Human sexuality

• 1. Introduction

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  Human sexuality lacks a precise definition. It is a broad term that has varied across different historical contexts, touching biological, psychological, erotic, emotional, social, and spiritual feelings all at once. The Egyptian creation myth held that the sun god Atum masturbated in the water and created the Nile River. In Sumerian myth, the gods' semen filled the Tigris. These are the kinds of stories civilizations have always told to make sense of an impulse that increases when a person reaches puberty. The question of why people experience desire, and why they direct it the way they do, has drawn in mythmakers, doctors, colonizers, and clergy alike. What follows traces how the body responds, where sexual orientation comes from, who first dared to study it in a laboratory, and how power has tried to govern it.

• 2. The Roots Of Orientation

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  For sexual orientation, there is considerably more evidence supporting innate causes than learned ones, especially for males. The evidence includes a cross-cultural correlation between homosexuality and childhood gender nonconformity, moderate genetic influences in twin studies, prenatal hormonal effects on brain organization, and the fraternal birth order effect. In rare cases where infant males were raised as girls due to physical differences, they nevertheless turned out attracted to females. Cultures that are very tolerant of homosexuality do not show significantly higher rates of it. Homosexual behavior is relatively common among boys in British single-sex boarding schools. Yet adult Britons who attended such schools are no more likely to engage in homosexual behavior than those who did not. The Sambia people offer the most striking example. They ritually require their boys to engage in homosexual behavior during adolescence before they have any access to females, and most of these boys go on to lead heterosexual lives. A puzzle remains: why do genes linked to homosexuality persist in the gene pool? One hypothesis involves kin selection, the idea that homosexuals invest in relatives enough to offset reproducing less directly. Studies in Samoa have found some support, while Western studies have not. Another hypothesis points to sexually antagonistic genes, which cause homosexuality when expressed in males but increase reproduction when expressed in females.

• 3. How The Body Responds

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  The hypothalamus is the most important part of the brain for sexual functioning, a small area at the base of the brain that receives input from the limbic system. In lab animals, destroying certain areas of the hypothalamus eliminates sexual behavior. The hypothalamus sits just above the pituitary gland, which secretes the four important sexual hormones: oxytocin, prolactin, follicle-stimulating hormone, and luteinizing hormone. Oxytocin, sometimes called the love hormone, is released in both sexes during intercourse when an orgasm is achieved. It is also released in women during birth and breastfeeding, and has been suggested as critical to maintaining close relationships. The sexual response cycle was mapped by William Masters, a physician, and Virginia Johnson, a behavioral scientist. Their EPOR model breaks human sexual response into four phases: excitement, plateau, orgasm, and resolution. During orgasm, rhythmic contractions occur every 0.8 seconds. In the male resolution phase, a refractory rest period must pass before the cycle can begin again, and this period may increase with age. The female excitement phase can last from several minutes to several hours, marked by flushed skin, swelling of the clitoris, and the production of lubricating liquid by the vaginal walls.

• 4. Mapping The Anatomy

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  Unlike most other primates, male humans lack a penile bone. The penis consists of three parallel cylinders of spongy tissue that fill with blood during arousal to produce an erection. In the scrotum, the testicles are held away from the body, one possible reason being that sperm can be produced slightly below normal body temperature. Inside, several hundred seminiferous tubules produce millions of sperm daily. The clitoris develops from the same embryonic tissue as the penis. It or its glans alone holds as many nerve endings as the penis, sometimes more, and the clitoral glans has only one known function, sexual sensation. The ovaries, also developed from the same embryonic tissue as the testicles, store and develop ova. About 60,000 ova are present at birth, only 400 of which will mature during a woman's lifetime. The G-spot was named after Ernst Gräfenberg, who first reported it in 1950. It may lie in the front wall of the vagina, though various researchers dispute its structure, its existence, or regard it as an extension of the clitoris. The uterus usually tilts forward at a 90-degree angle, though in about 20 percent of women it tilts backwards. The vagina can expand to 10 centimeters during labor and delivery.

