1981;Turke, 1984). Indeed, the standard argument for women's "extended sexuality" (sexual receptivity outside the fertile estrus phase) is that it evolved to help women extract material resources from males (Gangestad et al., 2005;Thornhill, 2006), and some evidence suggests that women outside estrus place a higher value on male wealth relative to other male traits (Haselton & Miller, 2006). By this reasoning, nonestrous women in their extended sexuality phase should be better adapted to maximize tip earnings through displays of (nonfertile) sexual receptivity such as lap dancing. ...
To see whether estrus was really "lost" during human evolution (as researchers often claim), we examined ovulatory cycle effects on tip earnings by professional lap dancers working in gentlemen's clubs. Eighteen dancers recorded their menstrual periods, work shifts, and tip earnings for 60 days on a study web site. A mixed-model analysis of 296 work shifts (representing about 5300 lap dances) showed an interaction between cycle phase and hormonal contraception use. Normally cycling participants earned about US260 per shift during the luteal phase, and US$185 per shift during menstruation. By contrast, participants using contraceptive pills showed no estrous earnings peak. These results constitute the first direct economic evidence for the existence and importance of estrus in contemporary human females, in a real-world work setting. These results have clear implications for human evolution, sexuality, and economics.
... This relatively new approach to examining human mating and associated outcomes has in turn started a vast amount of research in the area. There are numerous chapters devoted to the various aspects of mating in evolutionary psychology handbooks (for example see, Campbell & Ellis, 2005;Gangestad, Thornhill, & Garver-Apgar, 2005;Malamuth, Huppin, & Paul, 2005;Schmitt, 2005;Shackelford, Pound, Goetz, & LaMunyon, 2005;Sugiyama, 2005;Symons, 2005), and indeed entire texts devoted to aspects of mating intelligence (e.g., . Thus, it is beyond the scope of this thesis to cover all the research and theories within this area. ...
... Males on the other hand, if they are to invest their potential resources into the relationship want to ensure that they are mating with a female with good genes that will ensure the survival of the children. The best indicator of good genes is physical attractiveness (Gangestad & Simpson, 2000;Gangestad et al., 2005). These sex differences have consistently been found across cultures even within traditional hunter-gather societies (Marlowe, 2004). ...
Sociometer Theory (Leary & Downs, 1995; Leary, Tambor, Terdal, & Downs, 1995) proposes that state self-esteem is a gauge of social inclusion. Expansions to this theory by Kirkpatrick and Ellis (2001) suggest that this is a domain specific process with different sociometers for different adaptive domains. Two studies were conducted to test predictions derived from the domain specific sociometer model of self-esteem proposed by Kirkpatrick and Ellis (2001). In Study 1, participants (N = 83) who were currently single, received feedback to indicate either acceptance (inclusion) or rejection (exclusion) for a potential dating situation. The results indicated that participants who were accepted versus rejected reported increases in state self-esteem and higher mating aspirations. The same effects were not present for either friendship aspiration or friendship investment, indicating domain specificity. The effect of the manipulation on mating aspirations was also significantly mediated by state self-esteem. Study 2 replicated Study 1 using participants (N = 81) who were currently in an intimate relationship. The results indicated that participants who were accepted versus rejected reported increases in state self-esteem and decreases in perceived relationship quality (commitment and satisfaction). The same effects were not present for either friendships aspirations or friendship investment. The association between the manipulation and resulting changes in perceived relationship quality were significantly mediated by state self-esteem, with state self-esteem acting as a suppressor. The results from both studies support a domain-specific conceptualisation of sociometer theory.
... Consequently, men are expected to increase their mate retention tactics when women are fertile 118 (Gangestad et al., 2005). Men who fail at such mate retention tactics during the fertile window 119 potentially pay steep reproductive costs of genetic cuckoldry, that is when their female partners 120 are fertilised by a rival man (Buss, 2002). ...
Understanding how human mating psychology is affected by changes in female cyclic fertility is informative for comprehending the evolution of human reproductive behavior. Based on differential selection pressures between the sexes, men are assumed to have evolved adaptations to notice women's within-cycle cues to fertility and show corresponding mate retention tactics to secure access to their female partners when fertile. However, previous studies suffered from methodological shortcomings and yielded inconsistent results. In a large, preregistered online dyadic diary study (384 heterosexual couples), we found no compelling evidence that men notice women's fertility status (as potentially reflected in women's attractiveness, sexual desire, or wish for contact with others) or display mid-cycle increases in mate retention tactics (jealousy, attention, wish for contact or sexual desire towards female partners). These results extend our current understanding of the evolution of women's concealed ovulation and oestrus, and suggest that both might have evolved independently.
... Pe scurt, grila de lectură evoluţionistă în psihologie ilustrează cum temeiul ultim al relaţiei este regăsit în selectarea unui partener care, pe termen lung,din punctul de vedere al unei femei, poate fi un "bun părinte" şi care să întreţină o implicare consistentă în raportul conjugal, iar pentru un bărbat poate deveni o "bună mamă", ce poate îngriji cu responsabilitate şi căldură copiii potenţiali care s-ar naşte în cadrul angajamentului erotic (Simpson & Gangestad, 2001). Multe din concluziile acestei abordări sunt contrariante, evidenţiind determinări inconştiente ale alegerilor noastre, care ţin de mecanisme biologice, encriptate genetic (Gangestad, Thornhill & Garver-Apgar, 2018). ...
Studiile de psihologie socială atestă cum deseori conduitele noastre se bizuie pe mobiluri implicite şi puţin conştientizate, care ordonează chiar şi opţiuni foarte implicante, cu miză, precum alegerea partenerului într-o relaţie romantică sau chiar a unui partener de viaţă (Branscombe & Baron, 2017; Aronson et al., 2018). Ultima decadă a impus în cîmpul cogniţiei sociale tot mai influent o perspectivă de înţelegere a deciziilor bazată pe o logică ascunsă, dar foarte pregnantă, mobilizată de către o serie de resorturi psihofiziologice înnăscute şi care porneşte de la premisa alegerii "celuilalt" de gen opus care poate contribui "mai bine" la perpetuarea speciei, pe calea "selecţiei naturale". Pe scurt, grila de lectură evoluţionistă în psihologie ilustrează cum temeiul ultim al relaţiei este regăsit în selectarea unui partener care, pe termen lung, din punctul de vedere al unei femei, poate fi un "bun părinte" şi care să întreţină o implicare consistentă în raportul conjugal, iar pentru un bărbat poate deveni o "bună mamă", ce poate îngriji cu responsabilitate şi căldură copiii potenţiali care s-ar naşte în cadrul angajamentului erotic. Multe din concluziile acestei abordări sunt contrariante, evidențiind determinări inconștiente ale alegerilor noastre, care țin de mecanisme biologice, encriptate genetic (Gangestad, Thornhill, & Garver-Apgar, 2018)...
