Objectives:(1) To investigate sex differences in molar wear in known-age Cayo Santiago rhesus macaques (Macaca mulatta) and, (2) To explore sex differences in body weight and molar eruption timing as factors influencing sex differences in molar wear. Materials and methods: Data set I comprises wear scores, ages and body weights of 212 living monkeys included in the 1985 roundup. Data set II consists of molar wear measurements taken on 2D images of 103 of these monkeys' dental remains. Ordinal logistic regression was used to analyze the first data set. General linear models were used to analyze the second.Results: Males generally exhibited more wear than females at equivalent chronological ages, though results varied by tooth type for the second data set. Male body weight in the full 1985 living sample was significantly related to dental wear, when age was taken into account; however, when males less than 8 years of age were eliminated from the sample, the association between dental wear and weight became statistically insignificant. Analysis of the second data set suggested no statistically significant sex difference in dental wear for third molars, despite the approximately 2 year sex difference in eruption age for this tooth type.Discussion: This study suggests that body weight in males might be a predictor of dental wear and that if it is, body weight might also influence sex differences in dental wear. Sex differences in dental eruption timing do not appear to explain sex differences in dental wear in this sample.
Objectives To investigate whether the Cayo Santiago, Puerto Rico (Latitude: 18.1564°N; temperature range 19°C to 32°C) rhesus macaque population has acclimated to their tropical island conditions since arriving from Lucknow, India (Latitude: 26.8470°N; temperature range 8°C to 41°C) in 1938. Materials and Methods Using the derived skeletal collection, measurements were taken of long bone lengths, diaphyseal circumference, and body weight using 635 (237 males and 398 females) skeletally mature individuals. Measurements sampled colony members born over a 51‐year time span at Cayo Santiago, from 1951 to 2002. Results Results demonstrated that body weights and diaphyseal circumferences significantly declined in both males and females. Long bone lengths relative to body weight and diaphyseal circumference also increased in females. Whereas body weight, long bone length and diaphyseal circumference declined at near parallel rates in males. Discussion The population has acclimated to homogenous, tropical, conditions of the Caribbean island since their arrival over 80 years ago. Trends in both sexes aligned with Bergmann's rule, though females displayed a greater decline in body weight, as well as greater affinity with Allen's rule, than did males. Buffering effects related to male competition may be responsible for this discrepancy. Overall, the Cayo Santiago populations, as shown over a significant period (1951–2002) of their history, have acclimated to their island conditions by decreasing in size and altering body proportions.
The impact of anthropogenic pressures upon primates is increasingly prevalent, and yet the phenotypic aspects of these impacts remain understudied. Captive environments can pose unique pressures based on factors like physical activity levels and caloric availability; thus, maturation patterns should vary under differing captive conditions. Here, we evaluate the development and growth of two Macaca mulatta populations (N = 510) with known chronological ages between 9 months and 16 years, under different levels of captive management, to assess the impact of varying anthropogenic environments on primates. To track growth, we scored 13 epiphyseal fusion locales across long bones in a skeletal sample of lab-reared M. mulatta (n = 111), including the right tibia, femur, humerus, ulna, and radius. We employed a three-tier scoring system, consisting of "0" (unfused to diaphysis), "1" (fusing), and "2" (fused). To record body size, we collected five linear measures of these long bones, from the proximal and distal ends, and total lengths. Means and standard deviations were generated to compare samples; t-tests were used to determine significant differences between means. These values were compared to available data on the freeranging, provisioned M. mulatta population of Cayo Santiago. The free-ranging monkeys (n = 274) were found to exhibit larger linear skeletal lengths (p < 0.05) than lab-reared specimens. Generally, the free-ranging macaques reached fusion at earlier chronological ages and exhibited an extended duration of the fusing growth stage. These observations may reflect the protein-rich diet provided to free-ranging monkeys and conversely, restricted movement and relaxed natural selection experienced by lab-reared monkeys.
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