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Born Gay? The Psychobiology of Human Sexual Orientation
Abstract
Sexual orientation is fundamental to evolution and shifts from the species-typical pattern of heterosexuality may represent biological variations. The growth of scientific knowledge concerning the biology of sexual orientation during the past decade has been considerable. Sexual orientation is characterised by a bipolar distribution and is related to fraternal birth order in males. In females, its distribution is more variable; females being less prone towards exclusive homosexuality. In both sexes homosexuality is strongly associated with childhood gender nonconformity. Genetic evidence suggests a heritable component and putative gene loci on the X chromosome. Homosexuality may have evolved to promote same sex affiliation through a conserved neurodevelopmental mechanism. Recent findings suggest this mechanism involves atypical neurohormonal differentiation of the brain. Key areas for future research include the neurobiological basis of preferred sexual targets and correlates of female homosexuality.
... Psychological and behavioral differences between the sexes have been studied scientifically for more than a century (Archer, 2019;Darwin, 1871;Woolley, 1910). As findings on sex differences have accumulated over time, the way in which non-heterosexual individuals may differ from heterosexuals on a range of psychobehavioral traits has received increasing attention (Allen & Robson, 2020;Luoto, 2021a;Zheng et al., 2011), as have the evolutionary-developmental mechanisms that create sex differences (Archer, 2019;Luoto & Varella, 2021) and sexual orientation differences (Luoto, 2020a;Luoto et al., 2019a,b;Rahman & Wilson, 2003) in such psychobehavioral traits. ...
... Sexual differentiation of the mammalian brain constitutes an integral evolutionary-developmental process which causes a cascade of sexually differentiated outcomes in men and women, ranging from physiological, cognitive, and behavioral traits to different life outcomes, for instance, in health and in educational and professional trajectories (Archer, 2019;Luoto, 2020b;Luoto et al., 2019a,b;Luoto & Varella, 2021;Mauvais-Jarvis et al., 2020;McCarthy, 2020;. Developmental disturbances in the sexual differentiation of the brain may result in various kinds of non-heterosexual phenotypes, which show sexatypicality across a range of biobehavioral traits (Luoto, 2021a;Luoto et al., 2019a,b;Rahman & Wilson, 2003;Swift-Gallant et al., 2019). One conceptualization of personality traits is that they are behavioral syndromes (e.g., complexes of correlated behaviors creating patterns) as opposed to internal traits, and as such, might also be subject to such differentiation (Woodley of Menie et al., 2021). ...
... Natural variation in neurodevelopmental processes may lead to sex-atypical behaviors and attitudes (e.g., sexual desire, sexual orientation, and personality) as in the case of non-heterosexual men and women. This hypothesis has received broad though not fully clear support across several studies (Abé et al., 2021;Lippa, 2020;Luoto, 2020a;Luoto et al., 2019a;Luoto, 2021a;Rahman & Wilson, 2003;Schmitt, 2006). Moreover, bisexual men and women tend to show gender nonconformity and cross-sex neuroanatomical changes which place them between heterosexual and homosexual participants (Abé et al., 2021;Rieger et al., 2020). ...
Research on the Dark Triad traits — psychopathy, Machiavellianism, and narcissism — reveals malevolent, transgressive, and self-centered aspects of personality. Little is known about the Dark Triad traits in individuals differing in sexual orientation, with some studies showing that non-heterosexual individuals have Dark Triad profiles resembling those of opposite-sex heterosexual individuals. In a cross-national sample (N = 4063; 1507 men, 2556 women; M age = 24.78, SD age = 7.55; 90.58% heterosexual, 5.74% bisexual, 2.83% homosexual) collected online via student and snowball sampling, we found in sex-aggregated analyses that bisexuals and homosexuals were more Machiavellian than heterosexuals. Bisexuals were more psychopathic and narcissistic than heterosexuals. The only significant findings in within-sex comparisons showed that self-identified bisexual women scored higher on all Dark Triad traits than heterosexual women. The findings support the gender shift hypothesis of same-sex sexual attraction in bisexual women, but not in lesbians nor in men. The finding that bisexuals are the sexual orientation group with the most pronounced Dark Triad profiles is opposite to what would be predicted by the prosociality hypothesis of same-sex sexual attraction. The life history and minority stress implications of these findings are discussed as alternative hypotheses to the gender shift hypothesis.
... First, this review consolidates the causation and correlations linked with ASO; it also tries to address the evolutionary paradox it poses. Although previous reviews in this field (e.g., Alexander, Skinner, & Roselli, 2011;Bailey et al., 2016;LeVay & Hamer, 1994;Pillard & Bailey, 1998;Rahman, 2005;Rahman & Wilson, 2003) offer a broad analysis, they lack the recent findings in this field. Hence, this review adds to what is already known. ...
... III) Meta-analysis carried out by 5 Aromatase activity Proposed by Rahman & Wilson (2003), Rahman (2005) (Decreased aromatase activity in the embryo leads to an excess of testosterone in the brain, which causes undermasculinization of the male brain due to lack of estrogen). I) Stress experienced by female rats during pregnancy affects preoptic aromatase activity and copulatory behaviors in prenatal male rats (reviewed in Alexander et al., 2011). ...
... Testosterone also gets converted to estradiol by aromatase enzyme, which binds to ERs. Both of these activities cause masculinization of the male fetal brain (reviewed in Rahman & Wilson, 2003). For male homosexuality, Rahman and Wilson (2003) put forward two hypotheses. ...
Since the 20th century, multiple studies have linked the variations in human sexual orientation, from heterosexuality to bisexuality or homosexuality, to a wide range of biological factors. However, a clear mechanism that leads to the development of these variations has not been established yet. This review consolidates various comprehensive studies on the possible biological factors in the fields of genetics, epigenetics, uterine environment, hormones , neuroanatomy, and neurobiology that lead to these variations. One intriguing question that 'homosexuality phenotype' faces is its ability to avoid elimination by Darwinian selection. This review tries to explain why natural selection is not eliminating the genetic factors associated with homosexuality even at the cost of the evolutionary fitness of homosexual individuals. Studies supporting certain strong candidates for alternative sexual orientation (ASO) are highlighted, which can become new research avenues for investigators in this field. Further, a novel speculation is proposed that might be contributing to the development of variation in human sexuality.
... However, one could assume that changes in the ERs in human females prevent the development of a sexual preference typical of females but this speculation lacks research support. Interestingly, women exposed in utero to the synthetic estrogen, diethylstilbestrol (DES) also report bisexual or homosexual preferences (reviewed in Rahman et al., 2003) which further suggests an estrogenic pathway to female homosexuality. ...
... As inclusive fitness involves both direct fitness (via reproduction) and indirect fitness (via altruism), kin selection might be at play in keeping and propagating the gay gene in a subset of community. Wilson in 1975 made the first attempt to explain the propagation of homosexuality via indirect mechanisms.He linked it to the sterile castes of insects which channelize the energy saved from being spent on reproduction towards their kin, maximising the indirect fitness (reviewed inRahman et al., 2003). He assumed that homosexual male humans benefitted their kin by acting as hunters or domestic helpers. ...
This dissertation (which was submitted as part of coursework for M.S. degree in Zoology) summaries various biological factors which are linked with the development of alternative sexual orientation in mammals.
... Such figures are likely underestimates because MHP continues to be viewed negatively in many cultures. A working range of 2-5% for MHP probably reflects the situation reasonably accurately in most cultures, making up a small but significant cohort in society (Rahman & Wilson, 2003;Bailey et al., 2016). ...
... Differences between studies may point to additional epigenetic effects operating over and above chromosomal genetic effects (Rice, Friberg & Gavrilets, 2012;Ngun & Vilain, 2014). In their review of several studies, Rahman and Wilson (2003) conclude that 50-60% of the variance in sexual orientation is due to genetic factors. A more recent study of almost half a million individuals established a heritability range of 8-25%, although it was not able to determine conclusively the relative contributions of nature and nurture (Ganna et al., 2019). ...
Male homosexual preference (MHP) is present in many human societies, making up a small but significant cohort. Because homosexual mate preferences are associated with lower fecundity, many evolutionary explanations have been advanced to account for the persistence of this trait. After reviewing a number of these hypotheses and finding room for additional explanations, we propose a new hypothesis that depends on the observed greater empathy and reduced hostility of men who express MHP. This gives them a central role in the performance of groups or teams (all male and mixed) where cooperation and intra-team coherence are at a premium. In this view, teams that contain men with MHP will outcompete teams without such men, other variables being similar. The links between personality traits and team performance do not require homosexual activity within the group. The hypothesis is supported by observations of the personality traits associated with MHP, such as increased agreeableness, which is linked to the literature on team cohesion and performance in sports and other kinds of teams and groups. This novel hypothesis could be examined through direct study of team performance. The proposed hypothesis may also have relevance to better performance among the diverse teams whose efficient performance is so important in modern society.
... Thus, sex-atypical neurodevelopment does not necessarily entail the development of sex-atypical genitalia. Furthermore, while some studies have indeed found sexual orientation differences in genital size in males (reviewed in Breedlove, 2017a;Rahman & Wilson, 2003), large-scale studies on genital anatomy classifying women by sexual orientation are scarce (Rahman & Wilson, 2003;Terry, 1990), and so the question has not even been properly addressed by scientists (for understandable ethical reasons). It should nevertheless be highlighted that a range of other androgen-related biomarkers, including anthropometric ones, have shown significant degrees of masculinization in nonheterosexual women (see Harris, Bewley, & Meads, 2020;Luoto et al., 2019a). ...
... Thus, sex-atypical neurodevelopment does not necessarily entail the development of sex-atypical genitalia. Furthermore, while some studies have indeed found sexual orientation differences in genital size in males (reviewed in Breedlove, 2017a;Rahman & Wilson, 2003), large-scale studies on genital anatomy classifying women by sexual orientation are scarce (Rahman & Wilson, 2003;Terry, 1990), and so the question has not even been properly addressed by scientists (for understandable ethical reasons). It should nevertheless be highlighted that a range of other androgen-related biomarkers, including anthropometric ones, have shown significant degrees of masculinization in nonheterosexual women (see Harris, Bewley, & Meads, 2020;Luoto et al., 2019a). ...
