Publications

strong vaccine-induced cd8 t-cell responses have cytolytic function in a chimpanzee clearing hcv infection.	a single correlate of effective vaccine protection against chronic hcv infection has yet to be defined. in this study, we analyzed t-cell responses in four chimpanzees, immunized with core-e1-e2-ns3 and subsequently infected with hcv1b. viral clearance was observed in one animal, while the other three became chronically infected. in the animal that cleared infection, ns3-specific cd8 t-cell responses were observed to be more potent in terms of frequency and polyfunctionality of cytokine producin ...	2014	24740375
chimpanzees preferentially select sleeping platform construction tree species with biomechanical properties that yield stable, firm, but compliant nests.	the daily construction of a sleeping platform or "nest" is a universal behavior among large-bodied hominoids. among chimpanzees, most populations consistently select particular tree species for nesting, yet the principles that guide species preferences are poorly understood. at semliki, cynometra alexandri constitutes only 9.6% of all trees in the gallery forest in which the study populations ranges, but it was selected for 73.6% of the 1,844 chimpanzee night beds we sampled. to determine whethe ...	2014	24740283
the risk of disease to great apes: simulating disease spread in orang-utan (pongo pygmaeus wurmbii) and chimpanzee (pan troglodytes schweinfurthii) association networks.	all great ape species are endangered, and infectious diseases are thought to pose a particular threat to their survival. as great ape species vary substantially in social organisation and gregariousness, there are likely to be differences in susceptibility to disease types and spread. understanding the relation between social variables and disease is therefore crucial for implementing effective conservation measures. here, we simulate the transmission of a range of diseases in a population of or ...	2014	24740263
evolutionary biology: dating chimpanzees.		2014	24740060
assessment of chimpanzee adenovirus serotype 63 neutralizing antibodies prior to evaluation of a candidate malaria vaccine regimen based on viral vectors.	prior to a chimpanzee adenovirus-based (chad63) malarial vaccine trial, sera were collected to assess chad63-specific neutralizing antibody titers in banfora (burkina faso). the low neutralizing antibody titers reported in both adults and children (median titers, 139.1 and 35.0, respectively) are encouraging for the potential use of chad63 as a malarial vaccine vector.	2014	24739980
why primate models matter.	research involving nonhuman primates (nhps) has played a vital role in many of the medical and scientific advances of the past century. nhps are used because of their similarity to humans in physiology, neuroanatomy, reproduction, development, cognition, and social complexity-yet it is these very similarities that make the use of nhps in biomedical research a considered decision. as primate researchers, we feel an obligation and responsibility to present the facts concerning why primates are use ...	2014	24723482
using cross correlations to investigate how chimpanzees (pan troglodytes) use conspecific gaze cues to extract and exploit information in a foraging competition.	in a dyadic informed forager task, chimpanzees (pan troglodytes) are known to exploit the knowledge of informed subordinates; however, the behavioral mechanisms they employ are unknown. it is tempting to interpret outcome measures, such as which individual obtained the food, in a cognitively richer way than the outcomes may justify. we employed a different approach from prior research, asking how chimpanzees compete by maneuvering around each other, whether they use gaze cues to acquire informat ...	2014	24710756
chimpanzees prefer african and indian music over silence.	[correction notice: an erratum for this article was reported in vol 40(4) of journal of experimental psychology: animal learning and cognition (see record 2014-35305-001). for the article, the below files were used to create the audio used in this study. the original west african akan and north indian raga pieces were used in their entirety and the japanese taiko piece was used from the 0:19 second mark through the end. the tempo of each piece was adjusted so that they maintained an identical ba ...	2014	25546107
why vocal production of atypical sounds in apes and its cerebral correlates have a lot to say about the origin of language.	ackermann et al. mention the "acquisition of species-atypical sounds" in apes without any discussion. in our commentary, we demonstrate that these atypical sounds in chimpanzees not only include laryngeal sounds, but also have a major significance regarding the origins of language, if we consider looking at their context of use, their social properties, their relations with gestures, their lateralization, and their neurofunctional correlates as well.	2014	25514955
suffodit inguina.	when julius caesar was stabbed, 23 times, on the ides of march, at least one of the daggers is supposed to have gone into his groin. he wasn't the last roman to have his privates attacked. and he wasn't the last primate. in competition for sexual access, gonads are occasionally targeted: canine incisions in monkey and ape scrota are not uncommon; and rumors had a number of roman emperors--from caligula and nero, to galba, vitellius, domitian, commodus, caracalla, elagabalus, to balbinus, pupienu ...	2014	25514523
effective population size does not predict codon usage bias in mammals.	synonymous codons are not used at equal frequency throughout the genome, a phenomenon termed codon usage bias (cub). it is often assumed that interspecific variation in the intensity of cub is related to species differences in effective population sizes (n e), with selection on cub operating less efficiently in species with small n e. here, we specifically ask whether variation in n e predicts differences in cub in mammals and report two main findings. first, across 41 mammalian genomes, cub was ...	2014	25505518
when maths trumps logic: probabilistic judgements in chimpanzees.	when searching for hidden food, do chimpanzees take into account both the number of hidden items and the number of potential hiding locations? we presented chimpanzees with two trays, each of them containing a different food/cup ratio and therefore a different likelihood of finding a baited cup among empty alternatives. subjects' performance was directly influenced by the relative difference (probability ratio (pr)) between the two given probabilities. interestingly, however, they did not apprec ...	2014	25505056
