The Intimate Animal: The Science of Sex, Fidelity, and Why We Live and Die for Love
Justin R. Garcia, 2026
The most expensive service at a legal brothel in Nevada turned out to be the “Girlfriend Experience” at $20,000, and sex wasn't necessarily part of it. The executive director of the Kinsey Institute explains why our need for intimacy lives apart from sexual desire and can be stronger than it, and how the tension between the two gives rise to both happiness and infidelity. You'll learn how to choose a partner, get through a breakup and keep passion alive for years.
Who it is for
For anyone in a relationship who feels something is missing, anyone looking for a partner on dating apps, and anyone going through a breakup. And for everyone curious why love and sex so often pull in different directions.
It's possible to fall out of love, it's okay to grieve that loss, and it's in our nature as the intimate animal to learn a new song and love again.
The most expensive service, and sex isn't necessarily included
In the Nevada desert, an hour's drive from Las Vegas, lies the town of Pahrump with its two legal brothels. Justin Garcia went there with colleagues in the name of science: to study the workers and the clients. Their guide led them to the menu of services. The most expensive line, starting at $20,000, was the “White Whale,” the full “Girlfriend Experience.” Sex wasn't necessarily part of it. Instead, she said, the client could expect a cuddle he would never forget.
The most expensive thing you could buy in a brothel might not involve sex at all. What people were buying was intimacy: the feeling of being seen, heard and known.
Garcia is an evolutionary biologist, the eighth and youngest director in the history of the Kinsey Institute, and a scientific adviser to the dating service Match. Together with the late Helen Fisher, he spent many years running Singles in America, a study of single Americans. His central idea: our longing for intimacy is separate from sexual desire, and it's stronger than we've been taught to think. Humans are built to live in committed couples, usually one at a time. Scientists have a name for this: social monogamy. But sexual fidelity to one person isn't necessarily built into us. Out of this tension grow both the best and the most painful moments of love.
It also explains our times. In the US almost 40% of adults are single, roughly one in four people in the world feels lonely at any given moment, and loneliness is growing even among people in relationships. Ahead: why the brain gets confused on dating apps, what drives people to cheat, why a breakup feels like withdrawal, and how passion survives for decades. If you've ever wondered why you can feel lonely next to someone, you're already looking at your life more honestly than many people do. Let's begin.
Sex and intimacy live separately in the brain, and they may not line up
On a flight to Vancouver, Garcia got talking to the woman in the next seat. Her name was Ginny. A few years earlier her mother had been diagnosed with Alzheimer's disease, and for a long time Ginny couldn't climb out of depression, until she started going dancing in the evenings. When the conversation turned to her tenth wedding anniversary, Ginny sighed. She loved her husband, but more and more they were living parallel lives, and she could no longer remember the last time they had had sex.
There is love, and yet something essential is missing. Garcia explains it like this: what we experience as one strong feeling is assembled in the brain from parts. Studies using fMRI, a scan that shows which areas of the brain are working harder, find several systems at work in romantic intimacy at once: attachment, reward and sexual desire. When they switch on together, a person feels warmth, understanding and safety. But these parts can also work on their own. You can enjoy sex, friendship or trust, and none of it will add up to intimacy.
Picture a chord on a piano. Each note sounds on its own, but you only hear the chord when the keys are pressed together. For Ginny and her husband, the notes of shared life and attachment still sound, but the note of desire went silent long ago.
It can work the other way too. A friend of Garcia's broke up with his boyfriend but kept having “slumber parties” with him for months: they slept in the same bed and cuddled during movies, though nothing sexual happened between them anymore. It fed their hunger for intimacy but kept them from starting new relationships. Garcia stresses the difference: sexual tension is relatively easy to release, while intimacy brings a different, rarer flood of hormones, and it's harder to find.
Hence the first step, which Garcia sees as the start of everything: work out exactly what you're missing. Desire, trust, conversation or touch? In one national survey by his team, more than a third of Americans in couples said their partner doesn't touch them enough. Sometimes it's worth starting not with a big talk but with a hand on the shoulder.
About the author
Justin R. Garcia is an evolutionary biologist, executive director of the Kinsey Institute at Indiana University and chief scientific adviser to Match, for which he leads the annual Singles in America study.
All books by this author: Justin R. Garcia
Terms from the book
- Fisher
- Ginny
- Aron
- Companionate love
- Dave
- Pahrump: A small town in the Nevada desert, about an hour's drive from Las Vegas, known for its two legal brothels.
- Kinsey: Alfred Kinsey, the American biologist often called the grandfather of Western sexology. The Kinsey Institute at Indiana University was founded in 1947 and studies sex, love and relationships; Garcia has led it since 2019.
- Match: An American online dating company, the owner of the Match.com website and app.
- Singles in America: An annual study of single adults in the US that Match has run together with scientists since 2010.
- Social monogamy: Living as a committed couple, usually with one partner at a time, sharing a home and caring for children together. It doesn't necessarily mean sexual fidelity.
- Alzheimer's disease: An incurable brain disease in which memory and thinking are gradually destroyed.
- fMRI: Functional magnetic resonance imaging: a scan that uses the flow of oxygen-rich blood to show which areas of the brain are working harder.
- Conroy-Beam: Daniel Conroy-Beam, an American psychologist who studies how people choose their partners.
- Misattribution of arousal: An effect in which a person credits the excitement of fear or novelty not to its real cause but, for example, to whoever happens to be nearby.
- Dutton: Donald Dutton, a Canadian psychologist and co-author of the 1974 experiment with the shaky suspension bridge.
- Catron: Mandy Len Catron, a writer. In a 2015 New York Times column she described going through Aron's 36 questions and falling in love.
- Slow love: Helen Fisher's term: today's singles take longer to get to know a partner and commit to relationships and marriage later.
- Hrdy: Sarah Blaffer Hrdy, an American anthropologist who studies the role of mothers and shared child rearing in human evolution.
- Pair bond: A lasting emotional bond between two individuals who live and act as a couple. Biologists use the term for what we call romantic attachment in humans.
- Coolidge effect: A phenomenon in biology: a new partner can restore a male's readiness to mate more quickly. It's named after an anecdote about US President Calvin Coolidge.
- DRD4: The gene for the dopamine D4 receptor. Its long variant has been linked to seeking novelty and risk.
- Selterman: Dylan Selterman, an American psychologist who studies relationships, and Garcia's co-author on a study of the motives for infidelity.
- Gibbons: Small apes of Southeast Asia. Apart from humans, they are the only apes that live in pairs.
- Jen: Garcia's only cousin. She fought brain cancer for thirteen years.
- Holt-Lunstad: Julianne Holt-Lunstad, an American psychologist who studies how our relationships with other people affect health and life expectancy.
All terms
Similar books
- The Montessori Method, Maria Montessori
- The Seven Principles for Making Marriage Work, John Gottman, Nan Silver
- Toxic Parents: Overcoming Their Hurtful Legacy and Reclaiming Your Life, Susan Forward, Craig Buck
- The Whole-Brain Child, Daniel J. Siegel, Tina Payne Bryson
- Why Does He Do That? Inside the Minds of Angry and Controlling Men, Lundy Bancroft
- Women Who Love Too Much, Robin Norwood
- The Language of Trust, Michael Maslansky
- The Let Them Theory, Mel Robbins
Read in Livria