... Under the motivation of breeding, ovulating females will conduct more frequent sexual behaviors, and even seek short-term sexual partners, so that they tend to invest more psychological resources in case of the opposite sex with high attractiveness (Gueguen, 2009;Röder, Brewer, & Fink, 2009). Therefore, FOs prefer highly attractive male faces (which signal good genes), which is similar to males (Gangestad, Thornhill, & Garver-Apgar, 2005;Johnston, Hagel, Franklin, Fink, & Grammer, 2001;Little, Jones, Burt, et al., 2007;Little, Jones, Pentonvoak, Burt, & Perrett, 2002). That is why the amplitude of vMMN in FOs was similar as the males. ...
Facial attractiveness plays important roles in social interaction. Electrophysiological and neuroimaging studies found several brain areas to be differentially responsive to attractive relative to unattractive faces. However, little is known about the time course of the information processing, especially under the unattended condition. Based on a "cross-modal delayed response" paradigm, the present study aimed to explore the automatic mechanism of facial attractiveness processing of females with different physiological cycles and males, respectively, through recording the event-related potentials in response to (un)attractive opposite-sex faces by two experiments. The attractiveness-related visual mismatch negativity (attractiveness vMMN) in posterior scalp distribution was recorded in both the experiments, which indicated that attractive faces could be processed automatically. And high-attractive opposite-sex faces can elicit larger vMMN in males than females in menstrual period in Study 1, but similar as females in ovulatory period in Study 2. Furthermore, by comparison, the latency of attractiveness vMMN in females with the ovulatory period was the longest. These results indicated as follows: (1) Males were more sensitive to attractive female faces, (2) females in ovulatory period were also attracted by the attractive male faces, (3) the long vMMN latency in females during ovulatory period suggested a special reproductive motivation to avoid being tainted by genes, which takes priority over the breeding motivation.
... This increases her CDM partner's paternity uncertainty. Partly consistent with this interpretation, the mate retention efforts of relatively "unsexy" men (at risk of infidelity) evidently increase when their partners are most fertile (Gangestad et al. 2005). Whereas male partners of highly attractive women guard them more throughout their ovulatory cycle, partners of less attractive women intensify their mate guarding only when it matters for preventing impregnation by another male. ...
Here we review some of the theory and evidence that account for sexual coercion (SC) and intimate partner violence (IPV) as related phenomena understood from evolutionary perspectives.
... Consistent with this analysis, women do selectively discriminate between potential mates on the basis of good genes-signaled by phenotypic traits such as bilateral bodily symmetry, muscularity, facial masculinity, and body odor and by behavioral evidence of creativity and intelligence (G. Miller & Todd, 1998)-and they do so especially during the most fertile phase of their menstrual cycles (Gangestad, Thornhill, & Garver-Apgar, 2005;Haselton & Miller, 2006;Penton-Voak & Perrett, 2000). ...
We focus here on evolutionary social cognition—how everyday cognition is tied to the fundamental, recurring adaptive challenges of social life. We begin by articulating the logical foundations of evolutionary social cognition. We then discuss the ways in which evolutionary social cognition is inherently motivated social cognition and subsequently review a rapidly growing body of research demonstrating the presence of adaptation-based, functional social-cognitive processes aimed at managing challenges of self-protection, disease avoidance, resource acquisition, social affiliation, status acquisition, mate seeking, mate retention, and kin care. We close by briefly revisiting big lessons and highlighting promising arenas for future theorizing and exploration. (PsycINFO Database Record (c) 2016 APA, all rights reserved)
... The neophilia-as-mating-display hypothesis may shed light on the connection we discovered between men's food neophilia and their short-term mating orientation. Immunological competence has been hypothesized to be an important marker of genetic quality, or "good genes" (Fessler et al., 2004;Hamilton & Zuk, 1982;von Schantz, Bensch, Grahn, Hasselquist, & Wittzell, 1999), which women prioritize more in short-term than long-term mating (Buss & Schmitt, 1993;Gangestad & Thornhill, 1997b;Waynforth, Delwadia, & Camm, 2005), and whose importance increases at ovulation -when women's short-term mating psychology looms largest Gangestad, Thornhill, & Garver-Apgar, 2005; Garver-Apgar, Gildersleeve, Haselton, & Fales, 2014). Consequently, men's displays of food neophilia should be more relevant and more effective as mating advertisements in short-term than in long-term mating contexts. ...
... Sexual attractiveness in men is reasonably hypothesized to be an indicator of genetic fitness (ancestrally, even if not now), but we cannot be certain that it is. The key is not whether there are other potential causes of sexual attractiveness-very clearly, there are (e.g., Kokko et al., 2003)-but rather whether any of these alternatives could generate and account for our specific findings concerning ovulatory cycle variation (or, for that matter, the many other studies that have documented ovulatory cycle shifts in female mate preferences or sexual interests; e.g., Gangestad et al., 2005a). ...
Thirty-eight normally cycling women provided daily reports of sexual interests and feelings for 35 days. Near ovulation , both pair-bonded and single women reported feeling more physically attractive and having greater interest in attending social gatherings where they might ...
... Additional evidence indicates that this desire may be directed toward nonprimary partners (Gangestad, Thornhill, & Garver, 2002), particularly if a woman's primary partner lacks specific indicators of genetic fitness, for example, symmetry (Gangestad, Thornhill, & Garver-Apgar, 2005b), sexual attractiveness (Haselton & Gangestad, 2006;Pillsworth & Haselton, 2006), and major histocompatibility complex gene compatibility (Garver-Apgar, Gangestad, Thornhill, Miller, & Olp, 2006). In line with such evidence, there is a rapidly growing body of work documenting corresponding shifts across the cycle in women's mate preferences (see Gangestad, Thornhill, & Garver-Apgar, 2005a, for a review). ...
