What's the Purpose of Human Female Orgasm?

Unlike male orgasm, which propels sperm into the female reproductive tract, female orgasm seems superfluous to human reproduction and, in fact, is difficult to achieve through penetrative intercourse. These authors ask, “What is female orgasm there for?”

Physiologically, many mammals can only reproduce during a limited season with specific environmental cues and conditions (e.g., daylight length, pheromones, copulation) and availability of a mate to induce ovulation. In humans, ovulation is spontaneous — reliant on a hormonal cycle independent of copulation or other cues — but may have originally been copulation-induced, as evidenced by the surges of prolactin and oxytocin that still accompany female orgasm. In mammals in which copulation-in…