Ectocranial suture closure in Pan troglodytes and Gorilla gorilla: pattern and phylogeny

The order in which ectocranial sutures undergo fusion displays species-specific variation among primates. However, the precise relationship between suture closure and phylogenetic affinities is poorly understood. In this study, we used Guttman Scaling to determine if the modal progression of suture closure differs among Homo sapiens, Pan troglodytes, and Gorilla gorilla. Because DNA sequence homologies strongly suggest that P. troglodytes and Homo sapiens share a more recent common ancestor than either does with G. gorilla, we hypothesized that this phylogenetic relationship would be reflected in the suture closure patterns of these three taxa. Results indicated that while all three species do share a similar lateral-anterior closure pattern, G. gorilla exhibits a unique vault pattern, which, unlike humans and P. troglodytes, follows a strong posterior-to-anterior gradient. P. troglodytes is therefore more like Homo sapiens in suture synostosis.     

Food Preferences Among Captive Western Gorillas (Gorilla gorilla gorilla) and Chimpanzees (Pan troglodytes)

I used a zoological park setting to address food preferences among gorillas (Gorilla gorilla gorill) and chimpanzees (Pan troglodytes). Gorillas and chimpanzees are different sizes, and consequently, have been traditionally viewed as ecologically distinct. Sympatric western gorillas and chimpanzees have proved difficult to study in the wild. Limited field data have provided conflicting information about whether gorillas are fundamentally different from chimpanzees in diet and behavior. Fruit eating shapes the behavior of most apes, but it is unclear whether the large-bodied gorillas are an exception to this rule, specifically whether they are less selective and more opportunistic fruit eaters than chimpanzees are. My research provides experimental observational data to complement field data and to better characterize the diets and food preferences of the African apes. During laboratory research at the San Francisco Zoological Gardens, I examined individual and specific differences in food preferences of captive gorillas and chimpanzees via experimental paired-choice food trials with foods that varied in nutritional content. During the study, I offered 2500 paired-food choices to 6 individual gorillas and 2000 additional pairs to them as a group. I also proffered 600 food pairs to 4 individual chimpanzees. Despite expectations of the implications of body size differences for diet, gorillas and chimpanzees exhibited similar food preferences. Both species preferred foods high in non-starch sugars and sugar-to-fiber ratios, and low in total dietary fiber. Neither species avoided foods containing tannins. These data support other suggestions of African apes sharing a frugivorous adaptation.     

Pneumatic processes in the temporal bone of chimpanzee (Pan troglodytes) and gorilla (Gorilla gorilla)

The ontogeny of human temporal bone pneumatization has been well studied from both comparative and clinical perspectives. While a difference in the extent of air cell distribution has been noted in our closest living relatives, chimpanzees and gorillas, the processes responsible have been relatively unexplored. To examine these processes, a large, age‐graded series of hominoid skulls was radiographed and the progress of pneumatization recorded. Additionally, a subsample of 30 chimpanzees and 12 gorillas was subjected to high‐resolution CT scanning. Neonatal specimens show a well‐developed mastoid antrum, as well as a capacious hypotympanum extending into the petrous apex. In African apes, as in humans, the mastoid antrum serves as the focus for air cell expansion into the mastoid and immediately adjacent areas. In chimpanzees and gorillas, however, a pronounced lateral structure, described as the squamous antrum, serves as the focus of pneumatization for anterior structures such as the squamous and zygomatic. The diminution of this structure in Homo sapiens explains the difference in air cell distribution in these regions. J. Morphol. 241:127–137, 1999. © 1999 Wiley‐Liss, Inc.     

Anterior dental microwear and its relationship to diet and feeding behavior in three african primates (Pan troglodytes troglodytes,Gorilla gorilla gorilla andPapio hamadryas)

Anterior dental microwear is shown to be related to diet and to feeding habits in three groups of extant African primates includingPan troglodytes troglodytes, Gorilla gorilla gorilla andPapio hamadryas. Five distinct types of incisal microwear are found in these groups. These include: fine wear striae, polish, small pits, large pits and microflakes. It is demonstrated that each species exhibits a different set of microwear types. Chimpanzees exhibit extensive pitting, mesiodistally oriented fine wear striae and small areas of polish, features of microwear that are probably related to the husking of hard fruit skins and the occasional stripping of leaves. Gorillas show large areas of polish, small pits and labiolingually oriented wear striae, a combination of features that may be associated with the stripping of leaves and pith. Baboons show extensive edge damage involving clusters of large pits and microflakes; this set of microwear types may be related to the initial chewing of gravel-laden seeds, roots and rhizomes. Microwear found on the canine/premolar complex of all three groups corresponds to the puncture-crushing and to the slicing of food.     

