Rhythmic Changes in the Copulatory Frequency of Rhesus Monkeys ( Macaca Mulatta ) in Relation to the Menstrual Cycle and a Comparison With the Human Cycle

Summary. The frequency of ejaculation in thirty-two pairs of rhesus monkeys studied during seventy-five menstrual cycles was significantly higher (P<0·001) in the follicular than in the luteal phase of the cycle: this pattern was closely similar to the changes in the incidence of sexual intercourse reported in a human population.