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PubMed2006

Three studies on configural face processing by chimpanzees.

Previous studies have demonstrated the sensitivity of chimpanzees to facial configurations. Three studies further these findings by showing this sensitivity to be specific to second-order relational properties. In humans, this type of configural processing requires prolonged experience and enables subordinate-level discriminations of many individuals. Chimpanzees showed evidence of a composite-like effect for conspecific but not human faces despite extensive experience with humans. Chimpanzee face recognition was impaired only when manipulations targeted second-order properties. Finally, face processing was impaired when individual features were blurred through pixelation. Results confirm that chimpanzee face discrimination, like humans, depends on the integrity of second-order relational properties.

Analysis of Variance↗
PubMed2004

Facial responses to four basic tastes in newborn rhesus macaques (Macaca mulatta) and chimpanzees (Pan troglodytes).

Newborn humans are known to show specific facial expressions in response to various kinds of taste stimuli and are presumed to be able to discriminate those kinds of tastes from just after birth. As the closest relatives to humans, the taste reactivity (threshold, preference and taste-elicited facial expression) of non-human primates has long been of great interest. To date, however, there have been few investigations in newborn non-human primates. In the present study, we investigated the facial expressions elicited in response to four basic taste stimuli, sweet, salty, sour and bitter, in the newborns of two non-human primate species, rhesus macaques and chimpanzees. The taste-elicited facial expressions were compared among the kinds of taste stimuli and between the two species. Rhesus macaques of less than 7 days old showed different patterns of facial expressions for water/sweet than for bitter, and chimpanzees less than 30 days old did so for sweet and bitter. The differences between these two species were evident in the presence and absence of certain facial expressions and the emerging patterns of certain components for each stimulus. In particular, chimpanzee response patterns to the bitter stimulus resembled to those of humans rather than rhesus macaques. Overall, rhesus macaques and chimpanzees responded differently to the same kinds of tastes, presumably reflecting differences in their evolutionary backgrounds.

Animals↗
PubMed2006

Chimpanzees deceive a human competitor by hiding.

There is little experimental evidence that any non-human species is capable of purposefully attempting to manipulate the psychological states of others deceptively (e.g., manipulating what another sees). We show here that chimpanzees, one of humans' two closest primate relatives, sometimes attempt to actively conceal things from others. Specifically, when competing with a human in three novel tests, eight chimpanzees, from their first trials, chose to approach a contested food item via a route hidden from the human's view (sometimes using a circuitous path to do so). These findings not only corroborate previous work showing that chimpanzees know what others can and cannot see, but also suggest that when competing for food chimpanzees are skillful at manipulating, to their own advantage, whether others can or cannot see them.

Animals↗
PubMed2006

Sequence analysis of major histocompatibility complex class-II DQB1 (Patr-DQB1) alleles in chimpanzees by polymerase chain reaction-based methods.

The major histocompatibility complex (MHC) class-II genes are described as the genes that encode the antigen-presenting molecule. In particular, functional alleles of MHC class-II genes in nonhuman primates have been analyzed as part of the study of infectious and immune-mediated diseases in animal models and as part of efforts to understand the molecular evolution of human leukocyte antigen. The polymorphisms and sequence analysis of MHC class-II genes in a large number of subjects is necessary for the group management of nonhuman primates. In the present study, we attempted to analyze the DQB1 polymorphism in the common chimpanzee (Pan troglodytes) by exon 2 sequencing. For exact typing of Patr-DQB1 alleles, we carried out polymerase chain reaction-restriction fragment length polymorphism and sequence analysis. In the genomic DNA of 25 chimpanzees, 6 Patr-DQB1 alleles, including 2 new alleles, were detected. Identification and analysis of Patr-DQB1 alleles using this method may contribute to our understanding of Patr-DQB1 allelic diversity in individual chimpanzees and should be useful in facilitating colony management of chimpanzee groups in Japan.

Amino Acid Sequence↗
PubMed2005

Ethnomedicinal and bioactive properties of plants ingested by wild chimpanzees in Uganda.

