Experimental assessments of behavioral and anatomical components of female chacma baboon (Papio ursinus) sexual attractiveness.

Two experiments were carried out in order to separate the effects of the behavioral and the anatomical components of female sexual attractiveness in baboons. In the first experiment, two ovariectomized females were given increasing dosages of exogenous estradiol benzoate, and data were collected on their behavior as well as on male sexual arousal as assessed by the occurrence of coagulated seminal emissions of the type that result from masturbation. Male sexual arousal levels increased positively with the females' perineal swellings and appeared relatively unrelated to the females' behavior. In the second experiment, data were collected from five different groups of males in a systematic fashion across the period of a full menstrual cycle for their varied stimulus female partners. Behavior observations were carried out on the five different stimulus females, and ratings also were made of fluctuations in their perineal tumescence. The results of this experiment make it clear that male sexual arousal fluctuated across the study cycles in a fashion very similar to that of the perineal swellings of the stimulus females. Behavior was shown during all phases of the cycle, and, although it may have had a positive influence on male arousal during the follicular phase of the female's cycle, it had no apparent effect during the luteal phase. These results taken together establish for the first time that an estrogen stimulated female perineum per se has the potential to sexually arouse the male baboon. In addition, the data suggest that, although behavior may exert a positive effect on male arousal, in the absence of an estrogen stimulated perineum it is not sufficient to arouse males to masturbate. Finally the results establish that, although intact females appear to show behavior increases which may be arousing to males around the time of ovulation, these behaviors do not have to be shown by a female in order to arouse a male, provided she is swollen.

Testosterone propionate treatment of an XY gonadal dysgenetic chacma baboon.

Behavioral studies of an XY gonadal dysgenetic chacma baboon prior to and during testosterone propionate treatment were carried out. The orchidectomized dysgenetic individual, two intact males, a castrate male, and two ovariectomized females were pair-tested with a group of eight ovariectomized stimulus females prior to and during their treatment with estradiol benzoate. Three test series were carried out. One series occurred prior to any treatment of the agonadal focal subject animals. During this series it was only the intact males who showed behavior change during their testing with the estrogen treated females. A second test series occurred after a month of daily testosterone propionate injections (1 mg/kg/day) had been given to the four agonadal subjects. During this test series the castrate male ejaculated once with one of the estrogen-treated females. All of the treated subjects showed increases in their frequency of yawning. Upon completion of this test series the androgen dosage was increased (2 mg/kg/day) and 2 weeks later a third test series was carried out. During this series the castrate male ejaculated with five of his eight estrogen-treated partners. The yawning of all the treated subjects continued. As had been the case in the second series the XY gonadal dysgenetic individual continued to behave as did the ovariectomized females. None of these animals showed any increase in any measure of male sexual behavior. This study establishes the fact that a genetic male primate deprived of in utero exposure to testicular hormones will go on to develop as a normal genetic female and will fail to exhibit increased levels of male sexual behavior during androgen treatment.

Estradiol benzoate treatment of an XY gonadal dysgenetic chacma baboon.

Behavioral studies of an XY gonadal dysgenetic chacma baboon under estradiol benzoate treatment were carried out. The dysgenetic individual and two ovariectomized conspecific control females were given a total of three testing series. The dysgenetic individual showed progressive success in her sexual interactions with her male partners and during her third testing series she was copulated with to ejaculation by five of the eight male partners. This study provides the first supportive evidence from a nonhuman primate for the predicted development of female sexual behavior in a genetic male deprived of testes prior to the sensitive period for sexual differentiation.

The social interactions of adult conspecifics with an adult XY gonadal dysgenetic chacma baboon (Papio ursinus).

Two separate behavioral studies on an XY gonadal dysgenetic chacma baboon were carried out. In the first experiment the focal subject was treated identically as the control females by her adult male test partners. In contrast to the controls in this experiment the dysgenetic animal reciprocated the agonistic behaviors directed by the males toward her. In the second study intact and castrated males as well as ovariectomized females served as controls for the dysgenetic subject in tests with ovariectomized adult females. The stimulus females presented more to both classes of males than either the subject females or the gonadal dysgenetic individual, suggesting that the focal subject was treated by other female conspecifics as a female.

Influences of ovarian hormones on the food intake and feeding of captive and wild female chacma baboons (Papio ursinus).

The relationship between ovarian hormone changes and food intake was examined in three separate studies using captive intact, captive ovariectomized and wild intact chacma baboons (Papio ursinus). Measures of body weight, perineal turgescence and food intake all varied across the menstrual cycle for a group of seventeen intact laboratory housed females. Body weights showed steady increases up until the day of sex skin detumescence or breakdown. Perineal swell ratings also showed a constant rise ending with breakdown. Food intake, however, showed a pattern of decrease until three days preceding breakdown. Statistical analysis revealed a significant difference between food intake during the preovulatory and luteal period phases. Exogenous estradiol benzoate (EB) and progesterone treatments to a group of ten ovariectomized females demonstrated an inhibitory effect of EB upon food intake. No effects for progesterone were demonstrated. A field study of two wild troops confirmed a difference in percentage of time spent feeding for females in the fully swollen condition as contrasted to those whose perineums were flat. Data collected on fully swollen females suggested that consort relations had little effect upon the females' feeding time percentages.

Male chacma baboon (Papio ursinus) sexual arousal: mediation by visual cues from female conspecifics.

(1) The changes in masturbatory behavior for nine adult males exposed to, but not allowed to contact, naturally cycling stimulus females were quite similar to the changes in perineal swelling shown by these females. (2) Serum testosterone concentrations of seven adult males exposed to a cycling stimulus female were related to their masturbatory behavior, with high levels occurring during the females follicular phase, (3) Graded estradiol benzoate treatments of ovariectomized stimulus females revealed individual dosage levels below which there was no positive effect on the occurrence of visually stimulated male masturbation, (4) The present series of experiments documents the importance which visual cues have in the sexual interactions of this particular species.

Seasonal influences of births and male sex skin coloration in rhesus monkeys (macaca mulatta) in the southern hemisphere.

The annual distribution of births of rhesus monkey in zoos in the southern hemisphere and changes in sex skin coloration in one colony were examined. Most (79%) of the births occurred between October and January and the sex skin reached its greatest development during spring and early summer (i.e. at the time of mating). These results demonstrate a 6-month reversal from the breeding activity of rhesus monkeys in the northern hemisphere.

Diurnal variations in serum testosterone concentrations of captive adult male chacma baboons (Papio ursinus).

Captive adult male chacma baboons (Papio ursinus) housed with natural lighting exposure and blood sampled at 3-hr intervals showed significant diurnal variations in serum testosterone concentrations. Low mean concentrations were found at 0800 hr approximately 1 hr after sunrise and mean concentrations were their highest at 2000 hr approximately 1 » hr after sunset.