Behavioral Adaptation of Pan troglodytes troglodytes

As wild primate populations decline, numbers of orphaned primates, sanctuaries, and attempts to release primates back to the natural environment increase. Release projects frequently are poorly documented despite IUCN guidelines recommending post-release monitoring and systematic data collection as central to the process. Since 1996, Habitat Ecologique et Liberté des Primates (HELP) has been releasing wild-born orphaned chimpanzees into natural habitat in the Conkouati-Douli National Park, Republic of Congo. HELP developed a post-release monitoring system as an integral component. We present activity budgets and diet of released chimpanzees, and compared them to those of wild chimpanzee, as primary indicators of successful release. Feeding, moving, and resting dominated activity budgets, reflecting the overall patterns in wild populations. Diet was diverse and dominated by fruit, and the released chimpanzees showed specialization on a smaller number of species, as in many wild communities. The high survival rates of the chimpanzees and overall success of the release program are attributed to careful planning and post-release support facilitated via the monitoring process. Systematic post-release data collection monitoring has confirmed that wild-born chimpanzees can adjust behaviorally and nutritionally to the wild. Survival statistics of the reintroduced chimpanzees—confirmed 56%, possible 88%— reflect the behavioral adaptability.2nd revision March 11, 2005An erratum to this article can be found at     

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.     

Detection and molecular characterization of foamy viruses in Central African chimpanzees of the Pan troglodytes troglodytes and Pan troglodytes vellerosus subspecies

BACKGROUND: Foamy viruses are exogenous retroviruses that are highly endemic in non-human primates (NHPs). Recent studies, mainly performed in North America, indicated frequent simian foamy virus (SFV) infection in persons occupationally exposed to NHPs. This zoonotic infection was demonstrated mainly after bites by chimpanzees [Pan troglodytes (P. t.)] of the West African P. t. verus subspecies in primatology centers or zoos in the USA. METHODS: We studied 32 chimpanzees from the Central African subspecies P. t. troglodytes and P. t. vellerosus, originating from Cameroon (29 cases) or Gabon (3 cases). We screened first plasma or sera of the animals with a Western blot detecting the SFVs Gag doublet proteins. Then, we performed two nested polymerase chain reactions (PCRs) amplifying a fragment of the integrase and LTR regions and, finally, we made phylogenetical analyses on the sequences obtained from the integrase PCR products. RESULTS: By serological and/or molecular assays, we detected foamy viruses (FVs) infection in 14 chimpanzees. Sequence comparison and phylogenetic analyses of a 425 bp fragment of the integrase gene obtained for 10 of the 14 positive apes, demonstrated a wide diversity of new FVs strains that belong phylogenetically either to the P. t. troglodytes or P. t. vellerosus foamy viral clade. CONCLUSIONS: This study shows that chimpanzees living in these areas of Central Africa are infected by several specific foamy viruses. This raises, in such regions, the potential risk of a human retroviral infection of zoonotic origin linked to chimpanzees contacts, as already exemplified for STLV-1 and SIV infections.     

Occlusal relief changes with molar wear in Pan troglodytes troglodytes and Gorilla gorilla gorilla

Most research on primate tooth form-function relationships has focused on unworn teeth. This study presents a morphological comparison of variably worn lower second molars (M(2)s) of lowland gorillas (Gorilla gorilla gorilla; n=47) and common chimpanzees (Pan troglodytes troglodytes; n=54) using dental topographic analysis. High-resolution replicas of occlusal surfaces were prepared and scanned in 3D by laser scanning. The resulting elevation data were used to create a geographic information system (GIS) for each tooth. Occlusal relief, defined as the ratio of 3D surface area to 2D planometric area of the occlusal table, was calculated and compared between wear stages, taxa, and sexes. The results failed to show a difference in occlusal relief between males and females of a given taxon, but did evince differences between wear stages and between taxa. A lack of significant interaction between wear stage and taxon factors suggests that differences in occlusal relief between chimpanzees and gorillas are maintained throughout the wear sequence. These results add to a growing body of information on how molar teeth change with wear, and how differences between primate species are maintained at comparable points throughout the wear sequence. Such studies provide new insights into form-function relationships, which will allow us to infer certain aspects of diet in fossils with worn teeth.     

Home range size in central chimpanzees (Pan troglodytes troglodytes) from Loango National Park,Gabon

Primates - Ranging behavior has been studied extensively in eastern (Pan troglodytes schweinfurthii) and western (P. t. verus) chimpanzees, but relatively little is known regarding home ranges of...     