Use of space in a non-naturalistic environment by chimpanzees (Pan troglodytes) and lowland gorillas (Gorilla gorilla gorilla)

Chimpanzees and gorillas are the two most common species of great ape in captive facilities in North America. This study examined patterns of space use by 14 gorillas and six chimpanzees housed in similar non-naturalistic environments at Lincoln Park Zoo in Chicago, IL. The location of each individual was recorded in relation to elements of the environment over a two-year period. These data were compared to volumetric measurements of the enclosures to determine “preferences” for particular environmental elements. Chimpanzees preferred the highest tier of the enclosure and the gorillas preferred the floor level. Both species showed preferences for doorways, corners and the mesh barriers adjacent to keeper areas. These data supplement data from wild populations of apes and provide information useful for those seeking to design new ape enclosures or renovate existing facilities.     

A Survey of Chimpanzees (Pan troglodytes troglodytes) and Gorillas (Gorilla gorilla gorilla) in the Selectively Logged Ngotto Forest,Central African Republic

Currently, the timber company Industrie Forestiére du Batalimo is selectively logging the Ngotto Forest in the Central African Republic. The forest is home to a population of chimpanzees (Pan troglodytes troglodytes) and gorillas (Gorilla gorilla gorilla) and provides the Bofi-speaking people of Grima with food, medicine, housing material, and other commodities. Over a 7-month period, the research team conducted a line-transect survey of the great ape population in the forests to the south of Grima to document their distribution. For comparison purposes, the team also surveyed a section of adjacent forest that had already been logged. Ape nests were significantly rarer in the logged forest than in the unlogged forest, and ape nests were most common in the more pristine forests to the south. This report further discusses the effects of logging and other human activities.     

PCDH11 is X/Y homologous in Homo sapiens but not in Gorilla gorilla and Pan troglodytes

Protocadherin X (PCDHX) and Protocadherin Y (PCDHY) are cell-surface adhesion molecules expressed predominantly in brain. The human PCDH11X/Y gene pair is located in the non-pseudoautosomal X-Y homologous region (Xq21.3/Yp11.2). The possible existence of PCDH11 gene dosage differences between human and non-human primates is of evolutionary significance with respect to species differences and escape from X inactivation, and has been repeatedly debated. Previous investigations on the X/Y homologous status of PCDH11 and adjacent sequences in non-human primates have highlighted the complexity of the molecular pattern and evolutionary history of this genomic region. This paper provides for the first time direct evidence for the absence of the PCDH11 genefrom the Y chromosome of chimpanzee (Pan troglodytes) as well as gorilla (Gorilla gorilla). By confirmingthe suspected lack of X-Y homologous status for PCDH11 in non-human primates, our results reinforce the hypothesis of a hominid-specific role for this gene in brain development.     

Management of respiratory complications in a western lowland gorilla (Gorilla gorilla gorilla) born by cesarean section

A female western lowland gorilla (Gorilla gorilla gorilla) infant was delivered by cesarean section (C‐section) to an 18‐year‐old primiparous dam after prolonged labor. The infant required resuscitation at birth and was hospitalized for management of pneumonia and associated respiratory distress secondary to the aspiration of meconium‐stained amniotic fluid. The infant received nine days of intensive care with respiratory support, antibiotics, intravenous fluid therapy, anti‐inflammatory drugs, bronchodilators, and chest physiotherapy. Respiratory support included nasal continuous positive airway pressure (CPAP), and supplemental oxygen. Complications included right lung atelectasis secondary to bronchial obstruction and pneumonia. Following the resolution of pneumonia, visual reintroductions with the troop were initiated. The dam was given a medical lactation supplement (metoclopramide) and her mammary glands were stimulated to increase milk production. After several days of visual and olfactory introductions, the infant was successfully physically reintroduced to her dam at 12 days of age; the dam showed appropriate maternal response and nursing of the infant. The infant had appropriate growth and development, and 4 years later, has no evidence of negative side effects of neonatal respiratory disease. This is the first reported case of management of neonatal gorilla respiratory disease associated with a C‐section, with successful reintroduction to the family group after hospitalization.     

Dental topography and molar wear in Alouatta palliata from Costa Rica

Paleoprimatologists depend on relationships between form and function of teeth to reconstruct the diets of fossil species. Most of this work has been limited to studies of unworn teeth. A new approach, dental topographic analysis, allows the characterization and comparison of worn primate teeth. Variably worn museum specimens have been used to construct species-specific wear sequences so that measurements can be compared by wear stage among taxa with known differences in diet. This assumes that individuals in a species tend to wear their molar teeth in similar ways, a supposition that has yet to be tested. Here we evaluate this assumption with a longitudinal study of changes in tooth form over time in primates. Fourteen individual mantled howling monkeys (Alouatta palliata) were captured and then recaptured after 2, 4, and 7 years when possible at Hacienda La Pacifica in Costa Rica between 1989-1999. Dental impressions were taken each time, and molar casts were produced and analyzed using dental topographic analysis. Results showed consistent decreases in crown slope and occlusal relief. In contrast, crown angularity, a measure of surface jaggedness, remained fairly constant except with extreme wear. There were no evident differences between specimens collected in different microhabitats. These results suggest that different individual mantled howling monkeys wear their teeth down in similar ways, evidently following a species-specific wear sequence. Dental topographic analysis may therefore be used to compare morphology among similarly worn individuals from different species.     