katie e. slocombe: award for distinguished scientific early career contributions to psychology.	apa's awards for distinguished scientific early career contributions to psychology recognize excellent young psychologists who have not held a doctoral degree for more than nine years. one of the 2014 award winners is katie e. slocombe, for "outstanding contributions to understanding the communication and cognition of our closest living animal relatives, the chimpanzees." slocombe's award citation, biography, and a selected bibliography are presented here.	2014	25486147
first description of the complete human xylosyltransferase-i promoter region.	human xylosyltransferase-i (xt-i) catalyzes the rate-limiting step in proteoglycan glycosylation. an increase in xylt1 mrna expression and serum xt activity is associated with diseases characterized by abnormal extracellular matrix accumulation like, for instance, fibrosis. nevertheless, physiological and pathological mechanisms of transcriptional xt regulation remain elusive.	2014	25480529
insights into the possible role of ifng and ifngr1 in kala-azar and post kala-azar dermal leishmaniasis in sudanese patients.	little is known about the parasite/host factors that lead to post kala-azar dermal leishmaniasis (pkdl) in some visceral leishmaniasis (vl) patients after drug-cure. studies in sudan provide evidence for association between polymorphisms in the gene (ifngr1) encoding the alpha chain of interferon-γ receptor type i and risk of pkdl. this study aimed to identify putative functional polymorphisms in the ifngr1 gene, and to determine whether differences in expression of interferon-γ (ifng) and ifngr ...	2014	25466928
sexual conflict: nice guys finish last.	male chimpanzees are often aggressive towards females. a new study from gombe national park in tanzania reports that persistent attacks increase a male's probability of siring offspring.	2014	25465331
sexually coercive male chimpanzees sire more offspring.	in sexually reproducing animals, male and female reproductive strategies often conflict. in some species, males use aggression to overcome female choice, but debate persists over the extent to which this strategy is successful. previous studies of male aggression toward females among wild chimpanzees have yielded contradictory results about the relationship between aggression and mating behavior. critically, however, copulation frequency in primates is not always predictive of reproductive succe ...	2014	25454788
histological features of layers and sublayers in cortical visual areas v1 and v2 of chimpanzees, macaque monkeys, and humans.	the layers and sublayers of primary visual cortex, or v1, in primates are easily distinguishable compared to those in other cortical areas, and are especially distinct in anthropoid primates - monkeys, apes, and humans - where they also vary in histological appearance. this variation in primate-specific specialization has led to a longstanding confusion over the identity of layer 4 and its proposed sublayers in v1. as the application of different histological markers relate to the issue of defin ...	2014	25788835
mouse models of human evolution.	the genotype-phenotype map of human evolution is difficult to access since humans cannot be crossed with other species. most of the ∼20 million genetic changes that occurred since the human and the chimpanzee lineage split, are fixed and hence completely correlated with all phenotypic changes that occurred during human evolution. while patterns of selection and functional information on genomic regions are crucial to prioritize on particular genetic changes, experimental access is needed to test ...	2014	25218860
the role of gene regulatory factors in the evolutionary history of humans.	deciphering the molecular basis of how modern human phenotypes have evolved is one of the most fascinating challenges in biology. here, we will focus on the roles of gene regulatory factors (grfs), in particular transcription factors (tfs) and long non-coding rnas (lncrnas) during human evolution. we will present examples of tfs and lncrnas that have changed or show signs of positive selection in humans compared to chimpanzees, in modern humans compared to archaic humans, or within modern human ...	2014	25215414
evaluating the y chromosomal timescale in human demographic and lineage dating.	y chromosome is a superb tool for inferring human evolution and recent demographic history from a paternal perspective. however, y chromosomal substitution rates obtained using different modes of calibration vary considerably, and have produced disparate reconstructions of human history. here, we discuss how substitution rate and date estimates are affected by the choice of different calibration points. we argue that most y chromosomal substitution rates calculated to date have shortcomings, inc ...	2014	25215184
fish choose appropriately when and with whom to collaborate.	collaborative abilities are integral to human society [1] and their evolutionary origins are of great interest. chimpanzees are capable of determining appropriately when and with whom to collaborate in a rope-pull experiment [2]--the only non-human species known to possess both abilities. chimpanzees are thought to share these abilities with humans as a result of common ancestry [2]. here, we show that a fish--the coral trout plectropomus leopardus--has partner-choice abilities comparable to tho ...	2014	25202866
alloparenting for chimpanzee twins.	in april 2009, a female chimpanzee named sango, living in a captive group at the noichi zoo, japan, gave birth to dizygotic male-female twin chimpanzees (male: daiya, female: sakura). the extent to which adult group members cared for the twins was investigated using a focal animal sampling method targeting six adults (one male) when the twin chimpanzees were two years old. data were collected for an average of 6.78 h (sd = 0.79) per focal participant. an unaffiliated female adult of sango was en ...	2014	25200656
identification of species-specific nuclear insertions of mitochondrial dna (numts) in gorillas and their potential as population genetic markers.	the first hyper-variable region (hv1) of the mitochondrial control region (mcr) has been widely used as a molecular tool in population genetics, but inadvertent amplification of nuclear translocated copies of mitochondrial dna (numts) in gorillas has compromised the use of mitochondrial dna in population genetic studies. at least three putative classes (i, ii, iii) of gorilla-specific hv1 mcr numts have been uncovered over the past decade. however, the number, size and location of numt loci in g ...	2014	25194325
task design influences prosociality in captive chimpanzees (pan troglodytes).	chimpanzees confer benefits on group members, both in the wild and in captive populations. experimental studies of how animals allocate resources can provide useful insights about the motivations underlying prosocial behavior, and understanding the relationship between task design and prosocial behavior provides an important foundation for future research exploring these animals' social preferences. a number of studies have been designed to assess chimpanzees' preferences for outcomes that benef ...	2014	25191860
