Publications

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sex differences in the relationship between planum temporale asymmetry and corpus callosum morphology in chimpanzees (pan troglodytes): a combined mri and dti analysis.increases brain size has been hypothesized to be inversely associated with the expression of behavioral and brain asymmetries within and between species. we tested this hypothesis by analyzing the relation between asymmetries in the planum temporale (pt) and different measures of the corpus callosum (cc) including surface area, streamline count as measured from diffusion tensor imaging, fractional anisotropy values and the ratio in the number of fibers to surface area in a sample of chimpanzees. ...201627055947
malignant neoplasia of the sex skin in 2 chimpanzees (pan troglodytes).this report describes 2 cases of spontaneous malignant neoplasia within the sex skin of aged female chimpanzees. in both cases, the initial presentation resembled nonhealing traumatic wounds to the sex skin, with different degrees of infection, ulceration, and tissue necrosis. histopathology of the lesions confirmed the diagnosis of squamous cell carcinoma in one case and of adenocarcinoma with metastasis in the other. advanced age and previous trauma likely contributed to the development of the ...201627053571
measuring hair cortisol concentrations to assess the effect of anthropogenic impacts on wild chimpanzees (pan troglodytes).non-human primates face major environmental changes due to increased human impacts all over the world. although some species are able to survive in certain landscapes with anthropogenic impact, their long-term viability and fitness may be decreased due to chronic stress. here we assessed long-term stress levels through cortisol analysis in chimpanzee hair obtained from sleeping nests in northwestern uganda, in order to estimate welfare in the context of ecotourism, forest fragmentation with huma ...201627050418
establishment of an intermittent cold stress model using tupaia belangeri and evaluation of compound c737 targeting neuron-restrictive silencer factor.previous studies have shown that intermittent cold stress (ics) induces depression-like behaviors in mammals. tupaia belangeri (the tree shrew) is the only experimental animal other than the chimpanzee that has been shown to be susceptible to infection by hepatitis b and c viruses. moreover, full genome sequence analysis has revealed strong homology between host proteins in tupaia and in humans and other primates. tupaia neuromodulator receptor proteins are also known to have a high degree of ho ...201627041457
first observation of dorylus ant feeding in budongo chimpanzees supports absence of stick-tool culture.the use of stick- or probe-tools is a chimpanzee universal, recorded in all long-term study populations across africa, except one: budongo, uganda. here, after 25 years of observation, stick-tool use remains absent under both natural circumstances and strong experimental scaffolding. instead, the chimpanzees employ a rich repertoire of leaf-tools for a variety of dietary and hygiene tasks. one use of stick-tools in other communities is in feeding on the aggressive dorylus 'army ant' species, con ...201627038810
a novel trim family member, trim69, regulates zebrafish development through p53-mediated apoptosis.trim69 contains the hallmark domains of a tripartite motif (trim) protein, including a ring-finger domain, b-box domain, and coiled-coil domain. trim69 is structurally and evolutionarily conserved in zebrafish, mouse, rat, human, and chimpanzee. the role of this protein is unclear, however, so we investigated its function in zebrafish development. trim69 is extensively expressed in zebrafish adults and developing embryos-particularly in the testis, brain, ovary, and heart-and its expression decr ...201627031046
impaired air conditioning within the nasal cavity in flat-faced homo.we are flat-faced hominins with an external nose that protrudes from the face. this feature was derived in the genus homo, along with facial flattening and reorientation to form a high nasal cavity. the nasal passage conditions the inhaled air in terms of temperature and humidity to match the conditions required in the lung, and its anatomical variation is believed to be evolutionarily sensitive to the ambient atmospheric conditions of a given habitat. in this study, we used computational fluid ...201627010321
how comparative psychology can shed light on human evolution: response to beran et al.'s discussion of "cognitive capacities for cooking in chimpanzees".we recently reported a study (warneken & rosati proceedings of the royal society b, 282, 20150229, 2015) examining whether chimpanzees possess several cognitive capacities that are critical to engage in cooking. in a subsequent commentary, beran, hopper, de waal, sayers, and brosnan learning & behavior (2015) asserted that our paper has several flaws. their commentary (1) critiques some aspects of our methodology and argues that our work does not constitute evidence that chimpanzees can actually ...201627007910
recombination hotspots: models and tools for detection.recombination hotspots are the regions within the genome where the rate, and the frequency of recombination are optimum with a size varying from 1 to 2kb. the recombination event is mediated by the double-stranded break formation, guided by the combined enzymatic action of dna topoisomerase and spo 11 endonuclease. these regions are distributed non-uniformly throughout the human genome and cause distortions in the genetic map. numerous lines of evidence suggest that the number of hotspots known ...201626991854
species diversity regarding the presence of proximal tubular progenitor cells of the kidney.the cellular source for tubular regeneration following kidney injury is a matter of dispute, with reports suggesting a stem or progenitor cells as the regeneration source while linage tracing studies in mice seemingly favor the classical theory, where regeneration is performed by randomly surviving cells. we, and others have previously described a scattered cell population localized to the tubules of human kidney, which increases in number following injury. here we have characterized the species ...201626972712
reference in human and non-human primate communication: what does it take to refer?the concept of functional reference has been used to isolate potentially referential vocal signals in animal communication. however, its relatedness to the phenomenon of reference in human language has recently been brought into question. while some researchers have suggested abandoning the concept of functional reference altogether, others advocate a revision of its definition to include contextual cues that play a role in signal production and perception. empirical and theoretical work on func ...201626971953
human fibroblasts display a differential focal adhesion phenotype relative to chimpanzee.there are a number of documented differences between humans and our closest relatives in responses to wound healing and in disease susceptibilities, suggesting a differential cellular response to certain environmental factors. in this study, we sought to look at a specific cell type, fibroblasts, to examine differences in cellular adhesion between humans and chimpanzees in visualized cells and in gene expression. we have found significant differences in the number of focal adhesions between prim ...201626971204
