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ABSTRACT Increased fluctuating asymmetry, or random differences between right and left sides, has been associated with developmental stress or developmental instability. This study examines fluctuating asymmetry (FA) of mesio‐distal and bucco‐lingual dimensions of deciduous maxillary molars (m¹, m²), and permanent maxillary premolars and molars (P³, P⁴, M¹, M²) of 466 rhesus macaques (Macaca mulatta) born between 1950 and 2018 from Cayo Santiago (CS), Puerto Rico. All included individuals were of known age, sex, birth year, and matriline. We assess whether a secular trend occurs in FA over a 68‐year period, sex differences in FA, and whether environmental or management factors in the colony history resulted in decreased FA. Regression of FA on birth year tested for a secular trend in FA. A mixed‐model two‐way analysis of variance was used to test for the influence of food supplementation, tetanus vaccination and hurricane experience during dental development on FA. Differences across matrilines in response to the management or environmental factors were tested by ANOVA. There was no significant secular trend in FA. There was limited reduction of FA with implementation of the high protein diet, and limited support for the decreased FA associated with the implementation of tetanus vaccination. There is also limited difference in dental FA associated with exposure to a hurricane during dental development. Matrilineal differences in FA were observed for several teeth. The free‐ranging environment of Cayo Santiago is a complex environment, with many factors influencing the development of young rhesus macaques. While the introduction of a high protein diet or the implementation of a tetanus vaccination program may have improved individual health overall, there are likely other factors that may cause developmental stress and result in dental FA. 

ABSTRACT The Cayo Santiago (CS) rhesus macaque colony has raised a total of over 11,000 animals in a free‐ranging setting very close to the natural environment. The well‐kept individual and family records, as well as social group management data, have been a valuable source for anthropological research. However, the various sources of data have been stored in separation, and there was no straightforward way for researchers to access them directly. Since 2019, an ongoing effort supported through an NSF collaborative grant has been collecting morphology and imagery data from the CS‐derived skeleton collection. One specific aim is to build an integrative database to combine newly collected osteology data (bone measurement) and existing genealogy and demographic information. A second aim is to develop a software application (codenamed as CSViewer for Analysts) to provide user‐friendly interfaces for the research community to access and analyze the data. In this paper, we present a set of results generated by using standard data science tools and techniques, which help construct a holistic view of the CS rhesus colony along multiple dimensions. The matrilineal family lineage and pedigree can be visualized using various tree forms, as well as patrilineal lineages traced back to the mid‐1970s. Social group evolution charts are generated and add new features to the original records. Reproduction patterns are studied in the context of group interaction and animal transfer logs. Cross‐referencing between genealogy and osteology data can also be accomplished. Most of these charts are supported in the CSViewer app with convenient tooltip features to show details as needed. Selection based on attributes like founder line, sex, and birth season can be applied to tailor charts to a research project so that researchers can zoom into a data set that can best support their analytics goals. 

Abstract ObjectivesThis 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 MethodsThe 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. ResultsTalon 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. ConclusionsThis 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. 

Abstract The Cayo Santiago rhesus macaque colony represents one of the most important nonhuman primate resources since their introduction to the Caribbean area in 1938. The 85 years of continuing existence along with the comprehensive database of the rhesus colony and the derived skeletal collections have provided and will continue to provide a powerful tool to test hypotheses about adaptive and evolutionary mechanisms in both biology and medicine. 

ABSTRACT Linear enamel hypoplasias (LEHs) are development defects appearing as lines or grooves on enamel surfaces. Forming when physiological stressors disrupt developing teeth, LEHs provide retrospective insight into stress experienced in early development. Here, LEHs in Cayo Santiago rhesus macaques (Macaca mulatta) were observed with respect to decade of birth, whether an individual was transferred from the free‐ranging colony to the captive facility during probable crown formation periods, and matriline of birth. It was hypothesized that later decades would exhibit higher prevalence than earlier decades as climatic conditions in Puerto Rico worsened over time. Transfer was expected to affect LEH formation because the process of transfer, and subsequent restriction to captivity, is thought to be stressful. Matriline membership was hypothesized to relate to LEH formation because there is some evidence of a genetic influence on susceptibility to form LEH and because offspring of matrilines of different dominance ranks are known to experience different levels of aggression. Lower third premolars with minimal enamel surface wear were scored for LEH using a digital microscope, while a follow‐up analysis of the two matrilines with the most extreme differences in LEH frequency was conducted using enamel surface profiles. Results were: (1) individuals born during the 1990s had significantly greater LEH prevalence than those born in the 1960s, (2) transferred individuals exhibited weak evidence of greater LEH prevalence than nontransferred comparison groups, and (3) matrilines did not differ in LEH expression in the initial or follow‐up analysis. Although sample sizes were small for some comparisons, these results suggest that not all decades saw an equal prevalence of LEH, that there might be a small effect of transfer from free‐ranging to captive conditions on LEH prevalence that is difficult to detect, and that the matriline into which an individual is born is not related to LEH expression. 

ABSTRACT The Cayo Santiago rhesus colony and its derived skeletal collections provide abundant data made available since its founding in 1938. A project supported by an NSF collaborative grant has been committed to building a database that integrates the genetic and age‐related information of the colony, together with social group interactions and environmental effects, aiming to provide a knowledge model to researchers with insights from this powerful non‐human data repository for analyzing human conditions including growth, development, adaption, resilience, aging, and disease in a contextualized manner. This paper introduces CSViewer for Analysts, a computer application that provides user‐friendly tools for researchers to access the integrated database and to generate a variety of visuals encompassing matrilineal or patrilineal family lines, social groups, time spans, phenotypic measurements, and photos recently collected through this project. Adopting Java‐based technologies and third‐party libraries for data analytics and visualization, CSViewer can help its users select meaningful datasets using various criteria, conduct data analytics and visualization tasks, and manage their “project artifacts” (such as selected datasets, models, and charts, etc.). Version 1.0 of the CSViewer app has been tested by collaborators and in a workshop by a limited number of researchers and science educators since 2023. Based on users' feedback, additional features have been implemented in version 1.1.0, and more features are planned for subsequent subversions with bundles for researchers to download and explore. 

