The evolution of human sexuality revisited
Abstract
Patterns in the data on human sexuality support the hypothesis that the bases of sexual emotions are products of natural selection. Most generally, the universal existence of laws, rules, and gossip about sex, the pervasive interest in other people's sex lives, the widespread seeking of privacy for sexual intercourse, and the secrecy that normally permeates sexual conduct imply a history of reproductive competition. More specifically, the typical differences between men and women in sexual feelings can be explained most parsimoniously as resulting from the extraordinarily different reproductive opportunities and constraints males and females normally encountered during the course of evolutionary history. Men are more likely than women to desire multiple mates; to desire a variety of sexual partners; to experience sexual jealousy of a spouse irrespective of specific circumstances; to be sexually aroused by the sight of a member of the other sex; to experience an autonomous desire for sexual intercourse; and to evaluate sexual desirability primarily on the bases of physical appearance and youth.
The evolutionary causes of human sexuality have been obscured by attempts to find harmony in natural creative processes and human social life and to view sex differences as complementary. The human female's capacity for orgasm and the loss of estrus, for example, have been persistently interpreted as marriage-maintaining adaptations. Available evidence is more consistent with the view that few sex differences in sexuality are complementary, that many aspects of sexuality undermine marriage, and that sexuality is less a unifying than a divisive force in human affairs.
... First, though, some personal context. I became an evolutionary psychologist in 1984 while reading Donald Symons's The Evolution of Human Sexuality (Symons, 1979(Symons, , 1980 during graduate school. I found Symons's analysis novel, beautifully coherent, and persuasive. ...
... Symons discussed the different natures of male and female erotica; whether female orgasm is adaptive; the Coolidge Effect (and its flip side, the diminution of a man's appreciation of a woman's sexual charms after orgasm); the sexual promiscuity of homosexual men (before AIDS), showing what men might do if they could; and possible hormonal contributions to the sex differences. Symons (1979Symons ( , 1980 provided a wealth of hypotheses-ranging from highly plausible to compelling-before evolutionary psychology was a discipline. When I reread his book 40 years after its publication, I was both reimpressed (restunned is more apt) with Symons and somewhat disappointed with the progress that has been made in advancing the ideas he advanced. ...
... How Does It Develop? The Need for More Attention to Biological and Social Development Symons (1979Symons ( , 1980 reviewed the limited evidence regarding organizational effects of androgens on the aspects of mating psychology that his book addressed. He found, for example, that natal female individuals exposed in utero to high levels of androgens showed aspects of a "male pattern of sexuality" (Symons, 1980, p. 181). ...
Tinbergen (1963) classified 4 conceptual domains necessary for understanding behavior: evolutionary function, phylogeny, mechanism, and development. Evolutionary psychology has primarily focused on the 1st 2. I propose that evolutionary psychology will advance more solidly and steadily by increasing attention to putative adaptations’ mechanism and development. To illustrate, I mainly focus on the sex difference in casual sex interest (sociosexuality) as discussed by Symons (1979).
... A large body of evidence supports general expectations concerning sex differences in perceptions of sexual behaviour and psychology. An early compilation of various surveys, primarily from the United States (US), suggests that men prefer young, healthy and physically attractive partners, whereas women seek ambitious, generous and socially and economically successful partners when evaluating potential mates (Symons 1979). Related research finds males more than females utilise prostitutes, consume pornography, require less time before consenting to sex and sex with a stranger, and display higher rates of sex with farm animals (Gray and Garcia 2013;Mealey 2000). ...
... Sexual selection theory and data on sexuality suggest that heterosexual women's short-term sexual strategies may be motivated by accumulation of resources (Buss 2008;Hrdy 1999;Symons 1979;, mate switching (Betzig 1989), or out of a desire to evaluate a prospective long-term mate (Buss 2008;Buss and Schmitt 1993;Greiling and Buss 2000;Meston and Buss 2007) rather than motivation to find momentary sexual pleasure. However, the emergent research on bisexual women finds they have on average more sexual partners than heterosexual or lesbian women. ...
... In this way, evidence for heterosexual women's preference for 'no strings attached' sex, or, sexual variety for its own sake, continues to be absent. This is consistent with other studies (Buss 2008;Jankowiak, Gray and Hatman 2008;Schmitt, Shackelford and Buss 2001;Symons 1979;) that repeatedly found women to be the choosier sex, showing overwhelming preference for some form of a 'relationship partner' over an anonymous 'one-night stand' sexual encounter. ...
... Humans use a complex set of mating strategies. One of these strategies is long-term mating, which typically involves heavy commitment, pair-bonding, investment by both parents in offspring, and a reported feeling of being in love (e.g., Buss, 2003; Symons, 1979; Trivers, 1972). At the other end of the mating spectrum is short-term mating, which typically involves much less commitment and investment and places a greater emphasis on sexual behavior than long-term mating (e.g., Buss and Schmitt, 1993; Buss, 2003). ...
... As a result of men's minimum parental obligation, one effective method for men to increase their reproductive success is to increase the number of their sexual partners (Buss and Schmitt, 1993; Symons, 1979), suggesting they may benefit more from adopting a short-term mating strategy than a long-term strategy. For example, a man who already had one child could double his reproductive success by engaging in an additional short-term mateship resulting in pregnancy and successful childbirth, all else equal. ...
... Previous research suggests historically it was not the amount of times a man impregnated one woman that increased his reproductive success but instead it was the number of women he impregnated that mattered (see Betzig, 1988 for review). Therefore one adaptive problem ancestral men would have to solve in order to increase their reproductive success would be the problem of partner number (Symons, 1979). One way to solve this would be to have sexual desire for a large number of sexual partners. ...
Evolutionary perspectives on human mating have generated a substantial corpus of work that reveals important sex differences in mate choice and preferences. Both men and women engage in multiple mating strategies, from long-term committed relationships to short-term sexual liaisons. This article summarizes how sex-specific adaptive problems faced by our ancestors shaped men's mate choices, including preferences for cues to fertility, sexual availability, faithfulness, and numerous partners; and women's mate choices, including preferences for cues to ambition, dependability, and investment potential. We also examine how these preferences differ in long-term compared to short-term mating contexts. Understanding the evolved nature of these differences is crucial not only in expanding understanding of human mating behaviors, but also in understanding the sexual conflict that results from sex differences in mate choice.
... Thus, the most desirable escorts should charge a higher fee than less desirable competitors (Baumeister & Vohs, 2004). The physical attractiveness of women is a principal determinant of their mate value (Buss & Schmitt, 1993; Symons, 1979). Specifically, men are attracted to sexually dimorphic and age-related traits that serve as honest indicators of fertility and reproductive value. ...
... Body attractiveness depends on a number of factors including breast size (Furnham & Swami, 2007), waist-to-hip ratio (WHR; Singh, 1993), and body mass index (BMI; Tovee, Maisey, Emery, & Cornelissen, 1999). These body traits are valid cues of current fertility and reproductive value (Lake, Power, & Cole, 1997; Singh, 1993, Symons, 1979). ...
... Age is another significant trait associated with female attractiveness. Female reproductive value declines with age and fertility peaks during early adulthood, so it is not surprising that males seem to possess an evolved preference for young, nubile females (Buss, 1989, Symons, 1979). Especially for short-term mating prospects, selection pressures seem to have left men with a strong attraction toward fertile women, and preferences for youth and health solve the fitness problem of identifying fertile females (Buss & Schmitt, 1993). ...
Female escorts represent an occupational group that charges a fee for sex, which can be regarded as an extreme form of short-term mating. The present study examined if the fees charged by escorts are related to traits typically associated with female short-term mate value. A total of 2,925 advertisements for female escorts offering sexual services in the United States were examined, as a customized software program was used to download all the advertisements from an online escort directory. The advertisement content was coded, and relationships between advertised physical characteristics and the hourly rate charged by female escorts were examined. The analyses showed that higher fees were associated with female escorts who advertised a waist-to-hip ratio near 0.7, lower weight and body mass index, younger age, and photographic displays of breast and buttocks nudity. The findings provide evidence that evolutionarily relevant traits associated with female short-term mate value are systematically related to fees charged for sexual services.
... Ein zusätzliches Farbmerkmal, das das Product Gender beeinflussen könnte, ist das Reflexionsvermögen der Produktoberfläche. Neben bestimmten Körper-und Gesichtsformen kann kräftiges und glänzendes Haar als Zeichen körperlicher Gesundheit und Fruchtbarkeit bei Frauen angesehen werden (Etcoff 2000 (Symons 1979): Glatte Haut steht für weibliche Fruchtbarkeit und beeinflusst männliche Attraktivitätsbeurteilungen ( Johnston et al. 2001 Zur Überprüfung der vorgestellten Theorien über den Einfluss der Produktästhetik auf das Product Gender wurden mit Experten umfassende Interviews mit einer Reihe offener Fragen geführt. Eine iterative Erhebungsmethode ermöglichte es, die Fragen auf die Antworten der Befragten abzustimmen. ...
... Prototypische Illustrationen von Frauen oder Männern sind attraktiv, da sie belastbare Indikatoren für den Partnerwert liefern (Symons 1979). Auch wenn diese Eigenschaften keine biologische Bedeutung haben, kann ihre Anziehungskraft auf nichtmenschliche Wesen übertragen werden. ...
... They also found that traits linked to biological quality were more highly valued in a wife or a daughter-in-law than in a husband or son-in-law, while traits indicating investment potential were more highly valued in a husband or son-in-law. This result can be explained by the different specializations with respect to reproduction: because of the high physiological costs of pregnancy and lactation, women's fitness is closely linked to their physical condition, making biological quality more crucial in a female mate than in a male mate (Buss, 1989b(Buss, , 2003(Buss, , 2015Jones, 1996;Symons, 1980). Biological quality being reflected by physical appearance, this can explain why women's physical attractiveness is more decisive than men's during mate choice (see for instance Buss, 1989a;Buss & Schmitt, 1993;Li et al., 2002;or Chang et al., 2011 for an example in China). ...
