The Sexual Evolution

The Sexual Evolution
Published : 5 Jun 2025 - Canongate

A perspective-altering and deeply researched journey through the history of sexuality and gender across the animal kingdom by forensic biologist and university professor Nathan H. Lents.

We find ourselves in a time of great social upheaval. People are testing the boundaries of just about everything related to sex and gender. Biological sex, long thought to be a simple binary, is now being understood as a spectrum. Gender is being uncoupled from sex and expanded to an astounding range of diversity. The traditional categories of sexual attraction are being supplanted by more creative labels. Where is this shift coming from? The answer may surprise you. Diverse sexual behaviour is not a new development, or even a human one. It didn’t emerge from recent progressive culture, it’s the product of billions of years of experimentation throughout the animal kingdom.

Evolutionary biologist Nathan H. Lents takes readers on a journey from silent crickets to lesbian albatrosses to bonobos who kiss, revealing what this incredible array of sexual diversity can teach us about our own. Amusing, enlightening and meticulously researched, Lents convincingly shows that diverse genders and sexuality have evolutionary functions far beyond procreation. THE SEXUAL EVOLUTION is a perspective-altering book that advocates understanding and demolishes biases held by even the most open-minded among us.

Reviews

At a time when diversity is fast becoming a dirty word, THE SEXUAL EVOLUTION provides a powerful argument about why diversity not only exists, but wins. Lents’ scholarly tome never lectures but guides the reader through a glorious array of gender and sexual diversity from across the animal kingdom, with authority and humour. An important addition to this important genre. My copy of this book will be read many times

Lucy Cooke, author of BITCH

A fascinating and important exploration of nature in all its rich, queer glory.

David Farrier, author of FOOTPRINTS and NATURE'S GENIUS

An unnaturally good book - funny, informative and refreshingly frank. THE SEXUAL EVOLUTION injects a timely splash of colour into a field increasingly polarised towards black and white. A must read

Ed Watkins, producer and director of QUEER PLANET

THE SEXUAL EVOLUTION is a thoughtfully and delightfully written book full of illuminating and entertaining information that will be new to most readers. At a time when ignorance and misinformation about sex, gender, reproduction and intimacy abound, we could all benefit from reading this research-packed tour

Science

Enthralling … Lents gleefully tears down cis, hetero and monogamous norms, outlining surprising case studies that give the lie to restrictive conceptions of gender and sex. The result is an indispensable glimpse into the queerness of animals.

Publishers Weekly

In this multi-layered exploration of gender biology, Nathan Lents takes us on a wonderfully thoughtful journey through some of today's most challenging scientific terrain. The result is a book that expertly balances the complexity of the issues and the compassion needed to navigate them

Deborah Blum, Pulitzer-prize winning author of THE POISON SQUAD

Read this book - it's fascinating, charming and eye-opening. It dispels misconceptions about life in the animal kingdom and our place in it, but most importantly it shows clearly that nature's beautiful sexual diversity extends to all living things

Joan Roughgarden, author of EVOLUTION'S RAINBOW and THE GENIAL GENE

A refreshing read that puts human sexuality in perspective without cultural dogma and indoctrination. With eye-opening stories of animal behaviour, Lents highlights the fundamental role of sexual diversity for all animals - including humans

Darrel Ray author of SEX AND GOD

An excellent, easy-to-read, science-based summary of what we know about the incredible array of sexual diversity among other animals. A fascinating and eye-opening book

Marc Bekoff, author of DOGS DEMYSTIFIED

An entertaining and informative romp through mating strategies in nature . . . Garter snake orgies, gender-masking hyenas, lusty bonobos and the lesbian Laysan albatrosses of Hawaii – this book has it all. All that diversity is fascinating, and frequently funny.

The Guardian

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