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Science Advances Jan 2016Animal sociality facilitates the transmission of pathogenic microorganisms among hosts, but the extent to which sociality enables animals' beneficial microbial...
Animal sociality facilitates the transmission of pathogenic microorganisms among hosts, but the extent to which sociality enables animals' beneficial microbial associations is poorly understood. The question is critical because microbial communities, particularly those in the gut, are key regulators of host health. We show evidence that chimpanzee social interactions propagate microbial diversity in the gut microbiome both within and between host generations. Frequent social interaction promotes species richness within individual microbiomes as well as homogeneity among the gut community memberships of different chimpanzees. Sampling successive generations across multiple chimpanzee families suggests that infants inherited gut microorganisms primarily through social transmission. These results indicate that social behavior generates a pan-microbiome, preserving microbial diversity across evolutionary time scales and contributing to the evolution of host species-specific gut microbial communities.
Topics: Animals; Gastrointestinal Tract; Genetic Variation; Host Specificity; Microbiota; Pan troglodytes; Social Behavior; Species Specificity
PubMed: 26824072
DOI: 10.1126/sciadv.1500997 -
Philosophical Transactions of the Royal... Nov 2020In humans, senescence increases susceptibility to viral infection. However, comparative data on viral infection in free-living non-human primates-even in our closest...
In humans, senescence increases susceptibility to viral infection. However, comparative data on viral infection in free-living non-human primates-even in our closest living relatives, chimpanzees and bonobos ( and )-are relatively scarce, thereby constraining an evolutionary understanding of age-related patterns of viral infection. We investigated a population of wild eastern chimpanzees (), using metagenomics to characterize viromes (full viral communities) in the faeces of 42 sexually mature chimpanzees (22 males, 20 females) from the Kanyawara and Ngogo communities of Kibale National Park, Uganda. We identified 12 viruses from at least four viral families possessing genomes of both single-stranded RNA and single-stranded DNA. Faecal viromes of both sexes varied with chimpanzee age, but viral richness increased with age only in males. This effect was largely due to three viruses, salivirus, porprismacovirus and chimpanzee stool-associated RNA virus (chisavirus), which occurred most frequently in samples from older males. This finding is consistent with the hypothesis that selection on males for early-life reproduction compromises investment in somatic maintenance, which has delayed consequences for health later in life, in this case reflected in viral infection and/or shedding. Faecal viromes are therefore useful for studying processes related to the divergent reproductive strategies of males and females, ageing, and sex differences in longevity. This article is part of the theme issue 'Evolution of the primate ageing process'.
Topics: Age Factors; Animals; Feces; Female; Gastrointestinal Microbiome; Life History Traits; Male; Pan troglodytes; Population Dynamics; Sex Factors; Virome; Viruses
PubMed: 32951554
DOI: 10.1098/rstb.2019.0613 -
Primates; Journal of Primatology Mar 2021Between 1966 to 1969, Bernhard Grzimek (Frankfurt Zoological Society, FZS) introduced chimpanzees (Pan troglodytes) previously held in European institutions to Rubondo...
Between 1966 to 1969, Bernhard Grzimek (Frankfurt Zoological Society, FZS) introduced chimpanzees (Pan troglodytes) previously held in European institutions to Rubondo Island in Lake Victoria in Tanzania. Earlier publications report various numbers of released animals and that all founders originated from West Africa. We revise these assumptions through consultation of archived FZS records and genetic analyses of surviving descendants. Accordingly, 17 chimpanzees were transported to Africa in four waves, with male-female ratios of 3:8, 1:0, 1:0 and 2:2; one female died in transit. Thus, 16 chimpanzees were released in total. FZS and studbook records allocate a West African provenance to only 19% of the founders and a generic "Africa" origin to 56%. Still, studbook records render it unlikely that any of the founders were captive-born. In addition, our genetic analyses based on biological samples from the current descendants trace the geographical origin of their ancestors back to West Africa (P. t. verus) and Central Africa (P. t. troglodytes). Based on counts of individuals and night nests, we estimate that the population, since 1969, grew to around 35 individuals in 2014 (annual increase 3.3%). Thus, chimpanzees released onto a large forested island free from predators or hunting pressure, habitat destruction and conspecific competition can form a self-sustaining island population without human support.
