Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| opportunistic feeding strategy in wild immature chimpanzees: implications for children as active foragers in human evolution. | modern human (homo sapiens) children are generally considered to be dependent on older individuals for foods, even after weaning. however, recent studies of hunter-gatherer societies have reported that children can also acquire food by themselves, although the degree of self-provisioning by children differs among groups and is considered a facultative adaptation. to investigate the dependence of children on older individuals for food and the importance of self-provisioning in early hominins, i e ... | 2019 | 31358176 |
| travel linearity and speed of human foragers and chimpanzees during their daily search for food in tropical rainforests. | to understand the evolutionary roots of human spatial cognition, researchers have compared spatial abilities of humans and one of our closest living relatives, the chimpanzee (pan troglodytes). however, how humans and chimpanzees compare in solving spatial tasks during real-world foraging is unclear to date, as measuring such spatial abilities in natural habitats is challenging. here we compared spatial movement patterns of the mbendjele bayaka people and the taï chimpanzees during their daily s ... | 2019 | 31363113 |
| short and long-term temporal consistency of hand preference in sanctuary chimpanzees (pan troglodytes) for unimanual and bimanual coordinated tasks. | longitudinal research on manual preferences in humans and non-human primates has mainly been conducted from a developmental perspective, with only a few studies exploring long-term stability of this trait during adulthood. therefore, we investigated short-term (1 year) and long-term (10 and 11 years) consistency of hand preference in a naturalistic group of 19 juvenile and adult chimpanzees (pan troglodytes) by using two experimental tasks, one unimanual (simple reaching) and one bimanual (tube ... | 2019 | 31374226 |
| response to garcia and dunn. | garcia and dunn [1] raise some interesting and valuable points regarding our recent paper in current biology[2]. as garcia and dunn [1] point out, cross-species variation in vocal and anatomical relations allows for the identification of relevant outliers from the body size - fundamental frequency (f0) regression. however, this depends on the premise that the chosen or available f0 and body size values are typical of the species. a motivation for our study [2] was in part to improve the accuracy ... | 2019 | 31386846 |
| evolutionary divergence of neuroanatomical organization and related genes in chimpanzees and bonobos. | given their close genetic relatedness to humans, bonobos (pan paniscus) and chimpanzees (pan troglodytes) offer an essential comparative framework for studying the evolution of uniquely human traits. these two species differ markedly in their socio-behavioral repertoires, which is reflected in neuroanatomical differences that have been reported in the literature. however, phylogenetic comparative methods have not yet been used to map the evolution of neuroanatomical traits in bonobos and chimpan ... | 2019 | 31422793 |
| optional-switch cognitive flexibility in primates: chimpanzees' (pan troglodytes) intermediate susceptibility to cognitive set. | within human problem-solving, the propensity to use a familiar approach, rather than switch to a more efficient alternative is pervasive. this susceptibility to "cognitive set" prevents optimization by biasing response patterns toward known solutions. in a recent study, which used a nonverbal touch screen task, baboons exhibited a striking ability to deviate from their learned strategy to use a more efficient shortcut. humans, on the other hand, displayed the opposite response pattern and almost ... | 2020 | 31424232 |
| exploring interactions between blastocystis sp., strongyloides spp. and the gut microbiomes of wild chimpanzees in senegal. | gut parasites exert an important influence on the gut microbiome, with many studies focusing on the human gut microbiome. it has, however, undergone severe richness depletion. hygienic lifestyle, antimicrobial treatments and altered gut homeostasis (e.g., chronic inflammation) reduce gut microbiome richness and also parasite prevalence; which may confound results. studying species closely related to humans could help overcome this problem by providing insights into the ancestral relationship bet ... | 2019 | 31442596 |
| the psychological mechanisms underlying reciprocal prosociality in chimpanzees (pan troglodytes). | in both the wild and captivity, chimpanzees engage in reciprocal patterns of prosocial behavior. however, the proximate mechanisms underlying these patterns are unclear. in the current study, we investigated whether chimpanzees prefer to act prosocially toward conspecifics who have directly benefited them (perhaps based on an affective bond) or whether they simply observe the prosocial behavior of others in general (including indirectly to third parties) and preferentially interact with and beha ... | 2020 | 31464454 |
| towards systematic and evidence-based conservation planning for western chimpanzees. | as animal populations continue to decline, frequently driven by large-scale land-use change, there is a critical need for improved environmental planning. while data-driven spatial planning is widely applied in conservation, as of yet it is rarely used for primates. the western chimpanzee (pan troglodytes verus) declined by 80% within 24 years and was uplisted to critically endangered by the iucn red list of threatened species in 2016. to support conservation planning for western chimpanzees, we ... | 2019 | 31468565 |
| do chimpanzees (pan troglodytes) console a bereaved mother? | comparative thanatology encompasses the study of death-related responses in non-human animals and aspires to elucidate the evolutionary origins of human behavior in the context of death. many reports have revealed that humans are not the only species affected by the death of group members. non-human primates in particular show behaviors such as congregating around the deceased, carrying the corpse for prolonged periods of time (predominantly mothers carrying dead infants), and inspecting the cor ... | 2020 | 31485897 |
| observational data reveal evidence and parameters of contagious yawning in the behavioral repertoire of captive-reared chimpanzees (pan troglodytes). | there is robust experimental evidence for contagious yawning, yet observational studies of naturalistic behavior have been fewer. without data from real-world behavior, researchers have questioned the existence of contagious yawning and made assumptions about some parameters (e.g., the duration of the effect). we observed contagious yawning in chimpanzees to confirm/disconfirm its existence in the behavioral repertoire of this species, and if present, provide some of the missing descriptives. we ... | 2019 | 31519942 |
| density and distribution of western chimpanzees around a bauxite deposit in the boé sector, guinea-bissau. | the boé sector in southeast guinea-bissau harbors a population of western chimpanzees (pan troglodytes verus) that inhabits a mosaic of forest and savanna. the boé sector contains a substantial bauxite deposit in a region called ronde hill, and there are plans for the construction of a mine, which may endanger the chimpanzee population. in 1-week survey in may 2013, we used the standing crop nest counts method to obtain the number of chimpanzee nests and from that estimate the density and abunda ... | 2019 | 31520454 |