Wild chimpanzees eat several plant species claimed by traditional healers to cure diseases. However, the behaviour leading apes to ingest these peculiar species is not clearly understood. Some of the items consumed by chimpanzees have low nutritional value, and there is a growing body of evidence suggesting that health might be improved or regulated by such ingestion. Observations concerning the diet and the health condition of wild chimpanzees (Pan troglodytes schweinfurthii) in the Kibale National Park (Uganda) are discussed in relation to the ethnomedicinal utilization of plant species reviewed in literature. Among the 163 plant parts known to be eaten by these chimpanzees, at least 35 (21.4%) are used in traditional medicine as treatments for intestinal parasites, skin infections, reproduction and respiratory diseases. Relationships with pharmacological properties are presented, taking into account the difficulties of interpreting ethnomedicinal data. In conclusion, a greater knowledge of ape's behaviour and health may provide a new complementary method to select plants for biomedical research.

Animals↗
PubMed2004

Climbing and the daily energy cost of locomotion in wild chimpanzees: implications for hominoid locomotor evolution.

As noted by previous researchers, the chimpanzee postcranial anatomy reflects a compromise between the competing demands of arboreal and terrestrial locomotion. In this study, we measured the distance climbed and walked per day in a population of wild chimpanzees and used published equations to calculate the relative daily energy costs. Results were used to test hypotheses regarding the arboreal-terrestrial tradeoff in chimpanzee anatomy, specifically whether arboreal adaptations serve to minimize daily locomotor energy costs by decreasing the energy spent climbing. Our results show that chimpanzees spend approximately ten-times more energy per day on terrestrial travel than on vertical climbing, a figure inconsistent with minimizing energy costs in our model. This suggests non-energetic factors, such as avoiding falls from the canopy, may be the primary forces maintaining energetically costly climbing adaptations. These analyses are relevant to anatomical comparisons with living and extinct hominoids.

Age Factors↗
PubMed2004

Complete nucleotide sequences and genome organization of four chimpanzee adenoviruses.

The complete nucleotide sequences for four adenoviruses-Simian Adenoviruses 21, 22, 23, and 24, originally isolated from chimpanzees, were determined. The genome organization of the chimpanzee adenoviruses was found to be similar to that of other adenoviruses. The viral gene products of the adenoviruses Simian Adenoviruses 22, 23, and 24 are very closely related to those of the (previously sequenced) chimpanzee adenovirus Simian Adenovirus 25. Simian Adenovirus 21 is most similar to human subgroup B adenoviruses HAdV-3, HAdV-7, and HAdV-35. Analysis of the capsid proteins hexon and fiber of the chimpanzee adenoviruses also supports the placement of Simian Adenovirus 21 in subgroup B and Simian Adenoviruses 22, 23, and 24 in subgroup E.

Adenovirus Early Proteins↗
PubMed2005

Chimpanzee adenovirus vaccine protects against Zaire Ebola virus.

This study evaluated the use of a chimpanzee-based adenovirus vaccine in mouse and Guinea pigs models of Zaire Ebola virus (ZEBOV) infection. Vaccine vector expressing the envelope glycoprotein of ZEBOV was created from the molecular clone of chimpanzee adenovirus pan7 (AdC7). AdC7 vaccine stimulated robust T and B cell responses to ZEBOV in naïve mice inducing complete protection to an otherwise lethal challenge of ZEBOV. Complete protection to Zaire Ebola virus was also observed in Guinea pigs vaccinated with a relatively low dose of AdC7 (5 x 10(9)/kg). Pre-existing immunity to AdHu5 was generated in mice following pre-exposure to AdHu5 or administration of pooled human immune globulin. Pre-existing immunity to human adenoviruses severely compromised the efficacy of the human AdHu5 vaccine but not the chimpanzee AdC7 vaccine. These results validate further development of Chimpanzee-based vaccine and highlight the impact of pre-existing immunity to the vaccine carrier.

Adenoviruses, Human↗
PubMed2004

Effects of chromosomal rearrangements on human-chimpanzee molecular evolution.

Many chromosomes are rearranged between humans and chimpanzees while others remain colinear. It was recently observed, based on over 100 genes, that the rates of protein evolution are substantially higher on rearranged than on colinear chromosomes during human-chimpanzee evolution. This finding led to the conclusion, since debated in the literature, that chromosomal rearrangements had played a key role in human-chimpanzee speciation. Here we re-examine this important conclusion by employing larger a data set (over 7000 genes), as well as alternative analyses. We show that the higher rates of protein evolution on rearranged chromosomes observed in the earlier study are not reproduced by our survey of the larger data set. We further show that the conclusion of the earlier study is likely confounded by two factors introduced by the relatively limited sample size: (1) nonuniform distribution of genes in the genome, and (2) stochastic noise in substitution rates inherent to short lineages such as the human-chimpanzee lineage. Our results offer a general cautionary note on the importance of controlling for hidden factors in studies involving bioinformatic surveys.

