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PubMed1980

Local differences in responses to water among wild chimpanzees.

Behaviors in relation with water are described in detail for wild chimpanzees of the Manhale Mountains, Tanzania: drinking, wading streams, feeding, responses to rain, etc. When the results are compared with those of Gombe National Park, some behavioral differences emerge: drinking directly from the lake, feeding on aquatic plants, back/shoulder rubbing behavior by making day-beds, etc. are observed only for chimpanzees of the Mahale Mountains, while sponging to obtain water is observed only for those of Gombe. These may be examples of "tradition drift' in wild chimpanzees. Moreover, it is suggested that there is no innate hydrophobia among any of the African great apes.

Animals↗
PubMed1986

Aggression toward large carnivores by wild chimpanzees of Mahale Mountains National Park, Tanzania.

In the Mahale Mountains National Park of Tanzania, a group of about 33 chimpanzees were observed to surround a leopard den containing a mother and at least one cub and to drag out and kill the cub. This is the first report of chimpanzees or any other primate species killing their potential predator's offspring. The incident suggests that chimpanzees, without any weapons, can manage to defend themselves against a carnivore of at least up to leopard size, and implicates how the early hominids may have reacted against their potential predators.

Aggression↗
PubMed1986

Evidence for social referencing in young chimpanzees (Pan troglodytes).

A captive chimpanzee group was observed in order to determine the extent to which the social interactions of the infants and juveniles (18-50 months) were affected by their mothers' relationships with other adult group members. It was found that the young chimpanzees initiated more interactions with adults who interacted more with their mothers. A vast majority of those interactions occurred at significant distances from the mother. It is argued that these data imply a social-cognitive ability in young chimpanzees closely related to the human infant's ability to use its mother in 'social referencing'.

Animals↗
PubMed1986

Behavioral responsiveness of young chimpanzees (Pan troglodytes) to a novel environment.

Behavioral responsiveness to a novel environment was documented in 22 chimpanzees grouped according to age; 6-months, 1-year, 2-years and 5-years. An attachment figure, a human caretaker, accompanied each subject during the 15-min test sessions so as to preclude confounding of responses to novelty with separation responses. Extreme distress reported previously for chimpanzees and human children when tested alone in a novel situation was rarely observed in these tests when an attachment figure was present. Stereotyped rocking, an indication of mild distress occurred more frequently in the younger animals. Younger animals engaged in distal visual exploration of the environment while remaining close to the attachment figure, whereas the older animals locomoted more frequently and explored the environment directly with their hands. Repeated exposure to the environment reduced the differences among the 6-month, 1-year and 2-year groups. The 6-month group, however, continued to locomote least and least frequently engaged in tactile exploration. These data on chimpanzees resemble data on human children which suggest that an attachment figure: attenuates the distress exhibited by young individuals of these species when exposed to novel stimuli, and thereby provides a secure base which supports the exploration of novel stimuli, a prerequisite to behavioral adaptation.

Adaptation, Psychological↗
PubMed1990

Comparison of auditory functions in the chimpanzee and human.

Absolute thresholds for pure tones, loudness, frequency and intensity difference thresholds and the resonance of the external auditory meatus were measured in chimpanzees and compared with those in humans. Chimpanzees were more sensitive than humans to frequencies higher than 8 kHz but less sensitive to frequencies lower than 250 Hz and 2- to 4-kHz tones. Difference thresholds for frequency and intensity were greater in chimpanzees than in humans. The resonance of the external ear was about the same in the two species. The effects of differences in hearing between species upon speech perception are discussed.

Adult↗
PubMed1996

Centre of gravity of the body during the ontogeny of chimpanzee bipedal walking.

Bipedal walking was studied in chimpanzees between 1 and 19 years of age by measuring the external energy generated by the movement of the centre of gravity of the body. The 'recovery' of external energy in infant chimpanzees less than five years of age is smaller than in juveniles from 5 to 19 years of age. During the single stance phase, the short, flexed hindlimb of chimpanzees younger than 5 years is not able to lift the body centre of gravity high enough, so that these infants have a considerable energy output during bipedal walking. Extension of the hindlimb is one of the bases for energy economy in human bipedalism. The development of this low-energy-cost mechanism is an important component of the evolution of human bipedalism.

Aging↗
PubMed1976

Technique of laparoscopy in the chimpanzee.

