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The Thornhill and Palmer Affair: When Evolutionary Biology Challenged Rape Orthodoxy

For their research showing that rape is generally motivated by sexual desire, Randy Thornhill and Craig Palmer were subjected to death threats and hounded in their personal and professional lives. And yet, they were right.

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Zoe Booth, Peggy Sastre
· 8 min read
Classical painting depicting a mythological scene of abduction and coercion, used here as historical illustration rather than endorsement.
Detail of The Rape of the Daughters of Leucippus by Peter Paul Rubens and Jan Wildens. 1618, Oil on canvas.

Based on an essay by Peggy Satre, presented by Zoe Booth.

In the late 1990s, biologist Randy Thornhill and anthropologist Craig Palmer became the focus of one of the most ferocious academic backlashes of the modern era. Their offence was not fraud, provocation, or moral advocacy, but the claim that rape is, at least in part, a sexual act shaped by evolutionary pressures. That argument—developed most fully in their book A Natural History of Rape—was widely treated as morally intolerable, regardless of whether it was empirically defensible.

This video essay reconstructs what came to be known as “the Thornhill and Palmer affair”: the threats, protests, professional sanctions, and personal devastation that followed their work. Drawing on court cases, media reporting, and first-hand testimony, it shows how a scientific dispute was reframed as a moral emergency, in which ideas were condemned not for being wrong but for being deemed dangerous. The episode also illustrates how theories denying any sexual motivation in rape migrated from academia into the legal system, with troubling consequences for victims, justice, and academic freedom alike.