Animals↗
PubMed2000

Goal attribution in chimpanzees.

Does the chimpanzee attribute goals to others? Recent infant studies using the looking time measure have been interpreted as evidence that human infants attribute goals. An experiment modeled on these studies was carried out on chimpanzees, and the chimpanzees responded the way infants do. This indicates that chimpanzees also attribute goals and hence that this capacity is not distinctively human.

Animals↗
PubMed1979

Object sorting by chimpanzees and monkeys.

Chimpanzees and two species of monkey were compared on sorting tasks. When the sets of objects differed in multiple ways, most chimpanzees learnt to sort whereas only a few monkeys performed better than chance (and then inconsistently). When the objects within a set differed in one or two respects, so that sorting by one principle entailed "unsorting" by one or more alternative principles, chimpanzees had greater difficulty. Two young animals did rapidly learn to sort by color and size ("unsorting" by size and shape or by color and shape). They did not sort pictorial material and had difficulty in sorting by shape if "unsorting" by both color and size. The sorting task differentiated between the cognitive capacities of chimpanzees and monkeys whereas other tasks did not.

Animals↗
PubMed1998

Hepatitis C virus-specific CTL responses in PBMC from chimpanzees with chronic hepatitis C: determination of CTL and CTL precursor frequencies using a recombinant canarypox virus (ALVAC).

The aim of this study was to evaluate HCV-cytotoxic T lymphocyte response from PBMC in bulk CTL assays and in CTL precursor analyses using in vitro stimulation with canarypox virus (ALVAC) expressing HCV-capsid/E1/E2/NS2/NS3 antigens. Canarypox virus is naturally host-range restricted and does not replicate or cause cytopathology on mammalian cells. PBMC were obtained from four chimpanzees with chronic hepatitis C infection and one uninfected chimpanzee. CTL from bulk culture of PBMC and CTL precursor frequencies were found in three of the four chronically infected chimpanzees using ALVAC in vitro stimulation. No CTL response was detected in PBMC from the uninfected chimpanzee. The precursor frequencies of CTL specific for capsid, NS2 and NS3 proteins ranged between 1/2663 and 1/27202. No correlation was observed between percent cytolysis in bulk culture and CTL precursor frequencies. This method may prove useful in assessing the correlation between HCV-CTL response and virological or histological status.

Animals↗
PubMed1978

Hepatitis B outbreak among chimpanzees at the London Zoo.

Persistent carriage of hepatitis B virus in extremely high titre was identified in 5 out of 9 chimpanzees kept at the London Zoo. Antibody to this virus was present in the other 4 chimpanzees. Serological survey of the other primates in the Regent's Park collection did not reveal the presence of the surface antigen in 2 gorillas, 11 orang-utans, and 2 gibbons, although surface antibody was present in the serum of 1 gorilla and 2 orang-utans. 3 of the carrier chimpanzees were born at the Zoo and were the offspring of either a carrier mother or a carrier father, and perinatal transmission may have occurred. A strict safety code of practice was introduced and hepatitis B immunoglobulin was given at intervals to designated staff members. Sero-conversion did not occur in any of the 38 staff members under surveillance for more than 2 years. Treatment of the carrier state in the chimpanzees was attempted with human leucocyte interferon, with and without ribavirin ('Virazole'), and with adenine arabinoside, but the effects were mostly temporary.

Animals↗
PubMed1992

Comparison of five tandem repeat loci between humans and chimpanzees.

Five tandem repeat loci were studied in humans and chimpanzees using VNTR probes derived from human DNA. Shared alleles were found at three loci and were often the modal allele in one species but never in both. There was no difference in the mean number of alleles per locus. However, these species exhibited substantially different levels of gene diversity, with chimpanzees monomorphic at two loci. Evidence of reduced variability in chimpanzees corroborates earlier comparisons using isozymes and plasma proteins. Molecular mechanisms, population dynamics, or both may be responsible for these differences. Equal numbers of alleles per locus may reflect high mutation rates. By one test, chimpanzees were out of equilibrium at one locus, which may reflect a typing error or population substructure. The long divergence time, and the high probability of backward mutations, precludes accurate estimation of genetic distance between these species.

