Bonk: The Curious Coupling of Science and Sex

Bonk: The Curious Coupling of Science and Sex (2008) is a work of narrative nonfiction by American science writer Mary Roach, whose previous bestsellers (Stiff: The Curious Lives of Human Cadavers and Spook: Science Tackles the Afterlife) tackle similarly sensitive topics. Known for blending humor, curiosity, and meticulous research, Roach approaches the science of sex with both intellectual seriousness and comedic irreverence. Bonk sits within the genre of popular science writing and examines the evolution of sex research from early physiological studies to modern laboratory and medical investigations. Drawing on interviews, archival research, and her own participation in sex-related experiments, Roach demystifies the scientific study of human arousal while challenging cultural discomfort around the subject. In addition, the text acknowledges the contributions of major researchers (including William Masters and Virginia Johnson, Alfred Kinsey, and Ahmed Shafik) whose work reshaped sex knowledge and public discourse.

This guide references the 2025 W. W. Norton e-book edition.

Content Warning: While Bonk maintains a light tone, it includes frank discussion of sexual acts, anatomical terms, and medical experiments, which may not be suitable for all readers. The source material and guide feature depictions of sexual stimulation and response.

Summary

Bonk begins by confronting the central paradox of sex research: While sex is one of humanity’s most common experiences, it remains one of science’s most awkward and stigmatized subjects. Roach opens with a historical survey of early researchers in the field of sexology, first introducing Alfred Kinsey, whose interviews in the mid-20th-century US shattered illusions of sexual conformity. However, as Roach explains, Kinsey’s work was based on self-reporting rather than direct physiological observation—a gap that later researchers attempted to fill.

The work of William Masters and Virginia Johnson in the 1950s and 1960s revolutionized sexual science through direct laboratory observation. Roach describes their controversial methods (monitoring couples engaged in sexual activity while measuring heart rate, respiration, and genital blood flow). Their landmark findings presented arousal as a measurable biological process rather than purely moral or emotional. However, their later endorsement of “conversion therapy” for gay clients complicates their legacy, reflecting the cultural and ethical influences on sex research.

Roach shifts to modern sexual physiology, exploring how contemporary researchers use advanced imaging and monitoring technologies to study arousal. She recounts experiments using MRI scanners to map genital blood flow and brain activation during sexual stimulation. One of the book’s recurring comic elements is Roach’s personal involvement: She voluntarily participated in several studies, including one in which she and her husband were observed inside an MRI machine during intercourse. Her participation underscores how the absurd nature of the field often pushes the limits of privacy and decorum.

Roach devotes several chapters to sexual response in women, exploring both historical neglect and modern breakthroughs. She examines the work of radiologist Ken Maravilla, whose MRI studies revealed that the clitoris, often misrepresented in anatomy, is far larger and more physiologically similar to the penis than previously recognized. She reports on her visit to Cindy Meston’s Female Sexual Psychophysiology Laboratory at the University of Texas, where scientists use devices like the vaginal photoplethysmograph to measure arousal through changes in vaginal blood flow. These experiments, Roach explains, illuminate the mismatch that often occurs between physical arousal and subjective desire, demonstrating that female sexuality resists simple quantification.

In exploring global approaches to sex research, Roach traveled to Cairo to meet Dr. Ahmed Shafik, a urologist famous for his eccentric but serious studies on sexual reflexes. Shafik’s experiments (which range from dressing rats in polyester pants to inflating balloon catheters inside the vagina) show both his willingness to test unusual ideas and the restrictive cultural conditions under which he works. Through Shafik, Roach illustrates how religious and political taboos shape the boundaries of scientific inquiry and how researchers must navigate censorship and risk to pursue knowledge.

Roach next examines hormones and animal behavior, particularly through the work of primatologist Kim Wallen at Emory University’s Yerkes National Primate Research Center. Observing rhesus monkeys, Wallen studies how hormonal fluctuations affect sexual motivation. Roach uses these observations to explain how human behavior, though filtered through social and emotional complexity, is still strongly influenced by biology. In addition, Roach highlights how hormonal contraceptives (especially birth control pills) alter libido by suppressing natural hormonal cycles.

Throughout Bonk, Roach explores the intersection of technology and sexuality, from medical devices like the Eros Clitoral Therapy Device (a suction-based arousal aid) to pharmaceutical efforts such as Viagra, bremelanotide, and flibanserin, sometimes referred to as “female Viagra.” She traces the often-disappointing outcomes of these drugs, revealing how female arousal depends on psychological and relational factors as much as on blood flow or hormones. Roach also addresses how pharmaceutical marketing has reshaped the public conversation about sexual “dysfunction,” blurring the line between medical treatment and consumer desire.

In the final chapters, Roach turns to Masters and Johnson’s later work, Homosexuality in Perspective (1979), which compared heterosexual and gay couples in laboratory studies. While much of their data focused on efficiency and performance, they discovered that committed gay and lesbian couples reported higher satisfaction—primarily because they took more time, communicated openly, and prioritized mutual pleasure. Roach uses this finding to suggest that “good sex” depends as much on empathy, attentiveness, and emotional connection as on technique or duration.

Roach concludes the book by reflecting on the persistence of mystery and humor in human sexuality. Despite decades of scientific progress, sex remains deeply personal, unpredictable, and resistant to full explanation. Bonk ultimately celebrates both the researchers who dared to study pleasure and the human capacity for curiosity itself. Through wit, candor, and empathy, Roach makes an often-taboo subject accessible and even funny, while still respecting the seriousness of scientific inquiry.