We have developed the technique of laparoscopy in the chimpanzee using a modification of the standard human procedure. The technique requires careful management, but permits repeated examination, high quality photography, ovarian biopsy, follicle aspiration and injections into the ovary. The chimpanzee may thus be useful for evaluating new techniques or instrumentation intended for human patients. In addition, laparoscopy access to the internal genitalia enhances the value of the chimpanzee as an experimental model.

Abdomen↗
PubMed1981

Diabetes mellitus in the chimpanzee (Pan troglodytes).

Glucose intolerance was found in four adult chimpanzees. The response of glucose, insulin, C-peptide, and glucagon to intravenous glucose and tolbutamide stimulations revealed impaired glucose clearance, deficient pancreatic secretion of insulin and C-peptide, and elevated glucagon levels. Pancreatic islets in a diabetic chimpanzee were hypercellular, possible due to alpha-cells. Minimal or no insulin was observed in beta-cells. Results are consistent with the occurrence of noninsulin-dependent diabetes mellitus, which may be more prevalent in chimpanzees than heretofore suspected.

Animals↗
PubMed1998

Why faces may be special: evidence of the inversion effect in chimpanzees.

Five chimpanzees were tested on their ability to discriminate faces and automobiles presented in both their upright and inverted orientations. The face stimuli consisted of 30 black and white photographs, 10 each of unfamiliar chimpanzees (Pan troblodytes), brown capuchins (Cebus apella), and humans (Homo sapiens). Ten black and white photographs of automobiles were also used. The stimuli were presented in a sequential matching-to-sample (SMTS) format using a computerized joystick-testing apparatus. Subjects performed better on upright than inverted stimuli in all classes. Performance was significantly better on upright than inverted presentations of chimpanzee and human faces but not on capuchin monkey faces or automobiles. These data support previous studies in humans that suggest the inversion effect occurs for stimuli for which subjects have developed an expertise. Alternative explanations for the inversion effect based on the type of spatial frequency contained in the stimuli are also discussed. These data are the first to provide evidence for the inversion effect using several classes of face stimuli in a great ape species.

Animals↗
PubMed1997

Prevention of rhinovirus infection in chimpanzees by soluble intercellular adhesion molecule-1.

Intercellular adhesion molecule-1 (ICAM-1) is the cell surface receptor for the major class of human rhinoviruses, and tICAM453, a truncated, soluble form of ICAM-1, has been shown previously to be a potent in vitro inhibitor of rhinovirus. In this report, we have investigated the in vivo efficacy of tICAM453 for the prophylaxis of rhinovirus serotype 16 infection in the chimpanzee. Because chimpanzees do not show clinical symptoms of infection after rhinovirus challenge, infection was followed by measuring antirhinovirus serum antibody responses and detection of virus shedding. By both of these measures, intranasal application of tICAM453 was efficacious in preventing rhinovirus infection in chimpanzees subsequently challenged with infectious doses of virus. These results suggest that the use of soluble rhinovirus receptor to inhibit virus binding to host cells should be feasible in humans.

Administration, Intranasal↗
PubMed1982

The evaluation of lung immunity in chimpanzees.

The development of immunity in the chimpanzee was evaluated at 5 through 14 days after the deposition of a particulate antigen into a single lung lobe. An increased number of IgA, IgM, and IgG antibody-forming cells were found in the immunized lung lobes and in the blood. Few antibody-forming cells were found in the control lung lobes. The results from the chimpanzees were qualitatively the same as those from previous studies in which single lung lobes of dogs were immunized. However, a higher number of IgA antibody-forming cells was observed in the lavage fluid from chimpanzees than in that from dogs.

Animals↗
PubMed1989

In vivo handling of soluble complement fixing Ab/dsDNA immune complexes in chimpanzees.

