The American physiologist Jared Diamond (author of the well-known book Guns, Germs and Steel) has written an intriguing book on the evolution of human sexuality, titled “Why Is Sex Fun?” That work examines the role of evolutionary biology in shaping human sexuality. In this episode, I’d like to pursue a related but perhaps somewhat broader topic: an examination of why intimacy is satisfying. That topic includes sex as a source of human pleasure, but it goes beyond that to also in...