... The incidence of homosexuality in brothers of homosexual males is evaluated at 9%, which clearly exceeds the incidence in the general population (Bailey and Pillard, 1991). Similarly sisters of lesbians have an increased probability of being homosexual (Diamond, 1993;Rahman and Wilson, 2003). This concordance could obviously reflect educational/social factors but the study of twins allows to a large extent to reject this interpretation. ...
... At the endocrine level, it has been pointed out that in humans (Bocklandt and Vilain, 2007;Mustanski et al., 2005b) and even in rats (Rahman and Wilson, 2003;Weisz and Ward, 1980) that are best studied, during most of the embryonic life testosterone concentrations overlap between males and females even if males have on average higher concentrations. The difference in plasma testosterone concentrations is therefore an ambiguous sexual signal that cannot explain alone the sex-specific phenotypes. ...
BALTHAZART J. Sex partner preference in animals and humans. NEUROSCI BIOBEHV REV XX (Y) ZZZ-KKK, 2020. aaaaaaaaaa
Sex differences in brain and behavior of animals including humans result from an interaction between biological and environmental influences. This is also true for the differences between men and women concerning sexual orientation. Sexual differentiation is mediated by three groups of biological mechanisms: early actions of sex steroids, more direct actions of sex-specific genes not mediated by gonadal sex steroids and epigenetic mechanisms. Differential interactions with parents and conspecifics have additionally long-term influences on behavior. This presentation reviews available evidence indicating that these different mechanisms play a significant role in the control of sexual partner preference in animals and humans, in other words the homosexual versus heterosexual orientation. Clinical and epidemiological studies of phenotypically selected populations indicate that early actions of hormones and genetic factors clearly contribute to the determination of sexual orientation. The maternal embryonic environment also modifies the incidence of male homosexuality via immunological mechanisms. The relative contribution of each of these mechanisms remains however to be determined.
... Others consider sexual orientation as a powerful tool for testing hypotheses regarding sex differences and answering various questions about the nature of human mating dynamics (e.g., Rahman & Wilson 2003;Rahman 2005;Bao & Swaab 2011). ...
... However, it is feasible to suppose that those neural differences also affect other aspects of both sexual and nonsexual behavior patterns. And indeed, it seems that homosexual women are exposed to a greater degree of masculinisation than heterosexual women, but homosexual men turn out to be either over-or under-masculinised, depending on the trait being studied (for a review, see Rahman & Wilson 2003). Men of different sexual orientations in our sample did not differ significantly regarding jealous reactions. ...
Although studies consistently show gender differences in emotional vs. sexual jealousy, a substantial part of variance in jealousy is left unexplained. Here, we present two studies with aim to explore other correlates of jealousy, aside from gender. In the first online study ( n = 2970), we found that participants who reported being more upset by the emotional infidelity scenario were older and more educated and had a higher income than those who reported being more upset by the sexual infidelity scenario. Those who expressed greater sexual jealousy gave higher ratings of importance of potential partner's mate value. Heterosexual women were more likely to report emotional jealousy than non-heterosexual women. Among men, sexual orientation did not predict type of jealousy. As the role of reproductive status was largely neglected in previous research, in the second study, we used a continuous measure to explore jealousy as a function of age (reproductive vs. post-reproductive; n = 199). We found that the older participants were less jealous overall, and that the previously reported gender differences disappeared in the post-reproductive group. These results provide further support for the notion that jealousy is a context-specific, adaptive response, which diminishes in both intensity and specificity as the threat that it was designed for wanes.
... В качестве классификационных критериев сексуальной ориентации могут использоваться: актуальное сексуальное поведение (например, количество партнеров своего и противоположного пола); имеющиеся чувства (например, фантазии и желания); самокатегоризация людей (кем они себя считают) , а также генитальные или мозговые реакции (физиологические измерения возбуждения в ответ на мужские и женские образы) (Wilson, Rahman, 2005). Практически всегда в качестве определяющих в литературе ссылаются на один или оба компонента: «поведенческий» и «психологический» . ...
... Ослабление жесткой гендерной дихотомии и ломка традиционной системы гендерной поляризации предоставляют возможность для личности обрести и реализовывать ту гендерную идентичность, которая выстроена не на основе пассивного усвоения норм и требований гендерной роли, а является результатом индивидуального опыта и его творческого переосмысления, соотнесения своих индивидных параметров/желаний с культуральными моделями. Wilson, G., & Rahman, Q. (2005). Born gay: The psychobiology of sex orientation. ...
... It revealed that a significantly rightward head-turning bias during kissing was apparent in left-to-right readers (e.g., English) and a significantly leftward head-turning bias in right-to-left the initiation of kissing and head-turning bias in kissing have not been studied systematically. Males and females are different in many ways, and such differences can vary as a function of handedness [33][34][35][36] , prenatal hormone levels 37 and dopaminergic levels in the brain [38][39][40] . A mounting body of evidence suggests that these factors can potentially modulate sexual dominance, romantic interactions, and behavioral laterality in humans 17,41,42 . ...
... Orientasi seksual adalah asas kepada seksualiti manusia yang merujuk kepada tarikan seksual sama ada terhadap lelaki atau wanita yang ditunjukkan melalui kepelbagaian seks (Rahman & Wilson, 2003). Definisi umum orientasi seksual bertumpu kepada konsep 'orientasi' iaitu kecenderungan erotik terhadap sesuatu jantina atau lebih, dan kebiasaannya digambarkan sebagai tarikan seksual atau tarikan erotik (Savin-Williams & Ream, 2007). ...
ABSTRAK Umumnya di Malaysia, homoseksualiti dan biseksualiti adalah satu bentuk peyimpangan seksual yang dianggap sebagai taboo kerana bertentangan dengan nilai dan norma masyarakat terutamanya dalam konteks hidup berpasangan yang mana lelaki seharusnya berpasangan dengan wanita dan bukannya dengan lelaki dan begitu juga sebaliknya. Berdasarkan kepada undang-undang Malaysia, individu yang didapati bersalah melakukan hubungan homoseksual atau lebih dikenali sebagai liwat boleh didakwa dan dihukum di bawah seksyen 25 dalam Akta Undang-undang Jenayah Syariah dan di bawah seksyen 377A dan 377B dalam Hukum Kanun Keseksaan Malaysia. Maka oleh itu, golongan seperti lelaki gay dan biseksual cuba mengarusperdanakan perjuangan mereka dengan cara memasuki institusi perkahwinan bersama dengan pasangan heteroseksual tanpa mendedahkan orientasi seksual sebenar mereka. Dengan mengkhususkan kepada lelaki biseksual, kajian ini adalah bertujuan untuk membincangkan faktor-faktor yang mendorong lelaki biseksual memilih untuk berkahwin dengan wanita heteroseksual. Seramai 15 orang informan terdiri daripada lelaki biseksual yang telah berkahwin dengan wanita heteroseksual lebih daripada lima tahun, di sekitar Selangor dan Kuala Lumpur telah ditemubual secara mendalam. Hasil dapatan kajian dibahagikan kepada dua tema utama iaitu faktor dalaman dan faktor luaran. Faktor dalaman adalah seperti, i) keinginan untuk memiliki zuriat sendiri, ii) jatuh cinta dengan pasangan, iii) ingin menghilangkan homoseksualiti dalam diri, iv) tawar hati dengan hubungan gay v) pengaruh agama. Manakala faktor luaran pula termasuklah i)desakan keluarga dan ii) desakan pasangan. Secara keseluruhannya, kajian ini amatlah relevan dan signifikan untuk dikaji kerana dapat memberi input yang signifikan dalam memahami fenomena lelaki biseksual yang berkahwin dengan wanita heteroseksual khususnya di Malaysia untuk mengelakkan ancaman dan diskriminasi terhadap mereka, Selain itu, hasil kajian ini boleh dimanfaatkan oleh pihak-pihak tertentu seperti individu, pusat-pusat sokongan sosial serta kerajaan dalam menangani isu-isu yang berkaitan dengan fenomena ini pada masa akan data
... We, however, did not choose to use these terms because here we review to a greater extent the considerable cross-cultural literature on "third" gender populations for which gynephilia and androphilia have been the terms typically employed. plays an appreciable role in the development of same-sex sexual orientation (for reviews, see Bailey et al., 2016;Wilson & Rahman, 2005), although one study reported that experiencing a lower quality parent-child relationship is associated with greater likelihood of nonheterosexuality in women (Xu et al., 2019). In contrast, research into biodevelopmental influences on sexual orientation has garnered considerable empirical support (for reviews, see Bailey et al., 2016;Balthazart, 2020;Roselli, 2018). ...
Sexual orientation is a core aspect of human experience and understanding its development is fundamental to psychology as a scientific discipline. Biological perspectives have played an important role in helping to uncover the processes that contribute to sexual orientation development. Research in this field has relied on a variety of populations, including community, clinical, and cross-cultural samples, and has commonly focused on female gynephilia (i.e., female sexual attraction to adult females) and male androphilia (i.e., male sexual attraction to adult males). Genetic, hormonal, and immunological processes all appear to influence sexual orientation. Consistent with biological perspectives, there are sexual orientation differences in brain development and evidence indicates that similar biological influences apply across cultures. An outstanding question in the field is whether the hypothesized biological influences are all part of the same process or represent different developmental pathways leading to same-sex sexual orientation. Some studies indicate that same-sex sexually oriented people can be divided into subgroups who likely experienced different biological influences. Consideration of gender expression in addition to sexual orientation might help delineate such subgroups. Thus, future research on the possible existence of such subgroups could prove to be valuable for uncovering the biological development of sexual orientation. Recommendations for such future research are discussed.KeywordsSexual orientationDevelopmentGeneticsSex hormonesMaternal immune hypothesisGender expression
... Having addressed the first principle captured in the dialectic between Socrates and Phaedrus (i.e., defining that which we wish to explain), we can proceed to the second principle and consider whether same-sex sexually oriented individuals can be divided into classes in relation to their development (i.e., discrete categories). There is relatively little evidence to suggest that socialization (e.g., parental rearing) plays an appreciable role in the development of same-sex sexual orientation (for reviews, see Bailey et al., 2016;Wilson & Rahman, 2005), although one study reported that experiencing a lower-quality parent-child relationship is associated with greater likelihood of nonheterosexuality in women (Xu et al., 2019). In contrast, research into biodevelopmental influences on sexual orientation has garnered considerable empirical support (for reviews, see Bailey et al., 2016;Balthazart, 2020;Roselli, 2018). ...