Intercommunity interactions and killings in central chimpanzees (Pan troglodytes troglodytes) from Loango National Park,Gabon

Primates - Intercommunity competition in chimpanzees (Pan troglodytes) has been widely studied in eastern (P. t. schweinfurthii) and western (P. t. verus) communities. Both subspecies show...     

External body dimensions ofPan paniscus andPan troglodytes chimpanzees

Postcranial skeletal studies have demonstrated thatPan paniscus is a more gracile animal thanPan troglodytes, with different arm to leg proportions. Published data on external body dimensions are extremely rare forPan paniscus, however. We present here a series of such measures for a sample ofpaniscus, and we compare these to similar measures forPan troglodytes. This comparison further clarifies the morphological distinctions between the two chimpanzee species, and indicates that bonobos have longer legs and smaller chest girths relative to overall body height than doPan troglodytes chimpanzees.     

Innovation in wild chimpanzees (Pan troglodytes)

Innovations of behavior have major implications for the concept of culture in animals. Innovation has rarefy been documented in wild animal populations. The chimpanzees of the Taï National Park, Côte d’Ivoire, spontaneously included new patterns of behavior in their repertoire during our study. Some innovations were incorporated into a minority of the group members’ repertoire, whereas others, such as building day nests in trees and on the ground more frequently, became general behaviors. Similarly, new contexts for use of leaf- clipping behavior and novel ways of feeding on some leaves appeared and rapidly became part of the behavior of most group members. The environmental parameters were too stable to explain these new forms of behavior, as most of them took place within 1 month during the same dry season. In a similar way, leaf- grooming acquired a new function in Gombe chimpanzees. A process similar to social conventions could explain the emergence of these new functions for an existing behavior in a way rather similar to human “fashion. ” Three major characteristics of human culture — the absence of individual variations in the performance of the behavior, the general use of the behavior by group members, and the ability to modify the function of a behavior — characterize leaf-clipping in Taï chimpanzees and leaf- grooming in Gombe chimpanzees.     

Imaginary Play in chimpanzees (Pan troglodytes)

Imaginary Play was studied in a group of five signing chimpanzees and it was found that chimpanzees engage in imaginary play similar to that found in human children. Fifteen hours of remote videotapes were analyzed for instances of imaginary play. Behaviors were defined as imaginary play by meeting a predetermined criteria which allowed them to be classified into one of six different categories of imaginary play. Six instances of imaginary play were found and these were classified into the two categories of Animation and Substitution. Observations of imaginary play in other research with chimpanzees were discussed.     

Spontaneous amyloidosis in twelve chimpanzees, Pan troglodytes

Spontaneous amyloidosis was diagnosed in 11 male and 1 female chimpanzees and confirmed histologically and immunohistochemically. The chimpanzees were > or = 15 years of age when first diagnosed and averaged 22.4 years of age. The average survival time after diagnosis of systemic amyloidosis was 1.86 years with a standard deviation of 4.06 years (n = 7). The chimpanzees with amyloidosis were asymptomatic except for hepatomegaly, which became more detectable with age. Significant increases in clinical chemistry values, as compared with referenced normals and established normals, of blood urea nitrogen (BUN), asparate aminotransferase (AST), gamma-glutamyltransferase (GGT), globulin, total protein, creatinine phosphokinase (CPK), sedimentation rate, and triglycerides were found in animals 7 years of age or older with amyloidosis. These serum chemistry values, while increased in chimpanzees with amyloidosis, were generally within normal limits. Immunohistochemistry for both amyloid A protein and amyloid P component-labeled extracellular amyloid in all chimpanzees with amyloidosis was determined. Amyloid was deposited primarily in the liver. Amyloidosis in the chimpanzee is a chronic, intractable, progressive, fatal disease, and appears to be similar to secondary amy loidosis in other species.     

