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The endangered mountain gorilla (Gorilla beringei beringei) in Rwanda, Uganda, and the Democratic Republic of Congo is frequently in contact with humans through tourism, research activities, and illegal entry of people into protected gorilla habitat. Herpesviruses, which are ubiquitous in primates, have the potential to be shared in any setting where humans and gorillas share habitat. Based on serological findings and clinical observations of orofacial ulcerated lesions resembling herpetic lesions, an alpha‐herpesvirus resembling human herpes simplex virus type 1 (HSV‐1) has long been suspected to be present in human‐habituated mountain gorillas in the wild. While the etiology of orofacial lesions in the wild has not been confirmed, HSV‐1 has been suspected in captively‐housed mountain gorillas and confirmed in a co‐housed confiscated Grauer's gorilla (Gorilla beringei graueri). To better characterize herpesviruses infecting mountain gorillas and to determine the presence/absence of HSV‐1 in the free‐living population, we conducted a population‐wide survey to test for the presence of orally shed herpesviruses. DNA was extracted from discarded chewed plants collected from 294 individuals from 26 groups, and samples were screened by polymerase chain reaction using pan‐herpesvirus and HSV‐1‐specific assays. We found no evidence that human herpesviruses had infected free‐ranging mountain gorillas. However, we found gorilla‐specific homologs to human herpesviruses, including cytomegaloviruses (GbbCMV‐1 and 2), a lymphocryptovirus (GbbLCV‐1), and a new rhadinovirus (GbbRHV‐1) with similar characteristics (i.e., timing of primary infection, shedding in multiple age groups, and potential modes of transmission) to their human counterparts, human cytomegalovirus, Epstein‐Barr virus and Kaposi's sarcoma‐associated herpesvirus, respectively. Research highlights: Discovery of mountain gorilla‐specific homologs to human herpesviruses, including cytomegaloviruses, a lymphocryptovirus, and a rhadinovirus with similar characteristics to their human counterparts.Human herpes simplex virus type 1 (HSV‐1) has not entered the wild mountain gorilla population despite frequent contact with humans.Any potential future consideration of reintroduction of captive mountain gorillas should carefully consider the possibiliy of introducing HSV‐1 and other human pathogens to the wild population. [ABSTRACT FROM AUTHOR]

Mountain gorillas are particularly inbred compared to other gorillas and even the most inbred human populations. As mountain gorilla skeletal material accumulated during the 1970s, researchers noted their pronounced facial asymmetry and hypothesized that it reflects a population-wide chewing side preference. However, asymmetry has also been linked to environmental and genetic stress in experimental models. Here, we examine facial asymmetry in 114 crania from three Gorilla subspecies using 3D geometric morphometrics. We measure fluctuating asymmetry (FA), defined as random deviations from perfect symmetry, and population-specific patterns of directional asymmetry (DA). Mountain gorillas, with a current population size of about 1000 individuals, have the highest degree of facial FA (explaining 17% of total facial shape variation), followed by Grauer gorillas (9%) and western lowland gorillas (6%), despite the latter experiencing the greatest ecological and dietary variability. DA, while significant in all three taxa, explains relatively less shape variation than FA does. Facial asymmetry correlates neither with tooth wear asymmetry nor increases with age in a mountain gorilla subsample, undermining the hypothesis that facial asymmetry is driven by chewing side preference. An examination of temporal trends shows that stress-induced developmental instability has increased over the last 100 years in these endangered apes. [ABSTRACT FROM AUTHOR]