Topics: Animals; Conservation of Natural Resources; DNA, Mitochondrial; Female; Genetics, Population; History, 20th Century; Islands; Male; Pan troglodytes; Pedigree; Tanzania
PubMed: 33532941
DOI: 10.1007/s10329-020-00884-5 -
Social Cognitive and Affective... Jan 2017The ability to recognize one's own reflection is shared by humans and only a few other species, including chimpanzees. However, this ability is highly variable across...
The ability to recognize one's own reflection is shared by humans and only a few other species, including chimpanzees. However, this ability is highly variable across individual chimpanzees. In humans, self-recognition involves a distributed, right-lateralized network including frontal and parietal regions involved in the production and perception of action. The superior longitudinal fasciculus (SLF) is a system of white matter tracts linking these frontal and parietal regions. The current study measured mirror self-recognition (MSR) and SLF anatomy in 60 chimpanzees using diffusion tensor imaging. Successful self-recognition was associated with greater rightward asymmetry in the white matter of SLFII and SLFIII, and in SLFIII's gray matter terminations in Broca's area. We observed a visible progression of SLFIII's prefrontal extension in apes that show negative, ambiguous, and compelling evidence of MSR. Notably, SLFIII's terminations in Broca's area are not right-lateralized or particularly pronounced at the population level in chimpanzees, as they are in humans. Thus, chimpanzees with more human-like behavior show more human-like SLFIII connectivity. These results suggest that self-recognition may have co-emerged with adaptations to frontoparietal circuitry.
Topics: Animals; Brain; Diffusion Tensor Imaging; Female; Functional Neuroimaging; Gray Matter; Male; Nerve Net; Pan troglodytes; Recognition, Psychology; Self Concept; White Matter
PubMed: 27803287
DOI: 10.1093/scan/nsw159 -
Behavior Genetics Mar 2017Polymorphisms of the arginine vasopressin receptor 1a (AVPR1a) gene have been linked to various measures related to human social behavior, including sibling conflict and...
Polymorphisms of the arginine vasopressin receptor 1a (AVPR1a) gene have been linked to various measures related to human social behavior, including sibling conflict and agreeableness. In chimpanzees, AVPR1a polymorphisms have been associated with traits important for social interactions, including sociability, joint attention, dominance, conscientiousness, and hierarchical personality dimensions named low alpha/stability, disinhibition, and negative emotionality/low dominance. We examined associations between AVPR1a and six personality domains and hierarchical personality dimensions in 129 chimpanzees (Pan troglodytes) living in Japan or in a sanctuary in Guinea. We fit three linear and three animal models. The first model included genotype, the second included sex and genotype, and the third included genotype, sex, and sex × genotype. All personality phenotypes were heritable. Chimpanzees possessing the long form of the allele were higher in conscientiousness, but only in models that did not include the other predictors; however, additional analyses suggested that this may have been a consequence of study design. In animal models that included sex and sex × genotype, chimpanzees homozygous for the short form of the allele were higher in extraversion. Taken with the findings of previous studies of chimpanzees and humans, the findings related to conscientiousness suggest that AVPR1a may be related to lower levels of impulsive aggression. The direction of the association between AVPR1a genotype and extraversion ran counter to what one would expect if AVPR1a was related to social behaviors. These results help us further understand the genetic basis of personality in chimpanzees.
Topics: Aggression; Alleles; Animals; Arginine; Behavior, Animal; Genotype; Models, Animal; Pan troglodytes; Personality; Phenotype; Polymorphism, Genetic; Receptors, Vasopressin; Social Behavior
PubMed: 27804047
DOI: 10.1007/s10519-016-9822-2 -
Folia Primatologica; International... 2020Social grooming is often exchanged between individuals in many primate species. Rates of bidirectional (or simultaneous mutual) grooming vary across primate species, and...