... It was originally thought that, because women do not display drastic physical changes associated with heightened fertility (like the swelling and reddening of genitals in Old World primates; Pagel, 1994;Wallis, 1983), ovulation was concealed in women. However, several emerging lines of research suggest otherwise and have led to the development of hypotheses regarding the presence of specific ovulatory cues in women (Gangestad, Thornhill, & Garver-Apgar, 2005). ...
Evolutionary theories of mating suggest that shifting fertility levels during a woman's menstrual cycle play an important role in the formation and maintenance of romantic relationships. In this article, we review a burgeoning literature that has applied this framework to the investigation of male adaptations to female fertility. The studies reviewed here illuminate the ways in which men evolved to overcome the challenge of finding and attracting mates with peak levels of fertility. In particular, we review research that highlights the types of cues men may use to detect heightened fertility as well as the types of mating processes men display when encountering those cues. We discuss important avenues for future research on this topic as well as implications for psychological theories of romantic attraction.
... Sexual attractiveness in men is reasonably hypothesized to be an indicator of genetic fitness (ancestrally, even if not now), but we cannot be certain that it is. The key is not whether there are other potential causes of sexual attractiveness-very clearly, there are (e.g., Kokko et al., 2003)-but rather whether any of these alternatives could generate and account for our specific findings concerning ovulatory cycle variation (or, for that matter, the many other studies that have documented ovulatory cycle shifts in female mate preferences or sexual interests; e.g., Gangestad et al., 2005a). ...
Thirty-eight normally cycling women provided daily reports of sexual interests and feelings for 35 days. Near ovulation, both pair-bonded and single women reported feeling more physically attractive and having greater interest in attending social gatherings where they might meet men. Pair-bonded women who were near ovulation reported greater extra-pair flirtation and greater mate guarding by their primary partner. As predicted, however, these effects were exhibited primarily by women who perceived their partners to be low on hypothesized good genes indicators (low in sexual attractiveness relative to investment attractiveness). Ovulation-contingent increases in partner mate guarding were also moderated by female physical attractiveness; midcycle increases in mate guarding were experienced primarily by less attractive women, whereas more attractive women experienced relatively high levels of mate guarding throughout their cycle. These findings demonstrate ovulation-contingent shifts in desires and behaviors that are sensitive to varying fitness payoffs, and they provide support for the good genes hypothesis of human female extra-pair mating. The daily assessment method provides an important supplement to existing studies using scheduled laboratory visits as the purpose of the study (examining cycle-related variation) is not known by participants.
Previous research reported ovulatory changes in women’s appearance, mate preferences, extra- and in-pair sexual desire, and behavior, but has been criticized for small sample sizes, inappropriate designs, and undisclosed flexibility in analyses. In the present study, we sought to address these criticisms by preregistering our hypotheses and analysis plan and by collecting a large diary sample. We gathered more than 26,000 usable online self-reports in a diary format from 1,043 women, of which 421 were naturally cycling. We inferred the fertile period from menstrual onset reports. We used hormonal contraceptive users as a quasi-control group, as they experience menstruation, but not ovulation. We probed our results for robustness to different approaches (including different fertility estimates, different exclusion criteria, adjusting for potential confounds, moderation by methodological factors). We found robust evidence supporting previously reported ovulatory increases in extra-pair desire and behavior, in-pair desire, and self-perceived desirability, as well as no unexpected associations. Yet, we did not find predicted effects on partner mate retention behavior, clothing choices, or narcissism. Contrary to some of the earlier literature, partners’ sexual attractiveness did not moderate the cycle shifts. Taken together, the replicability of the existing literature on ovulatory changes was mixed. We conclude with simulation-based recommendations for reading the past literature and for designing future large-scale preregistered within-subject studies to understand ovulatory cycle changes and the effects of hormonal contraception. Interindividual differences in the size of ovulatory changes emerge as an important area for further study.
There has been little work to determine whether attractiveness ratings of faces correspond to sexual or more general attraction. We tested whether a measure of women’s physiological arousal (pupil diameter change) was correlated with ratings of men’s facial attractiveness. In Study 1, women rated the faces of men for whom we also measured salivary testosterone. They rated each face for attractiveness, and for desirability for friendship and long- and short-term romantic relationships. Pupil diameter change was not related to subjective ratings of attractiveness, but was positively correlated with the men’s testosterone. In Study 2 we compared women’s pupil diameter change in response to the faces of men with high versus low testosterone, as well as in response to non-facial images pre-rated as either sexually arousing or threatening. Pupil dilation was not affected by testosterone, and increased relatively more in response to sexually arousing than threatening images. We conclude that self-rated preferences may not provide a straightforward and direct assessment of sexual attraction. We argue that future work should identify the constructs that are tapped via attractiveness ratings of faces, and support the development of methodology which assesses objective sexual attraction.
The effects of hormones on human behaviour have been extensively studied, but little attention has been paid to the influence of ovarian hormones on risky driving. Twenty-five normally cycling women took part in three sessions, including an ovulatory phase estimation session and two experimental sessions: high vs low fertile phases. These two phases were monitored through a urine-based luteinizing hormone predictor test. In the two experimental sessions, participants were administered the Driving Behaviour Questionnaire and the Vienna Risk-Taking Test. Results showed that women are more risk-averse in their driving behaviour during their high-fertile phase. The influence of hormonal fluctuations on self-perception of risk attitude when driving was non-significant. Findings are discussed from an evolutionary perspective.Copyright
Previous research finds that ovulation—the time each month when women are most fertile—can shift women’s mating psychology and increase their desire for new options in men. However, might ovulation also increase women’s desire for new products? Four studies find that women select a greater number of unique options from consumer product sets at high fertility. This effect is especially strong for women in committed relationships. Additional findings show that the fertility shift in desire for variety in products is driven by the fertility shift in desire for new options in men activating a variety-seeking mind-set. Subsequently, loyalty to a romantic partner, whether manipulated or measured, moderated the effect of fertility on consumer variety seeking. This research contributes to the literature by revealing when, why, and how fertility influences desire for variety in consumer choice and highlights the mating motives that underlie this effect.