... First, individuals looking for a husband are influenced by the level of income of the hypothetical profiles: a significant number of participants chose the profile with the unattractive face when it was associated with the higher income (large trade-off condition, see Figure 2). This is concordant with studies showing that the potential to attain resources is more important in a male than in a female mate and can once again be explained by the differences between males and females with respect to reproduction (Buss, 1989b(Buss, , 2003(Buss, , 2015Jones, 1996;Li et al., 2002;Symons, 1980). Second, we found some evidence of a conflict between parents and daughters, as parents were more likely than daughters to choose the male profile with the unattractive face. ...
Both parents and offspring have evolved mating preferences that enable them to select mates and children‐in‐law to maximize their inclusive fitness. The theory of parent–offspring conflict predicts that preferences for potential mates may differ between parents and offspring: individuals are expected to value biological quality more in their own mates than in their offspring's mates and to value investment potential more in their offspring's mates than in their own mates. We tested this hypothesis in China using a naturalistic ‘marriage market’ where parents actively search for marital partners for their offspring. Parents gather at a public park to advertise the characteristics of their adult children, looking for a potential son or daughter‐in‐law. We presented 589 parents and young adults from the city of Kunming (Yunnan, China) with hypothetical mating candidates varying in their levels of income (proxy for investment potential) and physical attractiveness (proxy for biological quality). We found some evidence of a parent–offspring conflict over mate choice, but only in the case of daughters, who evaluated physical attractiveness as more important than parents. We also found an effect of the mating candidate's sex, as physical attractiveness was deemed more valuable in a female potential mate by parents and offspring alike.
... Rejection is a ubiquitous, necessary component of sexual selection, and the study of human behavior is incomplete without considering it. Even though a fair portion of our potential reproductive success (i.e., number of offspring) is likely to be contingent on selecting the most evolutionarily advantageous partner (Symons, 1980), rejecting an unsuitable mate is also vital in determining whether and/or how our genes are passed on (Darwin, 1872; see also Darwin & Wallace, 1858). Rejection, however, is not just the inverse of selection. ...
... As Symons (1980) put it, ''Nowhere are people equally sexually attracted to all members of the other sex . . . .' ' (pp. ...
We argue that mate rejection and ex-partner relationships are important, multifaceted topics that have been underresearched in social and evolutionary psychology. Mate rejection and relationship dissolution are ubiquitous and form integral parts of the human experience. Both also carry with them potential risks and benefits to our fitness and survival. Hence, we expect that mate rejection would have given rise to evolved behavioral and psychological adaptations. Herein, we outline some of the many unanswered questions in evolutionary psychology on these topics, at each step presenting novel hypotheses about how men and women should behave when rejecting a mate or potential mate or in response to rejection. We intend these hypotheses and suggestions for future research to be used as a basis for enriching our understanding of human mating from an evolutionary perspective.
... However, it has only been in the past few decades that scientists have taken an evolutionary approach to studying these consistent sex differences systematically (e.g., Buss, 1989;Buss & Schmitt, 1993;Schmitt, 2005). From this perspective, sex differences only evolve when men and women recurrently faced dissimilar adaptive problems -and therefore selection pressures -over the course of human evolution (Buss, 2003(Buss, , 2007Symons, 1979). Nowhere are the selection pressures more sex-differentiated than in the domain of mating, and thus it is unsurprising that strong sex differences are reliably documented across a range of mechanisms involved in human mating such as sexual jealousy (Buss, 2013;Buss, Larsen, Westen, & Semmelroth, 1992), desire for casual sex (Kennair, Schmitt, Fjeldavli, & Harkem, 2009;Schmitt, 2005;Schmitt, Shackelford, & Buss, 2001), interest in visual sexual stimuli (Murnen & Stockton, 1997;Symons, 1979), mate preferences for social status (Buss, 1989;Okami & Shackelford, 2001), mate preferences for physical attractiveness (Buss, 1989;Meltzer, McNulty, Jackson, & Karney, 2008), and perception of sexual interest (Haselton & Buss, 2000;Perilloux, Easton, & Buss, 2012). ...
... From this perspective, sex differences only evolve when men and women recurrently faced dissimilar adaptive problems -and therefore selection pressures -over the course of human evolution (Buss, 2003(Buss, , 2007Symons, 1979). Nowhere are the selection pressures more sex-differentiated than in the domain of mating, and thus it is unsurprising that strong sex differences are reliably documented across a range of mechanisms involved in human mating such as sexual jealousy (Buss, 2013;Buss, Larsen, Westen, & Semmelroth, 1992), desire for casual sex (Kennair, Schmitt, Fjeldavli, & Harkem, 2009;Schmitt, 2005;Schmitt, Shackelford, & Buss, 2001), interest in visual sexual stimuli (Murnen & Stockton, 1997;Symons, 1979), mate preferences for social status (Buss, 1989;Okami & Shackelford, 2001), mate preferences for physical attractiveness (Buss, 1989;Meltzer, McNulty, Jackson, & Karney, 2008), and perception of sexual interest (Haselton & Buss, 2000;Perilloux, Easton, & Buss, 2012). ...
Most research into mating psychology focuses on heterosexual mating; however, it remains unknown whether the sex of the individual or the sex to whom that individual is attracted is most closely tied to mating psychology. In the current study, homosexual and heterosexual participants completed questionnaires designed to measure previously-documented sex differences in mating psychology from heterosexual samples. These included men's higher sociosexual orientation and number of lifetime sex partners, women's greater emotional attachment to casual sex partners, men's greater likelihood to overestimate women's sexual intent, women's greater likelihood to underestimate men's commitment intent, and differences in responses to emotional versus sexual infidelity. Based on our results, it appears that the sex of the individual and not the sex to whom that person is attracted tends to determine mating psychology. In particular, women, regardless of orientation, seem to share a similar mating psychology — supporting the idea female sexuality is relatively fluid. In comparison, there was greater variation between heterosexual men and gay men — consistent with the view that that male sexuality is more canalized. We conclude that homosexual mating strategies are complex: they represent neither a simple continuation of heterosexual evolved mating psychology nor a complete gender-role reversal.
... Long-term mating could be regarded as the typical mating option in humans as a monogamous species. The high investment into the offspring by mothers and by fathers is rare among mammals and is considered to favor long-term mating (Geary, 2000;Kenrick et al., 1990;Symons, 1980). One trait favored in partners to initiate and maintain long-term, romantic relationships is humility, which was also favored against arrogance in dating partners and beneficial in long-distance relationships (Van Tongeren et al., 2014). ...
... Our results show that fieldwork is a low-risk environment for perpetrators in regard to a lack of consequences, and that this may facilitate sexual misconduct. While there have been many theories as to why sexual misconduct occurs, one common theme is the concept of a low-risk environment (e,g, Hagen 1979;Symons 1979;Vandermassen 2011). ...
Fieldwork is crucial to advancing knowledge in archaeology and anthropology, but previous works suggests that between 64 and 68 percent of respondents experience sexual misconduct during fieldwork. Going forward, fieldwork must be made safe and inclusive. To achieve this, we must understand why sexual misconduct takes place during fieldwork. We surveyed an international sample of archaeologists and anthropologists ( n= 300) about their most recent fieldwork experience. We examine evidence for risk factors predicting sexual misconduct in fieldsites, and our findings suggest that length of fieldwork, presence and communication of policies and protocols, and the gender and sexuality of the individual are all significant. In particular, we find evidence for increased risk to nonmale and nonheterosexual individuals. We also gathered qualitative evidence from our respondents, who reported that in some cases they were discouraged from reporting and faced retaliation, they were dissatisfied with the handling of complaints, and fieldsite policies and protocols were not consistently or effectively implemented. Fieldwork can be a high‐risk environment for marginalized individuals to experience sexual misconduct, and when clear policies and procedures are lacking, it can also be a low‐risk environment for perpetrators in terms of consequences. To make fieldwork a safe environment for all, policies and protocols that mitigate the risk of sexual misconduct must be consistently implemented and properly communicated.
... Our results show that fieldwork is a low-risk environment for perpetrators in regard to a lack of consequences, and that this may facilitate sexual misconduct. While there have been many theories as to why sexual misconduct occurs, one common theme is the concept of a low-risk environment (e,g, Hagen 1979;Symons 1979;Vandermassen 2011). ...
Fieldwork is crucial to advancing knowledge in archaeology and anthropology, but previous works suggests that between 64-68% of respondents experience sexual misconduct during fieldwork. Going forward, fieldwork must be made safe and inclusive. To achieve this, we must understand why sexual misconduct takes place during fieldwork. We surveyed an international sample of archaeologists and anthropologists (n=300) about their most recent fieldwork experience. We examine evidence for risk factors predicting sexual misconduct on field sites, and our findings suggest that length of fieldwork, presence and communication of policies and protocols, and the gender and sexuality of the individual, are all significant. In particular, we find evidence for increased risk to non-male and non-heterosexual individuals. We also gathered qualitative evidence from our respondents, who reported that in some cases, they were discouraged from reporting and faced retaliation, they were dissatisfied with the handling of complaints, and field site policies and protocols were not consistently or effectively implemented.Fieldwork can be a high-risk environment for marginalized individuals to experience sexual misconduct, and when clear policies and procedures are lacking, it can also be a low-risk environment for perpetrators in terms of consequences. To make fieldwork a safe environment for all, policies and protocols that mitigate the risk of sexual misconduct must be consistently implemented, and properly communicated.