| how chimpanzees (pan troglodytes) share the spoils with collaborators and bystanders. | chimpanzees hunt cooperatively in the wild, but the factors influencing food sharing after the hunt are not well understood. in an experimental study, groups of three captive chimpanzees obtained a monopolizable food resource, either via two individuals cooperating (with the third as bystander) or via one individual acting alone alongside two bystanders. the individual that obtained the resource first retained most of the food but the other two individuals attempted to obtain food from the "capt ... | 2019 | 31545837 |
| chimpanzees use observed temporal directionality to learn novel causal relations. | we investigated whether chimpanzees use the temporal sequence of external events to determine causation. seventeen chimpanzees (pan troglodytes) witnessed a human experimenter press a button in two different conditions. when she pressed the "causal button" the delivery of juice and a sound immediately followed (cause-then-effect). in contrast, she pressed the "non-causal button" only after the delivery of juice and sound (effect-then-cause). when given the opportunity to produce the desired juic ... | 2019 | 31549268 |
| social relationships and greetings in wild chimpanzees (pan troglodytes): use of signal combinations. | signals of submission, so-called 'greetings', represent an important tool for the regulation of social life in primates. in chimpanzees, vocalizations and gestures are commonly employed to communicate greetings, however, the topic of signal complexity (i.e., combinations of signals) during greeting instances has been neglected by research to date. here, we investigate combinatorial possibilities in vocal greetings in a free-ranging group of chimpanzees (pan troglodytes) and study how greeter sex ... | 2019 | 31552566 |
| the cochlea of the sima de los huesos hominins (sierra de atapuerca, spain): new insights into cochlear evolution in the genus homo. | the cochlea contains taxonomic and phylogenetic information and its morphology is related with hearing abilities among fossil hominins. data for the genus homo is presently limited to early homo and the early neandertals from krapina. the present study of the middle pleistocene hominins from the sima de los huesos (sh) provides new evidence on cochlear evolution in the genus homo. we compared the absolute length, proportional lengths of each turn, number of turns, size and shape of the cross-sec ... | 2019 | 31569005 |
| novel y-chromosome long non-coding rnas expressed in human male cns during early development. | global microarray gene expression analyses previously demonstrated differences in female and male embryos during neurodevelopment. in particular, before sexual maturation of the gonads, the differences seem to concentrate on the expression of genes encoded on the x- and y-chromosomes. to investigate genome-wide differences in expression during this early developmental window, we combined high-resolution rna sequencing with qpcr to analyze brain samples from human embryos during the first trimest ... | 2019 | 31608120 |
| basicranial ontogeny comparison in pan troglodytes and homo sapiens and its use for developmental stage definition of knm-er 42700. | this study aims to develop a comparative basis for assessing the developmental stage of knm-er 42700 based on the ontogenetic pattern of the ectocranial surface of the basicranium in modern humans and chimpanzees. | 2019 | 31633198 |
| idiopathic myocardial fibrosis in captive chimpanzees (pan troglodytes). | cardiovascular disorders and predominantly idiopathic myocardial fibrosis are frequently associated with mortality among zoo-housed chimpanzees (pan troglodytes). formalin-fixed whole hearts of deceased chimpanzees housed in zoos (n = 33) and an african sanctuary (n = 2) underwent detailed macroscopic and histopathologic examination using a standardized protocol. archived histological slides from the hearts of 23 additional african sanctuary-housed chimpanzees were also examined. myocardial fibr ... | 2020 | 31640487 |
| assessment of in situ nest decay rate for chimpanzees (pan troglodytes ellioti matschie, 1914) in mbam-djerem national park, cameroon: implications for long-term monitoring. | accurate assessment of great ape populations is a prerequisite for conservation planning. indirect survey methods using nest and dung, and a set of conversion parameters related to nest decay rates, are increasingly used. most surveys use the standing crop nest count (scnc) method, whereby nests are counted along transects and the estimated nest density is converted into chimpanzee density using an often non-local nest decay rate. the use of non-local decay rate is thought to introduce substanti ... | 2020 | 31659555 |
| a modern approach to minimally invasive surgery and laparoscopic sterilization in a chimpanzee. | we present the case of ruby, a 21-year-old hand-reared chimpanzee (pan troglodytes) who had an obstetric history significant for a premature stillborn infant that was conceived while on oral contraceptive pills, followed by a full term healthy delivery complicated by neonatal demise attributed to inappropriate maternal care. she was recommended for permanent sterilization due to her history of conception while on oral contraceptives. she underwent uncomplicated laparoscopic bilateral tubal ligat ... | 2019 | 31662944 |
| faster growth corresponds with shallower linear hypoplastic defects in great ape canines. | deeper or more 'severe' linear enamel hypoplasia (leh) defects are hypothesized to reflect more severe stress during development, but it is not yet clear how depth is influenced by intrinsic enamel growth patterns. recent work documented inter- and intraspecific differences in leh defect depth in extant great apes, with mountain gorillas having shallower defects than other taxa, and females having deeper defects than males. here, we assess the correspondence of inter- and intraspecific defect de ... | 2019 | 31704354 |
| human-like adrenal development in wild chimpanzees: a longitudinal study of urinary dehydroepiandrosterone-sulfate and cortisol. | the development of the adrenal cortex varies considerably across primates, being most conspicuous in humans, where a functional zona reticularis-the site of dehydroepiandrosterone-sulfate (dhea/s) production-does not develop until middle childhood (5-8 years). prior reports suggest that a human-like adrenarche, associated with a sharp prepubertal increase in dhea/s, may only occur in the genus pan. however, the timing and variability in adrenarche in chimpanzees remain poorly described, owing to ... | 2020 | 31709585 |
| ontogenetic insights into the significance of mandibular corpus shape variation in hominoids: developmental covariation between m2 crypt formation and corpus shape. | here, we quantify and compare the cross-sectional shape of the mandibular corpus between m1 and m2 during growth in pan paniscus, pan troglodytes, and pongo pygmaeus. the goal is to assess the hypothesis that the shape of the corpus is influenced by the development of permanent molars in their crypts, by examining ontogenetic changes in corpus shape and investigating covariation between corpus shape and m2 and m3 molar crypt forms. | 2020 | 31710703 |
| potential adaptations for bipedalism in the thoracic and lumbar vertebrae of homo sapiens: a 3d comparative analysis. | a number of putative adaptations for bipedalism have been identified in the hominin spine. however, it is possible that some have been overlooked because only a few studies have used 3d and these studies have focused on cervical vertebrae. with this in mind, we used geometric morphometric techniques to compare the 3d shapes of three thoracic and two lumbar vertebrae of homo sapiens, pan troglodytes, gorilla gorilla, and pongo pygmaeus. the study had two goals. one was to confirm the existence of ... | 2019 | 31711026 |