the paleoecology of early pleistocene gigantopithecus blacki inferred from isotopic analyses.	this study presents isotopic analyses of gigantopithecus blacki and contemporaneous fauna from early pleistocene southern china cave localities with a view to reconstructing the paleoecology of this large extinct ape. carbon and oxygen stable isotope compositions were determined using tooth enamel carbonate of gigantopithecus and eight other taxa from longgudong cave and additional gigantopithecus specimens from juyuandong cave. carbon isotopic values of gigantopithecus fauna reflect a densely f ...	2014	25181425
towards a unified scheme of cortical lamination for primary visual cortex across primates: insights from neun and vglut2 immunoreactivity.	primary visual cortex (v1) is clearly distinguishable from other cortical areas by its distinctive pattern of neocortical lamination across mammalian species. in some mammals, primates in particular, the layers of v1 are further divided into a number of sublayers based on their anatomical and functional characteristics. while these sublayers are easily recognizable across a range of primates, the exact number of divisions in each layer and their relative position within the depth of v1 has been ...	2014	25177277
exploring the genesis and functions of human accelerated regions sheds light on their role in human evolution.	human accelerated regions (hars) are dna sequences that changed very little throughout mammalian evolution, but then experienced a burst of changes in humans since divergence from chimpanzees. this unexpected evolutionary signature is suggestive of deeply conserved function that was lost or changed on the human lineage. since their discovery, the actual roles of hars in human evolution have remained somewhat elusive, due to their being almost exclusively non-coding sequences with no annotation. ...	2014	25156517
adult humans' understanding of support relations: an up-linkage replication.	in an up-linkage replication, three experiments examined adult humans' folk physics, i.e., their naturally occurring and spontaneous understanding of the physical world, using a violation of expectation (voe) task and stimuli similar to those used to study chimpanzees', monkeys', and rooks' folk physics. unlike what has been reported with nonhuman primates, adult humans did not look longer at physically impossible than possible events, though they did rate the physically impossible events as mor ...	2014	25149282
chimpanzees (pan troglodytes) instrumentally help but do not communicate in a mutualistic cooperative task.	chimpanzees cooperate in a variety of contexts, but communicating to influence and regulate cooperative activities is rare. it is unclear whether this reflects chimpanzees' general inability or whether they have found other means to coordinate cooperative activities. in the present study chimpanzees could help a partner play her role in a mutually beneficial food-retrieval task either by transferring a needed tool (transfer condition) or by visually or acoustically communicating the hiding-locat ...	2014	25133465
the cortical microstructural basis of lateralized cognition: a review.	the presence of asymmetry in the human cerebral hemispheres is detectable at both the macroscopic and microscopic scales. the horizontal expansion of cortical surface during development (within individual brains), and across evolutionary time (between species), is largely due to the proliferation and spacing of the microscopic vertical columns of cells that form the cortex. in the asymmetric planum temporale (pt), minicolumn width asymmetry is associated with surface area asymmetry. although the ...	2014	25126082
the influence of body mass index, age and sex on inflammatory disease risk in semi-captive chimpanzees.	obesity and ageing are emerging issues in the management of captive primates, including chimpanzees, pan troglodytes. studies on humans show that obesity and old age can independently increase the risk of inflammatory-associated diseases indicated by elevated levels of pro-inflammatory cells and proteins in the blood of older or obese compared to levels in younger or non-obese individuals. in humans, sex can influence the outcomes of these risks. health management of these problems in chimpanzee ...	2014	25121995
nih finalizes chimpanzee housing requirements.		2014	25118460
finding faces among faces: human faces are located more quickly and accurately than other primate and mammal faces.	we tested the specificity of human face search efficiency by examining whether there is a broad window of detection for various face-like stimuli-human and animal faces-or whether own-species faces receive greater attentional allocation. we assessed the strength of the own-species face detection bias by testing whether human faces are located more efficiently than other animal faces, when presented among various other species' faces, in heterogeneous 16-, 36-, and 64-item arrays. across all arra ...	2014	25113852
playful expressions of one-year-old chimpanzee infants in social and solitary play contexts.	knowledge of the context and development of playful expressions in chimpanzees is limited because research has tended to focus on social play, on older subjects, and on the communicative signaling function of expressions. here we explore the rate of playful facial and body expressions in solitary and social play, changes from 12- to 15-months of age, and the extent to which social partners match expressions, which may illuminate a route through which context influences expression. naturalistic o ...	2014	25104942
improved calibration of the human mitochondrial clock using ancient genomes.	reliable estimates of the rate at which dna accumulates mutations (the substitution rate) are crucial for our understanding of the evolution and past demography of virtually any species. in humans, there are considerable uncertainties around these rates, with substantial variation among recent published estimates. substitution rates have traditionally been estimated by associating dated events to the root (e.g., the divergence between humans and chimpanzees) or to internal nodes in a phylogeneti ...	2014	25100861
why do chimpanzee males attack the females of neighboring communities?	our closest nonhuman primate relatives, chimpanzees, engage in potentially lethal between-group conflict; this collective aggressive behavior shows parallels with human warfare. in some communities, chimpanzee males also severely attack and even kill females of the neighboring groups. this is surprising given their system of resource defense polygyny, where males are expected to acquire potential mates. we develop a simple mathematical model based on reproductive skew among primate males to solv ...	2014	25100507
