At a time when political debates reduce human complexity to slogans, biologist Agustín Fuentes offers a fresh perspective. In his new book, Sex Is a Spectrum, he argues that sex is not a simple biological binary but a complex, fluid reality shaped by both genes and culture.
Fuentes, a respected biological anthropologist, tackles the controversy head-on. With clear reasoning and strong evidence, he dismantles the idea that “male” and “female” are fixed categories. Instead, he shows that nature thrives on variation—from sex-changing fish to hermaphroditic slugs. Humans, he argues, are no exception.
The book draws on genetics, fossils, and global cultural histories to paint a richer picture of sex. Traits like chromosomes, hormones, and anatomy don’t always fit neatly into binary boxes. What we call “male” or “female” are broad averages—not strict biological rules.
Fuentes also rethinks language. Moving beyond terms like “men” and “women,” he suggests a more flexible vocabulary that reflects scientific discoveries. The shift isn’t always easy, but it’s necessary—nature resists simplicity.
One powerful analogy compares sex differences to height. While men are generally taller than women, there’s significant overlap. The same applies to sex-related traits. By focusing on diversity rather than absolutes, Fuentes encourages curiosity and compassion.
Sex Is a Spectrum doesn’t deny differences—it celebrates them. It asks readers to embrace biology in all its complexity. More than just a book, it’s a new way to understand ourselves and each other.
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