Sexual orientation is a core aspect of human experience and understanding its development is fundamental to psychology as a scientific discipline. Biological perspectives have played an important role in uncovering the processes that contribute to sexual orientation development. Research in this field has relied on a variety of populations, including community, clinical, and cross-cultural samples, and has commonly focused on female gynephilia (i.e., female sexual attraction to adult females) and male androphilia (i.e., male sexual attraction to adult males). Genetic, hormonal, and immunological processes all appear to influence sexual orientation. Consistent with biological perspectives, there are sexual orientation differences in brain development and evidence indicates that similar biological influences apply across cultures. An outstanding question in the field is whether the hypothesized biological influences are all part of the same process or represent different developmental pathways leading to same-sex sexual orientation. Some studies indicate that same-sex sexually oriented people can be divided into subgroups who likely experienced different biological influences. Consideration of gender expression in addition to sexual orientation might help delineate such subgroups. Thus, future research on the possible existence of such subgroups could prove to be valuable for uncovering the biological development of sexual orientation. Recommendations for such future research are discussed.
... The neurobiological underlying support of preferred gender targets and strongly associated of female homosexuality. 36 Hypermethylation associated with CGG repeat has been reported in many cases incl. ...
The high prevalence of hypospadias is only the peak of the iceberg because there are stigma and isolation, which make not all patients seek a doctor to check up and do counseling. However, failure of psychical, anatomical, and metabolomic development should be faced from childhood age, adolescence, through the puberty years. One hundred years of congenital adrenal hyperplasia (CAH) in Sweden, open the failure of this labium minor fusion is associated with hypermethylation which has many names. Familial cases, in females, bring this case a gender reversal and reconstructive urology repair, were successful, while the cause, CYP21 mutation/blockade/deficiency also known as cytochrome P450 deficiency is neglected. In prevention, lose with reconstruction, psychologic and environmental which reported due to pesticide are favorite. Digging the cause of labium minus fusion failure, which given the real cause, is need to be chased for prevention in the population. Method: Systematic review (SR) using Science Direct search engine cross by PubMed, preferable SR and meta-analysis (MA) design than the other. Keywords: hypospadia-fragile (10),-CYP21 mutation (2). CYP21 deficiency-CAH is the core of this study. Result: Twenty-one references flowchart and table with 4 references in SR and MA which supported Hypospadia-CYP21 deficiency-CAH. More than 3126 cases were studied. Discussion: The association of CAH hormone and behavior (family-genetic), hypospadia-Parkinson (12),-pesticides, gen chromosome 6p,-autism (59),-bipolarism (22) bring to epigenetic hypermethylation cases. The CGG repeat-hypermethylation-gene silencing which produce protein enzyme is the cause of hypospadia. Geographical of Brazil, Latin American, incl. Argentine, SEA such as Thailand, Indonesia, and also Sweden, which all are in wet and warm climate area, has high hypermethylation prevalence due to RNAi in GMO green activity.
... Undoubtedly, this kind of conjecture about orientation identity has a passive, non-innate color. [5] Biological theories about the causes of homosexuality are mainly based on three hypotheses: genetic factors, sex hormone levels and brain structure [6]. The genetic hypothesis holds that homosexuality is inherited from a recessive gene. ...
... Although prenatal hormonal events exert substantial influence on sexual orientation in humans and non-human animals Luoto, Krams, & Rantala, 2019b;Swift-Gallant, 2019), genetic factors also play a role in inducing variation in human sexual orientation and behavior. Additionally, there are various ways in which genetic factors can interact with prenatal developmental events, causing variation in a range of phenotypes from morphometrics, cognition, behavioral dispositions, and sexual orientation Rahman & Wilson, 2003). This variation, and the evolutionary-developmental mechanisms underlying it, is described in more detail in the chapter by Luoto and Rantala (2021) in this Handbook and we refer interested readers to that chapter for a more detailed elaboration. ...
In this introductory chapter, we discuss the nexus between evolutionary theory and behavioral genetics, using it to elucidate the biological origins of human behavior and motivational predispositions. We introduce relevant behavioral genetics methods and evolutionary theoretical background to provide readers with the necessary conceptual tools to deepen their engagement with evolutionary behavioral genetics — as well as to help them take on the challenge of building a scientifically and evolutionarily more consilient account of human behavior. To demonstrate the utility of behavioral genetics in evolutionary behavioral science, our analytical examples range from personality, cognition, and sexual orientation to pair-bonding. We conclude by presenting a few recent landmark studies in behavioral genetics research with a particular focus on two aspects of sexual behavior: assortative mating and same-sex sexual behavior. This chapter considers behavioral genetics methods and their connection with evolutionary science more broadly while providing a succinct overview of recent advances in understanding the evolutionary genetic underpinnings of human sexual behavior, mate choice, and basic motivational processes. It is a sine qua non of scientifically principled evolutionary behavioral scientists to acknowledge the distal evolutionary and proximal genetic processes which, interlinked, underlie the psychobehavioral predispositions that form the variegated fabric of human societies and, more broadly, the diversity of life found in nature. These evolutionary processes operate from distal selection pressures acting on genetic material through hundreds of millions of years of natural selection — and from individual and population differences in genotypes to their manifestations in complex behavioral phenotypes and life outcomes in contemporary humans — which, in turn, enact concomitant selection pressures on the genetic material underlying and arising from them.
... Waites (2009) believes that the essentialist ideas underpinning sexual orientation discourse militate against the comprehensibility of 'bisexual' identities and ways of life. Sexual orientation is usually perceived to be an immutable trait of an individual's personality (Murphy 1997;Stein 1999;Wilson & Rahman 2005). Sexual minorities have frequently had recourse to what Yoshino (2000) calls the 'immutability defense', i.e., a pattern of argumentation which suggests that it is unethical to persecute or punish people who have no choice regarding their sexual attractions and behaviours, because they are allegedly 'born this way'. ...
... Homosexuality is a difference between people that can be likened to left-handedness; a difference indicating non-pathological variation in human development (Lalumière, Blanchard, & Zucker, 2000). It is likely to have some biological foundation (Rahman & Wilson, 2003). Though homosexuality was once a psychiatric diagnosis (and remained so, most believe, for rather too long), this was because Freudians saw the behaviour as a 'perversion' from normality (Roughton, 2002). ...
As bonding primates, human sexuality is fundamental to existence and well-being as a species and for most individuals. Sexual behaviour can be diverse or prosaic, as are the antecedent and consequent pathways, indicating individual differences are an influence. Biological dynamics such as puberty, independence, sexual preference, and the move from mating to parenting effort also influence these processes. Key findings observed by Eysenck and Wilson – extroverts are sociosexual, those high in neuroticism have more sexual problems, persons high in psychoticism (i.e., low Agreeableness and Conscientiousness, or high psychopathy/Machiavellianism) have impersonal, loveless, or deviant sexual expression – remain axiomatic. Sexual offenders and risk takers have this dispositional foundation, but are also troubled by sexual preoccupation, use sex for mood management, and have disturbed attachments, all of which are reconviction and relapse risk indicators. Intelligence is also relevant to human sexuality. Arousal and desire can overwhelm even the highly intelligent, as indicated by the risks and bad choices made by mostly rational and prudent individuals. Research into sexual behaviour (however operationalised), personality, and intelligence (and the multiple theories, models, methods, and forms of analysis it requires) helps inculcate an interest in differential psychology and its many applications.
... Bir kadının ikincil cinsiyet özelliklerinin daha belirgin olması onun erkeklere yönelik ilgisi olduğunu düşünmemize neden olmaz; gözlem ve muayene, bilinen herhangi bir tetkik yöntemi kullanarak bedensel olarak heteroseksüel, eşcinsel, biseksüel cinsel yönelimleri olan kişileri birbirinden ayırt etmek mümkün değildir (11). Cinsel yönelimin nasıl belirlendiğine ve geliştiğine ilişkin nörolojik, kalıtsal, genetik birçok çalışmalar yapılmış psikoloji çevrelerinden açıklamalar getirilmiştir ancak hiç birisi dikkate değer sonuç vermemiştir, cinsel yönelimin nasıl geliştiği bilinmemektedir (16,17). Cinsel yönelime ilişkin en açık bilgi kişinin istenci ile belirlenmediği ve ne yapılırsa yapılsın değiştirilemediğidir (15). ...
Cinsel yönelimi eşcinsel ve biseksüel olan bireyler
toplumdaki olumsuz tutumlardan ve yasal düzenlemelerdeki
eksikliklerden kaynaklanan birçok sorun ve ayrımcılıkla
karşı karşıya kalmaktadırlar. Toplumdaki olumsuz tutumlar
eşcinseller ve biseksüeller üzerinde etiketlenme, şiddete maruz
kalma, toplumdan dışlanma gibi çeşitli sorunlar doğururken,
yasal düzenlemelerdeki eksiklikler de bu kişilerin temel
insan haklarını kullanamamalarına neden olabilmektedir.
Bu yüzden eşcinsel ve biseksüel bireylerde, özellikle bazı
psikolojik sağlık sorunları (depresyon, anksiyete, stres
vb.) cinsel yönelimi heteroseksüel olanlara göre daha fazla
görülmektedir. Bunun yanı sıra eşcinsel ve biseksüel bireyler,
en önemli gereksinimlerden biri olan sağlık hizmetlerine
erişmede dahi sıkıntılarla karşılaşabilmektedirler. Erişimdeki
sorunların en önemlileri arasında kurumsal düzenlemelerdeki
eksikliklerin yanı sıra sağlık çalışanlarının büyük bir
çoğunluğunun bu kişiler hakkında yanlış ya da eksik bilgilere
sahip olması gösterilebilir. Ayrıca bazı sağlık çalışanları,
kendilerine başvuran eşcinsel ya da biseksüel yönelimli
olduklarını gizlemeyen kişilere cinsel yönelimlerinden dolayı
olumsuz bir tutum takınabilmektedirler. Bu nedenle eşcinsel
bireyler sağlık hizmetlerine başvurmaktan kaçınabilmekte,
başvurdukları zamanlarda ise kendilerini net olarak ifade
etmekten çekinme gibi bir davranış sergileyebilmektedirler.