density estimates and nesting-site selection in chimpanzees of the nimba mountains, côte d'ivoire, and guinea.	we investigated nesting behavior of non habituated chimpanzees populating the nimba mountains to document their abundance and their criterions of nesting-site selection. during a 19-month study we walked 80 km of transects and recces each month, and recorded 764 nests (mean group size = 2.23 nests) along with characteristics of vegetation structure and composition, topography, and seasonality. population density estimated with two nest count methods ranged between 0.14 and 0.65 chimpanzee/km(2) ...	2014	25099739
'adoption' by maternal siblings in wild chimpanzees.	the adoption of unrelated orphaned infants is something chimpanzees and humans have in common. providing parental care has fitness implications for both the adopter and orphan, and cases of adoption have thus been cited as evidence for a shared origin of an altruistic behaviour. we provide new data on adoptions in the free-living sonso chimpanzee community in uganda, together with an analysis of published data from other long-term field sites. as a default pattern, we find that orphan chimpanzee ...	2014	25084521
hunter-gatherer inter-band interaction rates: implications for cumulative culture.	our species exhibits spectacular success due to cumulative culture. while cognitive evolution of social learning mechanisms may be partially responsible for adaptive human culture, features of early human social structure may also play a role by increasing the number potential models from which to learn innovations. we present interview data on interactions between same-sex adult dyads of ache and hadza hunter-gatherers living in multiple distinct residential bands (20 ache bands; 42 hadza bands ...	2014	25047714
modular structure facilitates mosaic evolution of the brain in chimpanzees and humans.	different brain components can evolve in a coordinated manner or they can show divergent evolutionary trajectories according to a mosaic pattern of variation. understanding the relationship between these brain evolutionary patterns, which are not mutually exclusive, can be informed by the examination of intraspecific variation. our study evaluates patterns of brain anatomical covariation in chimpanzees and humans to infer their influence on brain evolution in the hominin clade. we show that chim ...	2014	25047085
unraveling recombination rate evolution using ancestral recombination maps.	recombination maps of ancestral species can be constructed from comparative analyses of genomes from closely related species, exemplified by a recently published map of the human-chimpanzee ancestor. such maps resolve differences in recombination rate between species into changes along individual branches in the speciation tree, and allow identification of associated changes in the genomic sequences. we describe how coalescent hidden markov models are able to call individual recombination events ...	2014	25043668
hypothesis: brain size and skull shape as criteria for a new hominin family tree.	today, gorillas and chimpanzees live in tropical forests, where acid soils do not favor fossilization. it is thus widely believed that there are no fossils of chimpanzees or gorillas. however, four teeth of a 0.5-million-year (ma)-old chimpanzee were discovered in the rift valley of kenya (mcbrearty and jablonski, 2005), and a handful of teeth of a 10-ma-old gorilla-like creature were found in ethiopia (suwa et al., 2007), close to the major sites of homo discoveries. these discoveries indicate ...	2014	25041944
characterization of a genogroup i sapovirus isolated from chimpanzees in the republic of congo.	sapoviruses, which are members of the caliciviridae family, are small nonenveloped viruses known to infect a large spectrum of mammalian hosts. we report here the first complete genome sequences of two genogroup i sapoviruses isolated from fecal samples from chimpanzees living in the tchimpounga sanctuary, republic of congo.	2014	25035327
suitable habitats for endangered frugivorous mammals: small-scale comparison, regeneration forest and chimpanzee density in kibale national park, uganda.	landscape patterns and chimpanzee (pan troglodytes schweinfurthii) densities in kibale national park show important variation among communities that are geographically close to one another (from 1.5 to 5.1 chimpanzees/km2). anthropogenic activities inside the park (past logging activities, current encroachment) and outside its limits (food and cash crops) may impact the amount and distribution of food resources for chimpanzees (frugivorous species) and their spatial distribution within the park. ...	2014	25033459
recombination in the human pseudoautosomal region par1.	the pseudoautosomal region (par) is a short region of homology between the mammalian x and y chromosomes, which has undergone rapid evolution. a crossover in the par is essential for the proper disjunction of x and y chromosomes in male meiosis, and par deletion results in male sterility. this leads the human par with the obligatory crossover, par1, to having an exceptionally high male crossover rate, which is 17-fold higher than the genome-wide average. however, the mechanism by which this obli ...	2014	25033397
uncovering adaptive evolution in the human lineage.	the recent increase in human polymorphism data, together with the availability of genome sequences from several primate species, provides an unprecedented opportunity to investigate how natural selection has shaped human evolution.	2014	25030307
chimpanzee intelligence is heritable.	the role that genes play in human intelligence or iq has remained a point of significant scientific debate dating back to the time of galton [1]. it has now become increasingly clear that iq is heritable in humans, but these effects can be modified by nongenetic mechanisms [2-4]. in contrast to human iq, until recently, views of learning and cognition in animals have largely been dominated by the behaviorist school of thought, originally championed by watson [5] and skinner [6]. a large body of ...	2014	25017206
the meanings of chimpanzee gestures.	chimpanzees' use of gesture was described in the first detailed field study [1, 2], and natural use of specific gestures has been analyzed [3-5]. however, it was systematic work with captive groups that revealed compelling evidence that chimpanzees use gestures to communicate in a flexible, goal-oriented, and intentional fashion [6-8], replicated across all great ape species in captivity [9-17] and chimpanzees in the wild [18, 19]. all of these aspects overlap with human language but are apparen ...	2014	24998524
chimpanzee isotopic ecology: a closed canopy c3 template for hominin dietary reconstruction.	the most significant hominin adaptations, including features used to distinguish and/or classify taxa, are critically tied to the dietary environment. stable isotopic analyses of tooth enamel from hominin fossils have provided intriguing evidence for significant c4/cam (crassulacean acid metabolism) resource consumption in a number of plio-pleistocene hominin taxa. relating isotopic tooth signatures to specific dietary items or proportions of c3 versus c4/cam plants, however, remains difficult a ...	2014	24993419