... They change their evaluation of self voice depending on the gender context; that is, they evaluated their own voice as more attractive in the opposite-sex context than that in the same-sex context. Because men have mate preferences for women who are physically attractive (Buss, 1989;Symons, 1980), when encountering male voices in the opposite-sex context, women chose to increase the rating score of their own voice. This indicates that males and females did have different coping strategies when evaluating attractiveness of the self voice in the same-sex and opposite-sex contexts. ...
People evaluated their own voices as sounding more attractive than others rated their voices (i.e., self‐enhancement effect from the perspective of the rater, termed “SE_rater”), and people also rated their own voices as more attractive than the voices of others (i.e., self‐enhancement effect from the perspective of the voice, termed “SE_voice”). The aim of the present study is to explore whether the gender context (i.e., same‐sex and opposite‐sex rating context) could influence the SE effect of voice attractiveness evaluation. Male and female participants were asked to rate the attractiveness of their own voices and other participants' voices, either in a same‐sex session or an opposite‐sex session. The results demonstrated both the SE_rater and SE_voice effect in the same‐sex and opposite‐sex contexts, for both male and female. More importantly, we found that the SE_rater for the male voices was significantly greater than that for the female voices in the same‐sex context whereas no such difference was found in the opposite‐sex context. In addition, the SE_voice effect in men was larger in the same‐sex context than that in the opposite‐sex context whereas the SE_voice in women was smaller in the same‐sex context than that in the opposite‐sex context. These findings indicated that the self‐enhancement effect of vocal attractiveness was modulated by the gender context.
... Unlike sociobiologists, evolutionary psychologists were less concerned with the ultimate causes of a behavioral adaptation than with the adaptation of humans and their immediate ancestors. Among the first topics studied by evolutionary psychologists (Symons 1979) were sexual strategies and mate selection (Buss 2016: 287;Kenrick, Maner, and Li 2016: 930-933). This emphasis is within Darwinian tradition because of its implication for how humans have achieved such reproductive success and, hence, fitness to pass on their genes. ...
... For one thing, the present model is by no means the final word on whether committing to a single partner can be an adap- tive strategy. Indeed, many theories have been put forth to explain why humans and other animals are monogamous (Kleiman, 1977;Wittenberger & Tilson, 1980), which depend on factors from which we have mostly abstracted away, such as parental investment (Trivers, 1972) and sex differences (Symons, 1980). Furthermore, as we have discussed, the present model still makes many simplifying assumptions, which may turn out to affect what conclusions we can draw. ...
... After the fall of the Qing empire, many sex-linked behaviors continue to cluster around specific orientations toward the erotic (Buss 2007;Symons 1979), parenting preferences (Gray 2010;Li and Lamb 2012), and risk-taking activities (Bribiescas 2006;Schlegel and Barry 1991;Shan et al. 2011). Clearly, there are differences and similarities in the ways that males and females are understood to think and behave (Brandtstadter and Santos 2009;Gutmann 1996). ...
... Enquanto para os machos vale a pena se arriscar fisicamente para lograr o maior número possível de parceiras sexuais, para as fêmeas um número maior de parceiros dificilmente se traduz em maior sucesso reprodutivo. É por isso que, parafraseando Symons (1979), enquanto a guerra é o caminho da imortalidade genética para um sexo, para o outro é o caminho da obliteração genética. Em outras palavras, de um ponto de vista reprodutivo os machos são muito mais dispensáveis e a variância de seu sucesso reprodutivo é muito maior. ...
p>Este breve artigo explora como a teoria evolucionária moderna pode ajudar os cientistas sociais no estudo do conflito e da guerra. Em particular, ele almeja mostrar como alguns desenvolvimentos teóricos da sociobiologia e da psicologia evolucionária podem vir a ser relevantes para a compreensão das relações internacionais. Para tanto, a metodologia do artigo resume-se basicamente à revisão de literatura ainda não muito explorada no Brasil. Começamos apresentando as principais proposições da teoria evolucionária e como ela gerou uma clivagem dentro do campo da antropologia, entre aqueles que acreditam que a guerra é uma instituição culturalmente construída e aqueles que veem as raízes da guerra na competição por recursos somáticos e reprodutivos no “estado de natureza”. Tomamos o lado dos segundos apresentando as evidências de guerra na sociedade dos chimpanzés e propondo a continuidade filogenética entre os chimpanzés e os nossos ancestrais caçadores-coletores. Por último, argumentamos que a teoria evolucionária pode nos ajudar a fundamentar melhor a concepção realista das relações internacionais e o próprio entendimento do Poder. </p
... In other words, female orgasm was ascribed to the cultural realm, rather than the natural one, and was identified with nonreproductive sexuality. Some argued that orgasm in females was not evolutionarily selected for but exists instead as a by-product of the existence of male orgasm (Symons 1979). Most women attain orgasm through clitoral stimulation rather than through vaginal intercourse, and the clitoris and the penis have a common embryological origin. ...
The first intensive studies of orgasmic responses in men and women were done by William Masters and Virginia Johnson (1966) and published in their book Human Sexual Response. They described orgasm in both sexes as occurring in four stages: (1) excitement, (2) plateau, (3) orgasm, and (4) resolution. For males, in the excitement phase, nipple erection and tumescence occur, involuntary or voluntary muscle spasms may be seen, the rectum contracts, the scrotum integu-ment tenses and thickens, the testes elevate, and the penis achieves full vasodistention. In the plateau phase, men may flush over the chest, neck, face, and forehead, involuntary and voluntary muscle spasms occur, the rectum again contracts, the testes elevate further, hyperventilation occurs, the heart rate increases, the glans of the penis may change color, and minor involuntary vasoconges-tive increases in diameter occur in the penis as the orgasmic phase approaches. Men ejaculate in the orgasm phase when recurring contractions of the sphincter urethrae, bulbospongiosus, ischiocaver-nosus, and transverse superficial and deep per-ineal muscles force the seminal fluid from the urethra. During the orgasm phase the rectal sphincter also contracts in regular patterns, hyperventilation occurs, and heart rate is at its maximum. Perspiration, especially on the palms of the hands and the soles of the feet, may increase immediately after ejaculation. Finally, during resolution , there is a slow detumescense of the penis, the scrotal integument relaxes, the testes descend, the sex flush disappears, and breathing returns to a pre-aroused state. Though Masters and Johnson equated male orgasm with ejaculation, there is evidence that men can experience an orgasmic response without ejaculation (a dry orgasm). For females, greater variability has been found in the orgasmic response compared with males. Masters and Johnson and others found that during the excitement phase the vagina becomes lubricated, engorged, rises in temperature, and may change in color. The shaft of the clitoris becomes larger, the major labia and minor labia become engorged, rise in temperature, and may change in color. The perineum also goes through a color change. The cervix will rise and the uterus will pull up. Changes also occur to the breasts in the excitement phase. The nipples become erect, the areolae become engorged, and the breasts go through vasocongestion. There is also a rise in blood pressure, an increase in heart rate, a decrease in skin resistance, and increase in skin conductance. In the plateau phase, the vagina will constrict, the clitoris retracts, the perineum tightens, the breasts become flushed, and blood pressure and heart rate again increase. Women will also begin to hyperventilate in this phase. During the actual orgasm phase, the vagina begins to contract and blood volume decreases. The perineum becomes elevated, the uterus contracts, and the sphincter in the rectum contracts. Blood pressure and heart rate again increase and hyperventilation occurs. In the final resolution phase, the vagina, clitoris, and major labia and minor labia go through detumescence and their color returns to a pre-aroused state. The cervix gapes and there is uterine suction of sperm. The perineum and the breasts return to their pre-aroused states, though hyperventilation may still be occurring. While male orgasm and the physical release of semen can be neatly tied to reproduction, female orgasm has evoked much more argument and debate in academic circles. In early literature, female orgasm was argued to be a unique ability among humans and was not thought to occur among nonhuman primates. In other words, female orgasm was ascribed to the cultural realm, rather than the natural one, and was identified with nonreproductive sexuality. Some argued that orgasm in females was not evolutionarily selected for but exists instead as a by-product of the existence of male orgasm (Symons 1979). Most women attain orgasm through clitoral stimulation rather than through vaginal intercourse, and the clitoris and the penis have a common embryological origin. In addition, female orgasm
... The research of Devendra Singh 3,4,5 (Waist-to-Hip Ratio) and Glenn Wilson (Bust/Waist Ratio) 6,7 speak of the fact that an overwhelming majority of men, regardless of their culture and age (from puberty until death), evaluate a woman as an attractive object if her body has a breast, waist, and hip circumference in the ratio of 1/0,7/1. The reasons for the universality of the B-W-H hypothesis are (according to R. Dawkins 8 and M. Ridley 9 ) a higher probability of the woman being in a young, healthy state (with a body with these characteristics) and thus a high probability of an efficiency of energy investing in her genes in order to bring up healthy offspring 10,11,12 . Other primary signs of health and youth, which are typical of an attractive woman, are the entire figure (breast size and shape, waist, hips, slim legs and face, particularly eyes and lips) complexion, and hair quality, etc. ...
... In another context, Katrien, Pandelaere, and Patrick (2014) discovered that preferences for glossiness are linked to humans' innate need for water. Furthermore, scholars have theorized that the pervasive preference for symmetric and prototypical design patterns results from the predictive value these cues hold in determining the physical value of mates (Etcoff 1999;Symons 1979). Beyond matters of preference, additional support for the relationship between design characteristics and physical stimuli can be found in research demonstrating that the mere position of design elements can inform judgments in ways consistent with physical laws. ...