| nhp-immunome: a translational research-oriented database of non-human primate immune system proteins. | we are currently living the advent of a new age for medicine in which basic research is being quickly translated into marketable drugs, and the widespread access to genomics data is allowing the design and implementation of personalized solutions to medical conditions. non-human primates (nhp) have gained an essential role in drug discovery and safety testing due to their close phylogenetic relationship to humans. in this study, a collection of well characterized genes of the human immune system ... | 2020 | 31733823 |
| cross-species validation of human specific str system, sureid® 21g and sureid® 23comp (health gene technologies) in chimpanzee (pan troglodytes). | the human specific commercially available strs system are often not tested in non human primates for their cross applicability. the aim of this study is to test cross-species validation of two commercially available human specific str kits i.e. sureid® 21g and sureid® 23comp (health gene technologies) for their positive application in chimpanzee (pan troglodytes). | 2019 | 31744541 |
| oral microbiome diversity in chimpanzees from gombe national park. | historic calcified dental plaque (dental calculus) can provide a unique perspective into the health status of past human populations but currently no studies have focused on the oral microbial ecosystem of other primates, including our closest relatives, within the hominids. here we use ancient dna extraction methods, shotgun library preparation, and next generation illumina sequencing to examine oral microbiota from 19 dental calculus samples recovered from wild chimpanzees (pan troglodytes sch ... | 2019 | 31758037 |
| trabecular variation in the first metacarpal and manipulation in hominids. | the dexterity of fossil hominins is often inferred by assessing the comparative manual anatomy and behaviors of extant hominids, with a focus on the thumb. the aim of this study is to test whether trabecular structure is consistent with what is currently known about habitually loaded thumb postures across extant hominids. | 2020 | 31762017 |
| social and ecological complexity is associated with gestural repertoire size of wild chimpanzees. | increasing our understanding of primate gestural communication can provide new insights into language evolution. a key question in primate communication is the association between the social relationships of primates and their repertoire of gestures. such analyses can reveal how primates use their repertoire of gestural communication to maintain their networks of family and friends, much as humans use language to maintain their social networks. in this study we examined the association between t ... | 2020 | 31773892 |
| differences in mhc-b diversity and kir epitopes in two populations of wild chimpanzees. | the major histocompatibility complex (mhc) class i genes play a critical role within the immune system, both by the presentation of antigens from intracellular pathogens to immunocompetent cells and by the interaction with killer cell immunoglobulin-like receptors (kir) on natural killer cells (nk cells). genes of the mhc are highly diverse, and mhc variation can have effects on the immune functionality of individuals; hence, comparisons of mhc diversity among closely related phylogenetic taxa m ... | 2019 | 31797008 |
| trabecular architecture of the capitate and third metacarpal through ontogeny in chimpanzees (pan troglodytes) and gorillas (gorilla gorilla). | chimpanzees (pan troglodytes) and gorillas (gorilla gorilla) both knuckle-walk in adulthood but are known to develop their locomotor strategies differently. using dentally defined age-groups of both pan and gorilla and behavioral data from the literature, this study presents an internal trabecular bone approach to better understand the morphological ontogeny of knuckle-walking in these taxa. capitate and third metacarpal bones were scanned by μct at 23-43 μm resolution with scaled volumes of int ... | 2020 | 31805487 |
| jaw elevator muscle coordination during rhythmic mastication in primates: are triplets units of motor control? | the activity of mammal jaw elevator muscles during chewing has often been described using the concept of the triplet motor pattern, in which triplet i (balancing side superficial masseter and medial pterygoid; working side posterior temporalis) is consistently activated before triplet ii (working side superficial masseter and medial pterygoid; balancing side posterior temporalis), and each triplet of muscles is recruited and modulated as a unit. here, new measures of unison, synchrony, and coord ... | 2020 | 31821998 |
| 3d shape analyses of extant primate and fossil hominin vertebrae support the ancestral shape hypothesis for intervertebral disc herniation. | recently we proposed an evolutionary explanation for a spinal pathology that afflicts many people, intervertebral disc herniation (plomp et al. [2015] bmc evolutionary biology 15, 68). using 2d data, we found that the bodies and pedicles of lower vertebrae of pathological humans were more similar in shape to those of chimpanzees than were those of healthy humans. based on this, we hypothesized that some individuals are more prone to intervertebral disc herniation because their vertebrae exhibit ... | 2019 | 31842740 |
| chimpanzees use tree species with a resonant timbre for accumulative stone throwing. | animals use tools for communication relatively rarely compared to tool use for extractive foraging. we investigated the tool-use behaviour accumulative stone throwing (ast) in wild chimpanzees, who regularly throw rocks at trees, producing impact sounds and resulting in the aggregations of rocks. the function of ast remains unknown but appears to be communication-related. we conducted field experiments to test whether impact sounds produced by throwing rocks at trees varied according to the tree ... | 2019 | 31847748 |
| rhythmic swaying induced by sound in chimpanzees (pan troglodytes). | music and dance are universal across human culture and have an ancient history. one characteristic of music is its strong influence on movement. for example, an auditory beat induces rhythmic movement with positive emotions in humans from early developmental stages. in this study, we investigated if sound induced spontaneous rhythmic movement in chimpanzees. three experiments showed that: 1) an auditory beat induced rhythmic swaying and other rhythmic movements, with larger responses from male c ... | 2020 | 31871195 |
| how to measure chimpanzee party size? a methodological comparison. | chimpanzees (pan troglodytes) live in fission-fusion societies where community members form temporary parties that frequently change in size and composition. chimpanzee party size and composition have been widely studied to identify proximate causes of grouping patterns, and party size estimates are used to assess population sizes and densities. numerous socio-ecological factors influence chimpanzee party size, but findings differ across studies. various methods to measure party size exist, incl ... | 2020 | 31894437 |
| chimpanzees (pan troglodytes) tolerate some degree of inequity while cooperating but refuse to donate effort for nothing. | in cooperative hunting, a carcass cannot be divided equally, and hunts may be unsuccessful. we studied how chimpanzees respond to these two variables, working for unequal rewards and no rewards, which have been rarely included in experimental cooperative tasks. we presented chimpanzees with a task requiring three chimpanzees to work together and varied the reward structure in two separate experiments. in experiment 1, two individuals received more rewards than the third, making the outcome unequ ... | 2020 | 31894611 |