daily travel distances of zoo-housed chimpanzees and gorillas: implications for welfare assessments and space requirements.the degree to which the relatively smaller area of artificial environments (compared with natural habitats) has measureable effects on the behavior and welfare of captive animals has been debated for many years. while there is little question that these spaces provide far less opportunity for natural ranging behavior and travel, less is known about the degree to which captive animals travel within their environments and what factors influence these travel patterns. we intensively studied the mov ...201626968410
cars kill chimpanzees: case report of a wild chimpanzee killed on a road at bulindi, uganda.roads have broadly adverse impacts on wildlife, including nonhuman primates. one direct effect is mortality from collisions with vehicles. while highly undesirable, roadkills provide valuable information on the health and condition of endangered species. we present a case report of a wild chimpanzee (pan troglodytes schweinfurthii) killed crossing a road in bulindi, uganda, where chimpanzees inhabit forest fragments amid farmland. details of the collision are constructed from eyewitness accounts ...201626960418
a time- and cost-effective strategy to sequence mammalian y chromosomes: an application to the de novo assembly of gorilla y.the mammalian y chromosome sequence, critical for studying male fertility and dispersal, is enriched in repeats and palindromes, and thus, is the most difficult component of the genome to assemble. previously, expensive and labor-intensive bac-based techniques were used to sequence the y for a handful of mammalian species. here, we present a much faster and more affordable strategy for sequencing and assembling mammalian y chromosomes of sufficient quality for most comparative genomics analyses ...201626934921
isotopic reconstructions of habitat change surrounding the extinction of oreopithecus, the last european ape.oreopithecus bambolii was the last hominoid to survive in europe. the purpose of this investigation was to reconstruct, through stable isotope analyses, oreopithecus' habitat, subsistence behavior, and changes in habitat that may have led to its extinction.201626932906
chimpanzee accumulative stone throwing.the study of the archaeological remains of fossil hominins must rely on reconstructions to elucidate the behaviour that may have resulted in particular stone tools and their accumulation. comparatively, stone tool use among living primates has illuminated behaviours that are also amenable to archaeological examination, permitting direct observations of the behaviour leading to artefacts and their assemblages to be incorporated. here, we describe newly discovered stone tool-use behaviour and ston ...201626923684
variation in carbon isotope values among chimpanzee foods at ngogo, kibale national park and bwindi impenetrable national park, uganda.stable isotope values in primate tissues can be used to reconstruct diet in the absence of direct observation. however, in order to make dietary inferences, one must first establish isotopic variability for potential food sources. in this study we examine stable carbon isotope (δ(13) c) values for chimpanzee (pan troglodytes) food resources from two ugandan forests: ngogo (kibale national park), and bwindi impenetrable national park. mean δ(13) c values for plant samples are equivalent at both s ...201626918258
dietary options and behavior suggested by plant biomarker evidence in an early human habitat.the availability of plants and freshwater shapes the diets and social behavior of chimpanzees, our closest living relative. however, limited evidence about the spatial relationships shared between ancestral human (hominin) remains, edible resources, refuge, and freshwater leaves the influence of local resources on our species' evolution open to debate. exceptionally well-preserved organic geochemical fossils--biomarkers--preserved in a soil horizon resolve different plant communities at meter sc ...201626903646
chimpanzee research and conservation in bossou and the nimba mountains: a long-term international collaborative effort in west africa.the nimba mountains are a west african natural world heritage site located in the range of the guineo-equatorial evergreen rainforest, renowned for its rich biodiversity with a high level of endemism. in 1976, yukimaru sugiyama from kyoto university initiated the long-term study of chimpanzees at bossou, a guinean village situated 5 km from the northern foothills of nimba. this japanese initiative has provided key discoveries and insights on our closest living evolutionary relatives over the 40 ...201626902853
evolution of brain and culture: the neurological and cognitive journey from australopithecus to albert einstein.fossil and comparative primatological evidence suggest that alterations in the development of prehistoric hominin infants kindled three consecutive evolutionary-developmental (evo-devo) trends that, ultimately, paved the way for the evolution of the human brain and cognition. in the earliest trend, infants' development of posture and locomotion became delayed because of anatomical changes that accompanied the prolonged evolution of bipedalism. because modern humans have inherited these changes, ...201626894688
use of an implantable loop recorder in a chimpanzee (pan troglodytes) to monitor cardiac arrhythmias and assess the effects of acupuncture and laser therapy.cardiovascular disease is a leading cause of death in captive chimpanzees and is often associated with myocardial fibrosis, which increases the risk of cardiac arrhythmias. in this case report, we present a 36-y-old male chimpanzee (pan troglodytes) diagnosed with frequent ventricular premature complexes (vpc). we placed a subcutaneous implantable loop recorder for continual ecg monitoring to assess his arrhythmias without the confounding effects of anesthetics. during his initial treatment with ...201626884410
robust retention and transfer of tool construction techniques in chimpanzees (pan troglodytes).long-term memory can be critical to a species' survival in environments with seasonal and even longer-term cycles of resource availability. the present, longitudinal study investigated whether complex tool behaviors used to gain an out-of-reach reward, following a hiatus of about 3 years and 7 months since initial experiences with a tool use task, were retained and subsequently executed more quickly by experienced than by naïve chimpanzees. ten of the 11 retested chimpanzees displayed impressive ...201626881941