A core assumption underlying brand logo design is that inferences generated from a logo’s design are applied to the consideration target (e.g., product or brand) to which the logo is attached, and designs should therefore reflect the beliefs one wishes to promote about the target. The current work demonstrates an important case in which consideration targets are resistant to particular inferences, which leads such inferences to be applied instead to one’s environment. Specifically, when considering safety-oriented products, consumers exposed to unstable-looking brand logos infer the presence of unsafe conditions, and because safety-oriented products are resistant to inferences that they are unsafe, the inference is instead applied to the environment (i.e., “the environment is unsafe”). This process subsequently increases the perceived utility of safety-oriented products. Five experiments collectively demonstrate the core effect, uncover the underlying inferential mechanism, and demonstrate the crucial role of inference resistance in the process. Overall, the present findings suggest that in some cases, a logo design that is opposed to desired product or brand beliefs may ironically help in boosting demand.
... It would be interesting to see whether this result could be replicated in a more diverse sample. The Body and the Beautiful The Body and the Beautiful Alternatively, the preference for lower body weight to optimise women's attractiveness than healthy appearance may reflect a preference for youthful women [13], since youth is associated with higher reproductive value (expected future reproductive output) in women [48]. Body fat increases across the lifespan [49], while muscle mass remains approximately stable until age 45 [50]. ...
The dominant evolutionary theory of physical attraction posits that attractiveness reflects physiological health, and attraction is a mechanism for identifying a healthy mate. Previous studies have found that perceptions of the healthiest body mass index (weight scaled for height; BMI) for women are close to healthy BMI guidelines, while the most attractive BMI is significantly lower, possibly pointing to an influence of sociocultural factors in determining attractive BMI. However, less is known about ideal body size for men. Further, research has not addressed the role of body fat and muscle, which have distinct relationships with health and are conflated in BMI, in determining perceived health and attractiveness. Here, we hypothesised that, if attractiveness reflects physiological health, the most attractive and healthy appearing body composition should be in line with physiologically healthy body composition. Thirty female and 33 male observers were instructed to manipulate 15 female and 15 male body images in terms of their fat and muscle to optimise perceived health and, separately, attractiveness. Observers were unaware that they were manipulating the muscle and fat content of bodies. The most attractive apparent fat mass for female bodies was significantly lower than the healthiest appearing fat mass (and was lower than the physiologically healthy range), with no significant difference for muscle mass. The optimal fat and muscle mass for men's bodies was in line with the healthy range. Male observers preferred a significantly lower overall male body mass than did female observers. While the body fat and muscle associated with healthy and attractive appearance is broadly in line with physiologically healthy values, deviations from this pattern suggest that future research should examine a possible role for internalization of body ideals in influencing perceptions of attractive body composition, particularly in women.
Have you ever wondered whether we are alone in the universe, or if life forms on other planets might exist? If they do exist, how might their languages have evolved? Could we ever understand them, and indeed learn to communicate with them? This highly original, thought-provoking book takes us on a fascinating journey over billions of years, from the formation of galaxies and solar systems, to the appearance of planets in the habitable zones of their parent stars, and then to how biology and, ultimately, human life arose on our own planet. It delves into how our brains and our language developed, in order to explore the likelihood of communication beyond Earth and whether it would evolve along similar lines. In the process, fascinating insights from the fields of astronomy, evolutionary biology, palaeoanthropology, neuroscience and linguistics are uncovered, shedding new light on life as we know it on Earth, and beyond.
In the Economic Theory, the study of the marriage market is relevant to understand how families are constituted and how changes in this market affect their decisions regarding consumption, savings, labor supply, and the human capital accumulation of its members. However, the marriage market is linked to another important market, the market for short-term relationships. The Economic Theory of Sex uses microeconomic tools to understand the behavior of individuals in the market for short-term relationships – the sex market for singles. This article empirically evaluates this theory through an econometric (Probit) model estimated with a representative database of the Brazilian population, the National Health Survey (NHS). The model evaluates how appearance and socioeconomic and geographic characteristics affect the probability of single individuals being sexually active in Brazil. The results indicate that, as the Economic Theory of Sex predicted, sexual activity decreases with age and that more attractive women and men with higher incomes are more sexually active. Furthermore, homosexuals are likelier to have an active sex life, while religious individuals are less likely. The article concludes that despite having some moral resistance, the Economic Theory of Sex can contribute to a better understanding of the sex market among singles and the marriage market.
Background
Evolutionary psychologists have demonstrated that humans are attracted to individuals who possess average anatomy for the population.
Objectives
It is the aim of this study to prove that a composite of average facial features would be more attractive to raters than the cohort utilized to create the composite.
Methods
Our male and female cohorts each consisted of 41 standardized frontal-view monochrome photos, with one composite image derived from the other forty real images. We utilized Amazon Mechanical Turk, a widely used crowdsourcing platform, to receive ratings of images ranging from 1-7, with 1 and 7 being least and most attractive, respectively. The strength of the preference for the composite over the real images was assessed by the difference between the mean rating of the composite and real images.
Results
We received 870 respondents and 876 respondents for the male and female cohorts respectively. For the male and female cohorts, the composite image was rated significantly higher than the rest of the cohort overall and across all ages, genders, and countries of residence (all p<0.0001). For both cohorts, the strength of the preference was significantly higher for European voters and lower for South American and non-binary raters (all p<0.05).
Conclusions
Our study reveals that average facial anatomy is perceived as most attractive across all demographics, which we hope will serve as a steppingstone for further studies that will lead to objective cosmetic quantifications and integrating evidence-based medicine into aesthetic surgery.
It is necessary to understand how giraffes could have evolved. We came up with Darwin's theory, Lamarckism, and so forth. However, in a manuscript, I classified the species of Giraffa Camelopardalis in light of the heights as an arbitrary principle. Nevertheless, I wrote a paper on classifying Giraffa Camelopardalis species using heights as the reference point. It highlights the evolution of the giraffe posture in light of two characteristics of its postures, namely ephemeral diversity and perpetual diversity. Our theory is based on the concept of provisional height and perpetual height groups of giraffes. Why do giraffes have a long neck? Why do not there be shorter ones? Could also be the question; Are there any groups of giraffes? The origin of the initial height or perpetual height? In Lamarck's discussion of heredity, he gave an imaginary example of how a giraffe stretching its neck to browse leaves high in a tree gradually strengthens and grows a longer neck as a consequence. The non-empirical approach of the theory manifests the following hypothetical testimony: Giraffe posture is a functional function of ephemeral and perpetual diversity.
In the article I defend some of the thesis presented in my book ‘Art as Adaptation: Universalism in Evolutionary Aesthetics’ (Sztuka jako adaptacja: uniwersalizm w estetyce ewolucyjnej) (2018) against the claims of my critics. I focus especialy on some misreadings regarding the explanatory power of evolutionary science. I try to show that even though evolutionarily informed aesthetics is not a handy tool for analyzing the intrinsically diverse currents of modern and neo-avant-garde art, it does an excellent job of explaining the mental tendencies and typical behaviors behind these practices. I also focus on the artistic abilities of animals and the problematic dominance of the visuality paradigm in the evolutionary approach, topics that are unjustifiably considered to be most momentous in evolutionary aesthetics.
Body genres represent ideal candidates for biocultural theorisation due to their almost universal effects on audiences. However, not all body genres can be interpreted at the formal level through a direct application of biological ideas; some require an indirect approach that emphasises cultural information as much as biological information. The article pursues this thesis by applying an understanding of heterosexual rape drawn from evolutionary psychology to the motifs of sexual coercion that structure two body genres: rape-revenge and postfeminist softcore. The biocultural approach may be applied in a direct way to rape-revenge, which has often been deemed offensive despite its critiques of male sexual coercion. This direct analysis may then be used as the foundation for a more indirect analysis of postfeminist softcore, a genre that stylises rape to remain inoffensive to women but in the process sacrifices its ability to critique the male aggression predicted by feminists and evolutionists alike.
Purpose
This study aims to explore innate and sociocultural forces that lead gay men to purchase invasive and non-invasive cosmetic medical treatments.
Design/methodology/approach
This work draws on a literature review and personal reflections to identify and interpret patterns and themes on drivers that encourage gay men to use cosmetic medical treatments.
Findings
In line with evolutionary theory, the authors suggest that the male proclivity to evaluate a partner’s sexual desirability on the basis of physical appearance and youth remains consistent among gay men. They also posit that sociocultural norms, such as media imagery, portray gay men as physically attractive and youthful. Among gay men, homonormative ideals that define attractiveness fall on a continuum ranging from hyper-masculinity to hypo-masculinity, with each end encouraging gay men to accept different beauty standards.
Research limitations/implications
To date, service researchers have mostly overlooked the role of evolution in consumers’ propensity to purchase professional services. This study sets the foundation for researchers to consider both instinctual and sociocultural norms that encourage consumers to purchase not only cosmetic medical treatments but also professional services in general.
Practical implications
Gay men represent a prime target market for cosmetic medical treatment providers, as their desire for physical attractiveness and youth remains constant as they age.
Originality/value
This study offers novel insights into gay male consumption of cosmetic medical treatments and services from theoretical and practical perspectives.
The book, here in its second edition, aims at uniting the processes of theory construction, empirical research and scientific communication as a single process of scientific production. After revising the development of philosophical approaches to science from early experimentalism through positivism to falsacionism, the book describes the end of that process as a cul-de-sac or dead end, whereas philosophical reasoning could not "justify" the validity of empirical science, and the subsequent turn towards a scientific understanding of science, anticipated first by Kuhn and Lakatos, and later by various empirical studies of science as an activity and as a process, best understood from an evolutionary perspective. The second part of the book discusses the practical implications of the nascent "science of science" to generate best practices for science practitioners.
This article was first published in 1992 in the journal Hypatia, vol. 7/3, pp. 39-76 and was subsequently included as Chapter 3 in Maxine Sheets-Johnstone's 1994 book The Roots of Power: Animate Form and Gendered Bodies.