ABSTRACT The Cayo Santiago rhesus macaque colony is a renowned primate population that has experienced significant natural and anthropogenic ecological variation in their 85‐year history. Demographic and familial information is also tracked and collated for the majority of monkeys. Thus, the health history of rhesus macaques at Cayo Santiago should reflect the impacts of both environmental and genetic factors. In this study, we utilized a sample of skeletal remains comprised of 2787 individuals (1571 females, 1091 males), born between 1938 and 2017 from the derived skeletal collection of the primate colony to assess variation in survivorship, pathology, bone mineral density (BMD), and dental eruption status, in the context of hurricane impacts, nutritional fluctuations, and matriline genealogy. Results demonstrated that rhesus macaques at Cayo Santiago exhibit a range of skeletal pathologies that encompass biomedical and archaeological significance, multiple etiologies, severities, locations, and types, in addition to a secular trend of declining BMD that is hypothesized to reflect decreasing physical activity levels under increasing population densities. Specifically, hurricane impacts were found to increase the rate of systemic disease, decrease BMD in young adults, and delay eruption of the primary dentition. Certain matrilines exhibited heightened levels of systemic disease at early ages while others exhibited greater rates of congenital disease. Early‐life adversity, through the experience of major hurricanes, may enhance inflammatory pathways, heightening the risk of disease and accelerating the aging process leading to reduced BMD. Such impacts may underly greater levels of observed infection post‐hurricane through intensification of pathogen transmission and disease rates brought on by hurricane‐adaptive social strategies that favor closer proximity. Familial susceptibility to disease indicates heritable host genetic factors are likely influencing disease patterning in the population. A cluster of congenital diseases may most convincingly illustrate this, or alternatively reflects low levels of genetic diversity in the population. 

Abstract ObjectivesTo 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 MethodsUsing 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. ResultsResults 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. DiscussionThe 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. 

Abstract The pterion is the sutural juncture of the frontal, parietal, sphenoidal, temporal, and zygomatic bones on the lateral aspect of the cranium. As a craniometric landmark, the pterion has a taxonomic valence, in addition to a common neurosurgical entry point in medicine. Variation in the articulation patterns at the pterion have been documented between primate species yet have a high degree of uniformity within species, suggesting a genetic control for this complex region of the skull. In this study, pterion pattern variation was investigated in 1627 Rhesus macaque crania of the Cayo Santiago colony. The colony's associated skeletal collections accompany known age, sex, and maternal lineages. Pterion pattern prevalence rates were tested against matrilines, as well as cranial shape, and cranial sutural fusion ages (including individuals with prematurely fused sutures). Five patterns were identified, the most prominent being the prevailing Old World Monkey frontotemporal (FT) articulation (83.4%). The relative frequency of those not exhibiting the FT pattern was found to vary considerably between matrilineal families (p = 0.037), ranging from 5.3% to 34.2%. Mothers with the non‐FT pterion pattern were three times as likely to bear non‐FT offspring. Cranial shape additionally varied with pterion type. Males exhibiting zygomaticotemporal (ZT) and sphenoparietal (SP) articulations possessed a relatively longer and narrower cranium than those with the default FT type (p = < 0.001). Cranial sutural fusion ages were not found to differ between pterion types, though all individuals with craniosynostosis (6; 0.38%) exhibited the FT type. The study provided strong evidence for a genetic source for pterion pattern as well as outlining a relatively novel relationship with cranial shape and sutural fusion ages. A unifying explanation may lie in those genes involved in both sutural and craniofacial development, or in the variation of brain growth processes channeling sutural articulation at the pterion. Both may be heritable and responsible for producing observed matrilineal differences in the pterion. 

Understanding factors affecting tooth wear in primates is of interest because as teeth wear, their chewing efficiency can change—in some species positively and in others negatively. It is well known that teeth wear with age, but relationships between sex and tooth wear and between body size and tooth wear are less well understood. Here we analyze molar wear scores from a cross-sectional sample of 212 Cayo Santiago rhesus monkey (Macaca mulatta) adults examined in 1985. Because males are generally larger than females --potentially processing more food over their lifetimes--we hypothesized that with age included in an ordinal logistic regression model, males would exhibit significantly greater wear than females. We further hypothesized that males of larger body mass would exhibit greater wear than males of smaller body mass. Finally, because many of the females were pregnant or lactating at the time of dental examination, we hypothesized that there would be no relationship between body mass and wear in females. We found that with age included in ordinal logistic regression models, males had significantly more worn molars than females, larger males had more worn molars than smaller males, and that for females, molar wear was not significantly related to body mass. These results suggest that over the life course, animals with larger body sizes (males vs. females and larger vs. smaller males) may accumulate more wear than those with smaller body sizes. Future analyses to be conducted on the Cayo Santiago monkeys’ skeletal remains will further evaluate this possibility. Funding Sources: The Cayo Santiago colony is supported by NIH 5P40OD012217. This project is supported by NSF grants to DG-S., LK., MZ, and QW (NSF #1926528, 1926481, 1926402, and 1926601).