Bu derlemede, sağlık hizmeti sunumunda önemli bir paya
sahip olan hemşirelerin eşcinsel ve biseksüel cinsel yönelimli
bireylere dair farkındalığa sahip olmaları, bu bireylerin
savunuculuğunu yapmaları ve bu bireylerin sağlık sorunlarını
ve bu sorunların çözümünde gerekli olan hemşirelik bakımını
bilmelerinin önemi vurgulanmaktadır.
... However, if one did apply the scientific method to the study of transgendered individuals, for example, I believe the results would be similar to the few studies that have evaluated the mental, social, and physical health of gays and lesbians. Gays are more likely than heterosexuals to have both mental and physical health problems: anxiety, depression, suicidal thoughts, and sexually transmitted diseases, low self-esteem, short-lived sexual partnerships, and unstable friendship networks, and have more problems with addictions to alcohol, drugs, and pornography (Wilson & Rahman, 2005). Some counter this by saying, "It's the stigma and ill-treatment of atypical sexual behavior in this country that increases their risk to mental and physical health problems." ...
... Third, psychosocial and cognitive developmental factors have been proposed and might apply. Although evidence in support of such factors has been limited (15,70), one recent study found that past same-sex behavior was more common among individuals who attended single-sex schools (71). In any case, findings pertaining to the nonheterosexual men in the other profiles provide evidence for distinct biodevelopmental pathways influencing same-sex sexual orientation in men. ...
Significance
Studying individual differences in gender and sexual orientation provides insight into how early-life biology shapes brain and behavior. The literature identifies multiple biodevelopmental influences on male sexual orientation, but these influences are generally studied individually, and the potential for association or interaction between them remains largely unexplored. We hypothesized that distinct biodevelopmental pathways correspond to specific subgroups of nonheterosexual men. We present evidence that nonheterosexual men can be categorized into at least four subgroups based on established biomarkers, and these biodevelopmental pathways differentially relate to gender expression and personality traits. These findings indicate individual differences in biodevelopmental pathways of male sexual orientation. They also illustrate the value of latent profile analyses for studying individual differences.
... Tanto las teorías biológicas como las sociales (Lippa 2005) tienden a presentar explicaciones plausibles. Los posibles factores biológicos incluyen los efectos de los genes, las hormonas prenatales y los procesos genéticos y ambientales que conducen a la inestabilidad del desarrollo (Ellis & Ames, 1987;Wilson & Rahman, 2005). Los posibles factores socioambientales que conducen a diferencias heterosexuales y homosexuales en la personalidad incluyen variaciones en la socialización de los padres y las prácticas de crianza de los hijos, los efectos de los estereotipos sociales sobre el género y la orientación sexual, y los efectos roles sociales, específicamente los roles de género y los roles de orientación sexual. ...
Los temas vinculados a la sexualidad, y más específicamente la orientación sexual, han tomado significativa importancia en los últimos años, sobre todo en la adolescencia tanto en ámbitos educativos como en el campo de la salud. En Argentina no se dispone de estudios que permitan com- prender la naturaleza de la orientación sexual en adolescentes. Ante la importancia de la temática, se llevó a cabo un estudio descriptivo con el objetivo de conocer cómo vivencian la orientación sexual los adolescentes y su relación con los factores de personalidad. La muestra se compuso de 418 adolescentes con edades entre 14 y 19 años (M = 16.76; DT = 1.478). Se realizaron una serie de preguntas acerca de la orientación se- xual, sentimientos, fantasías y experiencias sexuales. Un 60.3% de los adolescentes se identificó como heterosexual, un 23.2% como mayormente heterosexual, un 13.2% como bisexual, un 1.4% como mayormente homosexual, un 1% como homosexual y 0.9% otras orientaciones sexuales. Se observaron relaciones entre la orientación sexual y los factores de personalidad existiendo una relación positiva entre las mujeres que se identifican como bisexuales y la apertura a la experiencia, así como entre aquellos participantes de ambos sexos, heterosexuales y mayormente heterosexuales, y el factor extraversión. Se obtuvo una relación positiva entre el factor extraversión y los varones que poseen experiencia sexual. Los resultados aquí propuestos dan cuenta de la necesidad de no asumir a la heterosexualidad como norma entre la población adolescente y continuar trabajando en programas de educación sexual integral.
... It is still possible to find academic statements implicitly or explicitly suggesting that one is born gay. For example, LeVay (2010) declares that "I am inclined to place most of the developmental control in the hands of prenatal hormones" (p 279), and "Born Gay" is even the title of one book (Wilson & Rahman, 2005). By this, the authors mean that SSA is influenced predominantly by prenatal factors. ...
This paper combines the well-known concept of developmental milestones with standard statistical analysis of their spread in time, to gauge the milestone status/genetic influence on the timing of first SSA (same-sex attraction) by comparison with timing of puberty. SSA is not a developmental milestone, nor does its timing have high genetic influence. The relative standard deviation (RSD) of the average age of first SSA is 40%, which is very high compared with the approximately 7% for milestones with very high known genetic influence like puberty. As reported in many studies over 30 years, first attraction occurs at a mean age of 10 for both sexes, both orientations, and cross-culturally. While it is commonly claimed in the literature that first SSA is a genuine sexually-related attraction and biologically pre-programmed, both of these claims are doubtful. First attraction is on average about 2 years before puberty; hence it is mostly not puberty-driven. The 10-year age is possibly connected with peak awareness of social gender differences; alternatively but much less probably, age of first SSA is connected with adrenarche, i.e., the maturity of the adrenal glands. Age of first attraction turns out to be a poor choice to illustrate alleged innateness. Very few individuals have SSA as their earliest memories, which is hence a false stereotype. 3
... Tradicionalmente, la orientación sexual es definida como la inclinación o preferencia hacia miembros del sexo opuesto (heterosexualismo), del mismo sexo (homosexualismo) o de ambos sexos (bisexualismo). La investigación en este campo ha ido adquiriendo cada vez mayor interés por parte de la comunidad científica, especialmente de los evolucionistas, quienes afirman que la conducta homosexual pudo haber sido adaptativa a lo largo de la historia de la humanidad (Kirkpatrick, 2000;Rahman & Wilson, 2003). ...
The article presents results of a strategy to investigate the perception of some residents of the Municipality of Itagüí who identify with the homosexual orientation, about the recognition of the LGBTI community social level in Colombia "research. The study was qualitative approach and phenomenological method descriptive level. The sample of participants was intentional as the snow ball sampling type and a interview designed for this study. Participants believe they have advanced in its efforts to be a more visible, without discrimination or being marked or judged by others and have more equity in relation to their rights population, but are aware that there is still much more to move, but move on in this task, provided you
... Questo lavoro è anche in linea con un grado di "inversione di genere" nei gay e nelle lesbiche che è rilevante per gli attuali modelli di sviluppo dell'orientamento sessuale. Ad esempio, una delle più conosciute teorie biologiche che tentano di spiegare lo sviluppo dell'omosessualità ipotizza che i gay siano stati esposti a livelli di testosterone prenatale inferiori a quelli tipici, e le lesbiche a livelli di testosterone più alti, causando uno spostamento verso attrazioni sessuali, abilità cognitive e comportamenti di genere consistenti con i pattern dell'altro sesso (Ellis & Ames, 1987;Rahman & Wilson, 2003;Wilson & Rahman, 2005;Hines, 2006;Balthazart, 2011;Rosario & Schrimshaw, 2014;per una rassegna Bailey et al., 2016). ...
In questo articolo metteremo in evidenza come maschi e femmine differiscano per quanto riguarda le caratteristiche di personalità, così come state studiate attraverso i principali questionari di personalità come quelli fondati sui cosiddetti Big Five (anche conosciuti come Five Factors Model, FFM; Goldberg, 1993) e i sedici fattori di personalità di Cattell (1946), al fine di contribuire al dibattito in corso sulle differenze tra uomo e donna, con particolare attenzione al panorama scientifico e culturale italiano. A questo scopo abbiamo effettuato una rassegna e una sintesi delle principali ricerche svolte sulle differenze di personalità, per individuare i risultati più ricorrenti, significativi dal punto di vista statistico e importanti per delle caratteristiche precipue (ad es. la ricorrenza in periodi storici o in culture differenti). Da questa rassegna è emerso che, indubbiamente, esistono delle differenze tra maschi e femmine, con una sovrapposizione tra i profili di personalità tipici che oscilla tra il 10% e il 24% (Del Giudice, 2012). Queste differenze sono presenti in varie epoche e aree culturali e, in particolare, si amplificano in zone del mondo dove ci sarebbe la possibilità di maggiore uguaglianza di genere e dove c'è maggior benessere. Utilizzando come dimensioni di riferimento i Big Five, le caratteristiche che sembrano differenziare maggiormente gli uomini e le donne sono il Nevroticismo e l'Amicalità, in modo costante in differenti periodi storici e aree culturali, e quindi, rispetto alle altre caratteristiche, hanno una maggiore probabilità di essere influenzate dalla biologia. Importanti differenze sono emerse anche per una serie di sottodimensioni degli altri fattori di personalità.