In more than 95% of mammalian species, males provide little direct investment in the well-being of their offspring. Humans are one notable exception to this pattern and, to date, the factors that contributed to the evolution and the proximate expression of human paternal care are unexplained (T. H. Clutton-Brock, 1989). The nature, extent, and influence of human paternal investment on the physical and social well-being of children are reviewed in light of the social and ecological factors that are associated with paternal investment in other species. On the basis of this review, discussion of the evolution and proximate expression of human paternal investment is provided.
Although much research has explored the adaptive problems of mate selection and mate attraction, little research has investigated the adaptive problem of mate retention. We tested several evolutionary psychological hypotheses about the determinants of mate retention in 214 married people. We assessed the usage of 19 mate retention tactics ranging from vigilance to violence. Key hypothesized findings include the following: Men's, but not women's, mate retention positively covaried with partner's youth and physical attractiveness. Women's, but not men's, mate retention positively covaried with partner's income and status striving. Men's mate retention positively covaried with perceived probability of partner's infidelity. Men, more than women, reported using resource display, submission and debasement, and intrasexual threats to retain their mates. Women, more than men, reported using appearance enhancement and verbal signals of possession. Discussion includes an evolutionary psychological analysis of mate retention in married couples.
This article replies to commentaries by A. Weller and L. Weller (2002) and by C. A. Graham (2002). The author of this reply argues that A. Weller and L. Weller merely defined away the problem of cycle variability for synchrony by assuming either that all cycles are 28-days long or that the expected difference between 2 cycles is 1/4 the mean of the cycles of 2 rhythms. In her commentary, C. A. Graham stated that A. Weller and L. Weller's later research did not use recall data, but the author of this reply shows that this is not true. Menstrual-synchrony research taken as a whole is plagued by a multitude of systematic errors that lead inevitably to the conclusion that there is no evidence for menstrual synchrony among women.
J. C. Schank (2001) argued that biases in the calculation of synchrony (due to inherent variability in the menstrual cycle) and in respondents' recall of menstrual dates can produce spurious results. In this commentary, the major flaws in J. C. Schank's arguments regarding the calculation of synchrony are presented. Low standard deviations (< 2.0) of interwomen cycle lengths were found in a reanalysis of the Bedouin family data (A. Weller & L. Weller, 1997). This obviates J. C. Schank's major assumption that a high degree of cycle variability exists and his concern that high variability produces a spurious increase of onset differences over time. Furthermore, research that has used random control groups has found significantly greater levels of synchrony in their experimental groups, refuting J. C. Schank's arguments.
The aim of this review is to consider the potential benefits that females may gain from mating more than once in a single reproductive cycle. The relationship between non-genetic and genetic benefits is briefly explored. We suggest that multiple mating for purely non-genetic benefits is unlikely as it invariably leads to the possibility of genetic benefits as well. We begin by briefly reviewing the main models for genetic benefits to mate choice, and the supporting evidence that choice can increase offspring performance and the sexual attractiveness of sons. We then explain how multiple matin!: can elevate offspring fitness by increasing the number of potential sires that compete, when this occurs in conjunction with mechanisms of paternity biasing that function in copula or post-copulation. We begin by identifying cases where females use precopulatory cues to identify mates prior to remating. In the simplest case, females remate because they identify a superior mate and 'trade up' genetically. The main evidence for this process comes from extra-pair copulation in birds. Second, we note other cases where pre-copulatory cues may be less reliable and females mate with several males to promote post-copulatory mechanisms that bias paternity. Although a distinction is drawn between sperm competition and cryptic female choice, we point out that the genetic benefits to polyandry in terms of producing more viable or sexually attractive offspring do not depend on the exact mechanism that leads to biased paternity. Post-copulatory mechanisms of paternity biasing may: (1) reduce genetic incompatibility between male and female genetic contributions to offspring; (2) increase offspring viability if there is a positive correlation between traits favoured post-copulation and those that improve performance under natural selection; (3) increase the ability of sons to gain paternity when they mate with polyandrous females. A third possibility is that genetic diversity among offspring is directly favoured. This can be due to bet-hedging (due to mate assessment errors or temporal fluctuations in the environment), beneficial interactions between less related siblings of the opportunity to preferentially fertilise eggs with sperm of a specific genotype drawn from a range of stored sperm depending on prevailing environmental conditions. We use case studies from the social insects to provide some concrete examples of the role of genetic diversity among progeny in elevating fitness. We conclude that post-copulatory mechanisms provide a more reliable way of selecting a genetically compatible mate than pre-copulatory mate choice. Some of the best evidence for cryptic female choice by sperm selection is due to selection of more compatible sperm. Two future areas of research seem likely to be profitable. First, more experimental evidence is needed demonstrating that multiple mating increases offspring fitness via genetic gains. Second, the role of multiple mating in promoting assortative fertilization and increasing reproductive isolation between populations may help us to understand sympatric speciation.
The recognition that sexual desire is associated with several significant individual and interpersonal life events has led to a corresponding interest in delineating and exploring the correlates and potentially causal antecedents of this sexual phenomenon. Researchers interested in biological causes have focused on the sex hormones and on hormonally-mediated (female)life events. In this review, I first define sexual desire, distinguish sexual desire from other sexual experiences (i.e., arousal, activity), and discuss commonly used operationalizations. I then summarize empirical research exploring the relationship between one hormonally-mediated female life event - the menstrual cycle - and sexual desire. I conclude that sexual desire does appear to increase during certain menstrual cycle phases for some women (in particular, at ovulation and during the mid follicular and late luteal phases). However, no single rhythmic pattern emerges that can be said to definitively characterize the sexual experience of the human female.
Nachman and Heller recently suggested that previous estimates of the relative magnitude of fluctuating asymmetry in morphological characters have been biased because non-linear relationships between asymmetry and size have not been considered. This suggestion cannot generally be very important because (1) inclusion of a non-linear size term in regression models relating fitness components to asymmetry does not change the general conclusion that asymmetry is an important predictor of fitness components, and (2) experimental studies uncoupling the relationship between asymmetry and size have generally found significant effects of asymmetry independent of body size on mating success and locomotion.
This book provides an authoritative and comprehensive synthesis of current research on the evolution and physiological control of sexual behaviour in the primates - prosimians, monkeys, apes, and human beings. This new edition has been fully updated and greatly expanded throughout to incorporate a decade of new research findings. It maintains the depth and scientific rigour of the first edition, and includes a new chapter on human sexuality, written from a comparative perspective.