chimpanzees (pan troglodytes verus) and their mammalian sympatriates: mt. assirik, niokolo-koba national park, senegal.	in intact, mosaic ecosystems, chimpanzees are sympatric with a wide range of other mammals, which may be predators, prey, or competitors. we delve beyond the nominal data of species lists to interval-level data on 35 medium-bodied and large-bodied mammals encountered at a hot, dry, and open field site in far west africa. frequency of encounter, habitat where found, and number of individuals encountered are analysed for species for which enough data were accumulated. further, we compare findings ...	2014	24990446
the importance of social play network for infant or juvenile wild chimpanzees at mahale mountains national park, tanzania.	along with social grooming and food sharing, social play is considered to be an affiliative interaction among wild chimpanzees. however, infant, juvenile, and adolescent animals engage in social play more frequently than adult animals, while other affiliative interactions occur more commonly between adults. we studied the social play of well-habituated and individually identified wild chimpanzees of the m group in mahale mountains national park, tanzania over two research periods in 2010 and 201 ...	2014	24990324
chimpanzee-specific endogenous retrovirus generates genomic variations in the chimpanzee genome.	endogenous retroviruses (ervs), eukaryotic transposable elements, exist as proviruses in vertebrates including primates and contribute to genomic changes during the evolution of their host genomes. many studies about ervs have focused on the elements residing in the human genome but only a few studies have focused on the elements which exist in non-human primate genomes. in this study, we identified 256 chimpanzee-specific endogenous retrovirus copies (ptervs: pan troglodyte endogenous retroviru ...	2014	24987855
the ecology of primate material culture.	tool use in extant primates may inform our understanding of the conditions that favoured the expansion of hominin technology and material culture. the 'method of exclusion' has, arguably, confirmed the presence of culture in wild animal populations by excluding ecological and genetic explanations for geographical variation in behaviour. however, this method neglects ecological influences on culture, which, ironically, may be critical for understanding technology and thus material culture. we rev ...	2014	25392310
human children rely more on social information than chimpanzees do.	human societies are characterized by more cultural diversity than chimpanzee communities. however, it is currently unclear what mechanism might be driving this difference. because reliance on social information is a pivotal characteristic of culture, we investigated individual and social information reliance in children and chimpanzees. we repeatedly presented subjects with a reward-retrieval task on which they had collected conflicting individual and social information of equal accuracy in coun ...	2014	25392309
the social life of laughter.	laughter is often considered to be the product of humour. however, laughter is a social emotion, occurring most often in interactions, where it is associated with bonding, agreement, affection, and emotional regulation. laughter is underpinned by complex neural systems, allowing it to be used flexibly. in humans and chimpanzees, social (voluntary) laughter is distinctly different from evoked (involuntary) laughter, a distinction which is also seen in brain imaging studies of laughter.	2014	25439499
early social exposure in wild chimpanzees: mothers with sons are more gregarious than mothers with daughters.	in many mammals, early social experience is critical to developing species-appropriate adult behaviors. although mother-infant interactions play an undeniably significant role in social development, other individuals in the social milieu may also influence infant outcomes. additionally, the social skills necessary for adult success may differ between the sexes. in chimpanzees (pan troglodytes), adult males are more gregarious than females and rely on a suite of competitive and cooperative relati ...	2014	25422411
sperm preservation by freeze-drying for the conservation of wild animals.	sperm preservation is a useful technique for the maintenance of biological resources in experimental and domestic animals, and in wild animals. a new preservation method has been developed that enables sperm to be stored for a long time in a refrigerator at 4 °c. sperm are freeze-dried in a solution containing 10 mm tris and 1 mm edta. using this method, liquid nitrogen is not required for the storage and transportation of sperm. we demonstrate that chimpanzee, giraffe, jaguar, weasel and the lo ...	2014	25409172
sequence differences at orthologous microsatellites inflate estimates of human-chimpanzee differentiation.	microsatellites--contiguous arrays of 2-6 base-pair motifs--have formed the cornerstone of population-genetic studies for over two decades. their genotype data typically takes the form of pcr fragment lengths obtained using locus-specific primer pairs to amplify the genomic region encompassing the microsatellite. recently, we reported a dataset of 5,795 human and 84 chimpanzee individuals with genotypes at 246 human-derived autosomal microsatellites as a resource to facilitate interspecies compa ...	2014	25407736
human-chimpanzee alignment: ortholog exponentials and paralog power laws.	genomic subsequences conserved between closely related species such as human and chimpanzee exhibit an exponential length distribution, in contrast to the algebraic length distribution observed for sequences shared between distantly related genomes. we find that the former exponential can be further decomposed into an exponential component primarily composed of orthologous sequences, and a truncated algebraic component primarily composed of paralogous sequences.	2014	25443749
speciation, population structure, and demographic history of the mojave fringe-toed lizard (uma scoparia), a species of conservation concern.	the north american deserts were impacted by both neogene plate tectonics and quaternary climatic fluctuations, yet it remains unclear how these events influenced speciation in this region. we tested published hypotheses regarding the timing and mode of speciation, population structure, and demographic history of the mojave fringe-toed lizard (uma scoparia), a sand dune specialist endemic to the mojave desert of california and arizona. we sampled 109 individual lizards representing 22 insular dun ...	2014	25360285