Traditionalists affirm that in self-deception I intend to deceive myself; but, on the standard account of interpersonal deception, according to which deceiver intend to make their target believe a falsehood, traditionalism generates paradoxes, arising from the fact that I will surely know that I want to make myself believe a falsehood. In this thesis, I argue that these well-known paradoxes need not arise under my manipulativist account of deception. In particular, I defend traditionalism about self-deception by showing that what causes paradoxes is not the idea that self-deception is an intrapersonal analogue of interpersonal deception but rather our incorrect conceptions of deception, interpersonal deception, and lying.
If you enter the word “beauty” in a search engine, almost all the pictures you will see appear on your computer screen are of attractive young women. In Western society, the concept of beauty is closely associated with physical attractiveness and especially feminine physical attractiveness. Beautiful women are everywhere: on the walls of our cities, on the screens of our movie theaters, on the glossy paper of our magazines. But is this phenomenon restricted to contemporary societies? It does not seem so, as women’s beauty has occupied the minds of painters, poets, philosophers, musicians, and writers for centuries. Indeed, in arts, depictions of idealized female beauty far outweigh those depicting ideals of male beauty. Why are human beings so fascinated by female attractiveness? The aim of this chapter is to show how evolutionary theory can help us to understand this passion for women’s bodies and their beauty, and explore what the arts can teach us about human beauty while addressing the question of its universality.
Filosofie en wetenschap zijn sinds de oudheid met elkaar in wisselwerking: wetenschap zit meer aan de empirische kant, filosofie meer aan de kant van de reflectie. Beide zijn theoretisch, modellen vormend. De laatste eeuwen zijn filosofie en wetenschap te ver uit elkaar gegroeid: bij Kant, omdat deze ten onrechte dacht dat je vanuit de wetenschap niets kunt zeggen over het kenvermogen, bij de fenomenologen en hermeneuten, omdat deze wetenschap gelijkstelden met één soort wetenschap. Karikaturen van ‘de’ wetenschap verleiden filosofen zich er niet meer mee bezig te houden, met als gevolg dat zij niet mee kunnen groeien met de modernste wetenschap. Vanuit de moderne evolutiebiologie is er echter veel te zeggen over allerlei wijsgerige vragen. Er is bijvoorbeeld een nieuw beeld ontstaan van het leven: dat draait vooral om genen doorgeven. Het gaat niet om de overleving van de ‘soort’. Ook het geloof dat evolutie vooruitgang is blijkt niet te kloppen. De unieke menselijke geest lijkt het product van wapenwedlopen tussen samenlevingen van vroege mensen. Ook op de vraag naar zin werpt de evolutionaire benadering van de mens licht. Mensen zijn samenwerkers die taken verdelen binnen culturele en politieke systemen. Iedereen is daarom op zoek naar zijn unieke taak in de groep. Dat passen en meten is ook vaak een kwestie van je aansluiten bij de juiste groep en de juiste morele houding. Het zoeken naar zin is eigenlijk het zoeken naar een manier van leven die bij je past. Mensen objectiveren hun zoeken naar de zin-in-het-leven echter graag tot zin-van-het-leven, deels om anderen hun mening op te dringen, deels om te komen tot een gemeenschappelijke levenshouding en moraal.
This book discusses the nature and progress of science, considered as a human endeavour, including philosophical views on science and modern approaches to epistemology based on the historical-evolutionary study of how science emerged., proceeds, and advances. Approaching the analysis of science as an evolving social endeavour (a "science of science" complementing the "philosophy of science") emerged mostly in recent times, and leads to a discussion of scientific good practices concerning scientific research and scientific communication. The book includes an extensive discussion of scientific argumentation, research programmes, and scientific communication.
Sexuality engenders moral problems because it serves radically different kinds of goals. Reproductive sexuality focuses on bearing children and involves moral concerns about their healthy birth, as well as their successful physical, emotional, and social development. Societies have different, well-developed social institutions for reproductive sexuality and its consequences, usually ensconced within special social roles such as those of being a parent, a guardian, or a child. Sexuality also plays an important social role. Many have argued that the character of homo sapiens was influenced by the tendency of members of the species to form fairly stable and enduring male-female dyads marked by numerous non-reproductive acts of intercourse [5; 10; 12; 16]. Unlike many other species of primates, large harems are not the rule and complex social relations usually develop between one male and one female human. Sex makes a significant contribution to this pair bonding [22]. Finally, sexuality plays a recreational role. This is attested by the age-old presence of bordellos, catamites, and gigolos. Human males and females have sought sexual recreation apart from their commitments either to reproductive sex or to enduring social bonds.
As is common for many men, Shakespeare was idealising a woman. The search for an ideal partner was not only critical for Shakespeare — it is, by evolutionary standards, the central goal for all male and female life forms (Buss, 1985;Darwin, 1859;Vandenberg, 1972). Anthropological and psychological evidence continues to document the features women seek in a male partner (Symons, 1979), but for the purposes of this chapter we primarily focus on the features men seek in a female partner. The ideal feminine form has been characterised by painters and sculptors for as long as paintings and sculptures have existed (e.g., see Zollner & Nathan, 2003) and Shakespeare is, of course, hardly the first writer to try a verbal description.
Cross-culturally, humans make systematic use of physical attractiveness to discriminate among members of the opposite sex, and physical cues to youth, health, and fertility may be particularly important to men (Buss, 1989). Nevertheless, there is controversy over whether attraction preferences are adaptive, particularly in novel environments, and whether they are universal or flexible depending on cultural circumstances (Singh & Luis, 1995). To date, a good deal of research into somatic (i.e., body) attractiveness has focused on two particular characteristics: waist-to-hip ratio (WHR) and the body mass index (BMI). WHR is calculated as the circumference of the waist divided by circumference of the hips, and provides an index of a woman’s ‘curvaceousness.’ BMI is calculated as an individual’s weight (kilogrammes) divided by height (metres) squared, and provides an estimate of body fatness.
This article is about Eroticism as a key-concept in the psychological understanding
of the human mind. The meaning of the term can be defined as follows: Eroticism
is the way humans experience sexuality as a self-sufficient mental activity. Sexuality
underlies different social rules in varying cultural contexts and may lead to different
ways of thinking, but there is no evidence that cultural diversity actually leads
to fundamentally different ways of feeling. The constant disposition for recreational
rather than procreational sex makes eroticism a medium of human creativity. In this
sense, eroticism is considered a central factor in the process of hominisation.
The crucial cognitive competence which makes for the uniqueness of our species is
due to the transformation of sexuality into eroticism and its disposition for social
learning. In the animal kingdom, sex contributes to the welfare of the horde, while
in human society eroticism contributes to individual self-recognition and paves
the way to moral awareness. Methodologically, I plead for a cooperation of psychological
and anthropological research, each utilizing and combining the complementary aspects
of both approaches.
For 50 years, relationship researchers have primarily focused on two varieties of relationships; one-night stands and serious romantic relationships. Both of these are treated as (1) distinct relationships and (2) a comprehensive list of the relationships people of any sexual orientation engage in. However, over the last 10 years this apparent simplicity has been called into question; researchers have revealed a rainbow of potential relationships that individuals can and do engage in. From this perspective, relationships may act as “compromises” between two extremes (i.e., pure monogamy or pure zero-acquaintance sex) and are negotiated in the course of relationship development. Relationships then reflect different levels of short-term mating and long-term mating aspects simultaneously. In this review, we examine research on one-night stands, serious romantic relationships, booty-call relationships, friends-with-benefits, swinging, and polyamory. Throughout, we highlight the utility of evolutionary models to account for behaviors and patterns in these relationships and discuss the importance of an unbiased and unabashed look at the sex lives of people.
This chapter surveys the philosophical problems raised by two Darwinian claims: the existence of a “tree of life” and the explanatory power of natural selection. The first part explores philosophical issues concerning the process of evolution by natural selection. After laying out the nature of selectionist explanations, their conditions, and some of their correlated properties such as fitness, we present the epistemic issues raised by such explanations. These include the role of optimality considerations and dynamical modeling, as well as the respective contributions of analytical explanation and historical narratives to evolutionary understanding. Then the metaphysical aspects of natural selection are examined: whether it is a law or supports natural laws; whether it is a cause, and if so, the cause of what. The consequences of the answers to these questions for scientific practice, and especially for current controversies about a possible extension or revision of the Modern Synthesis, are highlighted. The chapter then presents two classical controversies regarding the target and the limits of selective explanations – units of selection, adaptationism – in both cases pointing out the promises of explanatory pluralism. The third section considers issues raised by evolutionary patterns: first, the interpretation of the nodes in the tree of life, where the notion of species is controversial; then, the question of the relationship between macro- and microevolution, and, relatedly, the connection between putative processes and plausible patterns. Consequences for the current controversy about the fate of the Modern Synthesis are also explained. We further explicate issues raised by general features of large-scale phylogenetic patterns, such as increases in complexity, and the question of evolutionary contingency, and discuss the chances of an empirical solution to these longstanding puzzles. The last section considers some consequences of evolutionary theory for philosophical questions about human nature, given the rise of hypotheses on the universality of selectionist explanations; it is mostly concerned with epistemology and psychology.
Der Zoologe Desmond Morris, eigentlich aus dem sittenstrengen England, war im Jahre 1967 sogar der west-deutschen Studentenrevolte voraus, als er sein Buch „The Naked Ape“ („Der nackte Affe“) veröffentlichte. Denn Morris war ungeniert und verglich, ohne zimperlich zu sein, das Sexualverhalten von Menschen mit dem von anderen Tieren – speziell dem von Affen und Menschenaffen.