The finding of parasites and bacterial pathogens in mountain gorilla feces and oral lesions in gorilla skeletal remains has not been linked to pathological evidence of morbidity or mortality. In the current study, we conducted a retrospective study of digestive tracts including oral cavity, salivary glands, esophagus, stomach, intestines (gastrointestinal tract [GI]), liver, and pancreas of 60 free‐ranging mountain gorillas from Uganda, Rwanda, and the Democratic Republic of Congo that died between 1985 and 2007. We reviewed clinical histories and gross pathology reports and examined histological sections. On histology, enteritis (58.6%), gastritis (37.3%), and colitis (29.3%) were the commonest lesions in the tracts. Enteritis and colitis were generally mild, and judged likely to have been subclinical. Gastritis was often chronic and proliferative or ulcerative, and associated with nematodiasis. A gastro‐duodenal malignancy (carcinoid) was present in one animal. A number of incidental lesions were identified throughout the tract and cestodes and nematodes were frequently observed grossly and/or histologically. Pigmentation of teeth and tongue were a common finding, but periodontitis and dental attrition were less common than reported from past studies of skeletal remains. Despite observing numerous GI lesions and parasites in this study of deceased free‐living mountain gorillas, we confirmed mortality attributable to gastroenteritis in just 8% (5/60) cases, which is less than that described in captive gorillas. Other deaths attributed to digestive tract lesions included cleft palate in an infant, periodontal disease causing systemic infection in an older adult and gastric cancer. Of all the parasitic infections observed, only hepatic capillariasis and gastric nematodiasis were significantly associated with lesions (hepatitis and gastritis, respectively). Understanding GI lesions in this endangered species is key in the management of morbidity associated with GI ailments. Research Highlights: Oral lesions were less than in previous skeletal studies.Nematodiasis and capillariasis were risks to gastritis and hepatitis, respectively. Cestodes reduced the risk for enteritis.Mortality due to gastrointestinal tract lesions was less than that in captive gorillas. [ABSTRACT FROM AUTHOR]

A 30‐year‐old free‐ranging female mountain gorilla (Gorilla beringei beringei) developed a perioral mass that was surgically debulked and diagnosed as malignant melanoma. After tumor recurrence, a canine melanoma vaccine was administered. However, the gorilla died shortly thereafter, and metastases to lymph nodes, lung, liver, and kidney were found post‐mortem. [ABSTRACT FROM AUTHOR]

Objectives While dental development is important to life history investigations, data from wild known-aged great apes are scarce. We report on the first radiographic examination of dental development in wild Virunga mountain gorillas, using known-age skeletal samples recovered in Rwanda. Materials and methods In 43 individuals (0.0-14.94 years), we collected radiographs of mandibular molars, and where possible, cone beam CT scans. Molar crown and root calcification status was assessed using two established staging systems, and age prediction equations generated using polynomial regression. Results were compared to available data from known-age captive and wild chimpanzees. Results Mountain gorillas generally fell within reported captive chimpanzee distributions or exceeded them, exhibiting older ages at equivalent radiographic stages of development. Differences reflect delayed initiation and/or an extended duration of second molar crown development, and extended first and second molar root development, in mountain gorillas compared to captive chimpanzees. However, differences in the duration of molar root development were less evident compared to wild chimpanzees. Discussion Despite sample limitations, our findings extend the known range of variation in radiographic estimates of molar formation timing in great apes, and provide a new age prediction technique based on wild specimens. However, mountain gorillas do not appear accelerated in radiographic assessment of molar formation compared to chimpanzees, as they are for other life history traits. Future studies should aim to resolve the influence of species differences, wild versus captive environments, and/or sampling phenomena on patterns observed here, and more generally, how they relate to variation in tooth size, eruption timing, and developmental life history. [ABSTRACT FROM AUTHOR]

ABSTRACT Objectives Great ape teeth must remain functional over long lifespans. The molars of the most folivorous apes, the mountain gorillas, must maintain shearing function for 40+ years while the animals consume large quantities of mechanically challenging foods. While other folivorous primates experience dental senescence, which compromises their occlusal surfaces and affects their reproductive success as they age, it is unknown whether dental senescence also occurs in mountain gorillas. In this article, we quantified and evaluated how mountain gorilla molars change throughout their long lifespans. Materials and Methods We collected high-resolution replicas of M1s ( n = 15), M2s ( n = 13), and M3s ( n = 11) from a cross-sectional sample of wild mountain gorilla skeletons from the Virunga Volcanoes, ranging in age from 4 to 43 years. We employed dental topographic analyses to track how aspects of occlusal slope, angularity, relief index, and orientation patch count rotated change with age. In addition, we measured the relative length of shearing crests in two- and three-dimensions. Results Occlusal topography was found to decrease, while 2D relative shearing crest length increased, and 3D relative crest lengths were maintained with age. Discussion Our findings indicate that shearing function is maintained throughout the long lifetimes of mountain gorillas. Unlike the dental senescence experienced by other folivorous primates, mountain gorillas do not appear to possess senesced molars despite their long lifetimes, mechanically challenging diets, and decreases in occlusal topography with age. Am J Phys Anthropol 160:3-15, 2016. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