children conform to the behavior of peers; other great apes stick with what they know.	all primates learn things from conspecifics socially, but it is not clear whether they conform to the behavior of these conspecifics--if conformity is defined as overriding individually acquired behavioral tendencies in order to copy peers' behavior. in the current study, chimpanzees, orangutans, and 2-year-old human children individually acquired a problem-solving strategy. they then watched several conspecific peers demonstrate an alternative strategy. the children switched to this new, social ...	2014	25355648
the origin of representational drawing: a comparison of human children and chimpanzees.	to examine the evolutional origin of representational drawing, two experiments directly compared the drawing behavior of human children and chimpanzees. the first experiment observed free drawing after model presentation, using imitation task. from longitudinal observation of humans (n = 32, 11-31 months), the developmental process of drawing until the emergence of shape imitation was clarified. adult chimpanzees showed the ability to trace a model, which was difficult for humans who had just st ...	2014	25376268
what did you choose just now? chimpanzees' short-term retention of memories of their own behavior.	many recent comparative studies have addressed "episodic" memory in nonhuman animals, suggesting that birds, rodents, great apes, and others can remember their own behavior after at least a half-day delay. by contrast, despite numerous studies regarding long-term memory, few comparable studies have been conducted on short-term retention for own behavior. in the current study, we addressed the following question: do chimpanzees remember what they have just done? four chimpanzees performed matchin ...	2014	25374781
the relationship between event-based prospective memory and ongoing task performance in chimpanzees (pan troglodytes).	prospective memory is remembering to do something at a future time. a growing body of research supports that prospective memory may exist in nonhuman animals, but the methods used to test nonhuman prospective memory differ from those used with humans. the current work tests prospective memory in chimpanzees using a method that closely approximates a typical human paradigm. in these experiments, the prospective memory cue was embedded within an ongoing task. tokens representing food items could b ...	2014	25372809
maternal behavior by birth order in wild chimpanzees (pan troglodytes): increased investment by first-time mothers.	parental investment theory predicts that maternal resources are finite and allocated among offspring based on factors including maternal age and condition, and offspring sex and parity. among humans, firstborn children are often considered to have an advantage and receive greater investment than their younger siblings. however, conflicting evidence for this "firstborn advantage" between modern and hunter-gatherer societies raises questions about the evolutionary history of differential parental ...	2014	25328164
wild chimpanzees on the edge: nocturnal activities in croplands.	in a rapidly changing landscape highly impacted by anthropogenic activities, the great apes are facing new challenges to coexist with humans. for chimpanzee communities inhabiting encroached territories, not bordered by rival conspecifics but by human agricultural fields, such boundaries are risky areas. to investigate the hypothesis that they use specific strategies for incursions out of the forest into maize fields to prevent the risk of detection by humans guarding their field, we carried out ...	2014	25338066
wild chimpanzees plan their breakfast time, type, and location.	not all tropical fruits are equally desired by rainforest foragers and some fruit trees get depleted more quickly and carry fruit for shorter periods than others. we investigated whether a ripe-fruit specialist, the chimpanzee (pan troglodytes verus), arrived earlier at breakfast sites with very ephemeral and highly sought-after fruit, like figs, than sites with less ephemeral fruit that can be more predictably obtained throughout the entire day. we recorded when and where five adult female chim ...	2014	25349399
lethal coalitionary aggression and long-term alliance formation among yanomamö men.	some cross-cultural evidence suggests lethal coalitionary aggression in humans is the product of residence and descent rules that promote fraternal interest groups, i.e., power groups of coresident males bonded by kinship. as such, human lethal coalitions are hypothesized to be homologous to chimpanzee (pan troglodytes) border patrols. however, humans demonstrate a unique metagroup social structure in which strategic alliances allow individuals to form coalitions transcending local community bou ...	2014	25349394
albuminoid genes: evolving at the interface of dispensability and selection.	the albuminoid gene family comprises vitamin d-binding protein (gc), alpha-fetoprotein (afp), afamin (afm), and albumin (alb). albumin is the most abundant human serum protein, and, as the other family members, acts as a transporter of endogenous and exogenous substances including thyroxine, fatty acids, and drugs. instead, the major cargo of gc is 25-hydroxyvitamin d. we performed an evolutionary study of albuminoid genes and we show that alb evolved adaptively in mammals. most positively selec ...	2014	25349266
early social deprivation negatively affects social skill acquisition in chimpanzees (pan troglodytes).	in a highly social species like chimpanzees, the process by which individuals become attuned to their social environment may be of vital importance to their chances of survival. typically, this socialization process, defined by all acquisition experiences and fine-tuning efforts of social interaction patterns during ontogeny, occurs in large part through parental investment. in this study, we investigated whether maternal presence enhances the socialization process in chimpanzees by comparing th ...	2014	23954954
when less is more: like humans, chimpanzees (pan troglodytes) misperceive food amounts based on plate size.	we investigated whether chimpanzees (pan troglodytes) misperceived food portion sizes depending upon the context in which they were presented, something that often affects how much humans serve themselves and subsequently consume. chimpanzees judged same-sized and smaller food portions to be larger in amount when presented on a small plate compared to an equal or larger food portion presented on a large plate and did so despite clearly being able to tell the difference in portions when plate siz ...	2014	23949698