Darwin conceived the theory of sexual selection in order to explain beauty in animal Kingdom. He hypothesised that most of the male ornaments had been developed to correspond to a female ‘sense of beauty’. His successors developed a theory of mate choice in which the aesthetic sense was left out. The male sexual ornaments were considered as salient cues that evolved because they are indicators of males’ fitness, which stimulate the female to mate. As a consequence “good genes” would spread to future generations. Such a perspective left no place for the males’ appearance and displays as a source of pleasure for females. More recently, authors have considered that male traits might evolve because they make discrimination, stimulus recognition, memorability and learning easier. The winner is the most attractive not necessarily the ‘strongest’ male. Moreover, male traits might be favoured because they happen to fit an already existing bias in the female sensory system. Such a sensory exploitation determines the direction of a “runaway process”.
Today, the “aesthetic sense” is back, the neurosciences study the chemistry and circuitry that support pleasure in the brains of humans and animals; social psychology and animal cognition focus on emotions, categorisation and prototype used for mate choice. Animals and humans in order to make a decision, have to evaluate both the sensation and the goal directed action. For this a salient hedonic value has to be built by the mind. Here are the processes involved in the ‘aesthetic judgement’.
Human life is a complex and rich endeavor, of which sexuality is but one element, albeit centrally important. As an element of a complex, the significance of sexuality must be judged in terms of its place in the constellation of human affairs. Moreover, concepts of sexuality have an evolving character. This is in part due to changes in our views of sex, which in turn depend on diverse evaluations and understandings of the world. These change and develop with changes in philosophical perspectives. Consequently, the significance of sexuality depends on its position with reference to a wide range of human values. Conversely, the position one gives to sexuality will determine the significance assigned to other endeavors we engage in. This essay investigates the significance philosophers have assigned to sexuality, particularly as it contributes to the good or moral life of individuals: How have philosophical traditions understood the interplay among issues in sexuality, ethics, and the lives of persons? Is there an ethics unique to sex? Are canons of moral probity regarding sex to be found in some concrete normative understanding of sexuality? Or, might they be found in that which is intrinsic to morality itself? If neither account is sustainable, what then can be said about the character of sexual ethics? Our answers to these questions are the culmination of two millenia of reflections.
What is bioethics? Who is a bioethicist? Who is a health care ethics consultant or clinical ethics consultant? There are no straightforward answers to such questions. Indeed, the attempt to answer such questions usually engenders controversies. Bioethics is a puzzle. Bioethics is itself a controversy, a theater of dispute. Across the world, there are persons who call themselves bioethicists. But there is no agreement as to what ends they are doing what they do, as to what they should be doing, or even as to what they are doing. In hospitals across the world, there are persons who are paid as clinical ethics consultants (aka health care ethics consultants) and who are often held to be engaged in helping resolve normative questions about health care decisions. But there is no agreement as to what norms they should engage. This is because there is real dispute about the content and character of both morality and bioethics. As a result, there is a puzzle as to how properly to characterize the nature of the normative questions posed to bioethicists, as well as the answers bioethicists give. Bioethicists are asked, for example, about when a particular medical intervention is inappropriate (or futile), about who should make life-or-death decisions, and concerning what information should be provided in order for a patient adequately to consent to treatment. The question is what kinds of norms and which norms should frame such questions. In answering such questions, what norms and which norms should guide the answers? Are the norms at stake those established at law? Is the ethics about which health care ethics consultants (HCEC) give advice simply an account of relevant law and public policy, as well as of how law and public policy is customarily applied? Or are the norms moral norms? If so, norms of which morality? These puzzles about the nature of bioethics justify second thoughts about the entire endeavor of bioethics.
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...
Describes a technique in which organisms are provided with extended exposure to mirrors and then given an explicit test of self-recognition (through the unobtrusive application of marks to facial features visually inaccessible without a mirror). Use of this procedure with chimpanzees and orangutans in a series of studies by the present author provided evidence of self-recognition, with patterns of self-directed behavior emerging after only 2–3 days. In support of the widely held view that the self-concept may develop out of social interaction with others, the capacity for self-recognition in chimpanzees appears to be influenced by early social experience. To date, however, attempts to demonstrate self-recognition in all other species except man have failed. The phyletic limits of this capacity may have important implications for claims concerning the evolutionary continuity of mental experience. (64 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Examines the possibility that pheromones can explain various aspects of primate reproductive and sexual behavior in the light of behavioral, olfactory, and biochemical evidence. Emphasis is on rhesus and human phenomena. Menstrual synchrony is suggested as the most promising area in which to search for pheromonal control of higher primate behavior. It is concluded that although it is probable that olfaction and olfaction-related phenomena influence behavior, it seems unlikely that chemical communication plays any significant role in the control of higher primate reproductive and sexual behavior. (3½ p ref)
Clinical work with offenders and victims is cited to support the concept of rape as a sexual deviation, as well as a sexual offense. It is suggested that rape is directed toward the sexual expression and gratification of needs that are not basically sexual, and that it represents a developmental crisis for the offender, which in turn triggers a situational crisis for the victim.
Sexual delinquency is probably on the increase in most countries; at least everywhere that statistical data are available this has been the case. This fact has aroused considerable concern among criminologists and the lay public. In the Netherlands the number of persons convicted of sexual offences amounted in 1925 to 886 and in 1954 to 2,224 — an increase of 157 per cent (table I). In England and Wales “on the average for the two years 1937 and 1938 the number of indictable sexual offences annually recorded was 4,448, whereas in 1954 the number had become 15,636, which is an increase of 252 per cent.”1 In Finland 125 sexual offences led to punishments in general courts of first instance in 1945, while in 1954 the figure was 465 — again an increase of 247 per cent.2 In Austria there was a rapid increase of sexual offences after the second world war.3
Publisher Summary Birds, in which, in the absence of lactation both sexes can play an equal role in feeding the young, monogamous mating systems are generally desirable, such that sexual dimorphisms in body size are unlikely to develop. This chapter describes the concept of sexual selection, reproduction in the gorilla, orangutan, chimpanzee, and man. Sexual selection can be subdivided into two components parts: somatic selection, the factors determining general body size, and genital selection, the factors determining the size of the gonads and external genitalia. While, somatic selection is apparently related to the mating system, and is concerned with successful competition for access to a mate, genital selection is far more complex; although influenced by mating type, it is ultimately a reflection of copulatory frequency. The chapter concludes that the most telling anatomical clues, probably, to the reproductive behavior of man and the Great Apes are the relative body sizes of the male and the female, and the relative sizes of the testis and the ovary. However, it remains to be seen whether the significance of these simple anatomical clues will be confirmed by the examination of a far wider range of species.
Male hoary marmots living in isolated colonies at Mount Rainier National Park demonstrated a significantly greater involvement with their infants than did males living in a larger, more interactive social situation. Paternal behavior correlated inversely with frequencies of extrapaternal social interaction. This pattern is seen as maximizing male fitness in each situation by providing for male defense of his reproductive interests when this is dictated by the proximity of other adults and facilitating direct paternal involvement when relative isolation reduces the advantages of extrapaternal sociality.
Current models for the evolution of polygyny and sexual dimorphism are largely derived from data on passerine birds. These models are less appropriate for taxa such as mammals, in which males emphasize mating strategies, than for those such as passerines, in which males emphasize progeny rearing strategies. The Orians-Verner model is inadequate as a general explanation of the evolution of polygyny in mammals because many species do not meet one or more of its assumptions: that the need for male parental care is the main factor opposing the evolution of polygyny; that females choose to mate with particular males; and that the female raises her young on the resources contained in the territory of the male with which she mates. A two-factor model incorporating the concept of sexual bimaturism, developed by Wiley for grouse, is more appropriate for many mammals but still too simple. In mammals, large male parental investment is a good predictor of both monogamy and reduced sexual dimorphism, but small male in...
Approximately 62 per cent of a group of university Freshmen women reported experiencing offensive male sexual aggression during the year prior to university entrance. Proneness to sexual aggression appears associated with a lack of parental sex guidance and the absence of older male siblings. Certain characteristics of the pair relationship also increase the probability of aggression. The adjustive reactions of the offended female are strongly influenced by prior parental guidance and the severity and provocation of the aggressive episode.
Failure of the behavioral sciences to develop an adequate general theory is seen as a result of the difficulty in deriving from evolutionary theory a subtheory, or set of subtheories, with satisfying applicability to the study of behavior. Efforts at general theories based on reflex concepts, or simple movements such as in orientation, have been unsuccessful in dealing with complex behaviors. Recent arguments that selection is focused at the level of the individual organism suggest the additional inadequacy that such theories fail to emphasize the selective compromises that exist at suborganismic levels. Evolutionary theories about behavior have tended to concentrate chiefly on patterns of historical change (phylogenies) without stressing adaptive (= reproductive) strategies, or have generally viewed adaptiveness erroneously as focused at group, population, or species levels. Human society is discussed briefly, in a context of selection focused at the individual level, considering six principal aspects: group-living, sexual competition, incest avoidance, nepotism, reciprocity, and parenthood. An effort is made to combine the approaches and data of biologists and social scientists in analyzing reciprocity in social interactions.
Comparative observations in a captive setting of the sexual behavior of wild born and reared Pan troglodytes and Pan paniscus revealed important and unexpected behavioral differences between these two closely related species. The external genitalia of the female Pan paniscus is rotated anteriorly, copulation takes place throughout the cycle in Pan paniscus, and homosexual copulation is a common occurrence. Vocal and gestural exchanges often precede and accompany copulation in Pan paniscus but not in Pan troglodytes. Feeding and food sharing elicit copulatory activity on virtually every occasion in Pan paniscus, but not in Pan troglodytes. Copulatory positioning among Pan paniscus is marked by considerable variability, including en face ventro-ventral positioning. These observations suggest that, at least in aspects of sexual behavior, the pygmy chimpanzee displays greater malleability and greater dependencyupon complex non-verbal signaling. In Pan paniscus, copulatory behavior is more closely intertwined with other forms of social interaction such as food sharing. The sexual behavior patterns of the pygmy chimpanzee, while still quite distinct from those of man, nevertheless display a greater degree of similarity to the sexual patterns of our own species than do those of any other living non-human primate.