using the nimh research domain criteria (rdoc) in human and nonhuman primate research.in this article, we provide a commentary on kozak and cuthbert ()'s theoretical paper discussing the nimh research domain criteria (rdoc) initiative and on latzman et al. (2016)'s empirical investigation of the rdoc negative valence systems domain in chimpanzees, conducted with experimental procedures across genetic, neurobiological, and behavioral levels of analysis. we discuss the pros and cons of the rdoc approach to research on mental illness as well as the strengths and weaknesses of the im ...201626877128
neuroethology as a translational neuroscience strategy in the era of the nimh research domain criteria.the article by latzman et al. in the current special issue utilizes a novel dataset consisting of behavioral, brain, and genomic data from a sample of 76 captive chimpanzees to make the case that negative affective expression is influenced by variation in the gene coding for arginine vasopressin receptor 1a (avpr1a), in a sex-linked manner. a novel feature of this study is the ethological approach employed by the authors, i.e., the use of scratching as a behavioral indicator of negative affectiv ...201626877127
displacement behaviors in chimpanzees (pan troglodytes): a neurogenomics investigation of the rdoc negative valence systems domain.the current study aimed to systematically investigate genetic and neuroanatomical correlates of individual variation in scratching behaviors, a well-validated animal-behavioral indicator of negative emotional states with clear links to the nimh research domain criteria (rdoc) response to potential harm ("anxiety") construct within the negative valence systems domain. utilizing data from a sample of 76 captive chimpanzees (pan troglodytes), we (a) examined the association between scratching and p ...201626877126
no distinction of orthology/paralogy between human and chimpanzee rh blood group genes.on human (homo sapiens) chromosome 1, there is a tandem duplication encompassing rh blood group genes (hosa_rhd and hosa_rhce). this duplication occurred in the common ancestor of humans, chimpanzees (pan troglodytes), and gorillas, after splitting from their common ancestor with orangutans. although several studies have been conducted on ape rh blood group genes, the clear genome structures of the gene clusters remain unknown. here, we determined the genome structure of the gene cluster of chim ...201626872772
analysis of hair cortisol levels in captive chimpanzees: effect of various methods on cortisol stability and variability.hair cortisol has been reported to be a useful measure of long-term hypothalamic-pituitary-adrenal (hpa) axis activation in several species. it serves as a practical tool for long-term stress assessment, but it is important to understand the methodological factors that can affects hair cortisol assays to avoid methodological artifacts. to that end, we tested several procedures for measuring cortisol levels in hair collected from captive chimpanzees. the results showed that reproducibility was hi ...201626870668
pitfalls reconstructing the last common ancestor of chimpanzees and humans. 201626862165
reply to almécija: a new direction for reconstructing our last common ancestor with chimpanzees. 201626862164
bystanders, parcelling, and an absence of trust in the grooming interactions of wild male chimpanzees.the evolution of cooperation remains a central issue in socio-biology with the fundamental problem of how individuals minimize the risks of being short-changed ('cheated') should their behavioural investment in another not be returned. economic decisions that individuals make during interactions may depend upon the presence of potential partners nearby, which offers co operators a temptation to defect from the current partner. the parcelling model posits that donors subdivide services into parce ...201626856371
differing views: can chimpanzees do level 2 perspective-taking?although chimpanzees understand what others may see, it is unclear whether they understand how others see things (level 2 perspective-taking). we investigated whether chimpanzees can predict the behavior of a conspecific which is holding a mistaken perspective that differs from their own. the subject competed with a conspecific over two food sticks. while the subject could see that both were the same size, to the competitor one appeared bigger than the other. in a previously established game, th ...201626852383
smoke and mirrors: testing the scope of chimpanzees' appearance-reality understanding.the ability to make appearance-reality (ar) discriminations is an important higher-order cognitive adaptation in humans but is still poorly understood in our closest primate relatives. previous research showed that chimpanzees are capable of ar discrimination when choosing between food items that appear, due to the effects of distorting lenses, to be smaller or larger than they actually are (krachun, call, & tomasello, 2009). in the current study, we investigated the scope and flexibility of chi ...201626848736
should i stay or should i go? initiation of joint travel in mother-infant dyads of two chimpanzee communities in the wild.it is well established that great apes communicate via intentionally produced, elaborate and flexible gestural means. yet relatively little is known about the most fundamental steps into this communicative endeavour-communicative exchanges of mother-infant dyads and gestural acquisition; perhaps because the majority of studies concerned captive groups and single communities in the wild only. here, we report the first systematic, quantitative comparison of communicative interactions of mother-inf ...201626833496
social behavior shapes the chimpanzee pan-microbiome.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 ...201626824072
spontaneous reproductive tract lesions in aged captive chimpanzees.chimpanzees (pan troglodytes) have served as an important model for studies of reproductive diseases and aging-related disorders in humans. however, limited information is available about spontaneously occurring reproductive tract lesions in aging chimpanzees. in this article, the authors present histopathologic descriptions of lesions identified in the reproductive tract, including the mammary gland, of 33 female and 34 male aged chimpanzees from 3 captive populations. the most common findings ...201626823448
atypical early histories predict lower extraversion in captive chimpanzees.although much research has been conducted to understand personality development in humans, there remain substantial gaps in our understanding of these processes, particularly in relation to social influences. as such, investigations into personality development in our closest living relative, the chimpanzee, may provide useful insight. we evaluated the impact of early social exposure (to both humans and conspecifics) on personality development by studying 88 chimpanzees, including former pets an ...201626814701
animal behaviour: friendship enhances trust in chimpanzees.individuals that participate in exchanges with delayed rewards can be exploited if their partners don't reciprocate. in humans, friendships are built on trust, and trust enhances cooperation. new evidence suggests that close social bonds also enhance trust in chimpanzees.201626811894