It is hypothesized that human faces judged to be attractive by people possess two features-averageness and symmetry-that promoted adaptive mate selection in human evolutionary history by way of production of offspring with parasite resistance. Facial composites made by combining individual faces are judged to be attractive, and more attractive than the majority of individual faces. The composites possess both symmetry and averageness of features. Facial averageness may reflect high individual protein heterozygosity and thus an array of proteins to which parasites must adapt. Heterozygosity may be an important defense of long-lived hosts against parasites when it occurs in portions of the genome that do not code for the essential features of complex adaptations. In this case heterozygosity can create a hostile microenvironment for parasites without disrupting adaptation. Facial bilateral symmetry is hypothesized to affect positive beauty judgments because symmetry is a certification of overall phenotypic quality and developmental health, which may be importantly influenced by parasites. Certain secondary sexual traits are influenced by testosterone, a hormone that reduces immunocompetence. Symmetry and size of the secondary sexual traits of the face (e.g., cheek bones) are expected to correlate positively and advertise immunocompetence honestly and therefore to affect positive beauty judgments. Facial attractiveness is predicted to correlate with attractive, nonfacial secondary sexual traits; other predictions from the view that parasite-driven selection led to the evolution of psychological adaptations of human beauty perception are discussed. The view that human physical attractiveness and judgments about human physical attractiveness evolved in the context of parasite-driven selection leads to the hypothesis that both adults and children have a species-typical adaptation to the problem of identifying and favoring healthy individuals and avoiding parasite-susceptible individuals. It is proposed that this adaptation guides human decisions about nepotism and reciprocity in relation to physical attractiveness.
Most evolutionary theories of human mating have focused on the adaptive benefits of short-term mating for men. Men cannot pursue a strategy of short-term mating, however, without willing women. Existing empirical evidence suggests that some women engage in short-term mating some of the time and probably have done so recurrently over human evolutionary history. The current studies tested hypotheses about the potential benefits women might derive from engaging in one type of short-term mating — extra-pair liaisons — and the contexts in which they do so. These include resource hypotheses (e.g. immediate resource accrual), genetic hypotheses (e.g. having genetically diverse offspring), mate switching hypotheses (e.g. acquiring a better mate), mate skill acquisition hypotheses (e.g. mate preference clarification) and mate manipulation hypotheses (e.g. deterring a partner's future infidelity). These hypotheses were tested by examining the perceived likelihood that women would receive particular benefits through a short-term extra-pair mating (Study 1); the perceived magnitude of benefits if received (Study 2); the contexts in which women engage in short-term extra-pair mating (Study 3); and individual differences among women in proclivity to pursue short-term matings in their perceptions of benefits (Study 4). Most strongly supported across all four studies were the mate switching and resource acquisition hypotheses. Discussion focuses on the distinction between functions and beneficial effects of short-term mating, limitations of the current studies and the consequences of women's short-term mating strategies for the broader matrix of human mating.
The reliable indicator hypothesis proposes that exaggerated sexual swellings in female primates serve as honest signals of female quality that function in female-female competition over mates. We examined a version of this hypothesis using interspecific data to test whether exaggerated sexual swellings are associated with female mating competition, as measured using the adult sex ratio, female canine size, and expected female mating synchrony. The ratio of females to males and relative canine size declined over evolutionary transitions in swelling state, thus providing no support for the reliable indicator hypothesis. Expected female mating synchrony increased over evolutionary transitions in swelling state, but this pattern did not approach significance, and the patterns were opposite to predictions when controlling for the number of males in the group. In addition to these comparative tests, we reviewed evidence concerning individual attributes of females relative to characteristics of their swellings. Contrary to the reliable indicator hypothesis, the least fertile females, or those least likely to raise surviving offspring, often have larger swellings. We consider the statistical power of our tests, discuss the theoretical and empirical bases for our compar- ative predictions, and consider other lines of evidence needed to test the reliable indicator hypothesis. We also discuss an alternative hypothesis, the graded signal hypothesis, which combines the benefits of biasing and confusing paternity through a novel mechanism and is testable in the field and the laboratory. Key words: comparative study, communication, honest signaling, independent contrasts, primates, sexual swellings. (Behav Ecol 12:646-654 (2001))
Species survival relies on rapid and accurate categorization of the sex of potential mates. Macrae, Alnwick, Milne, and Schloerscheidt (2002) showed females to have enhanced sensitivity to reproductively relevant stimuli (male faces) but not to reproductively irrelevant stimuli (female faces) during periods of high fertility. Extending this research, the present study considered the efficiency of person construal in a series of additional comparison groups - specifically, men, pregnant women, and women on the contraceptive pill. Participants completed a person-categorization task twice, with a two week interval between testing sessions. For normally ovulating women, testing occurred during phases of high (i.e., ovulation) and low (i.e., menstruation) conception probability. The results confirmed that women with cyclical fluctuations in fertility were faster to categorize males, but not females, during periods of high than low conception probability. Women on the pill, however, were faster to categorize male than female faces at both testing sessions. Pregnant women and men displayed no reliable effects. The findings are considered in terms of adaptive person perception.
Several hypotheses have been proposed to explain the occurrence of continual sexual receptivity and concealed ovulation in human females. In view of the large number of benefits that would accrue to females if they could sense their own ovulation, these explanations appear insufficient to explain why ovulation is concealed from females as well as from males. The hypothesis presented here is that the phenomenon occurs because of a hominid female tendency to avoid conception in biologically nonadaptive ways. This tendency was countered by natural selection by making ovulation virtually undetectable to women. The sequence of evolutionary adaptations culminating in concealed ovulation is most likely as follows. First, olfactory, visual, and pronounced behavioral cues to ovulation were lost to conspecifics. Coincidentally females evolved continuous receptivity, frequently copulating at times other than when ovulating. Finally, females lost conscious cues to their own fertility. This last step was predicated up...
Reproductive effort, defined as the cost in energy spent and risks taken in reproduction, has two components: parental effort and mating effort. Environmental uncertainties influencing juvenile survivorship affect the temporal pattern of parental effort: when the parent cannot decrease offspring mortality by increased investment, it must minimize the effort invested in offspring which die. Environmental uncertainty responsible for juvenile mortalities before the termination of parental care causes juveniles to have low reproductive values and is responsible for the apparently widespread tendency toward low early parental effort. Several predictions about the pattern of expenditure of parental effort result, although at present the empirical bases for testing these predictions fully are inadequate, and comparisons are largely inferential. A comparison of marsupial and placental parental strategies as a test of these predictions suggests that marsupials have long been under selection imposed by frequent los...