The menstrual cycle is a distinguishing character of the primates, and innovation in reproductive processes has been accompanied by rapid divergence, giving a wide range of anatomical, behavioral, and probably physiologidal characters. Variations in female willingness to mate range in magnitude from small or absent to periodic complete disruptions of normal behavior, and their timing from brief episodes precisely related to endocrine changes within the menstrual cycle, through as yet unexplained fluctuations with about the same periodicity as the menstrual cycle but varying in relationship with it, to fluctuations that are more usefully related to seasonal changes than to menstrual cycles. The simpler the social situation and the more restricted the physical environment of the animals, the better the correlation between hormone levels and behavior. It is clear that these correlations exist, but also that they must be extremely labile, responding to environmental influences of every kind from the food supply to the previous learning experience of the female. As a result, there are few examples of behavior changes that could reliably be predicted, in many individuals, from knowledge of endocrine changes in group-living female primates, with differences between cycling, pregnancy, and lactation interval being more reliable than changes within the menstrual cycle. The chapter discusses various studies, to investigate the relationship between all types of social behavior and female reproductive cycles in primates, which fall into four main types: (1) there are field studies, (2) there are studies of caged groups of relatively undisturbed animals, (3) there are laboratory studies on highly manipulated animals, and (4) there are laboratory studies where not only are the conditions under which behavior takes place rigidly controlled, but also is the endocrinal status of the animals, by castration and replacement therapy.
1.
The sexual behaviour of a chimpanzee community in the Gombe National Park, Tanzania, was studied intensively for 16 months. Additional information came from 15 years of demographic and behavioural data accumulated by Jane Goodall and members of the Gombe Stream Research Centre.
2.
The mating system of the Gombe chimpanzees is flexible and comprises three distinct mating patterns: (a) opportunistic, non-competitive mating, when an oestrous female may be mated by all the community males; (b) possessiveness, when a male forms a special short-term relationship with an oestrous female and may prevent lower-ranking males from copulating with her; and (c) consortships, when a male and a female leave the group and remain alone, actively avoiding other chimpanzees. While males took the initiative in possessive behaviour and consortships, females had to cooperate for a successful relationship to develop.
3.
Data from 14 conceptions indicated that the majority of females (9) became pregnant while participating in the restrictive mating patterns, possessiveness and consorting. It could be established definitely that seven of these females were consorting during the cycle in which they conceived. As 73% of the 1137 observed copulations occurred during opportunistic mating, 25% during possessiveness, and only 2% during consortships, there was no correlation between copulation frequency and reproductive success.
4.
Adult males showed differential frequencies of participation in the restrictive mating patterns. Male age, dominance rank, and the amount of agonistic behaviour directed to females showed no correlation with participation in the restrictive mating patterns. The following male characteristics did show significant, positive correlations with involvement in the restrictive mating patterns: (a) the amount of time spent in the same group as oestrous females, (b) the proportion of that time spent grooming oestrous females in groups, and (c) the frequency with which males shared food with females. While dominance ranks of the adult males showed no consistent correlation with involvement in the restrictive mating patterns, it was clear that the most dominant male did gain an advantage. He was the only male able to monopolise oestrous females by showing possessive behaviour.
5.
Consortships appeared to be the optimal reproductive strategy for males (with the exception of the most dominant) and females, as they gave males the highest probability of reproductive success, and allowed females to exercise choice. However, there appeared to be disadvantages associated with consort formation; the greatest of these was the increased risk of intercommunity encounters. While all individuals have the potential to practice each mating pattern, the strategy actually used at any moment will be determined by variables both within the individual, e.g. age, physical condition, dominance position; and by social factors in the group, e.g. general stability of male dominance relationships, presence of a strong alpha male, existence of special male-female relationships.
Eighteen Soviet female patients with the late-treated virilizing adrenogenital syndrome are described. In contrast to previous studies, homosexual experience and fantasies were not reported. In concordance with previous studies, there was the suggestion of enhanced intelligence as a function of increased levels of prenatal androgen.
Homo sapiens is unique among primates in that it is the only group-living species in which monogamy is the major mating system and the only species in which females do not reveal their ovulation by estrus. These unique traits can be explained in terms of natural selective and cultural selective theory applied at the level of the individual. The relative amount of parental investment by the sexes is an important correlate with the type of mating systems found in animal species. In human history the evolution of increased hunting abilities, bipedality, relatively altricial young and the concomitant dependency on the male for food by the female are viewed as the factors allowing and favoring increased male parental investment. The same scenario can explain the evolution of extensive female parental care in humans. Monogamy is the result of the male's investment being increased to approximate equality with that of the female and the male's attempt to insure his paternity. The incipient hunting activities of Australopithecus and small cranium would indicate polygyny at this stage of hominid evolution. The increase in hunting activities and brain size of Homo erectus may have favored monogamy. Polygyny may have reappeared to some extent with the evolution of Homo sapiens sapiens 40,000 B.P., but perhaps not until 15,000–11,000 B.P. did disparity in resources controlled by males allow some males to exceed the polygyny threshold. The loss of estrus in the female is regarded not as a precondition to pair-bonding, but as a means for increasing the likelihood of successful cuckoldry of the male after monogamy has been established. The human social setting of monogamous pairs in close proximity greatly reduces the costs of infidelity.
SINCE the publication of my work on Hereditary Genius in 1869, I have written numerous memoirs, of which a list is given in an earlier page, and which are scattered in various publications. They may have appeared desultory when read in the order in which they appeared, but as they had an underlying connection it seems worth while to bring their substance together in logical sequence into a single volume. I have revised, condensed, largely re-written, transposed old matter, and interpolated much that is new; but traces of the fragmentary origin, of the work still remain, and I do not regret them. They serve to show that the book is intended. to be suggestive, and renounces all claim to be encyclopedic.. I have indeed, with that object, avoided going into details. in not a few cases where I should otherwise have written with fulness, especially in the Anthropometric part. My general object has been to take note of the varied hereditary faculties of different men, and of the great differences in different families and races, to learn how far history may have shown the practicability of supplanting inefficient human stock by better strains, and to consider whether it might not be our duty to do so by such efforts as may be reasonable, thus exerting ourselves to further the ends of evolution more rapidly and with less distress than if events were left to their own course. The subject is, however, so entangled with collateral considerations that a straightforward step-by-step inquiry did not seem to be the most suitable course. I thought it safer to proceed like the surveyor of a new country, and endeavour to fix in the first instance as truly as I could the position of several cardinal points. The general outline of the results to which I finally arrived became more coherent and clear as this process went on;. they are briefly summarised in the concluding chapter.
This article presents a graphical approach to the genetical theory of sex change (similar to one recently applied to the evolution of simultaneous hermaphroditism). The graphs will help clarify a set of predictions to be tested against data from Pandalid shrimp. These shrimp are protandrous hermaphrodites (reproduce first as males). The goal is to use the genetical theory to predict the age of sex change. Since these shrimp show much geographic variation in this age, they provide a good opportunity to test the evolutionary model.
R. A. Fisher (1930) was perhaps the first to realize that the key to sex ratio evolution lay in the almost trivial fact that (under diploidy) everyone has one mother and one father; that in terms of autosomal genes males and females contribute equally to any zygote formed. This paper shows that his observations proves a useful key to a host of other sex related problems. It is for this intuitive reason that fitness measures for the alteration of sex function are often of the general form W = m̂/m + f̂/f. In such a measure male and female function are assigned equal weight. It is somewhat surprising that this notion continues to hold under haplodiploidy (at least from the mother's viewpoint). There is much that this paper has ignored--inbreeding, fluctuating or stochastic environments, etc. A treatment of many of these is much beyond me. It will be quite interesting to know how well the m̂/m + f̂/f notion holds up to alterations in the basic models proposed here.
Mammals exhibit a variety of density-dependent reproductive variables
that enable them to come into equilibrium with their environment. These
include the age at puberty, extent of embryonic and foetal death,
neonatal mortality rate, and the duration of lactational anoestrus or
amenorrhoea. These are all female-oriented mechanisms; most mammals are
polygynous, and as the female has the greatest energy investment in
reproduction she is the limiting resource. Unfortunately, man as a
species has chosen to eliminate these constraints, so that we are now
without any natural checks and balances on our rate of population
growth. We will be entirely dependent on artificial forms of
contraception for evermore. Since natural selection has always operated
in the past to maximize reproductive potential, women are
physiologically ill-adapted to spend the greater part of their
reproductive lives in the non-pregnant state. Tomorrow's contraceptives
need to be chosen with great care, as they will have a considerable
impact on our general health and social well-being.
An adaptationist programme has dominated evolutionary thought in England and the United States during the past 40 years. It is based on faith in the power of natural selection as an optimizing agent. It proceeds by breaking an oragnism into unitary 'traits' and proposing an adaptive story for each considered separately. Trade-offs among competing selective demands exert the only brake upon perfection; non-optimality is thereby rendered as a result of adaptation as well. We criticize this approach and attempt to reassert a competing notion (long popular in continental Europe) that organisms must be analysed as integrated wholes, with Baupläne so constrained by phyletic heritage, pathways of development and general architecture that the constraints themselves become more interesting and more important in delimiting pathways of change than the selective force that may mediate change when it occurs. We fault the adaptationist programme for its failure to distinguish current utility from reasons for origin (male tyrannosaurs may have used their diminutive front legs to titillate female partners, but this will not explain why they got so small); for its unwillingness to consider alternatives to adaptive stories; for its reliance upon plausibility alone as a criterion for accepting speculative tales; and for its failure to consider adequately such competing themes as random fixation of alleles, production of non-adaptive structures by developmental correlation with selected features (allometry, pleiotropy, material compensation, mechanically forced correlation), the separability of adaptation and selection, multiple adaptive peaks, and current utility as an epiphenomenon of non-adaptive structures. We support Darwin's own pluralistic approach to identifying the agents of evolutionary change.