multi-region hemispheric specialization differentiates human from nonhuman primate brain function.	the human behavioral repertoire greatly exceeds that of nonhuman primates. anatomical specializations of the human brain include an enlarged neocortex and prefrontal cortex (semendeferi et al. in am j phys anthropol 114:224-241, 2001), but regional enlargements alone cannot account for these vast functional differences. hemispheric specialization has long believed to be a major contributing factor to such distinctive human characteristics as motor dominance, attentional control and language. yet ...	2014	23928747
human cumulative culture: a comparative perspective.	many animals exhibit social learning and behavioural traditions, but human culture exhibits unparalleled complexity and diversity, and is unambiguously cumulative in character. these similarities and differences have spawned a debate over whether animal traditions and human culture are reliant on homologous or analogous psychological processes. human cumulative culture combines high-fidelity transmission of cultural knowledge with beneficial modifications to generate a 'ratcheting' in technologi ...	2014	24033987
the repertoire and intentionality of gestural communication in wild chimpanzees.	a growing body of evidence suggests that human language may have emerged primarily in the gestural rather than vocal domain, and that studying gestural communication in great apes is crucial to understanding language evolution. although manual and bodily gestures are considered distinct at a neural level, there has been very limited consideration of potential differences at a behavioural level. in this study, we conducted naturalistic observations of adult wild east african chimpanzees (pan trog ...	2014	23999801
fatal arrhythmogenic right ventricular cardiomyopathy in 2 related subadult chimpanzees (pan troglodytes).	cardiovascular disease is increasingly recognized as an important cause of morbidity and mortality in captive chimpanzees (pan troglodytes). this report records 2 cases of sudden cardiac death in closely related subadult captive chimpanzees with marked replacement fibrosis and adipocyte infiltration of the myocardium, which resemble specific atypical forms of the familial human disease arrhythmogenic right ventricular cardiomyopathy. changes were consistent with left-dominant and biventricular s ...	2014	23988399
response facilitation in the four great apes: is there a role for empathy?	contagious yawning is a form of response facilitation found in humans and other primates in which observing a model yawning enhances the chance that the observer will also yawn. because contagious yawning seems to be more easily triggered when models are conspecifics or have a strong social bond with the observer, it has been proposed that contagious yawning is linked to empathy. a possible way to test this hypothesis is to analyze whether individuals' responses differ when they observe models y ...	2014	23975161
deictic gesturing in wild chimpanzees (pan troglodytes)? some possible cases.	referential pointing is important in the development of language comprehension in the child and is often considered a uniquely human capacity. nonhuman great apes do point in captivity, usually for a human audience, but this has been interpreted as an interaction pattern learned from human caretakers, not indicative of natural deictic ability. in contrast, spontaneous pointing for other apes is almost unknown among wild ape populations, supporting doubts as to whether apes naturally have any cap ...	2014	24040760
gestures and social-emotional communicative development in chimpanzee infants.	communicative skills of chimpanzees are of significant interest across many domains, such as developmental psychology (how does communication emerge in prelinguistic beings?), evolution (e.g., did human language evolve from primate gestures?), and in comparative psychology (how does the nonverbal communication of chimpanzees and humans compare?). here we ask about how gestures develop in chimpanzee infants (n = 16) that were raised in an interactive program designed to study skill development. d ...	2014	24038115
[comparison of the latissimus dorsi insertions on the iliac crest in chimpanzee (pan troglodytes) and in man].	comparing to other primates, one of the most important specificities of the human anatomy are consequences of bipedalism. although bone consequences are well known (lumbar lordosis, horizontal position of the foramen magnum, lengthening of the lower limbs, reduction of the pelvis, specialization of the foot), consequences of our locomotion on the latissimus dorsi are still unclear.	2014	24071528
intracranial arachnoid cysts in a chimpanzee (pan troglodytes).	an intracranial arachnoid cyst was detected in a 32-year-old, 44.6-kg, female chimpanzee at the primate research institute, kyoto university. magnetic resonance imaging (mri) and computed tomography (ct) were performed and the cognitive studies in which she participated were reviewed. mri revealed that the cyst was present in the chimpanzee's right occipital convexity, and was located in close proximity to the posterior horn of the right lateral ventricle without ventriculomegaly. ct confirmed t ...	2014	24068629
public information use in chimpanzees (pan troglodytes) and children (homo sapiens).	the discernment of resource quality is pertinent to many daily decisions faced by animals. public information is a critical information source that promotes quality assessments, attained by monitoring others' performance. here we provide the first evidence, to our knowledge, that chimpanzees (pan troglodytes) use public information to guide resource selection. thirty-two chimpanzees were presented with two simultaneous video demonstrations depicting a conspecific acquiring resources at a fast (r ...	2014	24060244
cognitive and motor aging in female chimpanzees.	we present the first longitudinal data on cognitive and motor aging in the chimpanzee (pan troglodytes). thirty-eight adult female chimpanzees (10-54 years old) were studied. the apes were tested longitudinally for 3 years in a modified primate cognition test battery, which comprised 12 tests of physical and social cognition. the chimpanzees were also administered a fine motor task requiring them to remove a steel nut from rods of various complexity. there was little evidence for an age-related ...	2014	24112794
triggering social interactions: chimpanzees respond to imitation by a humanoid robot and request responses from it.	even the most rudimentary social cues may evoke affiliative responses in humans and promote social communication and cohesion. the present work tested whether such cues of an agent may also promote communicative interactions in a nonhuman primate species, by examining interaction-promoting behaviours in chimpanzees. here, chimpanzees were tested during interactions with an interactive humanoid robot, which showed simple bodily movements and sent out calls. the results revealed that chimpanzees e ...	2014	24096704