View full transcript Randy Thornhill stopped answering his phone. When you called, you'd hear a police sheriff's voice warning that the line was under surveillance—a bluff designed to stop the death threats flooding in. Meanwhile, 700 kilometers away, anthropologist Craig Palmer started each day checking under his car for bombs. He'd then take a different route to campus, following law enforcement recommendations, all because he and Thornhill had argued that rape is a sexual act. This became known as "the Thornhill and Palmer affair"—a textbook academic witch hunt. Journalist Jonathan Rauch called it a "humanitarian threat" response, where academic work gets condemned not for being wrong, but for the harm it might supposedly cause. Thornhill and Palmer didn't excuse rapists or absolve anyone. They simply argued that sexual violence has biological components, and ignoring this fact means misunderstanding rape and potentially harming victims. The backlash was immediate and brutal. There were hit pieces, bad-faith interpretations, insults, and threats serious enough to require police protection. Of the two researchers, Palmer was already familiar with academic hostility. In the mid-1980s, as a young PhD student, he'd abandoned his anthropology doctorate when postmodernism swept through academia. As he later told historian Alice Dreger, it didn't seem worth doing rigorous science only to have someone dismiss it by saying, "that's just your narrative." So Palmer left Arizona, moved to Maine, got married, and became a lobster fisherman. But a tragic event pulled him back. His neighbor's daughter was abducted, and the suspect quickly confessed to raping and murdering her. Yet the local press kept saying the attacker's motivations were unknown. To Palmer, this was absurd—refusing to acknowledge a rape and murder as a sexual crime gone horribly wrong. Then Palmer got a call from the Arizona Attorney General's office. The prosecutor was preparing for the trial and needed witnesses who'd seen angry interactions between the victim and the accused. Palmer had nothing to offer, but he asked a simple question: couldn't they just argue the man was sexually attracted to the girl and knew she'd never consent willingly? In other words, wasn't the sexual motive obvious, with murder committed to cover up the crime? The prosecutor explained that the defense had cited scientists who supposedly proved rape isn't sexually motivated. Instead, they claimed it's about violence, control, or power—and now the prosecution had to establish that specific motive. Palmer was furious. How could poorly supported theories potentially let a rapist and murderer escape justice? He remembered telling his thesis advisor that if he returned to academia, challenging the claim that rape isn't sexual might be worth it. With his wife's permission, Palmer converted his resignation into a sabbatical and came back to finish his doctorate. His research on sexual coercion led him to entomologist Randy Thornhill. Thornhill studied scorpionflies—insects where males have two mating strategies: offering gifts to seduce females, or forcing copulation. Here's where it gets interesting—male scorpionflies have a specialized organ for forced mating. It's like a pincer that holds the female down and prevents escape, and it seems to serve no other purpose. Thornhill proved this by covering the organ with beeswax—suddenly, males couldn't rape anymore. But here's the key: females clearly prefer males who bring gifts, and males themselves only resort to force when they can't find a suitable present. Thornhill and Palmer knew the obvious differences between humans and insects. No man seduces women with petrified saliva, and humans don't have specialized rape organs. But at a fundamental level, human sexuality is also a product of evolution. So using evolutionary biology to understand human rape wasn't completely unreasonable. The two published several studies through the 1990s. Then in 2000, they released an article called "Why Men Rape?" followed by their book, "A Natural History of Rape." The book presented two hypotheses. Palmer saw rape as a byproduct of indiscriminate male sexuality, while Thornhill considered it might also be a last-resort reproductive strategy. Without choosing between these theories, they cataloged sexual violence across species from the perpetrator's perspective. They argued that victim appearance matters to rapists, that rape is primarily sexual and only sometimes about domination, and that reproductive biology plays a role. They emphasized repeatedly that understanding why men rape never excuses or justifies it. But their explanations didn't matter—things were about to explode. Palmer remembered their first meeting at MIT Press expecting to discuss marketing. Instead, they walked into a room packed with fifty or sixty hostile people demanding the book not be published. When the book came out in January, chaos erupted. Palmer first learned about it when an old friend told him Rush Limbaugh was ranting about their work on his radio show. The pattern was always the same: attribute statements to them they never made, then condemn them for it. Time magazine suggested they trivialized victim suffering, when the book actually emphasized it deeply. The headlines wrote themselves: "Can't Help It Theory," "The Men Can't Help It," "Are Men Natural-Born Rapists?" The narrative was clear—if rape is biological, men must be powerless against it. Then came the academic death blow. In 2004, biologist Joan Roughgarden wrote in a prestigious journal that Thornhill and Palmer were "guilty of all allegations" and "deserve to hang." She urged readers to boycott their seminars and labs. This wasn't academic debate—it was a punitive campaign calling for organized activism against "junk science." Lectures were disrupted, talks were canceled, protests erupted on their campuses. Publishers faced harassment campaigns to make them disown the authors. Palmer learned the legal distinction between official death threats and regular hate mail. Thornhill's marriage ended in divorce, and Palmer slipped into chronic depression. As Palmer told Dreger, the experience taught him how humans can form lynch mobs and commit genocide. He wasn't sure he wanted that knowledge about his own species. So where did this rage come from? Psychologist Steven Pinker explained they'd threatened a consensus held for twenty-five years—the "blank slate" ideology that all behavior comes from upbringing and socialization. This ideology sees nature as good, so anything natural must be good. Since sexuality is natural and rape is harmful, rape supposedly can't be natural or sexual—it must stem from social institutions. According to this logic, rape is about power and control—anything except desire. This ignores the obvious fact that most rapes are committed with erect penises. But not everyone condemned them. Some rape survivors expressed relief that someone finally acknowledged their attackers had sought sexual gratification. Elizabeth Eckstein, a rape survivor, wrote an entire op-ed supporting their work. She described surviving aggravated sexual assault and the exhausting trauma that followed, including an obsessive need to understand why. She hated when people quoted experts saying "it's violence, not sex" or "it's about control." As she put it: "He didn't force me to break dishes—he made me have sex with him at gunpoint. Sex, people, sex." Jennifer Beeman, director of a campus violence prevention program, told the Boston Herald she hoped their work would prompt reexamination of assumptions. After years of saying "it's about power, not sex," maybe people were afraid to admit it might be both. Twenty-five years later, the controversy hasn't died. Peggy Sastre, a French journalist and author who writes about evolutionary biology and human sexuality, has faced similar attacks for following in Thornhill and Palmer's footsteps. In 2022, Sciences Po in France canceled an approved elective course Sastre was supposed to teach on their Reims campus. The cancellation came less than a month before classes were scheduled to begin, based on accusations of rape apologia. The Thornhill and Palmer affair is a cautionary tale. Two researchers challenged orthodoxy and found themselves in a world where rumor counts as proof and false accusations matter more than actual arguments. What's most troubling is how easily a truth-seeking community became an inquisitorial tribunal. Instead of refuting ideas scientifically, they destroyed them through fear—fear of offending, of dissenting, of becoming the next target. The threat to academic freedom doesn't only come from religious or political authorities. More often, it comes from within—from the thought police among our own colleagues. In the name of noble causes, the "kindly inquisitors" have turned universities into places where you learn how to stay quiet. Knowledge takes a backseat to keeping your head down. The rot runs deep. And the Thornhill and Palmer affair shows us exactly how deep it goes. This video was based on an essay by Peggy Sastre, a columnist and translator for Le Point, where this piece was first published in French on August 16, 2025. It was later translated into English for Quillette by Iona Italia. Peggy holds a PhD in the philosophy of science and has long focused on evolutionary and biological perspectives on sex and gender—positions that, much like those of Thornhill and Palmer, have earned her more than a few ideological enemies. In many ways, her own academic experiences mirror the story she tells—one of intellectual courage in the face of institutional hostility. If you found this story compelling, controversial, or just thought-provoking, consider giving it a like and subscribing for more deep-dive essays. And share it with someone who still believes that all academic debate is safe and civilized.

Chapters

00:00 — Thornhill and Palmer argue rape is a sexual act
01:11 — Palmer leaves academia amid postmodernism
01:37 — A murder case and the problem of motive
02:04 — When ideology enters the courtroom
02:59 — Evolutionary biology and sexual coercion
03:42 — Applying evolutionary reasoning to humans
04:06 — A Natural History of Rape and its hypotheses
05:01 — Media distortion and public outrage
05:56 — Calls for boycotts and academic punishment
06:09 — Personal consequences of the backlash
06:37 — The blank slate and rejection of biology
07:05 — Support from rape survivors
08:12 — A contemporary parallel in France
08:41 — Academia as inquisitorial culture

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