The sexual interactions of 10 pairs of rhesus monkeys were observed during a control and an experimental menstrual cycle of each female. During the experimental cycle the females were treated with an antiandrogen, flutamide. Daily peripheral serum levels of estradiol, testosterone, and progesterone in each female were determined by radioimmunoassay. Sexual behavior did not correlate reliably with female serum concentrations of any hormone measured nor with the menstrual cycle stage. Administration of the antiandrogen to the females did not affect the sexual behavior of the pairs, although female serum levels of estradiol and testosterone were reduced. It was concluded that although female ovarian hormones may influence rhesus sexual interactions under some circumstances, the normal hormonal fluctuations during the menstrual cycle need not regulate this behavior; a knowledge of an intact rhesus female's hormonal condition does not allow accurate predictions about behavior displayed during laboratory pair tests with a male.
Daily administration over a period of 6 weeks of increasing doses of dexamethasone sodium phosphate (DEX) to seven long-term ovariectomized female stumptail monkeys significantly lowered circulating levels of testosterone without reducing any aspect of the females' sexual behavior or that of their male partners. Since treatment with DEX failed to suppress serum testosterone levels completely an additional experiment was performed in which the sexual behavior of five ovariectomized stumptails was compared before and after bilateral adrenalectomy, combined with chronic administration of both gluco- and mineralocorticoids. Serum levels of both testosterone and estradiol were reduced to very low levels in females after ovariectomy and adrenalectomy, yet no significant depression of females' sexual performance or that of their male partners occurred. Subsequent sc administration of estradiol or estradiol + testosterone in Silastic capsules to ovariectomized, adrenalectomized stumptails had little effect on sexual interaction. In a third experiment five ovariectomized stumptails which initially were relatively unreceptive and unattractive to males were given first testosterone and then testosterone + estradiol sc in Silastic capsules. One of the three indexes of females' receptivity increased significantly after testosterone; however, no other essential aspect of sexual interaction was affected. These findings suggest that sex steroids are normally not required in the female stumptail macaque for activation of preceptive and receptive sexual behaviors or for maintenance of sexual attractivity.
The reproductive behavior of captive female rhesus monkeys living in a large social group was examined to determine what patterns of proceptive behavior occur and how they are distributed throughout the menstrual cycle. Ten intact adult females and six vasectomized adult males were observed during the breeding season. The males were housed separately overnight and released into the social group for a 4-hr observation period. The female menstrual cycles were monitored by daily capture for vaginal swabbing. A total of 18 cycles in which females showed estrous behavior between intervals of menstruation were observed for nine females between October 4 and February 4. A composite of all the cycles revealed a significant rise in proceptive behavior during the follicular period culminating in a midcycle peak, with an abrupt cessation of female sexual invitations during the early luteal period. The specific patterns of proceptive behavior observed consisted primarily of female-initiated proximity and following of males. Solicitation patterns such as sexual presentation, hand slap, head bob/duck, and threat out were displayed to a lesser extent. Overall, these data suggest that underlying endocrine events strongly influence the behavior of female rhesus monkeys living in a complex social environment and that social factors such as dominance rank do not appear to override these hormonal variables.
Sociobiology is discussed as an extreme example of the adaptationist program. This program attempts to describe all aspects of living organisms as optimal solutions to problems set by the environment and by the biology of the species. Sociobiology first describes human nature by generalizing about human behavioral universals, then asserts that these traits are controlled by genes and then provides an adaptive story to explain why individuals with these traits would leave more offspring. The theory takes no account of problems of correct description and makes four errors: Arbitrary agglomeration, reification, conflation, and confusion of levels. As a result, the human behavior described bears no necessary resemblance to actual biological traits. The theory depends upon assertions of genetic control that have no basis in experimental fact. Sociobiologists have made no critical evaluation of the extremely poor knowledge of human genetics. Finally, the assumption that all characteristics are adaptations is never examined by sociobiology. There are many alternative evolutionary forces besides direct adaptation for establishment of characters. These include genetic drift, multiple selective peaks, lack of correspondence between the result of natural selection and optimal solutions, pleiotropic gene action, allometry and developmental noise. If sociobiology is to become a real science instead of idle speculation, it must abandon the tautological adaptationist program which is untestable.
The effects of endogenous fluctuations in ovarian hormones during the female's menstrual cycle on heterosexual interaction was studied in groups of stumptail macaques. When 5 different trios of females were paired for 5 consecutive weeks with each of 5 males no aspect of male-female interaction changed as a function of phase of the menstrual cycle. Moreover, males usually preferred to copulate with the same female of each trio in consecutive tests, regardless of the ovarian condition of any of the females. It appeared that the most dominant females in the trios were sexually most preferred. Subcutaneous implantation of silastic capsules containing progesterone into the sexually most preferred females of each trio affected neither the males' sexual preference, nor the behavior of these females, nor the behavior of sexually non-preferred females in each trio. Likewise, progesterone in sexually preferred females had no effect on male-female interaction in pair tests. It is concluded that in stumptail macaques social factors are more important than ovarian hormones in regulating heterosexual interaction.
The recent rise of a high-ranking adult male chimpanzee to the alpha male position of the Gombe National Park's Kasakela chimpanzee community is reported. The male Figan is the fourth individual to assume this status in the wild chimpanzees' social hierarchy during Goodall's 16 year study in Tanzania. The paper describes the overthrow of the previous top-ranking male, and the manner in which Figan has maintained his new position after the take-over. Emphasis is placed upon his relationship with his elder male sibling, Faben, and the second highest-ranking male in the community, Evered.
RENSCH1,2 showed, more than 20 years ago, that sexual dimorphism in body size tends to increase with increasing body size in various arthropod and avian taxa. Recently, the same positive relationship has been suggested for mammals in general3, and primates in particular4. Based on their findings on primates, Clutton-Brock et al.4 discussed several possible functional explanations for this relationship, but considered none of them wholly satisfactory. In particular, they rejected the hypothesis that positive allometry in sexual dimorphism in weight may be the product of an association of size and polygyny; they did not present statistical data to that effect, however. I argue here that, on the contrary, there is a strong relationship between polygyny and positive allometry for sexual dimorphism in body size. The evidence is based on an analysis of the relationship between the scaling of sexual dimorphism in body weight and the breeding system for 53 primate species, which in most cases coincide with those chosen by Clutton-Brock et al.4 for their study. The findings are incorporated into a multifactorial system on the evolution of sexual dimorphism in body size.
This study was designed to test the hypothesis that women exhibit peaks of sexual activity at ovulation, as would be predicted from estrous effects in animals. Married women who used contraceptive devices other than oral contraceptives experienced a significant increase in their sexual behavior at the time of ovulation. This peak was statistically significant for all female-initiated behavior, including both autosexual and female-initiated heterosexual behavior, but was not present for male-initiated behavior except under certain conditions of contraceptive use. Previous failures to find an ovulatory peak may be due to use of measures of sexual behavior that are primarily determined by initiation of the male partner. Women using oral contraceptives did not show a rise in female-initiated sexual activity at the corresponding time in their menstrual cycles, probably owing to the suppression of ovulatory increases in hormone secretion by the oral contraceptives.
Females are larger than males in more species of mammals than is generally supposed. A provisional list of the mammalian cases is provided. The phenomenon is not correlated with an unusually large degree of male parental investment, polyandry, greater aggressiveness in females than in males, greater development of weapons in females, female dominance, or matriarchy. The phenomenon may have evolved in a variety of ways, but it is rarely, if ever, the result of sexual selection acting upon the female sex. The most common selective pressures favoring large size in female mammals are probably those associated with the fact that a big mother is often a better mother and those resulting from more intense competintion among females for some resource than among males. It appears that, in general, more than one such pressure must affect the females of a species, and that their combined effects must not be countered by even stronger selective pressures favoring large size in males, before the result is that of larger size in the female sex. Sexual selection may often be operating upon the male sux in mammals even when it is smaller. Present knowledge about the species of mammals in which females are lager than males is quite rudimentary. Much more information is needed before we will be able to speak of the selective pressures accounting for the phenomenon with any reasomable degree of certainty. Perhaps the most fruitful approach would be a series of field studies of groups of related species in which females are larger in some species and males are larger in others.
A replication of earlier studies of male sex aggression conducted during the mid 1950s basically finds little modification in incidence and frequency. Approximately 50% of a sample of university women report being victims of sexual aggression during the academic year. Major changes from the earlier research appear to be focused around the nature of the pair relationships and the characteristics of the offended females.
This review considers the behavioral, ecological, and reproductive characteristics of mammals exhibiting monogamy, i.e., mating exclusivity. From a discussion of the life histories of selected species of monogamous primates, carnivores, rodents and ungulates, several trends emerge. Two forms of monogamy occur, Type I, facultative, and Type II, obligate. The selective pressures leading to these two forms of monogamy may have been different. Facultative monogamy may result when a species exists at very low densities, with males and females being so spaced that only a single member of the opposite sex is available for mating. Obligate monogamy appears to occur when a solitary female cannot rear a litter without aid from conspecifics, but the carrying capacity of the habitat is insufficient to allow more than one female to breed simultaneously within the same home range. Within both types of monogamy, the following traits are typically seen: (1) adults show little sexual dimorphism either physically or behaviorally: (2) the adult male and female exhibit infrequent socio-sexual interactions except during the early stages of pair bond formation. Additional trends specific to mammals exhibiting obligate monogamy are: (1) the young exhibit delayed sexual maturation in the presence of the parents, and thus only the adult pair breeds; (2) the older juveniles aid in rearing young siblings; and (3) the adult male (father) aids in the rearing of young by any or all of the following: carrying, feeding, defending, and socializing offspring.