Transfer of [3H]estradiol-17β and [3H]progesterone from conspecifics to cohabiting female mice

Estradiol-17β (E2) and progesterone (P4) play critical roles in female reproductive physiology and behavior. Given the sensitivity of females to exogenous sources of these steroids, we examined the presence of E2 and P4 in conspecifics' excretions and the transfer of excreted steroids between conspecifics. We paired individual adult female mice with a stimulus male or female conspecific given daily injections of [3H]E2 or [3H]P4. Following 48 h of direct interaction with the stimulus animal, we measured radioactivity in the uterus, ovaries, muscle, olfactory bulbs, mesencephalon and diencephalon (MC+DC), and cerebral cortex of the untreated female cohabitant. Radioactivity was significantly present in all tissues of female subjects after individual exposure to a stimulus male or female given [3H]E2. In females exposed to males given [3H]P4, radioactivity was significantly present in the uterus, ovaries, and muscle, but not in other tissues. In females exposed to stimulus females given [3H]P4, radioactivity was significantly present in all tissues except the MC+DC. In mice directly administered [3H]steroids, greater radioactivity was found in the urine of females than of males. Among females directly administered [3H]steroids, greater radioactivity was found in urine of those given [3H]P4 than of those given [3H]E2. When females were administered unlabeled E2 before exposure to [3H]E2-treated females, less radioactivity was detected in most tissues than was detected in the tissues of untreated females exposed to [3H]E2-treated females. We suggest that steroid transfer among individuals has implications for the understanding of various forms of pheromonal activity.

Behavioural cues in sex recognition by two species of nocturnal lizards: Eublepharis macularius and Paroedura pictus

Although several senses are used in agonistic and sexual behaviours by Eublepharis macularius and Paroedura pictus, different cues do not have the same relative value for males of the two species. Behavioural patterns observed in the presence of anesthetized conspecifics of both sexes differed considerably. The agonistic and sexual behaviours of E. macularius underwent progressive changes in reaction time and the frequency and duration of other behaviours. Aggressive behaviour eventually almost completely disappeared in P. pictus and was replaced by sexual behaviour, whatever the sex of the stimulus-animal ; the lizards then appeared to be incapable of distinguishing males from females. Agonistic behaviour of both species was sensitive to the immobility of the conspecific, although to different degrees. These data concur with observations carried out under more natural conditions; sex recognition criteria differ between the species. E. macularius relies primarily on chemical signals for sex recognition and sex-related behaviours. In P. pictus, which depends primarily on visual signals, conspecific posture and behaviour are the main factors responsible for both sexual and agonistic reactions.

Pairwise Dominance and Social Preference in Squirrel Monkeys

5 male and 5 female squirrel monkeys, previously dominance tested, were observed in a noncompetitive social preference situation. Following nonsocial adaptation trials, all possible pairs of monkeys were observed, one pairmate serving as S and the other as a stimulus animal in a free-choice preference test. Ss' latencies to enter the apparatus and activity levels were greatly reduced by the addition of social partners. While social choices were largely uninfluenced by the dominance of the stimulus animal, the sex of the stimulus monkey proved to be an effective variable in that females elicited more approach behaviors than males. These results are consistent with previous studies of squirrel monkeys' preferences measured in noncompetitive social situations.

Personality in Monkeys: Factor Analyses of Rhesus Social Behaviour

Three factor analyses were performed on social interaction data from 168 juvenile macaques. Animals were tested in stable quadrad peer groups; in newly-formed dyads with infant, juvenile, and adult stimulus monkeys; and in similar triads with the stimulus animal plus a familiar cage-mate. Factors emerged, most strongly in the most stable condition, which were interpreted as affiliative, hostile and fearful. These factors were almost entirely independent and resembled the extraversion, psychoticism, and emotionality factors frequently found in humans.

Social Attachment in Rats By Odor and Age

The odor of rat litter-mates was experimentally modified from 3-10, 11-18, or 22-29 days of age. Acetophenone or ethyl benzoate were used during the experimental period and the natural odor was present during the other two periods. After living in the natural odor colony for another 2 weeks, Ss were compared on duration of time near each olfactory stimulus animal in an eight hour test. Ss preferred the stimulus animal characterized by the experimental odor with which they were reared. Age of exposure was not a significant factor. These results indicate that the odor of the species is learned, that the intensity of the odor is important, but that age is not a critical variable in the early learning of the species odor in the rat.