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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 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 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 (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. 

BackgroundComponents of diet known as fallback foods are argued to be critical in shaping primate dental anatomy. Such foods of low(er) nutritional quality are often non-preferred, mechanically challenging resources that species resort to during ecological crunch periods. An oft-cited example of the importance of dietary fallbacks in shaping primate anatomy is the grey-cheeked mangabeyLophocebus albigena. This species relies upon hard seeds only when softer, preferred resources are not available, a fact which has been linked to its thick dental enamel. Another mangabey species with thick enamel, the sooty mangabeyCercocebus atys, processes a mechanically challenging food year-round. That the two mangabey species are both thickly-enameled suggests that both fallback and routine consumption of hard foods are associated with the same anatomical feature, complicating interpretations of thick enamel in the fossil record. We anticipated that aspects of enamel other than its thickness might differ betweenCercocebus atysandLophocebus albigena.We hypothesized that to function adequately under a dietary regime of routine hard-object feeding, the molars ofCercocebus atyswould be more fracture and wear resistant than those ofLophocebus albigena. MethodsHere we investigated critical fracture loads, nanomechanical properties of enamel, and enamel decussation inCercocebus atysandLophocebus albigena.Molars ofCercopithecus, a genus not associated with hard-object feeding, were included for comparison. Critical loads were estimated using measurements from 2D µCT slices of upper and lower molars. Nanomechanical properties (by nanoindentation) and decussation of enamel prisms (by SEM-imaging) in trigon basins of one upper second molar per taxon were compared. ResultsProtocone and protoconid critical fracture loads were significantly greater inCercocebus atysthanLophocebus albigenaand greater in both than inCercopithecus. Elastic modulus, hardness, and elasticity index in most regions of the crown were greater inCercocebus atysthan in the other two taxa, with the greatest difference in the outer enamel. All taxa had decussated enamel, but that ofCercocebus atysuniquely exhibited a bundle of transversely oriented prisms cervical to the radial enamel. Quantitative comparison of in-plane and out-of-plane prism angles suggests that decussation in trigon basin enamel is more complex inCercocebus atysthan it is in eitherLophocebus albigenaorCercopithecus cephus. These findings suggest thatCercocebus atysmolars are more fracture and wear resistant than those ofLophocebus albigenaandCercopithecus. Recognition of these differences betweenCercocebus atysandLophocebus albigenamolars sharpens our understanding of associations between hard-object feeding and dental anatomy under conditions of routine vs. fallback hard-object feeding and provides a basis for dietary inference in fossil primates, including hominins. 

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.