Heterosexual men and women were told they were competing with another same-sex individual for a date with an attractive opposite-sex interviewer. After answering 6 questions, participants were asked to tell the competitor why the interviewer should choose them over the competitor. Participants' videotaped behavior was coded for different behavioral tactics. Men who were more symmetrical and who had a more unrestricted sociosexual orientation were more likely to use direct competition tactics than were less symmetrical and restricted men. Restricted men accentuated their positive personal qualities, presenting themselves as "nice guys." Structural equation modeling revealed that fluctuating asymmetry (FA) was directly associated with the use of direct competition tactics. However, the link between FA and presenting oneself as a nice guy was mediated through sociosexuality. No effects were found for women. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Examined the frequency of extra-pair copulations (EPCs) by 2,708 female humans in relation to the probability of conception on days 6–20 of a 28-day menstrual cycle. Data are interpreted as supporting a sperm competition theory of double-mating behavior. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
During human evolutionary history, there were “trade-offs” between expending time and energy on child-rearing and mating, so both men and women evolved conditional mating strategies guided by cues signaling the circumstances. Many short-term matings might be successful for some men; others might try to find and keep a single mate, investing their effort in rearing her offspring. Recent evidence suggests that men with features signaling genetic benefits to offspring should be preferred by women as short-term mates, but there are trade-offs between a mate's genetic fitness and his willingness to help in child-rearing. It is these circumstances and the cues that signal them that underlie the variation in short- and long-term mating strategies between and within the sexes.
Sexual Selection in Primates provides an account of all aspects of sexual selection in primates, combining theoretical insights, comprehensive reviews of the primate literature and comparative perspectives from relevant work on other mammals, birds and humans. Topics include sex roles, sexual dimorphism in weapons, ornaments and armaments, sex ratios, sex differences in behaviour and development, mate choice, sexual conflict, sex-specific life history strategies, sperm competition and infanticide. The outcome of the evolutionary struggle between the sexes, the flexibility of roles and the leverage of females are discussed and emphasised throughout. Sexual Selection in Primates is aimed at graduates and researchers in primatology, animal behaviour, evolutionary biology and comparative psychology.
Hadza huntergatherers display economic and social features usually assumed to indicate the dependence of wives and children on provisioning husbands and fathers. The wives and children of better Hadza hunters have been found to be betternourished, consistent with the assumption that men hunt to provision their families. Yet, as is common among foragers, the Hadza share meat widely. Analyses of meatsharing data confirm that little of the meat from large prey went to the hunters own household. These analyses also show that neither a mans hunting success nor the time he spent hunting made any difference in how much meat his family got from the kills of others. Here we address questions posed by this set of observations. What explains the better nutrition of the children of better hunters if they did not get differential rations of meat? If better hunters got no more meat for their effort and poorer hunters were not punished with less, what incentive could account for the continuing disproportionate contribution that some men made to the groups nutrition? If women were not dependent on their husbands hunting success for meat, an obvious incentive for women to marry hunters disappears. We briefly consider the implications of these patterns for the evolution of marriage and nuclear families.
The classic studies of Kinsey and his coworkers (1948, 1953) and of Masters and Johnson (1966) provided a major stimulus for the scientific investigation of human sexual behavior. Since those pioneering efforts, a number of reports have appeared concerned with physiological (Masters and Johnson, 1970), behavioral (Fisher, 1973) and social (Chesser, 1957) determinants of human sexuality.
The assumption that absence of oestrus and of manifestations of ovulation is specific to humans has given rise to various proposals of a role for selection pressures in the evolution of these features in the form of sexual selection or other behavioural adaptations. Analysis of the sexual behaviour of nonhuman primates and humans indicates, however, that constant receptivity is not unique to humans and that human sexual behaviour is not independent of the phases of the menstrual cycle. Quantitative differences in the distribution of sexual behaviour between humans and the nonhuman primates in question may be the result of many morphological, ecological, and cultural factors of which those differences are side effects. In the case of the postulated selection pressures on the disappearance of visual manifestations of ovulation, the rather unlikely chimpanzee model of anogenital swelling in the early Hominidae may be replaced by an early-hominoidal model in which the swelling was relatively small. Its reduction in anthropogenesis may have been caused by bipedal locomotion, the cost of water accumulation, hyperaemia of the area, and an increase in adipose tissue. Furthermore, olfactory communication in the context of sexual behaviour in the climatic conditions of the African savannah would have been sufficient for detection of the fertile periods of the menstrual cycle. Thus, assuming the existence of direct selection pressures on sexual behaviour in the Plio/Pleistocene evolution of the Homininae seems unjustified.
BACKGROUND: Recent attention has been paid to patterns of fluctuating asymmetry (FA) in paired bilateral traits and the extent
to which they reflect phenotypic and genetic quality. The FA–fertility hypothesis proposes that FA may be a reliable indicator
of ejaculate quality in humans and other animals. The common control by the Hox genes of the differentiation of both the urogenital system and the appendicular skeleton in vertebrates has been proposed
as an explanation for the recent finding that FA, and the second to fourth digit ratios (2D:4D) are both associated with semen
quality in men. METHODS: A group of 50 men was evaluated for FA, calculated by the sum of three different body FAs, 2D:4D
ratios, and seminal parameters of masturbatory semen samples. RESULTS: Composite FA had a significant effect on semen parameters;
the 2D:4D ratios did not predict semen quality. CONCLUSIONS: Comparison of our data with previous studies suggests that the
putative relationship between semen quality and 2D:4D may have been driven by the inclusion of severely oligozoospermic men
within the original subject group. Our sample included men with equally high 2D:4D ratios but who had normal semen. Thus,
the 2D:4D ratio may not reliably indicate poor semen quality although FA might.