The current series of studies are the first to examine brain responses to social aggression signals as a function of male and female sexual orientation. For the first set of studies (1a, 1b), axillary sweat had been collected from 17 heterosexual men and 17 heterosexual women aggressively responding to frustrating opponents (aggression condition) and while playing a construction game (control condition). Sweat samples were pooled according to sex and condition, and presented via a constant flow olfactometer to 17 gay and 23 heterosexual men (Study 1a), and 19 lesbian and 25 heterosexual women (Study 1b). Ongoing EEG was recorded from 61 scalp locations, chemosensory event-related potentials (CSERPs; P2, P3-1, P3-2) were analyzed, and neuronal sources calculated (low resolution electromagnetic tomography). Within the second set of studies (2a, 2b), pictures of males’ and females’ weak angry and neutral facial expressions were presented to 21 gay and 23 heterosexual men (Study 2a), and 19 lesbian and 26 heterosexual women (Study 2b), and ERPs (N170, P3) were analyzed. Gay men showed larger P3-1 amplitudes than heterosexual men upon presentation of male aggression sweat, accompanied by activation of the right inferior frontal gyrus (IFG, BA 10). Gay men also displayed longer N170 latencies in response to men’s compared to women’s angry facial expressions, while heterosexual men did not. In women, sexual orientation did not affect the processing of aggression sweat or anger expressions. Gay men showed preferential processing of chemosensory aggression signals (P3-1 amplitudes), indicating fine-tuned socioemotional sensitivity, related to activation of brain areas involved in emotion regulation (IFG). They further process the relative relevance of visual aggression signals (N170 latency). These results were in line with theories proposing a common evolutionary pathway for same-sex attraction and traits easing social integration.
ABSTRAK Agen sosialisasi merupakan faktor utama yang memberikan pengaruh terhadap lelaki gay. Walau bagaimanapun, agen sosialisasi mana yang paling dominan masih lagi menjadi tanda tanya dalam membentuk orientasi seksual seseorang gay. Justeru itu, objektif utama dalam makalah ini adalah untuk meneliti agen-agen sosialisasi yang dominan dalam membentuk orientasi seksual individu gay. Kajian ini menggunakan reka bentuk kajian kualitatif dengan menggunakan pendekatan fenomenologi. Seramai 10 orang informan yang terdiri daripada kalangan belia berumur 20-26 tahun dan masih belajar di sekitar Selangor dan Kuala Lumpur telah dipilih sebagai sampel kajian menggunakan kaedah snowball. Data-data yang terdapat dalam kajian ini diperoleh dengan menggunakan kaedah temubual mendalam. Hasil kajian mendapati bahawa terdapat tiga agen sosialisasi utama yang mempengaruhi orientasi seksual gay iaitu keluarga, rakan sebaya, dan media massa. Kesemua agen-agen sosialisasi ini seterusnya mewujudkan konsep diri tentang orientasi seksual gay dan akhirnya membentuk kesedaran dalam diri sebagai seorang homoseksual. Kesimpulannya, agen-agen sosialisasi memberikan pengaruh secara langsung kepada tingkah laku gay yang terdapat dalam masyarakat moden pada hari ini.
Kata kunci: sosialisasi, peranan agen-agen sosialisasi, gay, orientasi seksual
The interface of sexual behavior and evolutionary psychology is a rapidly growing domain, rich in psychological theories and data as well as controversies and applications. With nearly eighty chapters by leading researchers from around the world, and combining theoretical and empirical perspectives, The Cambridge Handbook of Evolutionary Perspectives on Sexual Psychology is the most comprehensive and up-to-date reference work in the field. Providing a broad yet in-depth overview of the various evolutionary principles that influence all types of sexual behaviors, the handbook takes an inclusive approach that draws on a number of disciplines and covers nonhuman and human psychology. It is an essential resource for both established researchers and students in psychology, biology, anthropology, medicine, and criminology, among other fields. Volume 1: Foundations of Evolutionary Perspectives on Sexual Psychology addresses foundational theories and methodological approaches.
In this introductory chapter, we discuss the nexus between evolutionary theory and behavioral genetics, using it to elucidate the biological origins of human behavior and motivational predispositions. We introduce relevant behavioral genetics methods and evolutionary theoretical background to provide readers with the necessary conceptual tools to deepen their engagement with evolutionary behavioral genetics – as well as to help them take on the challenge of building a scientifically and evolutionarily more consilient account of human behavior. To demonstrate the utility of behavioral genetics in evolutionary behavioral science, our analytical examples range from personality, cognition, and sexual orientation to pair-bonding. We conclude by presenting a few recent landmark studies in behavioral genetics research with a particular focus on two aspects of sexual behavior: assortative mating and same-sex sexual behavior. This chapter considers behavioral genetics methods and their connection with evolutionary science more broadly while providing a succinct overview of recent advances in understanding the evolutionary genetic underpinnings of human sexual behavior, mate choice, and basic motivational processes. It is a sine qua non of scientifically principled evolutionary behavioral scientists to acknowledge the distal evolutionary and proximal genetic processes which, interlinked, underlie the psychobehavioral predispositions that form the variegated fabric of human societies and, more broadly, the diversity of life found in nature. These evolutionary processes operate from distal selection pressures acting on genetic material through hundreds of millions of years of natural selection –and from individual and population differences in genotypes to their manifestations in complex behavioral phenotypes and life outcomes in contemporary humans – which, in turn, enact concomitant selection pressures on the genetic material underlying and arising from them.
Compared to the body of literature on male homosexuality, the continuum of bisexual orientations between the exclusively homosexual and heterosexual poles has been largely overlooked in the scientific and evolutionary literature. Possibly, male bisexuality is not as hard a puzzle to evolutionary thinking because it does not reduce individual direct reproductive success as much as exclusive male homosexuality. Or, bisexual men are expected to fall in between the exclusive poles of sexual orientation, and they thus would not differ from them in the studied characteristics. Moreover, the existence of bisexual men has sometimes been doubted or denied in scientific and lay literature. Despite recent Western biphobia (and homophobia) aimed specifically at men, we show that different forms of male sexuality aimed at both men and women are common among different human populations and non-human species, making it a viable candidate for evolutionary analysis. We first outline the concept and measurements of male bisexuality, its prevalence, and after reviewing the proximate socio-biological factors associated with male bisexuality, we outline evolutionary hypotheses on male bisexuality. We show that several hypotheses originally designed to explain exclusive homosexuality apply also to bisexuality, although most of them deal with the more feminine form of male non-heterosexuals. Finally, we outline the importance of studies on bisexuality for evolutionary psychological science.
Cinsiyetle ilgili değişkenlerin insanlık algısı üzerinde etkisi var mıdır? Bu araştırma sorusundan türetilen hipotezleri test etmek amacıyla 2 (atfedilen cinsiyet: kadın ismi veya erkek ismi) x 2 (cinsiyet ifadesi: kadınsı görünüm veya erkeksi görünüm) x 2 (cinsel yönelim bilgisi: heteroseksüel veya eşcinsel) gruplararası faktöryel desenin kullanıldığı iki ayrı deney yapılmıştır. İnsanlık algısı, insanı hayvanlardan (insan biricikliği) ve robotlardan (insan doğası) ayıran özelliklerinin hedef kişiye ne derece atfedildiği üzerinden elde edilmiştir. Toplamda 131 üniversite öğrencisinin (yaş Ort. = 20.05; SS = 2.12; 59 kadın) yer aldığı birinci deneyde, sadece cinsiyet ifadesinin insanlık algısı üzerindeki temel etkisinin anlamlı olduğu bulunmuştur. Kadınsı cinsiyet ifadesine sahip kişilere erkeksi cinsiyet ifadesine sahip olanlara kıyasla insan doğasına ait özellikler anlamlı şekilde daha fazla atfedilmiştir. Toplam 146 üniversite öğrencisinin (yaş Ort. = 21.59 SS = 1.69, 105 kadın) katıldığı ikinci deneyde ise hem cinsiyet ifadesi hem de cinsel yönelimin temel etkileri insanlık algısı üzerinde gruplar arasında anlamlı farklar ortaya çıkarmıştır. Kadınsı cinsiyet ifadesine sahip bireylere erkeksi cinsiyet ifadesine sahip olanlara kıyasla, ve eşcinsellere heteroseksüellere kıyasla insan doğasına ait özellikler anlamlı şekilde daha fazla atfedilmiştir. Ayrıca ikinci çalışmada, cinsiyet ve cinsiyet ifadesinin ortak etkisinin anlamlı olduğu, insan biricikliğine ait özelliklerin, erkeksi cinsiyet ifadesine sahip olan erkeklere (cinsiyetle uyumlu cinsiyet ifadesi) erkeksi cinsiyet ifadesine sahip olan kadınlara (cinsiyetle uyumsuz cinsiyet ifadesi) kıyasla daha çok atfedildiği bulunmuştur. İkinci çalışmada yazılı materyal (vinyet) yerine görsel materyalin (fotoğraf) kullanılması daha fazla hipotezin desteklendiği bulgular ortaya çıkarmıştır. Bulgular genel olarak değerlendirildiğinde, kadınsılığın doğayla ve duygusallıkla, erkeksiliğin ise kültürle ve rasyonellikle özdeşleştirildiğini ortaya koyan alan yazınla uyumlu yönde olduğu görülmektedir. Cinsiyet ifadesinin cinsiyetten ve cinsel yönelimden bağımsız bir değişken olduğunun ortaya konması, bu araştırmanın alana en önemli katkısıdır. Saç kesimi, giyim şekli gibi fiziksel görünümle dışa vurulan ve cinsiyetin önemli bir edimsel yönü olan cinsiyet ifadesi, insanlık algısında anlamlı bir fark ortaya çıkarmaktadır.
A recent evolutionary theory of female sexual fluidity suggests that women do not have sexual orientations in the same sense that men do, and instead women’s apparent sexual orientation is a function of their sociosexual orientation. Among other things, the theory predicts that women’s unrestricted sociosexual orientation decreases their negative attitude toward same-sex behavior, whereas men’s unrestricted sociosexual orientation increases it. An analysis of the General Social Surveys data shows that, net of age, education, race, religion, religiosity, political attitude, intelligence, urbanicity and region of residence, and survey year, sociosexually unrestricted women are less likely to believe homosexual relationships are always morally wrong, while sociosexuality was not associated with homophobia among men. The study provides further evidence for the evolutionary theory of female sexual fluidity.
A bstract
A polygyny hypothesis of female sexual fluidity proposes that women may have been evolutionarily selected to be sexually fluid, in order to have occasional sex with their cowives in polygynous marriage to reduce tension and conflict inherent in such marriage, while at the same time reproducing children with their husbands. Among others, the hypothesis predicts that women who are biologically (but not surgically) infertile would experience greater same‐sex attraction. Biological infertility stems from natural, evolutionarily familiar causes such as menopause, whereas surgical infertility stems from artificial, evolutionarily novel causes such as tubal ligation or hysterectomy. Consistent with the prediction, the analyses of the National Survey of Family Growth data showed that biological infertility, but not surgical infertility, was significantly associated with same‐sex self‐identified labels, behavior and sexual attraction in women. Biological infertility nearly doubled the odds of women having engaged in same‐sex behavior and the number of same‐sex partners in the last 12 months and nearly tripled the number of same‐sex partners in life. In sharp contrast, biological infertility was not associated (and surgical infertility was significantly negatively associated) with same‐sex attraction in men.