We used soluble, C-fixing antibody/dsDNA IC to investigate immune complex (IC) handling and erythrocyte (E)-to-phagocyte transfer in chimpanzees. IC bound efficiently to chimpanzee E in vitro and showed minimal release with further in vitro incubation in the presence of serum in EDTA (less than or equal to 15% within 1 h). These IC also bound rapidly to E in vivo (70-80% binding within 1 min) and did not show detectable release from E in the peripheral circulation after infusion in vivo (less than or equal to 2% within 1 h). Despite such slow C-mediated release of IC from E, IC were rapidly stripped from E by the mononuclear phagocyte system (T50 for E-IC1500 = 5 min) without sequestration of E. Treatment of the chimpanzees with the anti-Fc gamma RIII MAb 3G8 impaired the clearance of infused IC. This effect was most evident on the fraction of IC500 which did not bind to E and which presumably had captured less C3b (pre-MAb 3G8 T50: 45 min vs. post-MAb 3G8 T50: 180 min). With IC bound in vitro to E before infusion, anti-Fc gamma RIII MAb treatment led to significant amounts of non-E bound IC detectable in the circulation. Thus, the anti-Fc gamma RIII MAb appeared to interfere with the ability of fixed tissue mononuclear phagocytes to take up/or retain IC after their release from E. Both rapid stripping of IC from E, despite slow complement-mediated release of IC from E in the peripheral circulation, and blockade of IC clearance with anti-Fc gamma RIII MAb indicate that the interaction of IC with the fixed tissue phagocyte involves qualitatively different mechanisms than the interaction of IC with E. Fc gamma receptors appear to play an important role in the transfer and retention of IC by the phagocyte.

Animals↗
PubMed2003

Refinement of a chimpanzee pericentric inversion breakpoint to a segmental duplication cluster.

BACKGROUND: Pericentric inversions are the most common euchromatic chromosomal differences among humans and the great apes. The human and chimpanzee karyotype differs by nine such events, in addition to several constitutive heterochromatic increases and one chromosomal fusion event. Reproductive isolation and subsequent speciation are thought to be the potential result of pericentric inversions, as reproductive boundaries form as a result of hybrid sterility. RESULTS: Here we employed a comparative fluorescence in situ hybridization approach, using probes selected from a combination of physical mapping, genomic sequence, and segmental duplication analyses to narrow the breakpoint interval of a pericentric inversion in chimpanzee involving the orthologous human 15q11-q13 region. We have refined the inversion breakpoint of this chimpanzee-specific rearrangement to a 600 kilobase (kb) interval of the human genome consisting of entirely duplicated material. Detailed analysis of the underlying sequence indicated that this region comprises multiple segmental duplications, including a previously characterized duplication of the alpha7 neuronal nicotinic acetylcholine receptor subunit gene (CHRNA7) in 15q13.3 and several Golgin-linked-to-PML, or LCR15, duplications. CONCLUSIONS: We conclude that, on the basis of experimental data excluding the CHRNA7 duplicon as the site of inversion, and sequence analysis of regional duplications, the most likely rearrangement site is within a GLP/LCR15 duplicon. This study further exemplifies the genomic plasticity due to the presence of segmental duplications and highlights their importance for a complete understanding of genome evolution.

Animals↗
PubMed2003

The discrimination of faces and their emotional content by chimpanzees (Pan troglodytes).

The ability to recognize and discriminate conspecific faces and facial expressions has played a critical role in the evolution of social communication. Darwin was one of the first to speculate that human and nonhuman primate facial expressions share similar mechanisms for production and functions in expressing emotion. Since his seminal publication, numerous studies have attempted to unravel the meaning of animal signals, with the most success coming from the field of vocal communication, where researchers have identified the referential and emotional nature of specific vocalizations. Studies specifically addressing nonverbal facial displays, however, have faced numerous methodological challenges, including how to objectively describe facial movements and how to study the perception and production of these signals within a social context. In this paper, I will review my studies on chimpanzee face recognition, their ability to categorize facial expressions, and the extent to which chimpanzee facial expressions may convey information about emotion. Finally, recent studies from my lab have begun to address the role of auditory and visual cues in facial expression categorization. Chimpanzees were given the task of matching expressions according to which sensory modality was more salient, the visual or auditory component. For some expressions the visual modality was preferred, while for others the auditory modality was preferred. These data suggest that different social and ecological pressures may shift attention towards one sensory modality over another, such as during long-distance communication or emotional conflict.

Affect↗
PubMed2003

Visual field information in the face perception of chimpanzees (Pan troglodytes).

Evidence for a visual field advantage (VFA) in the face perception of chimpanzees was investigated using a modification of a free-vision task. Four of six chimpanzee subjects previously trained on a computer joystick match-to-sample paradigm were able to distinguish between images of neutral face chimeras consisting of two left sides (LL) or right sides (RR) of the face. While an individual's ability to make this distinction would be unlikely to determine their suitability for the VFA tests, it was important to establish that distinctive information was available in test images. Data were then recorded on their choice of the LL vs. RR chimera as a match to the true, neutral image; a bias for one of these options would indicate an hemispatial visual field advantage. Results suggest that chimpanzees, unlike humans, do not exhibit a left visual field advantage. These results have important implications for studies on laterality and asymmetry in facial signals and their perception in primates.