This article reviews evidence of coitus-induced ovulation. Maintenance of reproductive efficiency by more than 1 mechanism for triggering ovulation is interpreted as an evolutionary phenomenon aimed at ensuring the survival of the species. In earlier research estrogen levels or progesterone output were believed to regulate the ovulatory luteinizing hormone (LH) release and the length of the receptive period in spontaneous ovulators; more recently the effect of neural olfactory and emotional stimuli has been recognized. The neuroendocrine systems involved in spontaneous and reflex-induced ovulation include the hypothalamic-hypophyseal-gonadokinetic system and the neurohormonal pathways for coitomimetic stimuli. In spontaneously ovulating rodents the stimulus of coitus serves as an inducer for pseudopregnancy. The translation of vaginal stimulation into gonadomimetic humoral messages released from the hypothalamus and/or the posterior pituitary for the liberation of LH and prolactin is not completely understood. Nervous or biochemical influences resulting from coitus may even more directly affect ovarian functions by local sympathetic reflexes or by biochemical components of the ejaculate. In coitus-induced ovulation central nervous and/or peripheral autonomic nervous involvement may interact to push ovarian follicles toward maturation and ovulation or may help to ovulate nearly ripe or ripe follicles as a result of cohabitation. Acceptance of coitus-induced ovulation in humans renders rhythm methods of fertility control unreliable. In 1 large study of pregnancies resulting from rape 33-46% of conceptions occurred during what should have been a safe period. Emotions may also play a role in facilitating or predisposing to coitus-induced ovulation. There is a need for further biochemical statistical and demographic analyses of the frequency and sociologic importance of coitus-induced ovulation in humans.
As our closest living relatives, chimpanzees and bonobos have been widely used as models of the behavior of early hominids. In recent years, as information on the social behavior and ecology of bonobos has come to light, many interspecific comparisons have been made. Chimpanzees have been characterized in terms of their intercommunity warfare, meat eating, infanticide, cannibalism, male status-striving, and dominance over females. Bonobos, meanwhile, have been portrayed as the "Make love, not war" ape, characterized by female power-sharing, a lack of aggression between either individuals or groups, richly elaborated sexual behavior that occurs without the constraint of a narrow window of fertility, and the use of sex for communicative purposes. This paper evaluates the evidence for this dichotomy and considers the reasons that contrasting portrayals of the two great apes have developed. While there are marked differences in social behavior between these two species, I argue that they are more similar behaviorally than most accounts have suggested. I discuss several reasons that current Views of bonobo and chimpanzee societies may not accord well with field data. Among these are a bias toward captive data on bonobos, the tendency to see bonobos as derived because their behavior has been described more recently than that of chimpanzees, and the possibility that interpretations of bonobo-chimpanzee differences are reflections of human male-female differences.
Research literature in the field of extramarital sex (EMS) is reviewed. Initially, definitional problems which reveal the need for increased rigor in specifying the sexual behavior under consideration, the dyad or group outside of which the behavior occurs, and the consensual or non‐consensual nature of the behavior are discussed. Twelve surveys of EMS are examined and the limitations of incidence rate figures discussed. Empirical studies have attempted to identify key variables which discriminate between EMS and non‐EMS samples. The findings of this research are summarized according to four variable categories: social background characteristics, characteristics of the marriage, personal readiness characteristics, and sex and gender differences. Characteristics of the marriage and personal readiness characteristics are found to be of prime importance in understanding EMS, although sex and gender differences frequently qualify major empirical relationships. The attitude continuum of extramarital sexual permissiveness (EMSP) has received considerable research attention. Although premarital sexual permissiveness is the most significant correlate of EMSP, the tenuous results of research examining the attitude‐behavior (EMSP‐EMS) link demonstrate the need for new conceptualizations in this area. Finally, the conclusions of this review are presented in summary.
Olfactory cues play a prominent, yet underestimated role in shaping emotional attitudes towards conspecifics. Among humans olfactory cues can have effects on behavior. In a rating study (n = 290) females rated the smell of androstenone. The emotional reaction to androstenone changed during the menstrual cycle. Females rated the main component of male body odor unattractive. This changed to a neutral emotional response at the conceptive optimum around ovulation. The finding has direct consequences for hypotheses concerning the evolutionary loss of estrus. It is suggested that the cyclic-dependent emotional rating of androstenone may facilitate active female choice of sex partners and may be a proximate cue for female mate-choice.
Fluctuations in handgrip strength and reaction time were examined across the menstrual cycle. For handgrip strength, there was an interaction between menstrual cycle phase and whether testing involved overtones of sexual assault. Women who were in the ovulatory phase and read a sexual assault scenario were the only ones that showed an increase in handgrip strength. These results are consistent with other evidence that women may have been selected during human evolution to behave in ways that reduce the likelihood of conception as a consequence of rape.
There is accumulating evidence that women prefer symmetric men. This preference would be adaptive if symmetry was correlated with a fitness trait such as fertility. We show that, in a sample of 53 men from an infertility clinic, a measure of overall absolute fluctuating asymmetry (FA) in digits 2 to 5 was negatively related to sperm number per ejaculate, sperm speed, and sperm migration, and overall relative FA was negatively related to sperm number and sperm speed. Subjects who had few or no sperm in their ejaculates (azoospermics) tended to have high FA, particularly when obstructive azoospermia was the likely diagnosis. Controlling for weight, height, and age left sperm number, sperm speed, and sperm migration significantly related to both absolute and relative FA. The association between low digit FA and large ejaculates and high sperm quality may arise because (1) generalized developmental stability of the body is related to fertility or (2) Hox genes control differentiation of digits and the urinogenital system in vertebrates, and FA of the former is closely linked to developmental stability of the latter.