| between-group competition impacts reproductive success in wild chimpanzees. | between-group competition in social animals appears to be a prominent selective pressure shaping the evolution of territoriality and cooperation [1-4]. evidence for an effect of between-group competition on fitness in territorial species, however, is mostly lacking because of difficulty in measuring between-group competition and its long-term impact [5]. between-group competition corresponds to a complex set of interactions between neighboring groups, and its intensity seems to depend on the com ... | 2020 | 31902731 |
| adolescent male chimpanzees (pan troglodytes) form social bonds with their brothers and others during the transition to adulthood. | social relationships play an important role in animal behavior. bonds with kin provide indirect fitness benefits, and those with nonkin may furnish direct benefits. adult male chimpanzees (pan troglodytes) exhibit social bonds with maternal brothers as well as unrelated adult males, facilitating cooperative behavior, but it is unclear when these bonds develop. prior studies suggest that social bonds emerge during adolescence. alternatively, bonds may develop during adulthood when male chimpanzee ... | 2020 | 31903634 |
| maternal effects on offspring growth indicate post-weaning juvenile dependence in chimpanzees (pan troglodytes verus). | in animals with altricial offspring, most growth occurs after birth and may be optimized by post-natal maternal care. maternal effects on growth may be influenced by individual characteristics of the mothers, such as social status, individual investment strategies and the length of association with offspring. the prolonged juvenile dependence seen in humans is a distinctive life history adaptation, which may have evolved to facilitate sustained somatic and brain growth.in chimpanzees, offspring ... | 2020 | 31911809 |
| body perception in chimpanzees (pan troglodytes): the effect of body structure changes. | chimpanzees have been found to show the inversion effect to visual stimuli of intact chimpanzee bodies, suggesting that they have a specific way of body processing. in this study, we examined how changes of body structures affect the inversion effect to reveal the properties of their body processing. we focused on two aspects of body structures: the first-order relations (i.e., body part arrangements) and body proportions. the experimental conditions had stimuli of chimpanzee bodies with scrambl ... | 2020 | 31916785 |
| functional parameters of chimpanzee (pan troglodytes) sperm from ejaculates collected by rectal probe electrostimulation and by artificial vagina. | this study compares functional parameters of sperm from ejaculates collected from 15 adult male chimpanzees using rectal probe electrostimulation (rpe) and from 10 adult male chimpanzees trained to use an artificial vagina (av). computer assisted motion analysis (cama) showed no significant differences in mean values for straight line velocity (vsl), linearity (lin), curvilinear velocity (vcl), and lateral head movement (alh) of sperm from ejaculates collected by rpe and by av. there was, howeve ... | 1996 | 31918494 |
| characteristics of chimpanzee (pan troglodytes) ejaculates collected by rectal probe electrostimulation and by artificial vagina. | this study compares characteristics of ejaculates collected from 16 adult male chimpanzees using rectal probe electrostimulation (rpe) and from 10 adult male chimpanzees trained to use an artificial vagina (av). ejaculate weight, semen volume, and sperm number were significantly lower (p < 0.01) and percentage liquefaction was significantly higher (p < 0.01) in ejaculates collected by rpe. percentages of motile sperm and of live sperm in semen did not differ significantly between the two collect ... | 1995 | 31924077 |
| ontogeny and the evolution of adult body size dimorphism in apes. | this analysis investigates the ontogeny of body size dimorphism in apes. the processes that lead to adult body size dimorphism are illustrated and described. potential covariation between ontogenetic processes and socioecological variables is evaluated. mixed-longitudinal growth data from 395 captive individuals (representing hylobates lar [gibbon], hylobates syndactylus [siamang], pongo pygmaeus [orangutan], gorilla gorilla [gorilla], pan paniscus [pygmy chimpanzee], and pan troglodytes ["commo ... | 1995 | 31924084 |
| the use of citalopram hydrobromide to manage aggression in a male chimpanzee (pan troglodytes). | at times severe, and occasionally fatal, aggression plays an intrinsic role in chimpanzee behavior and social dynamics, particularly among male chimpanzees in both managed and free-ranging troops. at the los angeles zoo, one adult male's natural aggressive behavior developed into unmanageable violence during a period of social and emotional instability consequent to the lack of an established alpha male in the colony. the severity and duration of resulting attacks on a subdominant member of the ... | 2020 | 31926537 |
| a quantitative comparison of terrestrial herbaceous food consumption by pan paniscus in the lomako forest, zaire, and pan troglodytes in the kibale forest, uganda. | differences in the social organization and dental morphology of pan paniscus (bonobos) and pan troglodytes (chimpanzees) have been related to differences in the spatiotemporal availability of food and its exploitation. the presence of abundant terrestrial herbaceous vegetation (thv) in the bonobo's habitat and the apparent greater reliance on herbs for food has been used to explain differences in party size and, by extension, social organization. using fecal analysis, we assess quantitatively th ... | 1994 | 31936906 |
| drinking tools of wild chimpanzees at bossou. | use of drinking tools by wild chimpanzees (pan troglodytes) and the context in which the tools were used were studied at bossou, republic of guinea, west africa. during the middle to late dry season and early wet season liquids are available occasionally in the holes of trees. chimpanzees drank water or sap using a leaf (or fiber) as a sponge or spoon. when the chimpanzees were on the ground, they tended to use one of a few kinds of soft, hairless leaves, if they were available nearby. females, ... | 1995 | 31936951 |
| relationship of chimpanzee leaf-swallowing to a tapeworm infection. | leaf-swallowing by chimpanzees pan troglodytes has been hypothesized to control parasites, but it has not yet been shown to be associated with specific parasitic infections. this report takes advantage of a tapeworm infestation among wild chimpanzees to examine whether leaf-swallowing was associated with the presence of tapeworms. leaf-swallowing was monitored over 6.5 years in two chimpanzee communities in kibale national park (uganda). in one community, tape-worms ?bertiella studeri were found ... | 1995 | 31936954 |
| sodium, potassium, and protein concentrations and 2d-sds-page of epididymal luminal and ejaculated seminal fluids of the adult chimpanzee (pan troglodytes). | the concentration of soluble protein and of sodium and potassium ions was estimated in chimpanzee caput epididymal luminal fluid, cauda epididymal luminal fluid, and ejaculated seminal fluid. protein concentration was 48.5 ± 1.5 μg/μl in caput fluid, 26.8 ± 2.0 μg/μl in cauda fluid, and 53.0 ± 7.9 μg/μl in seminal fluid. sodium concentration was 127.0 ± 7.0 mm in caput fluid, 34.5 ± 1.8 mm in cauda fluid, and 18.8 ± 1.8 mm in seminal fluid. potassium concentration was 58.0 ± 0.0 mm in caput flui ... | 1994 | 31936966 |
