William C. Young’s scientific contributions

This chapter discusses the psychobiology of the sexual behavior in the guinea pig. When a female guinea pig is placed with a male, he begins to follow and circle her almost immediately, usually sniffing at the anogenital region. This behavior is called “nuzzling.” Within a few seconds he may mount her, usually posteriorly, but often elsewhere. Frequently, the mounting is accompanied by pelvic thrusts without intromission, but more commonly it is followed by intromission with or without pelvic thrusts. The duration of the pelvic thrusts varies, depending partly on the male and partly on the responsiveness of the female. Following ejaculation, both animals roll back on their haunches and lick the genitalia. The male can be seen to drag his butt along the floor of the cage somewhat like a dog infested with intestinal worms does. Unless the female with which copulation has occurred is replaced by another female ejaculation usually marks the end of any strong interest in the female. A behavior that is displayed by many males is a “nondirected hyper-excitability.” The frequency of this behavior is increased following castration of sexually experienced adult males and its frequency is much greater in intact males reared alone in which the organization of normal patterns has not been perfected.