Geschlecht ist gesellschaftlich gemacht. Dass das auch für das biologische Geschlecht sex gilt - ein Postulat queer-feministischer Theorien -, kann dieser Band anhand biologischer Theorien erstmals dezidiert und differenziert belegen. Die naturphilosophischen und biologisch-medizinischen Geschlechtertheorien unterschiedlicher Zeitabschnitte (Antike, beginnende Moderne, Gegenwart) werden dargestellt und mit gesellschaftlichen Geschlechterordnungen in Verbindung gebracht. Heinz-Jürgen Voß führt die miteinander ringenden Positionen differenziert aus und zeigt: Mit prozessorientierten Betrachtungsweisen sind in biologischen Theorien viele Geschlechter denkbar - statt nur zwei oder drei.
The biodevelopment of psychological sex differentiation is putatively reflected in several anthropometrics. We examined eight anthropometrics in 1404 Thai participants varying in sex, sexual orientation, and gender identity/expression: heterosexual men and women, gay men, lesbian women, bisexual women, sao praphet song (transgender birth-assigned males), toms (transgender birth-assigned females), and dees (birth-assigned females attracted to toms). Exploratory factor analyses indicated the biomarkers should be analyzed independently. Using regressions, in birth-assigned males, less male-typical second-to-fourth digit ratios in the left hand were associated with sexual orientation towards men regardless of gender identity/expression, whereas shorter height and long-bone growth in the arms and legs were more evident among sao praphet song—who are both sexually oriented towards men and markedly feminine. In birth-assigned females, there were no clear sexual orientation effects, but there were possible gender-related effects. Groups of individuals who tend to be more masculine (i.e., toms, lesbians) showed more male-typical patterns on weight and leg length than some groups of individuals who tend to be less masculine (i.e., heterosexual women, dees). Thus, it appears the various anthropometrics inform separate biodevelopmental processes that differentially relate to sexual orientation and gender identity/expression depending on the measure in question as well as birth-assigned sex.
In the last few years there has been a shift in the view on pedophilia and its treatment in international diagnostic manuals and expert consensus documents. This study seeks to investigate the approach of health care professionals’ on some of the topics that are mostly debated: whether pedophilia without distress or acting out should be considered a mental disorder, whether there can be a changeability of pedophilic sexual interest over life and what the main aim of treatment should be. Qualitative content analysis was used to analyze the responses in semi-structured interviews of eight Swedish health care professionals with significant clinical experience from this patient category. These results suggest that there is a lack of consensus regarding all three topics, and that the opinions of the experienced health care professionals did not fully comply with the international experts agreements. This might lead to differences in clinical practice depending on who meets the patient, it can make the patients unsure about how they will be treated if they seek help, and it demonstrates a gap between published international research and clinical practice.
Sexual orientation and sexual fluidity are examined in this chapter. The antecedents and the environmental and cultural influences on our sexual orientation are described, along with the difference between sexual orientation, identity, behavior, and preference. The chapter ends with an attempt to provide an answer as to whether changing one’s orientation is possible.
Research on the causes of human sexual orientation has been marshaled in support of predetermined and opposing theological viewpoints. Whilst acknowledging that there is still much that is not known, the peer reviewed scientific literature clearly shows that a combination of genetic and environmental factors contribute to sexual orientation, with approximately one third of variance currently attributed to the former. Much of the known environmental influence appears to be intra-uterine and there is no currently convincing evidence that social environment plays a significant part. This body of evidence is relevant to theology. Greater attention should be given to critical interdisciplinary engagement of the theology and science of sexual orientation.
In questo articolo analizzeremo come maschi e femmine differiscano per quanto riguarda le caratteristiche di personalità, così come state studiate attraverso i principali questionari di personalità come quelli fondati sui cosiddetti Big Five (anche conosciuti come Five Factors Model, FFM; Goldberg, 1993) e i sedici fattori di personalità di Cattell (1946), al fine di contribuire al dibattito in corso sulle differenze tra uomo e donna, con particolare riferimento al panorama scientifico e culturale italiano.A questo scopo abbiamo effettuato una rassegna e una sintesi delle principali ricerche svolte sulle differenze di personalità, per individuare i risultati più ricorrenti, significativi dal punto di vista statistico e importanti per delle caratteristiche precipue (ad es. la ricorrenza in periodi storici o in culture differenti).Da questa rassegna è emerso che, indubbiamente, esistono delle differenze tra maschi e femmine, con una sovrapposizione tra i profili di personalità tipici che oscilla tra il 10% e il 24% (Del Giudice, 2012).Queste differenze sono presenti in varie epoche e aree culturali e, in particolare, si amplificano in zone del mondo dove le persone hanno maggiore libertà di comportamento rispetto ai tipici ruoli di genere e dove c'è maggior benessere.Utilizzando come dimensioni di riferimento i Big Five, le caratteristiche che sembrano differenziare maggiormente gli uomini e le donne sono il Nevroticismo e l'Amicalità, in modo costante in differenti periodi storici e aree culturali e, quindi, rispetto alle altre caratteristiche, hanno una maggiore probabilità di essere influenzate dalla biologia. Importanti differenze sono emerse anche per una serie di sottodimensioni degli altri fattori di personalità del Big Five o in dimensioni misurate con altri strumenti di valutazione.
Human papillomavirus (HPV) is a sexually transmittable virus infection, which is a necessary risk factor for developing cervical cancer, first killer for working women in Moldova. Since 2018 Moldova has modified the screening program and the vaccination program (mainly funded externally). To assess the performance of the mitigation policy we propose the cost-effectiveness analysis according to 2 already implemented strategies. (1) Vaccination of a single age-cohort, although vaccinating a single cohort may not have a substantial effect in other countries with distinct socio-economic situation. (2) Transition to more technologically advance screening ecosystem (changing from Romanowski to Pap smear), which might not necessary be cost-efficient in low resource settings (if GDP per capita doesn’t grow substantially at the same time). (1) We verified that single cohort vaccination is both cost-beneficial (total costs reduction will balance intervention costs around the year 2040) and cost-efficient (with incremental impact in 20 years perspective on the level of 2300 EUR/QALY). Moreover, we found out that single year cohort is more beneficial than 5-years cohort vaccination scenarios in our mathematical model. This behaviour could be explained by a transitional situation in Moldova (HPV epidemic is near outbreak threshold), still small changes of model parameters and initial conditions could cause strong effect in the epidemiology. However, a definitive answer cannot be given with the chosen methodology. (2) Transition between Romanowski -> Pap smear cytology in screening benefits unquestionably in epidemiology e.g. due to a higher specificity. However, further maintenance and higher procedure costs could exceed treatment costs, hence intervention costs would gather an unacceptable share of national resources that are limited and that are dedicated to public health.
In the current context of the redefinition of financial markets due to the challenges generated by the multi-polarity phenomenon, virtual space becomes the main trading place for financial products, and our role as a researcher is to identify new financial instruments appropriate to this reality, which is why we consider that a market trend financial is that of a new network architecture in the virtual financial space based on nodes of financial interference. Moreover, financial space is a monetary representation of all other areas that can be identified and defined in society, especially in the economy, and can be considered as a set of specific financial interconnections with defining characteristics that determine them. Along with the profound changes in the interconnection of the socio-economic entities, using the new information channels, more and more often in the discussions of the specialists and not only a number of monetary issues are debated, in its virtual aspect, respectively the financial risks related to the virtual space, as well as the degree of "mastery" of information networks. In this context, in this paper we will try to make a series of contributions on how this financial space is designed – as a complex network with an adequate degree of risk.
Keywords: finance, financial network, digitization, financial risk and sustainability.
Human sleep patterns differ across age groups and between males and females, and their association with age and gender suggest that they might have been the target of sexual selection during human evolutionary history. In this study, I will test the hypothesis that a phase-delayed circadian phase is a sexually selected trait in humans. A short version of the Horne and Ostberg questionnaire and a questionnaire on sexual behaviour were administered to 134 males and 140 females. A significant negative relationship was found between the MEQ score and the number of sexual partners among males, with evening types reporting more sexual partners than morning types. No significant relationship between females MEQ and number of sexual partners was found. Findings support the hypothesis that evening preference in males is a sexually selected trait.
A recent evolutionary theory of female sexual fluidity suggests that women may not have sexual orientations in the same sense that men do, and that women's apparent sexual orientation may instead be a byproduct of their sociosexual orientation. One developmental factor that has consistently been shown to influence sociosexual orientation is father absence in childhood. Consistent with the prediction of the theory, the analyses of the National Longitudinal Study of Adolescent to Adult Health (Add Health) data show that father absence significantly increases women's, but not men's, same‐sex sexuality in adulthood, whether it is measured by self identity, sexual behaviour, or romantic attraction. Further consistent with the theory, the association between father absence and same‐sex sexuality in women is entirely mediated by their sociosexual orientation.
Christian debates about human sexuality are often presented as being concerned primarily with differences regarding authority of scripture. It is proposed here that they might more constructively be understood as debates about science and theology. Just as cosmology, evolution and demonology have variously been perceived as presenting conflict between scientific theories and biblical texts, so human sexuality presents similar points of tension. The issue at stake is not really about biblical authority, but rather about how the “book of nature” and the book of scripture are understood to mutually interpret each other. Lessons learned from debates between science and theology in other domains, may usefully facilitate a more constructive debate on sexuality.