| range use of the forest chimpanzees of kibale: implications for the understanding of chimpanzee social organization. | we contrast the range use patterns of male and female chimpanzees (pan troglodytes) based on repeated sightings over three years of 19 individuals in the kanyawara community of kibale forest reserve, uganda. depending on how home range size was calculated, male chimpanzees used an area that was 1.5 to 2 times greater than that of females. there was no difference between the sexes in whether their home ranges were used in a clumped or uniform fashion. however, males were more likely to be seen in ... | 1993 | 31936990 |
| anogenital swelling in pregnant chimpanzees of gombe national park. | previous studies show that anogenital swelling patterns of pregnant chimpanzees in captivity are correlated with the female's age during pregnancy and are associated with changes in social behavior. the purpose of the present study was to investigate whether the anogenital swelling patterns of free-ranging pregnant chimpanzees resemble those reported for captive chimpanzees. we reviewed the records of 47 pregnancies experienced by 20 female chimpanzees living in gombe national park from 1975 to ... | 1993 | 31937004 |
| composition of the diet of chimpanzees and comparisons with that of sympatric lowland gorillas in the lopé reserve, gabon. | over an eight-year period, a total of 174 food items were recorded for chimpanzees (pan t. troglodytes) in the lopé reserve in central gabon. plant foods, principally fruit, dominated the diet but insects were eaten regularly, and predation on at least three species of mammal occurred infrequently. the diversity of the vegetative component of the diet (leaves, stems, and bark) was probably underestimated by fecal analysis. comparison of chimpanzee diet at lopé with that of sympatric lowland gori ... | 1993 | 31937009 |
| early life experience and alterations of group composition shape the social grooming networks of former pet and entertainment chimpanzees (pan troglodytes). | the long-term effects of early life adversities on social capacities have been documented in humans and wild-caught former laboratory chimpanzees (pan troglodytes). however, former pet and entertainment chimpanzees have received little attention to date. this study aimed to investigate the long-term effects of early life experience on 18 former pet and entertainment chimpanzees, based on social grooming data collected at a primate rescue centre over a 12-year period. moreover, we also focused on ... | 2020 | 31940322 |
| semen characteristics of the adult male chimpanzee (pan troglodytes). | the chimpanzee, because of its similarities to the human, is especially valuable in studies of reproductive function. however, relatively little is known about the physiology of reproduction in the adult male chimpanzee. this study provides, for five adult male chimpanzees, baseline values for testicular volume without and with pressure and for cellular and biochemical characteristics of ejaculates collected by artificial vagina (av). there was no correlation between body weight and testicular v ... | 1993 | 31941187 |
| chimpanzee genital swelling and its role in the pattern of sociosexual behavior. | behavioral observations were made on thirteen female and seven male adult group-living chimpanzees (pan troglodytes). the behavioral data were analyzed as a function of the day of the females' menstrual cycles to explore the possible interrelationship between genital swelling and sociosexual behavior of female chimpanzees. copulatory behavior was confined almost entirely to the period of genital swelling and the occurrence of male-to-female genital inspection (both female- and male-initiated) wa ... | 1992 | 31941218 |
| insect-eating by sympatric lowland gorillas (gorilla g. gorilla) and chimpanzees (pan t. troglodytes) in the lopé reserve, gabon. | sympatric populations of lowland gorillas (gorilla gorilla gorilla) and chimpanzees (pan troglodytes troglodytes) in the lopé reserve in central gabon consumed insects at similar average frequencies over a 7-year period (30% versus 31% feces contained insect remains). data came mostly from fecal analysis supplemented by observation and trail evidence. the weaver ant (oecophylla longinoda) was the species eaten most frequently by both gorillas and chimpanzees. other species of insects wore eaten ... | 1992 | 31941221 |
| forest fragments become farmland: dietary response of wild chimpanzees (pan troglodytes) to fast-changing anthropogenic landscapes. | behavioral flexibility, including an ability to modify feeding behavior, is a key trait enabling primates to survive in forest fragments. in human-dominated landscapes, unprotected forest fragments can become progressively degraded, and may be cleared entirely, challenging the capacity of primates to adjust to the changes. we examined responses of wild chimpanzees (pan troglodytes schweinfurthii) to major habitat change: that is, clearance of forest fragments for agriculture. over 7 years, fragm ... | 2020 | 31944360 |
| abnormal behaviors, with a special focus on rocking, and reproductive competence in a large sample of captive chimpanzees (pan troglodytes). | chimpanzees (pan troglodytes) are endangered in the wild and may no longer be imported into the united states. of those animals presently in captivity, candidates for breeding programs must be identified to insure a self-sustaining captive population. some have suggested that poor reproductive performance might be linked to the performance of abnormal behaviors. in study 1, three institutions housing breeding colonies of chimpanzees (86 males, 103 females) surveyed their animals for abnormal beh ... | 1992 | 31948132 |
| male chimpanzee behavior in relation to female ano-genital swelling. | this study examined the relationships between male agonistic, affiliative, and sexual behaviors and female estrus condition in captive adolescent and young-adult chimpanzees (pan troglodytes). data on agonistic, affiliative, and sexual behaviors of 11 males living in three social groups were collected during daily 45 minute observations over a 5 month period. female estrus condition was assessed daily using the relative size of the female's ano-genital swelling. it was hypothesized that the pres ... | 1992 | 31948163 |
| color discrimination and color preferences in chimpanzees (pan troglodytes). | chimpanzees (pan troglodytes) have been known for a long time to have color vision identical to humans (grether in j comp psychol 29(2):167-177, 1940b; jacobs et al. in vis res 36(16):2587-2594, 1996). with this study, we wonder if chimpanzees, as humans, show preferences for some colors rather than others. during a first range of experiments, we test their ability to discriminate all the colors from our set, through easy matching-to-sample tasks. the seven chimpanzees that participate in this f ... | 2020 | 31950319 |
| postpartum infertility in common chimpanzees. | the endocrine profile during normal postpartum amenorrhea in chimpanzees (pan troglodytes) closely resembles that of women, and its duration is similarly extended by nursing. however, when infant chimpanzees in our colony were removed at birth, excessively prolonged postpartum amenorrhea (7-26 months duration) occurred in 24% of cases. our endocrine studies indicate that such prolonged postpartum amenorrhea (ppam) is a pathological condition associated with chronically elevated serum prolactin l ... | 1991 | 31952381 |