Animals↗
PubMed1998

Destructible toys as enrichment for captive chimpanzees.

The use of destructible objects or toys as enrichment for nonhuman primates has had promising results in terms of increased use and positive behavioral effect. The purpose of this project was to determine the use and durability of a number of inexpensive, destructible toys provided one at a time or several at once. Nine singly caged chimpanzees were provided with 8 different toys made of plastic, vinyl, or cloth, and the frequency of use of the toys was determined during 15 min trials 2 times per day. A toy was removed when it was destroyed or when it was not contacted during 4 trials. The chimpanzees contacted the toys an average of 11 times per trial, and the use of the individual toys was significantly higher when provided 1 at a time rather than all at once. Use of the toys was fairly stable over time, and the toys remained in the cages an average of 3.2 days. The durability of the toys was related to the type of toy (e.g., more flexible cloth and vinyl toys lasted longer than rigid plastic toys). The destructible toys were used significantly more often than other permanent cage toys or televisions. Toy use was not related to age, level of abnormal behavior, or use of existing permanent toys or television. The implications of the results were related to the management of an environmental enrichment program and indicated that the provision of flexible, inexpensive toys 1 at a time can be an effective method of enrichment for captive chimpanzees.

Journal Article↗
PubMed1999

The nuts and bolts of captive chimpanzee diets and food as enrichment: a survey.

Beyond planning for good nutrition, one of the Cornerstones of a successful captive-chimpanzee wellness program is the opportunity for the nonhuman primates to express normal feeding and foraging behaviors. This study presents the results of a survey of 11 institutions-8 zoological and 3 research facilities-given to ascertain how daily diets and feeding enrichments were accomplished. Information represents 806 captive chimpanzees, and entails a composite of captive chimpanzee daily diets, forage and browse materials, periodic treats, medicating and supplemental foods, alternative feeding techniques, and food devices. Results suggest facilities are moving away from timed feeding schedules, which tend to increase prefeeding levels of agonism, to feeding a wide variety of foods throughout the day and using a wide variety of feeding techniques.

Journal Article↗
PubMed1983

Effects of naloxone and an enkephalin analog on serum prolactin, cortisol, and gonadotropins in the chimpanzee.

To assess a possible regulatory influence of opioids upon anterior pituitary function in the chimpanzee, we evaluated the effects of the specific opiate receptor antagonist naloxone and the agonistic enkephalin analog [D-Ala2, MePhe4,Met(o)-ol]enkephalin (FK 33-824; Sandoz) on serum levels of PRL, cortisol, FSH, and LH. Under ketamine anesthesia, the following were administered by iv injection during the early follicular phase of successive menstrual cycles in nine female chimpanzees: naloxone (10 mg; n = 7) or saline vehicle (n = 7) randomly assigned in the first two cycles, FK 33-824 0.25 mg (n = 3) in the third cycle, FK 33-824 0.50 mg (n = 4) in the fourth cycle, and FK 33-824 (0.50 mg) immediately preceded by naloxone (10 mg; n = 4) in the last cycle. Five pretreatment and 12 posttreatment serum samples were obtained at 10- to 15-min intervals for subsequent RIA. Naloxone caused a significant reduction in PRL levels from a pretreatment mean of 29.3 ng/ml to a mean of 11.1 ng/ml at 180 min. Values from 60-180 min were significantly below the saline control group at comparable times. A dose-related increment in PRL levels was seen after FK 33-824 administration, with mean peak values at 30 min of 61.0 and 92.3 ng/ml after the low and high doses, respectively. Naloxone pretreatment markedly attenuated the response to high dose FK 33-824. Cortisol levels rose in all groups throughout the study period, a presumed effect of the ketamine anesthesia. Compared to the saline group, no effects of FK 33-824 were observed. Naloxone, given alone or with FK 33-824, had a small, but significant, stimulatory effect on cortisol from 60-120 min posttreatment compared to the control group. Naloxone caused a significant increment in LH levels from a pretreatment mean of 11.7 micrograms/dl to a peak of 19.1 micrograms/dl at 30 min and in FSH level from 33.2 micrograms/dl before therapy to 40.0 micrograms/dl at 45 min. There was no influence of FK 33-824 on gonadotropin levels, although the high dose did blunt the response to naloxone. Taken together, these effects suggest that opiate agonists and endogenous opioid pathways may modulate anterior pituitary function in the chimpanzee, as in man.

Animals↗