Acute appendicitis in a chimpanzee (Pan troglodytes)

BACKGROUND: A 7-year old, female chimpanzee (Pan troglodytes) developed acute abdominal pain and anorexia. An irregular, mineral opacity was identified in the caudal right quadrant of the abdomen on radiographs and computed tomography scan, which appeared to be in the region of the cecal appendage. RESULTS AND CONCLUSIONS: A diagnosis of acute appendicitis was made based on clinical signs, abnormal haematology findings, and consultation with a human radiologist. Exploratory laparotomy was performed and the cecal appendage was removed. On histologic examination, the mucosal epithelium contained eosinophilic and neutrophilic inflammation. The inflammation extended through the tunica muscularis to the serosal surface and adjacent mesentery. The histologic findings were consistent with acute appendicitis in humans. The chimpanzee recovered well from surgery with immediate improvement in clinical signs and no post-operative complications.     

Nutritional composition of the diet of the western gorilla (Gorilla gorilla): Interspecific variation in diet quality

To meet nutritional needs, primates adjust their diets in response to local habitat differences, though whether these dietary modifications translate to changes in dietary nutrient intake is unknown. A previous study of two populations of the mountain gorilla (MG: Gorilla beringei) found no evidence for intraspecific variation in the nutrient composition of their diets, despite ecological and dietary differences between sites. One potential explanation is that nutritional variability in primate diets requires greater ecological divergence than what was captured between MG sites, underpinning environmental differences in the nutrient quality of plant foods. To test whether Gorilla exhibits interspecific variation in dietary composition and nutrient intake, we studied the composition and macronutrients of the western gorilla (WG: Gorilla gorilla) staple diets and compared them with published data from the two MG populations. We recorded feeding time and food intake of four adult female WGs from one habituated group over a period of 11 months (December 2004–October 2005) at the Mondika Research Center, Republic of Congo, allowing for assessment of seasonal patterns of nutrient intake. Staple diets of WGs and MGs diverged in their dietary and macronutrient composition. Compared to MGs, the staple diet of WGs (by intake) contained higher proportions of fruit (43%) and leaf (12%) and a lower proportion of herb (39%), resulting in a higher intake of total nonstructural carbohydrate and fiber and a lower intake of crude protein. Staple gorilla fruits and herbs differed in nutrient quality between sites. Gorillas exhibit nutritional flexibility that reflects ecological variation in the nutrient quality of plant foods. Since dietary quality typically affects rates of growth and reproduction in primates, our results suggest that interspecific differences in nutrient intake and food quality may shape differences in gorilla nutrient balancing and female life history strategies.     

Etiology of reactive arthritis in Pan paniscus, P. troglodytes troglodytes, and P. troglodytes schweinfurthii

The character of arthritis has not received the same attention in Pan paniscus as it has in P. troglodytes. Reactive arthritis (a form of spondyloarthropathy) in the latter has been considered to be either a sexually transmitted or an infectious-agent diarrhea-related disorder. The unique sexual promiscuity of P. paniscus enables us to distinguish between those hypotheses. The macerated skeletons of 139 adult P. paniscus, P. troglodytes troglodytes, and P. troglodytes schweinfurthii were macroscopically analyzed for osseous and articular pathologies. The sex of the animal was recorded at the time of acquisition. Twenty-one percent of the P. paniscus, 28% of the P. t. troglodytes, and 27% of the P. t. schweinfurthii specimens had peripheral and central joint erosive disease characteristic of spondyloarthropathy. Subchondral pauciarticular distribution and reactive new bone clearly distinguish this disease from rheumatoid arthritis, osteoarthritis, and direct bone/joint infection. The fact that P. paniscus and P. t. troglodytes were similar in terms of disease frequency makes the notion of sexual transmission unlikely. While the frequencies of spondyloarthropathy were indistinguishable among all species/subspecies studied, the patterns of joint involvement were disparate. The Pan paniscus and P. t. troglodytes home ranges are geographically separate. We assessed possible habitat factors (e.g., exposure to specific infectious agents of diarrhea) by comparing P. paniscus and P. t. troglodytes with P. t. schweinfurthii. The latter shared similar patterns and habitats (separated by the Congo River) with P. paniscus. The explanation offered for habitat-specific patterns is differential bacterial exposure-most likely Shigella or Yersinia in P. paniscus and P. t. schweinfurthii.