Age, Weight and Weight Gain in the Individual Pubertal Female Rhesus Monkey (Macaca mulatta)1

The relationship between age, body weight and weight gain at puberty (first perineal turgescence and menarche) in the normal untreated rhesus monkey was determined from a longitudinal growth study of seven individual rhesus, 30 individual rhesus previously studied by other investigators and a review of 50 years of reported similar observations on captive rhesus at puberty. There was evidence of a secular trend towards an earlier age of puberty in the rhesus. Puberty was found to be generally coincident with the onset of the adolescent weight spurt and is invariably present before the maximum rate of pubertal weight gain. Although the average weight at puberty in the present study was consistent with prior studies, average pubertal age varied, suggesting a constant critical “demographic weight” at varying ages of puberty. Nevertheless, examination of 37 individual sexually mature rhesus from three separate studies showed age and weight at puberty were positively correlated. These data suggest that positive correlation in the pubertal age-weight distributions found in rodents and domestic animals may also occur in higher primates. A major species difference distinguishing the human from a general mammalian pubertal age-weight pattern, found in the rhesus, raises theoretical questions regarding the role “critical body weight” plays in triggering puberty.