Social grooming is often exchanged between individuals in many primate species. Rates of bidirectional (or simultaneous mutual) grooming vary across primate species, and its function is not yet fully understood. For example, mutual grooming is frequent in chimpanzees but rare in most primate species including wild bonobos. There are, however, no quantitative data available in captive bonobos. Therefore, through the direct comparison between captive bonobos and chimpanzees, this study aimed to (i) compare the frequency of mutual grooming between Pan species, (ii) explore and compare the function of mutual grooming, and (iii) discuss the rarity of this behavior in wild bonobo populations. We tested three hypotheses following the previous literature in wild chimpanzees. The social bonding hypothesis states that mutual grooming facilitates the maintenance of strong dyadic bonds. The immediate investment hypothesis states that it serves to signal willingness to invest in the interaction. The switching hypothesis states that mutual grooming serves no function but only occurs as an overlap to change the direction of unidirectional grooming. Our findings strongly supported the immediate investment hypothesis, but not the others. Grooming bouts that included mutual grooming were longer and more equitable than bouts without, illustrating that captive Pan species use mutual grooming to maximize their short-term benefits and increase the social value of their interaction. Captive bonobos performed mutual grooming in similar proportions and for similar functions as captive and wild chimpanzees do. This contrasts with wild bonobos who engage in this behavior only rarely. We suggest that the differences in patterns of mutual grooming between captive and wild bonobos might be explained by different degrees of kinship or by a potential intraspecies variation.
Topics: Animals; Animals, Zoo; Female; Grooming; Male; Pan paniscus; Pan troglodytes; Social Behavior
PubMed: 32229727
DOI: 10.1159/000506308 -
Journal of Comparative Psychology... Feb 2024Primate facial musculature enables a wide variety of movements during bouts of communication, but how these movements contribute to signal construction and repertoire...
Primate facial musculature enables a wide variety of movements during bouts of communication, but how these movements contribute to signal construction and repertoire size is unclear. The suggests that morphological constraints shape the evolution of facial repertoires: species with higher facial mobility will produce larger and more complex repertoires. In contrast, the suggests that social needs shape the evolution of facial repertoires: as social complexity increases, so does communicative repertoire size. We tested these two hypotheses by comparing chimpanzees () and gibbons (family ), two distantly related apes who vary in their facial mobility and social organization. While gibbons have higher facial mobility than chimpanzees, chimpanzees live in more complex social groups than gibbons. We compared the morphology and complexity of facial repertoires for both apes using Facial Action Coding Systems designed for chimpanzees and gibbons. Our comparisons were made at the level of individual muscle movements (action units [AUs]) and the level of muscle movement combinations (AU combinations). Our results show that the chimpanzee facial signaling repertoire was larger and more complex than gibbons, consistent with the On average, chimpanzees produced AU combinations consisting of more morphologically distinct AUs than gibbons. Moreover, chimpanzees also produced more morphologically distinct AU combinations than gibbons, even when focusing exclusively on AUs present in both apes. Therefore, our results suggest that socio-ecological factors were more important than anatomical ones to the evolution of facial signaling repertoires in chimpanzees and gibbons. (PsycInfo Database Record (c) 2024 APA, all rights reserved).
Topics: Animals; Animal Communication; Hylobates; Pan troglodytes; Facial Expression; Face
PubMed: 37166944
DOI: 10.1037/com0000350 -
Proceedings of the National Academy of... Jun 2022Human between-group interactions are highly variable, ranging from violent to tolerant and affiliative. Tolerance between groups is linked to our unique capacity for...
Human between-group interactions are highly variable, ranging from violent to tolerant and affiliative. Tolerance between groups is linked to our unique capacity for large-scale cooperation and cumulative culture, but its evolutionary origins are understudied. In chimpanzees, one of our closest living relatives, predominantly hostile between-group interactions impede cooperation and information flow across groups. In contrast, in our other closest living relative, the bonobo, tolerant between-group associations are observed. However, as these associations can be frequent and prolonged and involve social interactions that mirror those within groups, it is unclear whether these bonobos really do belong to separate groups. Alternatively, the bonobo grouping patterns may be homologous to observations from the large Ngogo chimpanzee community, where individuals form within-group neighborhoods despite sharing the same membership in the larger group. To characterize bonobo grouping patterns, we compare the social structure of the Kokolopori bonobos with the chimpanzee group of Ngogo. Using cluster analysis, we find temporally stable clusters only in bonobos. Despite the large spatial overlap and frequent interactions between the bonobo clusters, we identified significant association preference within but not between clusters and a unique space use of each cluster. Although bonobo associations are flexible (i.e., fission-fusion dynamics), cluster membership predicted the bonobo fission compositions and the spatial cohesion of individuals during encounters. These findings suggest the presence of a social system that combines clear in-group/out-group distinction and out-group tolerance in bonobos, offering a unique referential model for the evolution of tolerant between-group interactions in humans.
