How Sex Works: Why We Look, Smell, Taste, Feel, and Act the Way We Do is a 2009 book by evolutionary biologist and New York Times bestselling author Sharon Moalem, published by HarperCollins.

[3][4] How Sex Works uses evolutionary biology to explore human sexuality, and how sexuality can influence society in terms of human relations and belief systems.

[5] Moalem arguest that menstruation, fertility, penis size, orgasm, ejaculation and contraception all have traces back to the "survival of the fittest" and the human desire to find a healthy partner for reproduction.

[6] The book covers other evolutionary factors influencing sexual attraction include pheremones, genetic makeup, immune system compatibility and ovulation.

[7] The book uses various examples to illustrate the author's central point, including:[1][2] Kirkus Reviews called the book "provocative and entertaining" describing it as "a volume stuffed with information that avoids getting bogged down in difficult medical terms or complex biological concepts.