Homo sapiens is one of the few species on earth that care if they're seen having sex. The impala is unconcerned. The dingo roundly flaunts it. A masturbating chimpanzee will stare straight at you. To any creature other than you and I and 6 billion other privacy-needing H. sapiens, sex is like peeling a mango or scratching your ear. It's just something you do sometimes.