overexpression of p53 activated by small activating rna suppresses the growth of human prostate cancer cells.previous research has reported that a particular double-stranded rna, named dsp53-285, has the capacity to induce expression of the tumor suppressor gene tp53 in chimpanzee cells by targeting its promoter. usually, it is the wild-type p53 protein, rather than mutants, which exhibits potent cancer-inhibiting effects. in addition, nonhuman primates, such as chimpanzees, share almost identical genome sequences with humans. this prompted us to speculate whether dsp53-285 can trigger wild-type p53 pr ...201626811691
life history effects on the molecular clock of autosomes and sex chromosomes.one of the foundational results in molecular evolution is that the rate at which neutral substitutions accumulate on a lineage equals the rate at which mutations arise. traits that affect rates of mutation therefore also affect the phylogenetic "molecular clock." we consider the effects of sex-specific generation times and mutation rates in species with two sexes. in particular, we focus on the effects that the age of onset of male puberty and rates of spermatogenesis have likely had in hominids ...201626811451
spatio-temporal complexity of chimpanzee food: how cognitive adaptations can counteract the ephemeral nature of ripe fruit.ecological complexity has been proposed to play a crucial role in primate brain-size evolution. however, detailed quantification of ecological complexity is still limited. here we assess the spatio-temporal distribution of tropical fruits and young leaves, two primary chimpanzee (pan troglodytes) foods, focusing on the predictability of their availability in individual trees. using up to 20 years of information on monthly availability of young leaf, unripe and ripe fruit in plant species consume ...201626800493
unidirectional adaptation in tempo in pairs of chimpanzees during simultaneous tapping movement: an examination under face-to-face setup.many studies have reported a spontaneous nature to synchronized movement in humans and in non-human primates. however, it is not yet clear whether individuals mutually adapt their movement to each other or whether one individual significantly changes to synchronize with the other. in the current study, we examined a directionality of the tempo adaptation to understand an introductive process of interactional synchrony in pairs of chimpanzees. four pairs, consisting of five female chimpanzees, pr ...201626795540
characterization of a cardiorenal-like syndrome in aged chimpanzees (pan troglodytes).cardiorenal syndrome involves disease and dysfunction of the heart that leads to progressive renal dysfunction. this study investigated the relationship between cardiac and renal disease in 91 aged chimpanzees at the alamogordo primate facility by evaluation of the medical histories, metabolic parameters, functional measurements of the cardiovascular system, clinical pathology, and histopathology focused on the heart and kidney. cardiac fibrosis was the most frequent microscopic finding in 82 of ...201626792841
fifteen new species of penicillium.we introduce 15 new species of penicillium isolated from a diverse range of locations, including canada, costa rica, germany, italy, new zealand, tanzania, usa and the dry valleys of antarctica, from a variety of habitats, including leaf surfaces in tropical rain forests, soil eaten by chimpanzees, infrabuccal pockets of carpenter ants, intestinal contents of caterpillars and soil. the new species are classified in sections aspergilloides (1), canescentia (2), charlesia (1), exilicaulis (3), lan ...201627616792
a partial e3 deletion in replication-defective adenoviral vectors allows for stable expression of potentially toxic transgene products.adenovirus (ad) is used extensively for construction of viral vectors, most commonly with deletion in its e1 and/or e3 genomic regions. previously, our attempts to insert envelope proteins (env) of hiv-1 into such vectors based on chimpanzee-derived ad (adc) viruses were thwarted. here, we describe that genetic instability of an e1- and e3-deleted adc vector of serotype c6 expressing env of hiv-1 can be overcome by reinsertion of e3 sequences with anti-apoptotic activities. this partial e3 delet ...201627604324
familiar face + novel face = familiar face? representational bias in the perception of morphed faces in chimpanzees.highly social animals possess a well-developed ability to distinguish the faces of familiar from novel conspecifics to induce distinct behaviors for maintaining society. however, the behaviors of animals when they encounter ambiguous faces of familiar yet novel conspecifics, e.g., strangers with faces resembling known individuals, have not been well characterised. using a morphing technique and preferential-looking paradigm, we address this question via the chimpanzee's facial-recognition abilit ...201627602275
variation in the molecular clock of primates.events in primate evolution are often dated by assuming a constant rate of substitution per unit time, but the validity of this assumption remains unclear. among mammals, it is well known that there exists substantial variation in yearly substitution rates. such variation is to be expected from differences in life history traits, suggesting it should also be found among primates. motivated by these considerations, we analyze whole genomes from 10 primate species, including old world monkeys (owm ...201627601674
in-group defense, out-group aggression, and coordination failures in intergroup conflict.intergroup conflict persists when and because individuals make costly contributions to their group's fighting capacity, but how groups organize contributions into effective collective action remains poorly understood. here we distinguish between contributions aimed at subordinating out-groups (out-group aggression) from those aimed at defending the in-group against possible out-group aggression (in-group defense). we conducted two experiments in which three-person aggressor groups confronted thr ...201627601640
chimpanzees can point to smaller amounts of food to accumulate larger amounts but they still fail the reverse-reward contingency task.the reverse-reward contingency task presents 2 food sets to an animal, and they are required to choose the smaller of the 2 sets in order to receive the larger food set. intriguingly, the majority of species tested on the reverse-reward task fail to learn this contingency in the absence of large trial counts, correction trials, and punishment techniques. the unique difficulty of this seemingly simple task likely reflects a failure of inhibitory control which is required to point toward a smaller ...201627598059
normalization of human rna-seq experiments using chimpanzee rna as a spike-in standard.normalization of human rna-seq experiments employing chimpanzee rna as a spike-in standard is reported. human and chimpanzee rnas exhibit single nucleotide variations (snvs) in average 210-bp intervals. spike-in chimpanzee rna would behave the same as the human counterparts during the whole ngs procedures owing to the high sequence similarity. after discrimination of species origins of the ngs reads based on snvs, the chimpanzee reads were used to read-by-read normalize biases and variations of ...201627554056