| monitoring the ovarian cycles of pan troglodytes and p. paniscus: a comparative approach. | females of both species of chimpanzee, pan troglodytes and p. paniscus, exhibit conspicuous anogenital sex swellings that are useful external markers for assessing ovarian cyclicity. a new, quantitative method for describing these swelling cycles was refined during laboratory studies of four p. paniscus and nine p. troglodytes and was used to analyze variability in swelling patterns. clear-cut anatomical changes of the perineum were found to have both interindividual and interspecific reliabilit ... | 1991 | 31952385 |
| national chimpanzee breeding program: primate research institute. | the primate research institute (pri) dedicated a colony of 81 proven breeders (60 females, 21 males) to the national chimpanzee breeding and research program (ncbrp). when possible, infants were left with their mothers for a minimum of 18 months. programs to define and reduce fetal wastage and neonatal mortality were implemented. pregnancies were diagnosed both by ria for serum chorionic gonadotropin and by ultrasound prior to day 30 of pregnancy. of 65 pregnancies detected by ultrasound and ria ... | 1991 | 31952388 |
| dna "fingerprinting" and the genetic management of a captive chimpanzee population (pan troglodytes). | dna fingerprinting probes are cloned sequences which simultaneously detect a large number of similar hypervariable loci in the target dna. the resulting highly polymorphic pattern visualized on an autoradiograph allows resolution of questions concerning individual identification and parentage. m13 bacteriophage has been used as a dna fingerprinting probe for paternity ascertainment among captive chimpanzees housed in multi-male groups as part of the national chimpanzee breeding and research prog ... | 1991 | 31952396 |
| distribution of terrestrial herbaceous vegetation and its consumption by pan paniscus in the lomako forest, zaire. | data available on behavior and morphology of pan paniscus (bonobos) suggest that terrestrial herbaceous vegetation (thv) is an important component of their diet and that it may be preferred by bonobos to a greater extent than by chimpanzees (pan troglodytes). it has also been reported that thv is ubiquitously distributed in the lowland rain forests inhabited by bonobos. these data suggest that thv exploitation may be causally related to the evolution of the more cohesive social system found in b ... | 1991 | 31952402 |
| placenta accreta in an oragnutan (pongo abelii) and a chimpanzee (pan troglodytes). | placenta accreta is defined as abnormal adherence of the placenta to the uterine wall. placenta accreta is recognized as a common problem in human medicine, but has apparently not been reported previously in great apes, despite similarity in their reproductive biology. a 36-year-old multiparous female sumatran orangutan (pongo abelii) and a 20-year-old nulliparous female chimpanzee (pan troglodytes), with gross uterine and histological uterine vascular changes that are characteristic of placenta ... | 2020 | 31955798 |
| improved methods for freeze preservation of chimpanzee sperm. | freeze preservation of human and nonhuman semen has been used effectively for a number of years; however, the application of freezing to preserve nonhuman primate sperm has been less successful. this study compares five freeze methods and various concentrations of the cryoprotectants glycerol and dimethylsulfoxide (dmso) for cryopreservation of chimpanzee (pan troglodytes) sperm. the different methods were compared using quantitative analysis of sperm function and, by an indirect measure of fert ... | 1989 | 31964027 |
| features of meat digestion by captive chimpanzees (pan troglodytes). | the pronounced carnivory of many human populations contrasts sharply with feeding habits of other hominoidea. of extant great apes, only chimpanzees (pan spp.) actively seek out vertebrate prey, but meat is only a minor portion of their diet. some accounts suggest that wild chimpanzees digest prey inefficiently. to investigate the capacity of chimpanzees to digest meat, feeding trials were carried out on three captive chimpanzees (pan troglodytes) using a fixed amount of nonpurified diet with an ... | 1989 | 31964047 |
| uncertain availability of a preferred food affects choice in a captive group of chimpanzees (pan troglodytes). | food-choice was investigated in a social group of 16 chimpanzees (pan troglodytes) maintained in a large outdoor compound. three feeding stations located along the periphery of the compound were considered analogous to food patches. color-coded aluminum panels temporarily covered each feeding apparatus, with one color corresponding to nonpreferred food (commercial biscuits) available at two locations and other colors corresponding to the certain or uncertain availability of preferred food (orang ... | 1989 | 31968847 |
| intestinal parasites of sympatric pan troglodytes and papio spp. at two sites: gombe (tanzania) and mt. assirik (senegal). | experimental and clinical parasitology need natural baselines or "controls". we present normative data intestinal parasite loads in two genera of african primates. wild pan troglodytes and papio spp. were studied at two sites: gombe in tanzania (p. anubis) and mt. assirik in senegal (p. papio). presence or absence of parasites, especially nematodes, was recorded from fecal specimens. gombe's primates were more often infected than were mt. assirik's. at gombe, but not at mt. assirik, chimpanzees ... | 1989 | 31968849 |
| diet of wild chimpanzees (pan troglodytes verus) at mt. assirik, senegal: i. composition. | the composition of the diet of a savanna-living population of wild chimpanzees (pan troglodytes verus) at mt. assirik in senegal is presented. the study site had a prolonged dry season, high temperatures, and vegetation dominated by grasses. data came from direct observation, fecal specimens, and feeding traces; thus, strict criteria for acceptance of the indirect data were specified. composition of diet was given in terms of species and family of prey, parts eaten, life-form, type of habitat, a ... | 1988 | 31968861 |
| social factors influencing choice of food source in a captive group of chimpanzees (pan troglodytes). | the influence of social factors, including social relationship, kinship, estrous cycle stage and hierarchical rank, on choice of a food source was studied in a group of 16 chimpanzees (pan troglodytes) maintained in a large, outdoor compound. the subjects chose among three feeding stations that were spatially separated and located along the periphery of the compound. one feeding station was associated with a preferred food (orange), and two stations contained a less-preferred food (commercial ch ... | 1988 | 31968878 |
| long-term retention of self-recognition by chimpanzees. | two young chimpanzees showed retention of self-recognition after 1 year without access to mirrors. a year earlier the animals were positive on the gallup dye test. one year later they were once again anesthetized, marked on the brow and ears, and following recovery, exposed individually to a large mirror. both demonstrated mirror-orientated mark-directed responses. time-sample observations of behavior toward the mirror further support self-recognition. the chimpanzee's self-awareness, as inferre ... | 1988 | 31968884 |
| effect of solar eclipse on the behavior of a captive group of chimpanzees (pan troglodytes). | a captive group of chimpanzees, housed in an outdoor compound at the yerkes regional primate research center, was observed during the annular solar eclipse of may 30, 1984. the behavior of each animal was recorded using an instantaneous scan-sampling technique (altmann: behaviour 49:227-265, 1974). beginning 2 days prior to the eclipse and continuing through the day following the eclipse, data were collected from 1100 to 1300 hours daily. at 1214 hours on the day of the eclipse, when the sky beg ... | 1986 | 31979439 |