Topics: Aggression; Animals; Hostility; Mass Gatherings; Pan paniscus; Pan troglodytes; Social Behavior
PubMed: 35727986
DOI: 10.1073/pnas.2201122119 -
American Journal of Veterinary Research Jun 2019To comprehensively characterize cardiac structure and function, from infancy to adulthood, in male and female wild-born captive chimpanzees () living in sanctuaries.
OBJECTIVE
To comprehensively characterize cardiac structure and function, from infancy to adulthood, in male and female wild-born captive chimpanzees () living in sanctuaries.
ANIMALS
290 wild-born captive chimpanzees.
PROCEDURES
Physical and echocardiographic examinations were performed on anesthetized chimpanzees in 3 sanctuaries in Africa between October 2013 and May 2017. Results were evaluated across age groups and between sexes, and potential differences were assessed with multiple 1-way independent Kruskal-Wallis tests.
RESULTS
Results indicated that left ventricular diastolic and systolic function declined at a younger age in males than in females. Although differences in right ventricular diastolic function were not identified among age groups, right ventricular systolic function was lower in adult chimpanzees (> 12 years old), compared with subadult (8 to 12 years old) and juvenile (5 to 7 years old) chimpanzees. In addition, male subadult and adult chimpanzees had larger cardiac wall dimensions and chamber volumes than did their female counterparts.
CONCLUSIONS AND CLINICAL RELEVANCE
Results of the present study provided useful reference intervals for cardiac structure and function in captive chimpanzees categorized on the basis of age and sex; however, further research is warranted to examine isolated and combined impacts of blood pressure, age, body weight, and anesthetic agents on cardiac structure and function in chimpanzees.
Topics: Aging; Animals; Animals, Wild; Animals, Zoo; Blood Pressure; Body Weight; Echocardiography; Female; Heart; Male; Pan troglodytes; Reference Values
PubMed: 31140849
DOI: 10.2460/ajvr.80.6.547 -
Journal of Human Evolution May 2021Based on ontogenetic data of endocranial shape, it has been proposed that a younger than previously assumed developmental status of the 1.5-Myr-old KNM-ER 42700 calvaria... (Comparative Study)
Comparative Study
Based on ontogenetic data of endocranial shape, it has been proposed that a younger than previously assumed developmental status of the 1.5-Myr-old KNM-ER 42700 calvaria could explain why the calvaria of this fossil does not conform to the shape of other Homo erectus individuals. Here, we investigate (ecto)neurocranial ontogeny in H. erectus and assess the proposed juvenile status of this fossil using recent Homo sapiens, chimpanzees (Pan troglodytes), and Neanderthals (Homo neanderthalensis) to model and discuss changes in neurocranial shape from the juvenile to adult stages. We show that all four species share common patterns of developmental shape change resulting in a relatively lower cranial vault and expanded supraorbital torus at later developmental stages. This finding suggests that ectoneurocranial data from extant hominids can be used to model the ontogenetic trajectory for H. erectus, for which only one well-preserved very young individual is known. However, our study also reveals differences in the magnitudes and, to a lesser extent, directions of the species-specific trajectories that add to the overall shared pattern of neurocranial shape changes. We demonstrate that the very young H. erectus juvenile from Mojokerto together with subadult and adult H. erectus individuals cannot be accommodated within the pattern of the postnatal neurocranial trajectory for humans. Instead, the chimpanzee pattern might be a better 'fit' for H. erectus despite their more distant phylogenetic relatedness. The data are also compatible with an ontogenetic shape trajectory that is in some regards intermediate between that of recent H. sapiens and chimpanzees, implying a unique trajectory for H. erectus that combines elements of both extant species. Based on this new knowledge, neurocranial shape supports the assessment that KNM-ER 42700 is a young juvenile H. erectus if H. erectus followed an ontogenetic shape trajectory that was more similar to chimpanzees than humans.
Topics: Animals; Child; Child, Preschool; Fossils; Hominidae; Humans; Infant; Neanderthals; Pan troglodytes; Phylogeny; Skull
PubMed: 33794419
DOI: 10.1016/j.jhevol.2021.102980