ABSTRACT Gorillas include separate eastern ( Gorilla beringei) and western ( Gorilla gorilla) African species that diverged from each other approximately 2 million years ago. Although anatomical, genetic, behavioral, and socioecological differences have been noted among gorilla populations, little is known about variation in their brain structure. This study examines neuroanatomical variation between gorilla species using structural neuroimaging. Postmortem magnetic resonance images were obtained of brains from 18 captive western lowland gorillas ( Gorilla gorilla gorilla), 15 wild mountain gorillas ( Gorilla beringei beringei), and 3 Grauer's gorillas ( Gorilla beringei graueri) (both wild and captive). Stereologic methods were used to measure volumes of brain structures, including left and right frontal lobe gray and white matter, temporal lobe gray and white matter, parietal and occipital lobes gray and white matter, insular gray matter, hippocampus, striatum, thalamus, each hemisphere and the vermis of the cerebellum, and the external and extreme capsules together with the claustrum. Among the species differences, the volumes of the hippocampus and cerebellum were significantly larger in G. gorilla than G. beringei. These anatomical differences may relate to divergent ecological adaptations of the two species. Specifically, G. gorilla engages in more arboreal locomotion and thus may rely more on cerebellar circuits. In addition, they tend to eat more fruit and have larger home ranges and consequently might depend more on spatial mapping functions of the hippocampus. Am J Phys Anthropol 156:252-262, 2015. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: We have isolated and cultured three distinct adenoviruses from wild gorillas. Phylogenetic analysis grouped the viruses with human adenovirus species C based on DNA polymerase, hexon, and E4ORF6 genes. The three wild gorilla adenoviruses clustered with the other species C captive gorilla adenoviruses, forming a branch separate from human and chimpanzee/bonobo adenoviruses. Animal sera to the three newly isolated viruses did not cross-neutralize, demonstrating serological distinctiveness. The human adenovirus 5 fiber knob blocked infection, suggesting use of the Coxsackie and Adenovirus Receptor. These viruses may provide viral vectors with properties distinct from chimpanzee adenovirus and human adenovirus vectors. [Copyright &y& Elsevier]

We describe the bacterial diversity in fecal samples of a wild gorilla by use of a 16S rRNA gene clone library and terminal-restriction fragment length polymorphism (T-RFLP). Clones were classified as Firmicutes, Verrucomicrobia, Actinobacteria, Lentisphaerae, Bacteroidetes, Spirochetes, and Planctomycetes. Our data suggest that fecal populations did not change temporally, as determined by T-RFLP. [ABSTRACT FROM AUTHOR]

Deeper or more 'severe' linear enamel hypoplasia (LEH) defects are hypothesized to reflect more severe stress during development, but it is not yet clear how depth is influenced by intrinsic enamel growth patterns. Recent work documented inter- and intraspecific differences in LEH defect depth in extant great apes, with mountain gorillas having shallower defects than other taxa, and females having deeper defects than males. Here, we assess the correspondence of inter- and intraspecific defect depth and intrinsic aspects of enamel growth: enamel extension rates, outer enamel striae of Retzius angles, and linear enamel thickness. Thin sections of great ape canines (n = 40) from Gorilla beringei beringei , Gorilla gorilla gorilla , Pan troglodytes , and Pongo spp. were analyzed. Enamel extension rates were calculated within deciles of enamel-dentine junction length. Linear enamel thickness and the angle of intersection between striae of Retzius and the outer enamel surface were measured in the imbricational enamel. Mountain gorillas have faster enamel extension rates and shallower striae angles than the other taxa examined. Mountain gorillas have thinner imbricational enamel than western lowland gorillas and orangutans, but not chimpanzees. In the combined-taxon sample, females exhibit larger striae angles and thicker imbricational enamel than males. Enamel extension rates are highly negatively correlated with striae angles and LEH defect depth. Enamel growth variation corresponds with documented inter- and intraspecific differences in LEH defect depth in great ape canines. Mountain gorillas have shallower striae angles and faster extension rates than other taxa, which might explain their shallow LEH defect morphology and the underestimation of their LEH prevalence in previous studies. These results suggest that stressors of similar magnitude and timing might produce defects of different depths in one species or sex vs. another, which has implications for interpretations of stress histories in hominins with variable enamel growth patterns. [ABSTRACT FROM AUTHOR]