| hand preference in a captive island group of chimpanzees (pan troglodytes). | morphological cerebral asymmetries in chimpanzee brains, similar to those found in humans, in whom they are associated with speech and handedness, suggest the possibility of functional lateralization in the chimpanzee. this possibility was investigated by examining hand preferences in an island group of five chimpanzees on a series of unimanual and bimanual tasks that are diagnostic of human hand and cerebral dominance. each subject was tested in a double compartment cage on three unimanual nons ... | 1986 | 31979471 |
| social behavior and genital swelling in pregnant chimpanzees (pan troglodytes). | previous reports of increased sexual activity associated with genital swelling during chimpanzee pregnancy have suggested that the tumescent pregnant female may be regarded as a regularly cycling estrous female. analysis of additional data from seven pregnant and eight cycling females, however, indicated that tumescent pregnant females differed from cycling females in some social interactions with males. as in earlier reports, pregnant females were more receptive to male-initiated copulatory bou ... | 1986 | 31979487 |
| ontogeny of mirror behavior in two species of great apes. | mirror image reactions of two infant apes, a female chimpanzee (pan troglodytes) and a male orangutan (pongo pygmaeus), born at the zoo de vincennes and the jardin des plantes of paris, france, respectively, were studied and compared with those of children. self-recognition was also tested following 46.5 hours of mirror exposure by application of red marks on parts of the body invisible to the animal without the aid of the mirror. results indicated that the behavior of the two young apes followe ... | 1986 | 31979488 |
| focal epithelial hyperplasia of the oral mucosa in two chimpanzees (pan troglodytes). | papillomas in the oral mucosa compatible with focal epithelial hyperplasia are reported in two chimpanzees. the lesions were studied by light and electron microscopy. virus particles were not observed. the literature dealing with focal epithelial hyperplasia in humans and other animals is reviewed. | 1986 | 31979497 |
| serum levels of gonadotropins and gonadal steroids, including testosterone, during the menstrual cycle of the chimpanzee (pan troglodytes). | the objective of this study was to expand the data on menstrual cycle serum hormone patterns in female common chimpanzees, both in terms of the number of cycles analyzed and by the addition of data on testosterone levels. samples were obtained from 11 unanesthetized animals trained for conscious blood withdrawal. lh, fsh, 17β-estradiol (e2), progesterone (p), and testosterone (t) were measured by radioimmunoassay, genital swelling was recorded, and menstrual blood was noted. concurrent midcycle ... | 1985 | 31979509 |
| tool use by wild chimpanzees (pan troglodytes) to obtain termites (macrotermes herus) in the mahale mountains, tanzania. | wild chimpanzees (pan troglodytes) used probes made of vegetation to fish for termites (macrotermes herus) in the mahale mountains of western tanzania. data on both the artefacts and behavior associated with their use were recorded over a 5-month period. the chimpanzees of one unit group, b group, were seen four times to use the tools to extract the insects from their mounds. a sample of 290 tools was collected and analyzed in terms of age, seasonality, length, width, class of raw materials, spe ... | 1985 | 31986794 |
| improved method for artificial insemination in the great apes. | artificial insemination in the great apes has not achieved its potential as a tool in maintenance of the endangered captive population. three factors can influence the success rate of artificial insemination: sperm preparation, site of insemination, and timing of insemination. we have tried to optimize methods regarding these three steps. a modified method for insemination is described which has resulted in a 21% success rate (six term pregnancies from 29 inseminations) in the chimpanzee and whi ... | 1985 | 31986826 |
| brief report: differential oxidations of estradiol-17β by the chimpanzee in vivo. | the metabolism of estradiol-17β is primarily an oxidative process at either carbon-2 or carbon-16 in the human. the objective of this study was to determine the relative importance of these two oxygenation pathways in the chimpanzee. the rate of oxidation of estradiol-17β at each position was determined by measuring the release of tritium into body water from carbon-2 or carbon-16. [2-3h]-estradiol-17β or [16-3h]-estradiol-17β was injected intravenously into three adult male chimpanzees, and blo ... | 1983 | 31986865 |
| brief report: chimpanzees, tools, and termites: new record from gabon. | wild chimpanzees (pan troglodytes) in northeastern gabon use tools made of vegetation to obtain termites (macrotermes? nobilis) for food. they mostly use probes in termite fishing, as recorded elsewhere in eastern and far western africa. this is the first record of termite fishing by the central west african race of chimpanzees. there are signs that they also use stouter tools, perhaps to perforate the mounds of the termites. these new findings further complicate the status of material culture i ... | 1983 | 31991943 |
| biochemical detection of fecal hematin as a test for meat eating in chimpanzees (pan troglodytes). | meat-eating by wild chimpanzees has been reported by a number of workers during the last two decades. direct observation probably underestimates the incidence, even though the behavior occurs relatively infrequently. in 1978, moreno-black suggested that fecal analysis over a long period of time is probably the most effective means to determine the incidence of this behavior in wild chimpanzees and other nonhuman primate groups. a method currently employed by a number of fieldworkers involves the ... | 1982 | 31991988 |
| sexual behavior of captive chimpanzees (pan troglodytes): pregnant versus cycling females. | sexual behavior was observed in fifteen female and seven male captive adult chimpanzees over a period of three months. relative frequencies of successful and unsuccessful copulatory attempts were compared to levels of anogenital swelling and reproductive status. in addition, the data were analyzed in relation to three indicators of female primate sexuality: (1) proceptivity, indicated by female attempts at sexual interaction; (2) attractivity, indicated by male-initiated attempts; and (3) recept ... | 1982 | 31992001 |
| the effect of peer separation in young chimpanzees (pan troglodytes). | ten chimpanzees (pan troglogytes), aged 18-24 months, housed without mothers as two dyads and two triads, were subjected to social separation. two issues were addressed: the effects of peer separation in chimpanzees; and differential responses by subjects living in dyads compared with those living in triads. chimpanzees that were alone during separation reacted with high levels of "protest" alternating with "despair" throughout the separation period. the continued presence of one cagemate, durin ... | 1983 | 31992011 |
| social rank overrides environmental and community fluctuations in determining meat access by female chimpanzees in the taï national park, côte d'ivoire. | meat, long hypothesized as an important food source in human evolution, is still a substantial component of the modern human diet, with some humans relying entirely on meat during certain times of the year. understanding the socio-ecological context leading to the successful acquisition and consumption of meat by chimpanzees (pan troglodytes), our closest living relative, can provide insight into the emergence of this trait because humans and chimpanzees are unusual among primates in that they b ... | 2020 | 32002324 |