Molar development in common chimpanzees (Pan troglodytes)

Numerous studies have reported on enamel and dentine development in hominoid molars, although little is known about intraspecific incremental feature variation. Furthermore, a recent histological study suggested that there is little or no time between age at chimpanzee crown completion and age at molar eruption, which is unlikely given that root growth is necessary for tooth eruption. The study presented here redefines growth standards for chimpanzee molar teeth and examines variation in incremental features. The periodicity of Retzius lines in a relatively large sample was found to be 6 or 7 days. The number of Retzius lines and cuspal enamel thickness both vary within a cusp type, among cusps, and among molars, resulting in marked variation in formation time. Daily secretion rate is consistent within analogous cuspal zones (inner, middle, and outer enamel) within and among cusp types and among molar types. Significantly increasing trends are found from inner to outer cuspal enamel (3 to 5 microns/day). Cuspal initiation and completion sequences also vary, although sequences for mandibular molar cusps are more consistent. Cusp-specific formation time ranges from approximately 2 to 3 years, increasing from M1 to M2, and often decreasing from M2 to M3. These times are intermediate between radiographic studies and a previous histological study, although both formation time within cusps and overlap between molars vary considerably. Cusp-specific (coronal) extension rates range from approximately 4 to 9 microns/day, and root extension rates in the first 5 mm of roots range from 3 to 9 microns/day. These rates are greater in M1 than in M2 or M3, and they are greater in mandibular molars than in respective maxillary molars. This significant enlargement of comparative data on nonhuman primate incremental development demonstrates that developmental variation among cusp and molar types should be considered during interpretations and comparisons of small samples of fossil hominins and hominoids.     

Measurement of eye-gaze in chimpanzees (Pan troglodytes)

Gaze cues are used as an index of social cognition in primates, yet the sensitivity to different forms of gaze, and consequently the cues required to test gaze-following abilities remain understudied. Whereas the eye is attributed special signal value in humans, the camouflaged ocular morphology of non-human primates has led to the consensus that head orientation may be a more salient cue. This study presents the first documentation of the surface eye movements of the chimpanzee, Pan troglodytes, in order to determine the behavioral forms of eye-gaze and their saliency as signals, document their functional variation, and address the signal value of the eyes distinct from head orientation. Movements of the eye were identified as Scan (continuous movement), Glance (a single movement <1 sec), or Fixate (no movement). Scans, glances, and fixations were reliably detected by humans during live observation and from video (Cohen's kappa over 0.70) and, therefore, are likely also to be detected by conspecifics. Eye-gaze comprised a nonunitary measure of visual attention, reflecting the attentional task demands of different activities. Specifically, chimpanzees spent significantly more time scanning while feeding and resting, than grooming, F(2,28) = 10.23, P<0.001, and spent significantly more time fixating while grooming, than feeding or resting, F(2,28) = 7.52, P<0.01. Further, eye-gaze was often incongruent with head movement, varying significantly with the form of eye-gaze: incongruence was found during 12-21% of fixations, during 42-49% of scans, and during 70-100% of glances, F(2,16) = 30.17, P<0.001. These findings provide the basis for discrimination of the adaptive significance of gaze-processing abilities with emphasis on sensitivity to eye-gaze distinct from head orientation. If we are to continue exploring gaze-processing abilities in primates, then we need greater consideration of the precise nature of the signals themselves. Here we present evidence for special consideration of the eyes as a salient signal in P. troglodytes.     

Innovative social behavior in chimpanzees (Pan troglodytes)

We present evidence of agonistic buffering in captive chimpanzees, recorded from 1993 until 2005, mainly from ad libitum sampling in over 2000 hr of observation. A total of 33 agonistic buffering episodes were analyzed for context and effects of this complex social behavior. Agonistic buffering was directed at the whole chimpanzee colony as they supported an individual who initially received aggression from the alpha male, independently of the victim's age, sex or social rank. Chimpanzee agonistic buffering behavior is compared with that in other nonhuman primate species, and we describe some particularities of chimpanzee agonistic buffering: the status of the buffers used-socially important offspring such as those from the alpha female-and the social rank of the adult male responsible for the buffering episode-alpha male. Possible functions for this behavior in chimpanzees are suggested as appeasement of group members in a particularly crowded captive setting, and/or as a "forced reconciliation" mechanism. Chimpanzees exhibit behavioral flexibility by adapting themselves to new social and physical situations and use novel behavior to achieve social benefits.     

Odintologic studies on the dentition of Pan troglodytes verus

The examination of 90 Pan troglodytes verus skulls from the collection of the Institute of Anthropology of the University of Giessen did not reveal the existence of a tuberculum Carabelli. Against that a well marked cingulum of the upper molars could be observed. Nearly half of the P2 showed two roots; one of the P1 had only one root. The two-rooted P2 are characteristic by a longitudinal groove on the buccal side, which may indicate bifurcation of the teeth. Agenesia of teeth was found in 3.6% of all cases, supernumerous teeth in one, respectively, two cases. Furthermore, a number of similarities with the tooth form of modern man was ascertained.