Why is Sex Fun? by Jared Diamond Summary

Why Is Sex Fun? examines human sexuality through an evolutionary lens, exploring bizarre traits like concealed ovulation, menopause, recreational sex, and monogamy. Jared Diamond analyzes how these behaviors differ from other mammals and shaped human survival strategies, blending anthropology, biology, and cultural insights to explain why our sexual practices evolved uniquely.

This book suits readers interested in evolutionary biology, anthropology, or human behavior. It’s ideal for those curious about science-based explanations for sexual norms, students of biology, and fans of Diamond’s accessible writing style. Casual readers seeking thought-provoking perspectives on intimacy’s role in human evolution will also find it engaging.

Yes—Diamond’s concise, engaging analysis bridges scientific rigor and readability. While short, it offers groundbreaking insights into human sexuality’s evolutionary quirks, making it a valuable read for anyone intrigued by biology, anthropology, or the origins of social behaviors. Critics note its title may mislead those expecting titillation, but it delivers intellectually stimulating content.

Diamond argues human sexuality defies evolutionary norms: concealed ovulation strengthened pair bonding, menopause allowed older women to support grandchildren, and recreational sex reinforced monogamy. These traits, absent in most mammals, evolved to ensure prolonged parental care and cooperative societies, giving humans survival advantages.

Menopause, rare in mammals, is framed as an evolutionary strategy: older women boost grandchildren’s survival by sharing resources and knowledge, rather than risking late-life pregnancies. This “grandmother hypothesis” suggests menopause enhanced human longevity and intergenerational cooperation, contributing to societal stability.

Unlike animals with obvious fertility signals, humans evolved concealed ovulation to keep mates constantly attentive. This encouraged monogamy and male investment in child-rearing, as men couldn’t predict optimal mating times. Diamond ties this to the development of long-term partnerships critical for raising dependent human offspring.

• “We are the ones who are bizarre”: Highlights humanity’s unique sexual traits compared to animals.
• “Recreational sex is the glue holding couples together”: Posits non-reproductive sex strengthens pair bonds for cooperative parenting.
• “Menopause is among the most bizarre features”: Emphasizes its evolutionary puzzle and role in grandparental care.

Unlike Guns, Germs, and Steel (broad historical analysis) or Collapse (societal failures), Why Is Sex Fun? zooms in on evolutionary biology. It retains Diamond’s interdisciplinary approach but focuses narrowly on sexuality’s role in human development, offering a specialist complement to his macro-scale works.

Critics argue the title feels clickbait-like for a scholarly text and that its brevity leaves some concepts underexplored. Others note Diamond’s hypotheses, while compelling, rely heavily on speculative evolutionary psychology without conclusive fossil or genetic evidence.

Monogamy, rare in mammals, is presented as an evolutionary adaptation: by sharing childcare, parents increased offspring survival. Diamond links this to concealed ovulation and recreational sex, which kept partners bonded long-term, ensuring stable environments for raising cognitively complex yet vulnerable human children.

Key unique traits include:

• Recreational sex: For pleasure, not just reproduction.
• Concealed ovulation: No visible fertility signals.
• Menopause: Cessation of fertility in later life.
• Co-parenting: Shared childcare between parents.

Diamond uses evolutionary principles to explain seemingly illogical traits: extended female receptivity fostered pair bonding, menopause optimized resource allocation for grandchildren, and male parental investment ensured offspring survival. These adaptations collectively enhanced human cooperative capacity and societal complexity.