Male-female bonds in humans have long been attributed to the need for male assistance with provisioning of offspring (Westermarck 1929, Lovejoy 1981, Lancaster and Lancaster 1983). Recently, however, attention has been drawn to several features of modern foragers (and presumably our ancestors) that challenge the paternal-investment theory of human pair bonding: (1) Men in some foraging societies contribute less to the diet than women do (Hiatt 1974, Kelly 1995) yet marriage still exists. (2) Forager women are less dependent on husbands when they can gather food and when they live with their own kin, and postmarital residence is much more flexible among foragers than in traditional agricultural societies (van den Berghe 1979, Marlowe 2000a). (3) Hunting provides such unpredictable returns that it should be a poor strategy for provisioning children (Hawkes, O'Connell, and Blurton Jones 1991). (4) The foods men acquire (e.g., meat, fish, and honey) tend to be shared widely outside the household (Kaplan and Hill 1985, Bliege Bird and Bird 1997, Hawkes, O'Connell, and Blurton Jones 2001), with the result that the wives of good foragers may receive no more food than others in camp. (5) The effect of fathers' absence on offspring survival does not predict marital stability as well as do men's mating opportunities (Blurton Jones et al. 2000). These challenges to the paternal-investment theory have left some asking just how important provisioning by men is to forager women. Females should allocate available energy to reducing offspring mortality and/or increasing fertility in ways that maximize their own reproductive success (Lack 1968, Smith and Fretwell 1974). Therefore, in this paper I use demographic data on foragers to test whether male provisioning-for which male contribution to diet serves as a proxy-enhances female reproductive success. While others have analyzed the demography of some foraging populations (Hewlett 1991; Bentley, Jasienska, and Goldberg 1993; Kelly 1995; Pennington 1996; Sellen and Mace 1997, 1999) and some have analyzed male contribution to diet among foragers (Lee 1968, Hiatt 1974, Barry and Schlegel 1982, Ember 1978, Kelly 1995), here I consider the two together. In addition, I control for habitat quality. The comparative approach I adopt ignores variation within societies, which would be more informative about cause and effect, but allows me to generalize across all foraging societies. I will show that male contribution to diet does enhance female reproductive success and go on to discuss the implications of this for our mating system. © by The Wenner-Gren Foundation for Anthropological Research. All rights reserved.
Recently, women have been found to prefer the scent of symmetrical men and relatively masculine male faces more during the fertile (late follicular and ovulatory) phases of their menstrual cycles than during their infertile (e.g., luteal) phases. These findings make most theoretical sense if men's symmetry is associated with the masculinity of their faces and, therefore, men's symmetry and facial masculinity tap a shared underlying quality. This study examined associations between masculine facial features and nonfacial body symmetry as well as facial symmetry in samples of 141 men and 154 women. As predicted, a component of facial features that discriminates the sexes and reflects masculinization of the face significantly covaried with symmetry in men. No significant correlation was observed for women. These findings suggest that men's facial masculinity partly advertises underlying developmental stability.
Human skin has been shown to contain a high level of 5α-reductase activity, the enzyme that catalyses the conversion of the weak androgen testosterone into dihydrotestosterone, the most potent androgen. Because two types of 5α-reductase genes have been characterized in humans, we have cloned 5α-reductase cDNAs from adult human keratinocyte and skin fibroblast cDNA libraries to identify and gain better knowledge of the 5α-reductase expressed in normal human skin. Nucleotide sequence analysis shows that the clones obtained correspond to the type I 5α-reductase. RNase protection analysis using (poly A)+ RNA obtained from human skin and prostate also confirms that type I 5α-reductase is the predominant type expressed in normal skin, whereas type II 5α-reductase is the major form found in the prostate. Following polymerase chain reaction amplification of human keratinocyte and skin fibroblast cDNA, a low level of type II 5α-reductase cDNA has been detected. Using antipeptide antibodies raised in rabbits against the peptide sequence covering amino acids 227 – 240 to perform immunohistochemical localization of 5α-reductase, we have found that 5α-reductase is distributed in sweat and sebaceous glands, as well as in the epidermal cell layers, thus providing the basis for the important role of androgens in human skin and its appendages.
There is some evidence that women are less likely to be raped during the mid-portion of the menstrual cycle. In order to determine if women might be behaving in ways to decrease their chances of sexual assault when they are most likely to conceive, female college students were asked to complete a questionnaire about their activities during the past 24 hours and indicate the first day of their last menstruation. A statistically significant decrease in risk taking behavior during the ovulatory phase of the menstrual cycle was obtained for respondents who were not taking birth control pills.
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.
Interindividual variations in host immune responses to HPV infection are thought to be important determinants of viral persistence and progression to cervical intraepithelial neoplasia and cancer. However, few studies have measured local immune markers at the site of infection (e.g., the cervical mucosa). We sought to determine biologic correlates of IL-10 and IL-12 concentrations in cervical secretions. Cervical secretions were passively collected using a WeckCel sponge from 247 women participating in a natural history study of human papillomavirus infection as part of an immunologic ancillary study. IL-10 and IL-12 concentrations were determined using standard ELISA assays.In general, IL-10 and IL-12 levels were significantly intercorrelated (Pearson's correlation coefficient = 0.6) but had somewhat different determinants. Significant increases (P
Research has failed to reach consensus on the characteristics of attractive male faces. Different studies have reported preferences for phenotypically average faces, and faces with both exaggerated and reduced sexual dimorphism. Recent studies demonstrate cyclic changes in female sexual behavior and preferences for odors and facial characteristics that may reflect conditional mating strategies. We employed computer graphic techniques to manipulate the “masculinity” or “femininity” of a composite male face by exaggerating or reducing the shape differences between female and male average faces. Five stimuli with varying levels of masculinity and femininity were presented in a national U.K. magazine, with a questionnaire. Female respondents in the follicular phase of their menstrual cycle (n = 55) were significantly more likely to choose a masculine face than those in menses and luteal phases (n = 84). This study provides further evidence that when conception is most likely, females prefer testosterone-related facial characteristics that may honestly advertise immunocompetence.
Addresses the many psychological adaptations that underlie the diversity of aesthetic experiences of interest to aestheticians. First, the chapter briefly lists the experiential domain of interest academic aestheticians. It then discusses the adaptionist program and how it applies to these experiences in a general way. Next, it resolves some dilemmas in traditional aesthetics using the adaptionist perspective. Finally, it gives a taxonomy of the psychological adaptations underlying the diverse experiences of interest to aestheticians. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Evidence that women are less likely to be raped near ovulation than at other times in the ovarian cycle may reflect behavioral adaptations against the risk of fertile insemination by rapists. Chavanne and Gallup [Evol. Hum. Behav. 19 (1998) 27] proposed that women selectively reduce behaviors that expose them to a risk of rape during the ovulatory phase of their menstrual cycle, and reported supportive evidence. However, their study suffered from certain methodological shortcomings. In an improved test involving 51 subjects, repeated measurement, and an explicit distinction between risky and nonrisky activities, we confirmed all predictions: During the ovulatory phase, naturally cycling women reduced risky behaviors and increased nonrisky ones. Women using contraceptives causing hormonal suppression of ovulation showed neither effect.