Recent findings suggest that sexual orientation has an early neurodevelopmental basis. Handedness, a behavioral marker of early neurodevelopment, has been associated with sexual orientation in some studies but not in others. The authors conducted a meta-analysis of 20 studies that compared the rates of non-right-handedness in 6.987 homosexual (6,182 men and 805 women) and 16,423 heterosexual (14,808 men and 1,615 women) participants. Homosexual participants had 39% greater odds of being non-right-handed. The corresponding values for homosexual men (20 contrasts) and women (9 contrasts) were 34% and 91%, respectively. The results support the notion that sexual orientation in some men and women has an early neurodevelopmental basis, but the factors responsible for the handedness-sexual orientation association require elucidation. The authors discuss 3 possibilities: cerebral laterality and prenatal exposure to sex hormones, maternal immunological reactions to the fetus, and developmental instability.
Morphometric analysis of the human hypothalamus revealed that the volume of the suprachiasmatic nucleus (SCN) in homosexual men is 1.7 times as large as that of a reference group of male subjects and contains 2.1 times as many cells. In another hypothalamic nucleus which is located in the immediate vicinity of the SCN, the sexually dimorphic nucleus (SDN), no such differences in either volume or cell number were found. The SDN data indicate the selectivity of the enlarged SCN in homosexual men, but do not support the hypothesis that homosexual men have a 'female hypothalamus'.
Both the neurohormonal theory of sexual orientation and previous research on humans and animals suggest that male homosexuality may arise from prenatal stress during the brain's sexual differentiation. Stress-proneness and retrospective reports of stress during pregnancy were obtained from mothers of male and female heterosexuals, bisexuals, and homosexuals. Each mother also rated pregnancy stress for a heterosexual sibling of the subject. For males, neither between-family nor within-family analyses revealed a maternal stress effect for either sexual orientation or childhood gender nonconformity. However, mothers of effeminate children reported more stress-proneness than other mothers. Male homosexuality nevertheless was strongly familial, suggesting a reconsideration of genetic and familial environmental mechanisms.
The performance by groups of male and female homosexuals and heterosexuals on three tests of spatial ability was studied. The groups were closely matched in terms of age, education, and vocational interests. Male homosexuals performed more poorly than male heterosexuals on a version of the water jar test and on the Mental Rotation Test, but the groups did not differ on measures of geographical knowledge or verbal ability. Female homosexuals and heterosexuals attained similar scores on all cognitive variables except the water jar test; on this task, the homosexual females performed more poorly than the heterosexual females. The influence of sexual orientation on visuospatial tasks could not be explained on the basis of self-reports of masculinity and femininity, or on the basis of experience with activities thought to foster the development of spatial skills. Such factors, however, acting in concert with biological influences that are not yet known, may have parallel effects on the development of sexual orientation and visuospatial ability.
Early hormones have been hypothesized to influence both sexual orientation and related childhood sex-typed behaviors. This study examined hormonal influences on activity and playmate preferences in children with congenital adrenal hyperplasia (CAH) age 2.5 to 12 years (24 girls, 19 boys) and their relatives (16 girls, 25 boys). CAH girls preferred boys' toys and activities. They also had greater preference for boy playmates than controls, but this was largely attributable to 4 girls. CAH boys did not differ significantly from controls. Activity and playmate preferences were not related. It was concluded that early androgen has a major effect on childhood activity preferences but only a weak influence on playmate preferences; sex segregation does not arise from sex-typed activity preferences; activity and playmate preferences may be differently predictive of sexual orientation; and hormonal influences on sexual orientation are likely to be complex.
• Homosexual female probands with monozygotic cotwins, dizygotic cotwins, or adoptive sisters were recruited using homophile publications. Sexual orientation of relatives was assessed either by asking relatives directly, or, when this was impossible, by asking the probands. Of the relatives whose sexual orientation could be confidently rated, 34 (48%) of 71 monozygotic cotwins, six (16%) of 37 dizygotic cotwins, and two (6%) of 35 adoptive sisters were homosexual. Probands also reported 10(14%) nontwin biologic sisters to be homosexual, although those sisters were not contacted to confirm their orientations. Heritabilities were significant using a wide range of assumptions about both the base rate of homosexuality in the population and ascertainment bias. The likelihood that a monozygotic cotwin would also be homosexual was unrelated to measured characteristics of the proband such as self-reported history of childhood gender nonconformity. Concordant monozygotic twins reported similar levels of childhood gender nonconformity.
Both sexual orientation and pubertal onset are sexually dimorphic. Biologic theories of sexual orientation emphasize the role of early androgens in sexual differentiation of partner preference. If homosexual individuals have been subject to atypical androgenizing influences, such influences may also affect other sexually dimorphic traits, such as pubertal timing. Based on this rationale as well as promising evidence from a prior twin study, we examined the onset of puberty in lesbians. We hypothesized that lesbians would have a later (i.e., more masculine) age of pubertal onset compared to heterosexual women. We investigated this hypothesis in a sample of community volunteers and a second sample of discordant twins. Contrary to our hypothesis, we found no significant differences in pubertal onset between homosexual and heterosexual women.
We tested the kin selection hypothesis of male homosexuality using questionnaire data in a community sample of homosexual and heterosexual men. Homosexual men were no more likely than heterosexual men to channel resources toward family members. Indeed, heterosexual men tended to give more financial resources to siblings than homosexual men. Furthermore, homosexual men were somewhat more estranged from family members, especially from fathers and oldest siblings.
Dermal ridges on the fingertips are formed early in fetal life and remain unchanged throughout the life span. The researchers examined dermatoglyphic characteristics (total ridge count and directional ridge asymmetry) in homosexual and heterosexual men. There was no difference between the 2 groups of men in total ridge count, but more gay men demonstrated leftward asymmetry than did nongay men. Although this effect was not accounted for by differences in hand preference, an association was observed between leftward dermatoglyphic asymmetry and an increased incidence of adextrality in homosexual men, but not in heterosexual men. These findings are consistent with a biological contribution to sexual orientation and indicate that such an influence may occur early in prenatal life.
Homosexual behavior is defined as genital contact, genital manipulation or both between same-sex individuals. Available data
indicate that this behavior is phylogenetically widespread among the anthropoid primates, but totally absent among prosimians.
The majority of the 33 species that demonstrate homosexual behavior do so rarefy, but for a substantial number (N =12) it appears to be a more common pattern under free-ranging conditions. I summarize data on homosexual behavior as it relates
to form, living condition, age, sex, social organization, and ecological context, and discuss hormonal, demographic, and sociosexual
theories for primate homosexual behavior. Among adult primates, the behavior is not the product of abnormal excesses or deficiencies
in androgens. Prenatal excesses of androgens may have some effect on the expression of female homosexual behavior, but these
effects might vary over the life span, and data are equivocal at present. Demographic processes that result in skewed sex
ratios can favor the expression of homosexual behavior in a population, which causes intraspecific variation. I examine several
sociosexual explanations, including (a) proceptivity enhancement, (b) receptivity reduction, (c) dominance assertion, (d)
practice for heterosexual copulation, (e) tension regulation, (f) reconciliation, and (g) alliance formation. An evolutionary
scenario highlights the transformations this behavior underwent during the evolution of the anthropoid primates. I suggest
exaptation as a theoretical framework for interpreting homosexual behavior and conclude that future consideration of sexual
selection among primates should address homosexual components of this process.
A developmental theory of erotic/romantic attraction is presented that provides the same basic account for opposite-sex and same-sex desire in both men and women. It proposes that biological variables, such as genes, prenatal hormones, and brain neuroanatomy, do not code for sexual orientation per se but for childhood temperaments that influence a child's preferences for sex-typical or sex-atypical activities and peers. These preferences lead children to feel different from opposite-or same-sex peers - to perceive them as dissimilar, unfamiliar, and exotic. This, in turn, produces heightened nonspecific autonomie arousal that subsequently gets eroticized to that same class of dissimilar peers: Exotic becomes erotic. Specific mechanisms for effecting this transformation are proposed. The theory claims to accommodate both the empirical evidence of the biological essentialists and the cultural relativism of the social constructionists.
In psychobiological research on sexual orientation, the prenatal hormone theory has a central position. This article examines the hypothesis that prenatal estrogens contribute to the development of human sexual orientation. Several groups of women with a history of prenatal exposure to diethylstilbestrol (DES), a nonsteroidal synthetic estrogen, were compared with several samples of control women in the context of a comprehensive study of the psychiatric and psychologic effects of prenatal DES. Various aspects of sexual orientation were assessed by systematic interview. Consistently across samples, more DES-exposed women than controls were rated as bisexual or homosexual (scores 2-6 on Kinsey-format scales ranging from 0 to 6). The data are compatible with the hypothesis that prenatal estrogens may play a role in the development of human sexual orientation.
The bed nucleus of the stria terminalis (BST) in the rat forebrain differs between males and females. To test whether apoptosis may contribute to the development of sex differences in the BST, the incidence of apoptosis was determined in sham-treated males and sham-treated females sacrificed on postnatal days (PN) 2, 4, 6, 8, 10, and 12 (PN 1 being day of birth). More apoptotic nuclei were found in the principal nucleus of the BST (BSTpr) in females than in males, whereas the reverse was true for the lateral division of the BST (BSTI). Moreover, the volume of the BSTpr was larger in males than in females, whereas there was no sex difference in the volume of the BSTI. Our results also confirmed earlier reports indicating that the incidence of apoptosis in the central part of the medial preoptic nucleus (MPNc) is higher in females than in males. No sex difference in apoptosis was found in the ventromedial hypothalamus (VMH) and paraventricular nucleus (PVN). The volume of the MPNc and VMH was larger in males than in females, whereas the PVN volume did not differ between males and females. To test whether sex differences in neonatal levels of gonadal steroids may cause sex differences in the incidence of apoptosis in the BSTpr, the incidence of apoptosis was compared between castrated males and females that were treated with testosterone propionate or vehicle on the day of birth. In the BSTpr of gonadal steroid-treated animals, the incidence of apoptosis was lower when compared to animals treated with vehicle, which was also true for the MPNc. These results are consistent with the hypothesis that gonadal steroids contribute to the sexually dimorphic differentiation of the BST by controlling the incidence of apoptosis.
Several lines of evidence have implicated genetic factors in homosexuality. The most compelling observation has been the report
of genetic linkage of male homosexuality to microsatellite markers on the X chromosome. This observation warranted further
study and confirmation. Sharing of alleles at position Xq28 was studied in 52 gay male sibling pairs from Canadian families.