fecal carbon and nitrogen isotopic analysis as an indicator of diet in kanyawara chimpanzees, kibale national park, uganda.the shorter-term overview from feces provides scope to investigate dietary fluctuations. we assess the correlation of stable isotopic fecal values with recorded seasonal diet of 10 adult chimpanzees (p. t. schweinfurthii) of the kanyawara community (kibale national park, uganda) and whether fecal nitrogen levels (%n) indicate a change in crude protein intake.201627553783
how chimpanzees cooperate in a competitive world.our species is routinely depicted as unique in its ability to achieve cooperation, whereas our closest relative, the chimpanzee (pan troglodytes), is often characterized as overly competitive. human cooperation is assisted by the cost attached to competitive tendencies through enforcement mechanisms, such as punishment and partner choice. to examine if chimpanzees possess the same ability to mitigate competition, we set up a cooperative task in the presence of the entire group of 11 adults, whic ...201627551075
human feeding biomechanics: performance, variation, and functional constraints.the evolution of the modern human (homo sapiens) cranium is characterized by a reduction in the size of the feeding system, including reductions in the size of the facial skeleton, postcanine teeth, and the muscles involved in biting and chewing. the conventional view hypothesizes that gracilization of the human feeding system is related to a shift toward eating foods that were less mechanically challenging to consume and/or foods that were processed using tools before being ingested. this hypot ...201627547550
causal reasoning versus associative learning: a useful dichotomy or a strawman battle in comparative psychology?the debate about whether or not one could/should ascribe reasoning abilities to animals has deep historical roots and seems very up-to-date in the light of the immense body of new empirical data originating from various species and research paradigms. associative learning (al) seems to be a ubiquitous low-level contender for any cognitive interpretation of animal behavior, mostly because of the assumed mechanistic simplicity and phylogenetic prevalence. however, the implicit assumption that al i ...201627512825
passive acoustic monitoring reveals group ranging and territory use: a case study of wild chimpanzees (pan troglodytes).assessing the range and territories of wild mammals traditionally requires years of data collection and often involves directly following individuals or using tracking devices. indirect and non-invasive methods of monitoring wildlife have therefore emerged as attractive alternatives due to their ability to collect data at large spatiotemporal scales using standardized remote sensing technologies. here, we investigate the use of two novel passive acoustic monitoring (pam) systems used to capture ...201627507999
cross-cultural sex differences in post-conflict affiliation following sports matches.the nature of ancestral human social structure and the circumstances in which men or women tend to be more cooperative are subjects of intense debate. the male warrior hypothesis proposes that success in intergroup contests has been vital in human evolution and that men therefore must engage in maximally effective intragroup cooperation [1-3]. post-conflict affiliation between opponents is further proposed to facilitate future cooperation [4], which has been demonstrated in non-human primates [5 ...201627498561
laetoli footprints reveal bipedal gait biomechanics different from those of modern humans and chimpanzees.bipedalism is a key adaptation that shaped human evolution, yet the timing and nature of its evolution remain unclear. here we use new experimentally based approaches to investigate the locomotor mechanics preserved by the famous pliocene hominin footprints from laetoli, tanzania. we conducted footprint formation experiments with habitually barefoot humans and with chimpanzees to quantitatively compare their footprints to those preserved at laetoli. our results show that the laetoli footprints a ...201627488647
emergence of a homo sapiens-specific gene family and chromosome 16p11.2 cnv susceptibility.genetic differences that specify unique aspects of human evolution have typically been identified by comparative analyses between the genomes of humans and closely related primates, including more recently the genomes of archaic hominins. not all regions of the genome, however, are equally amenable to such study. recurrent copy number variation (cnv) at chromosome 16p11.2 accounts for approximately 1% of cases of autism and is mediated by a complex set of segmental duplications, many of which ar ...201627487209
the dau cluster: a comparative analysis of 18 rhd alleles, some forming partial d antigens.the rh system is the most complex and polymorphic blood group system in humans with more than 460 alleles known for the rhd gene. the dau cluster of rhd alleles is characterized by the single-nucleotide change producing the p.thr379met amino acid substitution. it is called the dau-0 allele and has been postulated to be the primordial allele, from which all other alleles of the dau cluster have eventually evolved.201627480171
tepitool: a pipeline for computational prediction of t cell epitope candidates.computational prediction of t cell epitope candidates is currently being used in several applications including vaccine discovery studies, development of diagnostics, and removal of unwanted immune responses against protein therapeutics. there have been continuous improvements in the performance of mhc binding prediction tools, but their general adoption by immunologists has been slow due to the lack of user-friendly interfaces and guidelines. current tools only provide minimal advice on what al ...201627479659
characterizing abnormal behavior in a large population of zoo-housed chimpanzees: prevalence and potential influencing factors.abnormal behaviors in captive animals are generally defined as behaviors that are atypical for the species and are often considered to be indicators of poor welfare. although some abnormal behaviors have been empirically linked to conditions related to elevated stress and compromised welfare in primates, others have little or no evidence on which to base such a relationship. the objective of this study was to investigate a recent claim that abnormal behavior is endemic in the captive population ...201627478710
differences in molecular evolutionary rates among micrornas in the human and chimpanzee genomes.the rise of the primate lineage is accompanied by an outstanding emergence of micrornas, small non-coding rnas with a prominent role in gene regulation. in spite of their biological importance little is known about the way in which natural selection has influenced micrornas in the human lineage. to study the recent evolutionary history of human micrornas and to analyze the signatures of natural selection in genomic regions harbouring micrornas we have investigated the nucleotide substitution rat ...201627474039