Alleles↗
PubMed2004

Body, head, and facial growth: comparison between macaques (Macaca fuscata) and chimpanzee (Pan troglodytes) based on somatometry.

Chimpanzees and macaques were compared in their growth of head, face and body, based on a large-scale somatometrical database. Their growth stages, i to v, were determined by inflection points in velocity curves. Sex differences in their growth are shown both by elongated stages in juvenile and adolescent and by the greater velocity in males in the stages. Chimpanzees need longer to get their full growth, especially in the later infantile and juvenile stages. The growth patterns are classified into three types of "sigmoid", "parabolic", and "fast & slow" in distance curves, and in velocity curves, they correspond to "convex", acceleration in mid-growth stage; "linear", linear deceleration with age; and "concave", rapid deceleration in earlier stages and slow velocity in later stages. Great differences between chimpanzees and macaques were found in their growth patterns of upper facial height and facial height, which are "linear" or intermediate of "linear" and "concave" in macaques and "concave" in chimpanzees. These differences in their growth patterns explain the characteristic development of craniofacial proportions.

Animals↗
PubMed2001

Chimpanzee social cognition.

In the late 1970s, Premack and Woodruff asked whether chimpanzees had a theory of mind. The answer to this question has remained elusive. Whereas some authors argue that chimpanzees are capable of mental state attribution, others maintain that they simply learn certain cues in ertain situations. Recent studies challenge both views. On the one hand, chimpanzees know much more about seeing than cue-based explanations suggest; on the other hand, this knowledge does not necessarily entail understanding of the mental states of others. The hypothesis I put forward here is that chimpanzees learn cues in social situations but that they are also capable of knowledge abstraction to solve novel problems.

Journal Article↗
PubMed1997

The glycophorin A gene family in gorillas: structure, expression, and comparison with the human and chimpanzee homologues.

Homologues of MN blood group antigens, encoded by members of the glycophorin A (GPA) gene family, are expressed in man, anthropoid apes, and some species of Old World monkeys. Previous studies had shown that a three-gene framework, most closely related to that in man, is present in the chimpanzee. Here we report the genomic structure, transcript map, and protein expression of the GYPA locus in gorillas. Compared to the corresponding human and chimpanzee homologues, gorilla GPA, GPB, and GPB/E genes each showed a high degree of sequence identity, with the same exon-intron organization. However, the expression of exons III, IV or V encoding the extracellular or membrane domains of homologous glycophorins varied among the three species. Gorilla GPA and GPB/E genes were unique in that the former occurred in two allelic forms with or without the expression of exon III, whereas the latter contained one (psi exon III) instead of two silenced exons (psi exons III and IV). Differences from human but not chimpanzee GPA also included the presence of a hybrid M/N epitope and the absence of the sequon for N-glycosylation. Owing to the retention of a functional exon III, gorilla GPB was more similar to chimpanzee GPB than human GPB. A transspecies allele was identified in the gorilla that gave rise to the Henshaw (He)-like antigen similar to that found in man. These results provide further insight into the model for evolution of the GPA gene family, indicating that the mechanisms underlying inter- and intraspecific polymorphism of glycophorins could predate the divergence of gorillas as the consequence of gene duplication and diversification.

Amino Acid Sequence↗
PubMed2002

Results of crossmatch between chimpanzee lymphocytes and sera of highly sensitized potential renal transplant recipients.

BACKGROUND: We tested the hypothesis that patients with a high frequency of lymphocytotoxic antibodies against human cells are not highly sensitized to major histocompatibility complexes expressed by chimpanzee cells. METHODS: Sera from six "hopelessly" sensitized patients (percentage reactive antibodies (PRA) > 99%) on the renal transplant waiting list were crossmatched with peripheral blood lymphocytes from 10 chimpanzees. Lymphocytotoxic antibodies reacting with chimpanzee peripheral blood lymphocytes were identified. RESULTS: Three of the six patients with a high frequency of lymphocytotoxic antibodies against human cells had no xenospecific antibodies. CONCLUSION: Patients with a high frequency of lymphocytotoxic antibodies against human cells are not all panel-reactive to chimpanzees. Unilateral donor nephrectomy in non-human primates may offer an opportunity for safe expansion of the donor organ pool for these patients.

Animals↗