• 5. The First Researchers

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  Until Sigmund Freud published his Three Essays on the Theory of Sexuality in 1905, children were often regarded as asexual. Freud was among the first to take child sexuality seriously, proposing psychosexual development and the Oedipus complex. He described two currents of emotional life: an affectionate current of bonds with important people, and a sensual current that wishes to gratify sexual impulses. During adolescence, a young person tries to integrate the two. Alfred Kinsey initiated the modern era of sex research, first collecting data from questionnaires given to his students at Indiana University, then switching to personal interviews. He and his colleagues sampled 5,300 men and 5,940 women. He found that most people masturbated, that many engaged in oral sex, that women are capable of multiple orgasms, and that many men had had some homosexual experience. Masters and Johnson moved the work into the laboratory, directly observing and recording physical responses. They watched 10,000 episodes of sexual acts between 312 men and 382 women. They opened the first sex therapy clinic in 1965, and in 1970 described their methods in their book Human Sexual Inadequacy. Evelyn Hooker, through her research on heterosexual and homosexual men, revealed no correlation between homosexuality and psychological maladjustment. Her findings helped shift the scientific community away from the view that homosexuality needed to be cured.

• 6. Sexuality In History

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  Before the rise of agriculture, hunter-gatherers and nomadic groups lived under less restrictive sexual standards that emphasized pleasure, though with definite rules. Their art emphasized male sexuality and prowess while also blurring gender lines. Once agricultural societies emerged, the framework shifted in ways that persisted for many millennia across Asia, Africa, Europe, and parts of the Americas. Urbanization brought collective supervision of sexual behavior. Families often shared sleeping quarters, so children commonly witnessed parents having sex. Because land ownership made paternity important, family life became patriarchal, and these ideologies were used to control female sexuality. Before the High Middle Ages, homosexual acts appear to have been ignored or tolerated by the Christian church. During the 12th century, hostility toward homosexuality began to spread through religious and secular institutions, and by the end of the 19th century it was viewed as a pathology. The Industrial Revolution of the 18th and 19th centuries brought new artificial birth control devices such as the condom and diaphragm. Doctors claimed a new role in sexual matters, marriage began to be seen as being for love rather than only economics, and Japan adopted its first laws against homosexuality. Havelock Ellis argued homosexuality was inborn, not immoral, and not a disease, noting that many homosexuals made significant contributions to society.

• 7. Colonialism And Control

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  In 1516, Vasco Núñez de Balboa, a Spanish explorer, encountered indigenous people in Central America among whom several men dressed like women and had sex with each other. He fed forty of these men to his dogs for their non-gender-conforming behavior. European conquerors had discovered that many non-European cultures expressed sexuality and gender differently from European heterosexual cisnormativity. In America, 155 native tribes are recorded as having embraced two-spirit people, members who fall under a third gender category rather than male or female. Two-spirit people were commonly revered for special wisdom and spiritual powers, and could take part in monogamous or polygamous marriages. Colonizers perceived these relationships as homosexuality and used them to claim native moral inferiority, then imposed their own religious and social norms. The Religious Crime Code of the 1880s explicitly aimed to aggressively attack Native sexual and marriage practices, pushing native peoples toward Euro-American family ideals. Laura Stoler, in her book Carnal Knowledge and Imperial Power, investigated how Dutch colonists used sexual control and gender-specific sanctions to separate rulers from ruled in Indonesia. According to Joane Nagel, sexual meanings are constructed to maintain racial, ethnic, and national boundaries through the denigration of others.

• 8. Rights, Stigma, And Faith

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  In 1915, Emma Goldman and Margaret Sanger, leaders of the birth control movement, began spreading information about contraception in defiance of laws such as the Comstock Law. They argued the movement was about empowering women with reproductive and economic freedom, especially lower-class women who needed access most. Birth control began to lose stigma in 1936, when the ruling in U.S. v. One Package declared that prescribing contraception to protect a person's life or well-being was no longer illegal. By 1938 there were 347 birth control clinics in the United States, though advertising their services remained illegal. In 1981, doctors diagnosed the first reported cases of AIDS in America, a disease that disproportionately affected gay and bisexual men, especially black and Latino men. The Reagan administration was criticized for apathy, and press secretary Larry Speakes mocked the epidemic as the gay plague. Cardinal Krol called AIDS an act of vengeance against the sin of homosexuality. Activists pushed back: gay men from San Francisco and New York City created the Denver Principles, demanding the rights and dignity of people living with AIDS. Religious traditions remain divided. Judaism holds that sex within marriage is sacred and considers celibacy sinful, while a 2011 Pew Research Center study found that 84 percent of surveyed evangelical leaders believed homosexuality should be discouraged.