kea cooperate better with sharing affiliates.controlled studies that focus on intraspecific cooperation tasks have revealed striking similarities, but also differences, in abilities across taxa as diverse as primates, fish, and birds. such comparisons may provide insight into the specific socio-ecological selection pressures that led to the evolution of cooperation. unfortunately, however, compared to primates data on birds remain relatively scarce. we tested a new zealand psittaciform, the kea, in a dyadic cooperation task using the loose ...201627473206
animal research. chimpanzee sanctuaries open door to more research. 201627471286
form and function of the human and chimpanzee forefoot: implications for early hominin bipedalism.during bipedal walking, modern humans dorsiflex their forefoot at the metatarsophalangeal joints (mtpjs) prior to push off, which tightens the plantar soft tissues to convert the foot into a stiff propulsive lever. particular features of metatarsal head morphology such as "dorsal doming" are thought to facilitate this stiffening mechanism. in contrast, chimpanzees are believed to possess mtpj morphology that precludes high dorsiflexion excursions during terrestrial locomotion. the morphological ...201627464580
effects of relocation and individual and environmental factors on the long-term stress levels in captive chimpanzees (pan troglodytes): monitoring hair cortisol and behaviors.understanding the factors associated with the long-term stress levels of captive animals is important from the view of animal welfare. in this study, we investigated the effects of relocation in addition to individual and environmental factors related to social management on long-term stress level in group-living captive chimpanzees by examining behaviors and hair cortisol (hc). specifically, we conducted two studies. the first compared changes in hc levels before and after the relocation of 8 c ...201627463685
chimpanzees can visually perceive differences in the freshness of foods.colour vision in primates is believed to be an adaptation for finding ripe fruit and young leaves. the contribution of the luminance distribution, which influences how humans evaluate the freshness of food, has not been explored with respect to the detection of subtle distinctions in food quality in non-human primates. we examined how chimpanzees, which are closely related to humans, perceive the freshness of foods. the findings suggest that chimpanzees were able to choose fresher cabbage based ...201627708365
neocortical grey matter distribution underlying voluntary, flexible vocalizations in chimpanzees.vocal learning is a key property of spoken language, which might also be present in nonhuman primate species, such as chimpanzees (pan troglodytes), to a limited degree. while understanding the origins of vocal learning in the primate brain may help shed light on the evolution of speech and language, little is still known regarding the neurobiological correlates of vocal flexibility in nonhuman primates. the current study used voxel-based morphometry (vbm) to assess whether the cerebral cortex o ...201627703216
disruption of an evolutionarily novel synaptic expression pattern in autism.cognitive defects in autism spectrum disorder (asd) include socialization and communication: key behavioral capacities that separate humans from other species. here, we analyze gene expression in the prefrontal cortex of 63 autism patients and control individuals, as well as 62 chimpanzees and macaques, from natal to adult age. we show that among all aberrant expression changes seen in asd brains, a single aberrant expression pattern overrepresented in genes involved synaptic-related pathways is ...201627685936
differences and similarities between human and chimpanzee neural progenitors during cerebral cortex development.human neocortex expansion likely contributed to the remarkable cognitive abilities of humans. this expansion is thought to primarily reflect differences in proliferation versus differentiation of neural progenitors during cortical development. here, we have searched for such differences by analysing cerebral organoids from human and chimpanzees using immunohistofluorescence, live imaging, and single-cell transcriptomics. we find that the cytoarchitecture, cell type composition, and neurogenic ge ...201627669147
from stem cells to comparative corticogenesis: a bridge too far?it has been hypothesized that the higher number of neurons in human cortex compared to the chimpanzee and other primate species is key to high cognitive function. are human cortical precursors endowed with specific properties that drive greater neuronal expansion than in other non-human primates? otani et al. 2016 addressed this issue taking advantage of comparative in vitro corticogenesis models based on human, chimpanzee and macaque pluripotent stem cells. clonal analysis revealed a heterochro ...201627668246
tool transfers are a form of teaching among chimpanzees.teaching is a form of high-fidelity social learning that promotes human cumulative culture. although recently documented in several nonhuman animals, teaching is rare among primates. in this study, we show that wild chimpanzees (pan troglodytes troglodytes) in the goualougo triangle teach tool skills by providing learners with termite fishing probes. tool donors experienced significant reductions in tool use and feeding, while tool recipients significantly increased their tool use and feeding af ...201627725706
human lice in paleoentomology and paleomicrobiology.lice are a classic example of cospeciation. human lice confirm this cospeciation with lice specialized in hominids which differ from those of gorillas and chimpanzees. head lice and body lice seem to belong to closely related species with different ecotypes and a different geographical distribution which may reflect population movements. paleo-entomology allows us in some cases to trace the migrations of archaic human populations. the analysis of lice found on mummies in egypt and south america ...201627726759
lateralization and performance asymmetries in the termite fishing of wild chimpanzees in the goualougo triangle, republic of congo.the nearly universal right hand preference manifested by human populations is one of the most pronounced manifestations of population-level lateralization. morphological and archeological evidence indicate that this behavioral specialization may have emerged among our hominin ancestors. whether population-level behavioral asymmetries are evident in non-human animals remains a topic of considerable scientific debate, with the most consistent evidence of population-level trends emerging from studi ...201627310151
chimpanzee females queue but males compete for social status.dominance hierarchies are widespread in animal social groups and often have measureable effects on individual health and reproductive success. dominance ranks are not static individual attributes, however, but instead are influenced by two independent processes: 1) changes in hierarchy membership and 2) successful challenges of higher-ranking individuals. understanding which of these processes dominates the dynamics of rank trajectories can provide insights into fitness benefits of within-sex co ...201627739527
