Talon cusp expression in Cayo Santiago rhesus macaques (Macaca mulatta).

OBJECTIVES: This brief communication documents the prevalence of maxillary central incisor talon cusps in Cayo Santiago rhesus monkeys (Macaca mulatta) and assesses whether talon cusp presence occurs at equivalent frequencies across matrilines. MATERIALS AND METHODS: The data on cusp presence vs. absence were analyzed by logistic regression in 170 monkeys (82 females, 78 males) from seven different matrilines. Sample sizes per matriline ranged from 10 to 42. Observations of talon cusps were blind with respect to matriline and sex. RESULTS: Talon cusps were present in 9.4% of the sample. By matriline, cusp frequencies ranged from 0%-Matrilines 073 and 106%-to 19.1% in Matriline 076. The frequency of the talon cusp in Matriline 076 was significantly greater than the frequency of the cusp in the remainder of the sample. There was no statistically significant difference in the frequency of the talon cusp by sex. CONCLUSIONS: This study suggests that the talon cusp in rhesus monkeys, as in humans and baboons, is a rare trait. Elevated prevalence of the talon cusp in Matriline 076 suggests the possibility of a genetic influence on talon cusp expression.

Male Cayo Santiago rhesus macaques (Macaca mulatta) tend to have greater molar wear than females at comparable ages: exploring two possible reasons why.

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 eight 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 two 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.

Developmental features of the canid proximocaudal femur.

We continued direct morphological studies of the canid coxofemoral joint, considering early-life spatial relationships around the locus of the proximocaudal joint capsule insertion. Our primary goal was to elucidate the postnatal developmental gross anatomy of the proximocaudal femur, among juveniles across Canidae. From an original database of 267 independent (museum) specimens from 11 canid taxa and 1 hybrid taxon, we identified 29 ancient or modern candidate juvenile specimens (nine taxa and one hybrid taxon). Based on optimal ability to recognize landmarks, the best photographic data were categorized into five groups of four each (n = 20). The data groups approximated early juvenile, early-mid juvenile, mid-juvenile, mid-late juvenile; and young adult stages. In this descriptive photographic essay, we demonstrate the developmental spatial proximity among (a) the dorsal meeting of the respective lateral and medial extensions from the growth centers of the femoral head and greater trochanter; (b) the caudodorsal aspect of the coxofemoral joint capsule attachment; (c) a segment of the proximocaudal femoral shaft physis; and (d) an eventual associated mineralized prominence. The latter occurs frequently but not universally, suggesting natural population variability across taxa. Across taxa and juvenile age categories, the morphology thus supports developmental conservation among ancient and modern Canidae. The biomechanical and biological cause-effect implications are not yet clear. For zoological purposes, we apply the term postdevelopmental mineralized prominence to the residual caudolateral surface feature. We extend the original anatomical work of Morgan in zoological and phylogenic arenas, using direct observation of cleared skeletal specimens.

Conceptual Design and Prototyping for a Primate Health History Knowledge Model.

Primate models are important for understanding human conditions, especially in studies of ageing, pathology, adaptation, and evolution. However, how to integrate data from multiple disciplines and render them compatible with each other for datamining and in-depth study is always challenging. In a long-term project, we have started a collaborative research endeavor to examine the health history of a free-ranging rhesus macaque colony at Cayo Santiago, and build a knowledge model for anthropological and biomedical/translational studies of the effects of environment and genetics on bone development, aging, and pathologies. This paper discusses the conceptual design as well as the prototyping of this model and related graphical user interfaces, and how these will help future scientific queries and studies.