| the macronutrient composition of wild and cultivated plant foods of west african chimpanzees (pan troglodytes verus) inhabiting an anthropogenic landscape. | agricultural expansion encroaches on tropical forests and primates in such landscapes frequently incorporate crops into their diet. understanding the nutritional drivers behind crop-foraging can help inform conservation efforts to improve human-primate coexistence. this study builds on existing knowledge of primate diets in anthropogenic landscapes by estimating the macronutrient content of 24 wild and 11 cultivated foods (90.5% of food intake) consumed by chimpanzees (pan troglodytes verus) at ... | 2020 | 32003053 |
| model life table for captive chimpanzees. | mortality statistics from three captive populations of chimpanzees (pan troglodytes) were combined to generate standard model life tables for each sex in this species. the model is compared to an estimate of survivorship of a group of wild animals, and is applied to an incomplete data set to illustrate how the model may be used to extend estimates of mortality statistics to missing older ages. © 1995 wiley-liss, inc. | 1995 | 32005046 |
| effect of liquefaction time on semen parameters in chimpanzee (pan troglodytes) ejaculates. | ejaculates were obtained from eight adult male chimpanzees trained to use an artificial vagina. spontaneously liquefied fractions were collected at 0-1, 1-2 and 2-4 h after ejaculation. the mean volumes of the spontaneously liquefied fractions did not differ significantly among the three fractions. the total number of sperm, the percentage of motile sperm and the percentage of live sperm decreased significantly (p < 0.005) between the 0-1 and 1-2 h fractions. citrate concentration and alpha-gluc ... | 1995 | 32005048 |
| altruistic food sharing behavior by human infants after a hunger manipulation. | altruistic behavior entails giving valuable benefits to others while incurring a personal cost. a distinctively human form of altruistic behavior involves handing nutritious food to needy strangers, even when one desires the food. engaging in altruistic food transfer, instead of keeping the food, is costly, because it reduces the caloric intake of the benefactor vis-à-vis the beneficiary. human adults engage in this form of altruistic behavior during times of war and famine, when giving food to ... | 2020 | 32019998 |
| no evidence of what-where-when memory in great apes (pan troglodytes, pan paniscus, pongo abelii, and gorilla gorilla). | episodic memory is the ability to recollect specific past events belonging to our personal experience, and it is one of the most crucial human abilities, allowing us to mentally travel through time. in animals, however, evidence of what-where-when memory (hereafter, www memory) is limited to very few taxa, mostly reflecting the socioecological challenges faced in their environment. in this article, we aimed to replicate 2 studies previously conducted on birds and primates to find convincing evid ... | 2020 | 32052981 |
| the hla a03 supertype and several pan species major histocompatibility complex class i a allotypes share a preference for binding positively charged residues in the f pocket: implications for controlling retroviral infections. | the major histocompatibility complex (mhc) class i region of humans, chimpanzees (pan troglodytes), and bonobos (pan paniscus) is highly similar, and orthologues of hla-a, -b, and -c are present in both pan species. based on functional characteristics, the different hla-a allotypes are classified into different supertypes. one of them, the hla a03 supertype, is widely distributed among different human populations. all contemporary known chimpanzee and bonobo mhc class i a allotypes cluster genet ... | 2020 | 32075930 |
| the implementation and initial evaluation of a physical therapy program for captive chimpanzees (pan troglodytes). | due to advances in captive nonhuman primate (nhp) medical care, the number of geriatric chimpanzees (≥35-years old) is growing. with old age comes a variety of physical conditions, including arthritis, stroke, and mobility impairments. programs aimed at enhancing the welfare of geriatric chimpanzees are now quite common, but there are few published empirical evaluations of the efficacy of such programs. the current study aimed to create, implement, and evaluate the effects of participation in a ... | 2020 | 32077522 |
| wood and meat as complementary sources of sodium for kanyawara chimpanzees (pan troglodytes). | sodium, a vital micronutrient that is often in scarce supply for tropical herbivores, is sometimes found at high concentration in decaying wood. we tested two hypotheses for chimpanzees: first, that wood-eating facilitates acquisition of sodium; second, that wood-eating occurs in response to the low availability of sodium from other dietary sources. | 2020 | 32091137 |
| da/dapi fluorescent bands in the chromosomes of pan paniscus. | the fluorochrome pattern produced by da/dapi double staining in pan paniscus chromosomes is reported. the location of da/dapi prominent bands differs from that reported for all other hominoid species. however, the pattern in the pygmy chimpanzee is most similar to that seen in pan troglodytes. comparison of the da/dapi pattern of the other hominoid species allows the construction of a proposed hominoid ancestral karyotype and a preliminary phylogenetic reconstruction of da/dapi bands for the gre ... | 1988 | 32093428 |
| longitudinal changes in the targets of chimpanzee (pan troglodytes) hunts at mahale mountains national park: how and why did they begin to intensively hunt red colobus (piliocolobus rufomitratus) in the 1980s? | the hunting activities of chimpanzees (pan troglodytes) at mahale mountains national park exhibited a significant change over a 46-year observation period, shifting from sporadic hunting for small ungulates and primates through seizure or chasing, to a specialized hunting habit for red colobus (piliocolobus rufomitratus). by the early 1980s, a new hunting habit had developed through the following stages: (1) occasional single kills by mature/adolescent males, (2) multiple kills by mature/adolesc ... | 2020 | 32095911 |
| my life among the apes. | i have spent over 40 years studying the behavior of our closest living relatives, the apes. in this paper, i review my research on the spacing, mating, and vocal behavior of gibbons and orangutans (pongo pygmaeus) and the vocal and social behavior of chimpanzees (pan troglodytes). i devote special attention to results derived from a 25-year-long study of a remarkable and extraordinarily large group of chimpanzees that has recently fissioned at ngogo in kibale national park, uganda. i conclude wi ... | 2020 | 32096269 |
| chimpanzee coordination and potential communication in a two-touchscreen turn-taking game. | recent years have seen a growing interest in the question of whether and how groups of nonhuman primates coordinate their behaviors for mutual benefit. on the one hand, it has been shown that chimpanzees in the wild and in captivity can solve various coordination problems. on the other hand, evidence of communication in the context of coordination problems is scarce. here, we investigated how pairs of chimpanzees (pan troglodytes) solved a problem of dynamically coordinating their actions for ac ... | 2020 | 32098996 |