genome sequences of polyomaviruses from the wild-living red colobus (piliocolobus badius) and western chimpanzee (pan troglodytes verus).we identified with pcr and sequencing the full genomes of the recently discovered pan troglodytes verus polyomavirus 8 and piliocolobus badius polyomavirus 2 in a western chimpanzee and a western red colobus free-ranging in taï national park of côte d'ivoire.201627738028
a single nucleotide polymorphism in human apobec3c enhances restriction of lentiviruses.humans express seven human apobec3 proteins, which can inhibit viruses and endogenous retroelements through cytidine deaminase activity. the seven paralogs differ in the potency of their antiviral effects, as well as in their antiviral targets. one apobec3, apobec3c, is exceptional as it has been found to only weakly block viruses and endogenous retroelements compared to other apobec3s. however, our positive selection analyses suggest that apobec3c has played a role in pathogen defense during pr ...201627732658
antibody responses to prime-boost vaccination with an hiv-1 gp145 envelope protein and chimpanzee adenovirus vectors expressing hiv-1 gp140.over 2 million individuals are infected with hiv type 1 (hiv-1) each year, yet an effective vaccine remains elusive. the most successful hiv-1 vaccine to date demonstrated 31% efficacy. immune correlate analyses associated hiv-1 envelope (env)-specific antibodies with protection, thus providing a path toward a more effective vaccine. we sought to test the antibody response from novel prime-boost vaccination with a chimpanzee-derived adenovirus (adc) vector expressing a subtype c env glycoprotein ...201627525550
foundations of cumulative culture in apes: improved foraging efficiency through relinquishing and combining witnessed behaviours in chimpanzees (pan troglodytes).a vital prerequisite for cumulative culture, a phenomenon often asserted to be unique to humans, is the ability to modify behaviour and flexibly switch to more productive or efficient alternatives. here, we first established an inefficient solution to a foraging task in five captive chimpanzee groups (n = 19). three groups subsequently witnessed a conspecific using an alternative, more efficient, solution. when participants could successfully forage with their established behaviours, most indivi ...201627775061
the apportionment of tooth size and its implications in australopithecus sediba versus other plio-pleistocene and recent african hominins.australopithecus sediba is characterized further by providing formerly unpublished and refined mesiodistal and buccolingual crown measurements in the mh1 and mh2 specimens. after size correction, these data were compared with those in other fossil and recent samples to facilitate additional insight into diachronic hominin affinities.201627402184
elevation of alanine aminotransferase activity occurs after activation of the cell-death signaling initiated by pattern-recognition receptors ‎but before activation of cytolytic effectors in nk or cd8+ t cells in the liver during acute hcv infection.pattern-recognition receptors (prrs) promote host defenses against hcv infection by binding to their corresponding adapter molecules leading to the initiation of innate immune responses including cell death. we investigated the expression of prr genes, biomarkers of liver cell-death, and t cell and nk cell activation/inhibition-related genes in liver and serum obtained from three experimentally infected chimpanzees with acute hcv infection, and analyzed the correlation between gene expression le ...201627788241
the molecular basis of human brain evolution.humans are a remarkable species, especially because of the remarkable properties of their brain. since the split from the chimpanzee lineage, the human brain has increased three-fold in size and has acquired abilities for vocal learning, language and intense cooperation. to better understand the molecular basis of these changes is of great biological and biomedical interest. however, all the about 16 million fixed genetic changes that occurred during human evolution are fully correlated with all ...201627780052
divergence and rewiring of regulatory networks for neural development between human and other species.neural and brain development in human and other mammalian species are largely similar, but distinct features exist at the levels of macrostructure and underlying genetic control. comparative studies of epigenetic regulation and transcription factor (tf) binding in humans, chimpanzees, rodents, and other species have found large differences in gene regulatory networks. a recent analysis of the cistromes of rest/nrsf, a critical transcriptional regulator for the nervous system, demonstrated that r ...201627900343
the impact of linked selection in chimpanzees: a comparative study.levels of nucleotide diversity vary greatly across the genomes of most species owing to multiple factors. these include variation in the underlying mutation rates, as well as the effects of both direct and linked selection. fundamental to interpreting the relative importance of these forces is the common observation of a strong positive correlation between nucleotide diversity and recombination rate. while indeed observed in humans, the interpretation of this pattern has been difficult in the ab ...201627678122
broader impacts: international implications and integrative ethical consideration of policy decisions about us chimpanzee research.recent decisions and unprecedented evaluative processes about research with chimpanzees (pan troglodytes) by the us national institutes of health (nih) continue to attract widespread attention by the public, media, and scientific community. over the past 5 years, actions by the nih and the united states fish and wildlife services, have significantly truncated valuable scientific research and jeopardized future research. from a global perspective, the decisions have broad consequences for researc ...201627434183
chimpanzees in an anthropogenic landscape: examining food resources across habitat types at bossou, guinea, west africa.many primate populations occur outside protected areas in fragmented anthropogenic landscapes. empirical data on the ecological characteristics that define an anthropogenic landscape are urgently required if conservation initiatives in such environments are to succeed. the main objective of our study was to determine the composition and availability of chimpanzee (pan troglodytes verus) food resources across fine spatial scales in the anthropogenic landscape of bossou, guinea, west africa. we ex ...201627332064
reply to schmidt and tomasello: chimpanzees as natural team-players. 201627791163
how chimpanzees cooperate: if dominance is artificially constrained. 201627791161
social support reduces stress hormone levels in wild chimpanzees across stressful events and everyday affiliations.stress is a major cause of poor health and mortality in humans and other social mammals. close social bonds buffer stress, however much of the underlying physiological mechanism remains unknown. here, we test two key hypotheses: bond partner effects occur only during stress (social buffering) or generally throughout daily life (main effects). we assess urinary glucocorticoids (ugc) in wild chimpanzees, with or without their bond partners, after a natural stressor, resting or everyday affiliation ...201627802260