Four markers at Xq28 were analyzed (DXS1113, BGN, Factor 8, and DXS1108). Allele and haplotype sharing for these markers was
not increased over expectation. These results do not support an X-linked gene underlying male homosexuality.
Estradiol provides physiological signals to the brain throughout life that are indispensable for the development and regulation of reproductive function. In addition to its multiple physiological actions, we have shown that estradiol is also selectively cytotoxic to beta-endorphin neurons in the hypothalamic arcuate nucleus. The mechanism underlying this neurotoxic action appears to involve the conversion of estradiol to catechol estrogen and subsequent oxidation to o-semiquinone free radicals. The estradiol-induced loss of beta-endorphin neurons engenders a compensatory increment in mu opioid binding in the medial preoptic area rendering this region supersensitive to residual beta-endorphin or to other endogenous opioids. The consequent persistent opioid inhibition results in a cascade of neuroendocrine deficits that are ultimately expressed as a chronically attenuated plasma LH pattern to which the ovaries respond by becoming anovulatory and polycystic. This neurotoxic action of estradiol may contribute to a number of reproductive disorders in humans and in animals in which aberrant hypothalamic function is a major component.
Background:
It has been postulated that schizophrenia represents a disorder of anomalous cerebral lateralization. This study is a replication of earlier preliminary findings using a multichannel neuromagnetometer, suggesting altered lateralization in schizophrenia in male subjects, with an extension of the findings to female subjects.
Methods:
We used magnetoencephalography-based magnetic source imaging to estimate the intracranial location of the 100-millisecond latency auditory-evoked field component (M100) in both left and right hemispheres of 20 patients with paranoid schizophrenia and 20 controls without schizophrenia. Neuroanatomical data were obtained by means of magnetic resonance imaging, from which we segmented and computed volumes of both total brain and left and right superior temporal gyri.
Results:
Locations of M100 source were compatible with neuronal generators located in the transverse gyri of Heschl on the superior temporal gyri in both study groups; M100 sources were asymmetric in all the control subjects. The male patient subgroup exhibited significantly less asymmetry than the control group, while the female patient subgroup actually showed significantly more asymmetry. The male patient subgroup generally had smaller superior temporal gyri than the control group. No evidence of total brain volume differences was observed.
Conclusions:
Our findings support previous magnetoencephalography-based studies suggesting anomalous cerebral lateralization in schizophrenia. Further, in extending our studies to female patients, our data suggest that the nature of this anomaly is sex specific, a finding that, to our knowledge, has not previously been reported.
We recruited 51 predominantly homosexual and 50 predominantly heterosexual men as index subjects for a family study of sexual orientation. The sexual orientation of siblings (115 sisters and 123 brothers) was ascertained in two ways: via interview with the index subjects and via interview of and/or mailed questionnaire to the siblings themselves. Index subjects' knowledge of the sexual orientation of their siblings was, for the most part, quite accurate. Moreover, heterosexual index men had about as many homosexual brothers as would be predicted given national prevalence figures for homosexuality, but homosexual index men had about four times as many homosexual brothers, although in both cases most brothers were heterosexual. There was no significant difference between the index groups in number of homosexual sisters. We conclude that there is a significant familial component to male homosexuality.
Homosexuality presents a paradox for evolutionists who explore the adaptedness of human behavior. If adaptedness is measured by reproductive success and if homosexual behavior is nonreproductive, how has it come about? Three adaptationist hypotheses are reviewed here and compared with the anthropological literature. There is little evidence that lineages gain reproductive advantage through offspring care provided by homosexual members. Therefore, there is little support for the hypothesis that homosexuality evolved by kin selection. Parents at times control children’s reproductive decisions and at times encourage children in homosexual behavior. There is therefore more support for the hypothesis of parental manipulation. Support is strongest, however, for the hypothesis that homosexual behavior comes from individual selection for reciprocal altruism. Same‐sex alliances have reproductive advantages, and sexual behavior at times maintains these alliances. Nonhuman primates, including the apes, use homosexual behavior in same‐sex alliances, and such alliances appear to have been key in the expanded distribution of human ancestors during the Pleistocene. Homosexual emotion and behavior are, in part, emergent qualities of the human propensity for same‐sex affiliation. Adaptationist explanations do not fully explain sexual behavior in humans, however; social and historical factors also play strong roles.
Sexual orientation is a complex trait that is probably shaped by many different factors, including multiple genes, biological, environmental, and sociocultural influences. In a 1993 report, my group ([1][1]) provided initial evidence that a locus at the q28 region of the X chromosome was involved in
This study used computer-generated (“virtual”) mazes to investigate sex differences in the efficiency of spatial route learning in humans. Correlations between maze performance and traditional psychometric measures of spatial ability also were examined. Male and female subjects completed a total of five learning trials on each of two spatial mazes and completed a battery of spatial and verbal cognitive tests. As well as demonstrating the typical male advantage on psychometric measures of spatial performance, robust sex differences favoring males were found for both the time required to solve the mazes (d = 1.59) and the number of spatial memory errors committed ( d = 1.40). Highly significant positive correlations were obtained between scores on the paper and pencil tests and performance on the maze task. The results of the present study are consistent with results from studies in other mammalian species suggesting a male advantage for spatial navigation through a novel environment.
We recruited two groups of women who differed in their number of lifetime sex partners in order to investigate several hypotheses related to female sociosexuality. Specifically, we explored whether women who engage in casual sex have low mate value, are especially likely to have come from stressful family environments, or are masculine in other respects besides their interest in casual sex. Women with many partners were not lower than other women on direct or indirect indicators of mate value. Nor were they more likely to recall adverse family environments during childhood. On several measures related to masculinity, women with many sex partners were elevated compared with other women.
Questions the findings of D. H. Hamer et al (see record
1994-01544-001) linking male sexual orientation with a region of chromosome Xq28. Scientific evidence is discussed and inconsistencies highlighted to suggest that this finding should be interpreted cautiously. Results are said to include undetermined sample biases, not to be consistent with any genetic model, and not free from assumptions. The authors assert that there are pitfalls in applying standards derived for Mendelian traits to complex ones. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Of several hypotheses proposed by sociobiologists to explain "homosexuality," the most widely discussed is the inclusive fitness hypothesis, which is exmained here in the work of the primary sociobiological proponents, E.O. Wilson, Michael Ruse, and James Weinrigh. After reviewing the basic evolutionary concepts of natural selection, adaptation, and inclusive fitness/kin selection, I analyze the inclusive fitness hypothesis of homosexuality, taking as an examplar the initial statement of E.O. Wilson. The implicit assumptions in this hypothesis are identified: that "homosexuality" is a unitary phenomenon, of direct genetic origin, occurring at similar frequencies across societies and through time, without direct reproductive gain, which therefore must be of genetic advantage to relatives. Each of these implicit assumptions is discussed and assessed in turn. The inclusive fitness hypothesis, derived primarily from current stereotypes about homosexuals in Western society, is found to be misconceived and without scientific merit. A general discussion of the nature-nurture, or essentialist-social-construcitonist, controversy as it involves this hypothesis concludes the essay.
There appears to be sufficient evidence that paraphilia, or the tendency to substitute reproductively non-significant sexual goals for a mate of the opposite sex, is sufficiently widespread in human populations, involves sufficiently lowered fertility and is under enough genetic control to affect the distribution of genotypes in such human populations as have been well studied. Psychoanalytic theory suggests that the most probable mode of operation of the genetic determinants is on the rates of development of neuro-psychological mechanisms involved in identification processes and other aspects of object relationship in infancy. As such, they may have pleiotropic effects of importance. A consideration of fetichism suggests that certain aspects of sexual selection in man may involve mechanisms neutralizing castration fear, and so may ultimately influence such maturation rates. The type of display involved, which seems different from ordinary epigamic display in the lower animals, is designated cryptandric.
This study was designed to test the hypothesis that prenatal environment contributes to the development of sexual orientation in females. The research involved a dermatoglyphic analysis of finger ridge count in two groups of female monozygotic twins: a study group which was discordant for sexual orientation, and a control group which was concordant for sexual orientation. The trait, total finger ridge count, was analyzed using the Wilcoxon matched pair statistic. In the female control group ridge counts were not significantly different. However, for the female twins discordant for sexual orientation, the null hypothesis was rejected (T = 0; p ≤ .01), with the lesbian twins showing a consistent trend for lower total finger ridge counts than their heterosexual cotwins. It is concluded that in females, prenatal environmental differences are correlated with differences in sexual orientation, and that second trimester prenatal environment is likely to be a contributing factor in the etiology of this trait.
Findings that implicate biological mechanisms in the etiology of homosexuality provoke a wide range of reactions concerning their ethical, legal, and policy ramifications. However, the mere fact of biological causation can have no implications which are not true of all behavior, because all behavior is biologically (specifically, neurophysiologically) caused at the most proximate level of explanation. Notwithstanding this conclusion, a particular type of biological causation that is not characteristic of all behavior could, in principle, have ethical, legal, or policy implications. We explore alternative senses in which homosexuality might be considered to be biological, including “innate” and “immutable,” and show that “innate” explanations, at least, have some limited (though important) policy implications. More generally, however, we conclude that inferring ethical, legal, or policy consequences from etiological knowledge is much less straightforward than typically assumed.
tinct and significant studies have pointed to the age of 10 as the mean age of first sexual attrac tion?well before puberty, which is typically defined as the age when the capacity to procreate is attained (Timiras, 1972). These findings are at odds with previous
Gallup (1995) argued that there has been selection for parents to counter any social process that would increase the likelihood of one of their children becoming homosexual, and he indicated that contact between adult homosexuals and children was such a process. He therefore predicted (and found) that homophobia would be exaggerated where there was perceived contact with children. In this commentary, I argue that this hypothesis is based on supposing that sexual orientation occurs through a modeling process, when in fact it operates via an imprinting-like process. The specific findings regarding negative attitudes to homosexuals can be explained in terms of a more general evolved response, xenophobia. I argue that Gallup's hypothesis comes from a general willingness to view specific aspects of contemporary human behavior as adaptive when there are a number of reasons—all consistent with modern Darwinian thinking—why many of these are not themselves adaptive.
