Sexual Performance Index of Male Rhesus Monkeys

ALTHOUGH information about ejaculation in infra-primate mammals is available1–4, quantitative data are lacking for most primates. Field studies5–6 have provided the basic information on the copulatory sequences of behaviour of adult rhesus monkeys; findings which have recently been confirmed in the laboratory7. The present investigation is concerned with a particular aspect of sexual behaviour: namely, the relation between mounting and thrusting activity on one hand and the timing of ejaculation on the other.