reflections of the social environment in chimpanzee memory: applying rational analysis beyond humans.in cognitive science, the rational analysis framework allows modelling of how physical and social environments impose information-processing demands onto cognitive systems. in humans, for example, past social contact among individuals predicts their future contact with linear and power functions. these features of the human environment constrain the optimal way to remember information and probably shape how memory records are retained and retrieved. we offer a primer on how biologists can apply ...201627853606
play-solicitation gestures in chimpanzees in the wild: flexible adjustment to social circumstances and individual matrices.social play is a frequent behaviour in great apes and involves sophisticated forms of communicative exchange. while it is well established that great apes test and practise the majority of their gestural signals during play interactions, the influence of demographic factors and kin relationships between the interactants on the form and variability of gestures are relatively little understood. we thus carried out the first systematic study on the exchange of play-soliciting gestures in two chimpa ...201627853603
distribution of a chimpanzee social custom is explained by matrilineal relationship rather than conformity.high-arm grooming is a form of chimpanzee grooming in which two individuals mutually groom while each raising one arm. palm-to-palm clasping (ppc) is a distinct style of high-arm grooming in which the grooming partners clasp each other's raised palms. in wild communities, samples of at least 100 observed dyads grooming with raised hands showed ppc frequencies varying from <5% (m group, mahale) to >30% dyads grooming (kanyawara, kibale), and in a large free-ranging sanctuary group, the frequency ...201627839974
the effects of tradition on problem solving by two wild populations of bearded capuchin monkeys in a probing task.the effects of culture on individual cognition have become a core issue among cultural primatologists. field studies with wild populations provide evidence on the role of social cues in the ontogeny of tool use in non-human primates, and on the transmission of such behaviours over generations through socially biased learning. recent experimental studies have shown that cultural knowledge may influence problem solving in wild populations of chimpanzees. here, we present the results from a field e ...201627881763
a human reproductive approach to the study of infertility in chimpanzees: an experience at leon's zoological park, mexico.great apes are mammals close to humans in their genetic, behavioral, social and evolutionary characteristics and new genomic information is revolutionizing our understanding of evolution in primates. however, all these species are endangered. while there are many global programs to protect these species, the international union for conservation of nature (iucn) projects that in a near future the wild populations will decrease significantly. nowadays, the relevance of captive populations of great ...201627872723
nut cracking tools used by captive chimpanzees (pan troglodytes) and their comparison with early stone age percussive artefacts from olduvai gorge.we present the results of a series of experiments at the kumamoto sanctuary in japan, in which captive chimpanzees (pan troglodytes) performed several nut cracking sessions using raw materials from olduvai gorge, tanzania. we examined captive chimpanzee pounding tools using a combination of technological analysis, use-wear distribution, and micro-wear analysis. our results show specific patterns of use-wear distribution across the active surfaces of pounding tools, which reveal some similarities ...201627870877
review of in vivo bone strain studies and finite element models of the zygomatic complex in humans and nonhuman primates: implications for clinical research and practice.the craniofacial skeleton is often described in the clinical literature as being comprised of vertical bony pillars, which transmit forces from the toothrow to the neurocranium as axial compressive stresses, reinforced transversely by buttresses. here, we review the literature on bony microarchitecture, in vivo bone strain, and finite-element modeling of the facial skeleton of humans and nonhuman primates to address questions regarding the structural and functional existence of facial pillars an ...201627870351
elastic properties of chimpanzee craniofacial cortical bone.relatively few assessments of cranial biomechanics formally take into account variation in the material properties of cranial cortical bone. our aim was to characterize the elastic properties of chimpanzee craniofacial cortical bone and compare these to the elastic properties of dentate human craniofacial cortical bone. from seven cranial regions, 27 cylindrical samples were harvested from each of five chimpanzee crania. assuming orthotropy, axes of maximum stiffness in the plane of the cortical ...201627870344
the biomechanics of zygomatic arch shape.mammalian zygomatic arch shape is remarkably variable, ranging from nearly cylindrical to blade-like in cross section. based on geometry, the arch can be hypothesized to be a sub-structural beam whose ability to resist deformation is related to cross sectional shape. we expect zygomatic arches with different cross sectional shapes to vary in the degree to which they resist local bending and torsion due to the contraction of the masseter muscle. a stiffer arch may lead to an increase in the relat ...201627870343
genomics: disclose the influence of human specific genetic variation on the evolution and development of cerebral cortex.cerebral cortex, whose complexity of structure and function has derived from human specific genetic variation, is the most advanced nerve center of human, controlling the cognitive ability which distinguishes human from any other creatures. using genomics technology, molecular mechanisms of cerebral cortex development and evolution have been disclosed. in this review, we summarize how genomics technologies are used in exploring the influence of human specific genetic variation on cerebral cortex ...201627867146
assessing the manipulative potentials of monkeys, apes and humans from hand proportions: implications for hand evolution.the hand structure possesses a greater potential for performing manipulative skills than is typically observed, whether in humans or non-human anthropoids. however, a precise assessment of the potential manipulative skills of hands has been challenging, which hampers our understanding of the evolution of manipulative abilities in anthropoid hands. here, we establish a functional model to quantitatively infer the manipulative potentials of anthropoid hands based on hand proportions. our results r ...201627903877
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