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.