a fine-scale recombination map of the human-chimpanzee ancestor reveals faster change in humans than in chimpanzees and a strong impact of gc-biased gene conversion.	recombination is a major determinant of adaptive and nonadaptive evolution. understanding how the recombination landscape has evolved in humans is thus key to the interpretation of human genomic evolution. comparison of fine-scale recombination maps of human and chimpanzee has revealed large changes at fine genomic scales and conservation over large scales. here we demonstrate how a fine-scale recombination map can be derived for the ancestor of human and chimpanzee, allowing us to study the cha ...	2014	24190946
sperm form and function in the absence of sperm competition.	sperm competition is a post-copulatory, sexual selection force that, together with phylogeny and fertilization mode, has been regarded as one of the main factors explaining the diversity in sperm size across species. this universal sperm selection mechanism favors traits that enhance a male's fertilizing ability and paternity success. surprisingly, however, sperm characteristics and semen quality in monogamous species, with low risk of sperm competition, have barely received any attention. in th ...	2014	24273026
capuchins' (cebus apella) sensitivity to others' goal-directed actions in a helping context.	as humans, our ability to help others effectively is at least in part dependent upon our capacity to infer others' goals in a variety of different contexts. several species of nonhuman primate have demonstrated that they will also help others in some relatively simple situations, but it is not always clear whether this helping is based on an understanding of another agent's goals. although the results of a number of different studies support the hypothesis that chimpanzees represent others' goal ...	2014	24146217
welfare based primate rehabilitation as a potential conservation strategy: does it measure up?	many primate species are threatened with extinction and are the focus of extensive conservation efforts including re-introduction, captive breeding and habitat conservation. welfare-based rehabilitation (hereafter also 'rehabilitation') is a management strategy commonly used for primates, particularly those species targeted by the pet and bush meat trades. rehabilitation of rescued primates typically has the dual motivation of welfare and conservation, but has not been assessed as a conservation ...	2014	24132600
the effective population sizes of the anthropoid ancestors of the human-chimpanzee lineage provide insights on the historical biogeography of the great apes.	the recent development of methods that apply coalescent theory to phylogenetic problems has enabled the study of the population-level phenomena that drove the diversification of anthropoid primates. effective population size, ne, is one of the main parameters that constitute the theoretical underpinning of these new analytical approaches. for this reason, the ancestral n(e) of selected primate lineages has been thoroughly investigated. however, for some of these lineages, the estimates of ancest ...	2014	24124206
local knowledge and perceptions of chimpanzees in cantanhez national park, guinea-bissau.	our study concerns local knowledge and perceptions of chimpanzees among farming communities within cantanhez national park, guinea-bissau. we submitted a survey questionnaire to 100 people living in four villages in the park to enquire about their knowledge of chimpanzee ecology and human-chimpanzee interactions. local farmers live in close contact with chimpanzees, consider them to be more similar to humans than any other species, and attribute special importance to them primarily due to expect ...	2014	24123061
prospective memory in children and chimpanzees.	prospective memory (pm) involves remembering to do something at a specific time in the future. here, we investigate the beginnings of this ability in young children (3-year-olds; homo sapiens) and chimpanzees (pan troglodytes) using an analogous task. subjects were given a choice between two toys (children) or two food items (chimpanzees). the selected item was delivered immediately, whereas the unselected item was hidden in an opaque container. after completing an ongoing quantity discriminatio ...	2014	23884791
field immobilization for treatment of an unknown illness in a wild chimpanzee (pan troglodytes schweinfurthii) at gombe national park, tanzania: findings, challenges, and lessons learned.	infectious diseases are widely presumed to be one of the greatest threats to ape conservation in the wild. human diseases are of particular concern, and the costs and benefits of human presence in protected areas with apes are regularly debated. while numerous syndromes with fatal outcomes have recently been described, precise identification of pathogens remains difficult. these diagnostic difficulties are compounded by the fact that direct veterinary intervention on wild apes is quite rare. her ...	2014	23872909
what makes wild chimpanzees wake up at night?	i examined the possible cause of night awakening among wild chimpanzees (pan troglodytes) in mahale mountains national park, tanzania. chimpanzee vocalizations and activity-related sounds (cvss) were used to indicate awakening because i was unable to visually observe them. over a 5-night observation period, cvss (n = 128) were heard every night, and most (n = 91) were observed within 5 min of previous cvss. chimpanzees use cvss as social communication to maintain spatial contact with other chimp ...	2014	23817693
chimpanzees (pan troglodytes) can wait, when they choose to: a study with the hybrid delay task.	self-control has been studied in nonhuman animals using a variety of tasks. the inter-temporal choice (itc) task presents choices between smaller-sooner (ss) and larger-later (ll) options. using food amounts as rewards, this presents two problems: (a) choices of the ll option could either reflect self-control or instead result from animals' difficulty with pointing to smaller amounts of food; (b) there is no way to verify whether the subjects would not revert their choice for the ll option, if g ...	2014	23774954
a review of the institute of medicine's analysis of using chimpanzees in biomedical research.	we argue that the recommendations made by the institute of medicine's 2011 report, chimpanzees in biomedical and behavioral research: assessing the necessity, are methodologically and ethically confused. we argue that a proper understanding of evolution and complexity theory in terms of the science and ethics of using chimpanzees in biomedical research would have had led the committee to recommend not merely limiting but eliminating the use of chimpanzees in biomedical research. specifically, we ...	2014	23616243
termite fishing by wild chimpanzees: new data from ugalla, western tanzania.	chimpanzees manufacture flexible fishing probes to fish for termites in issa, ugalla, western tanzania. these termite-fishing tools are similar in size and material to those used by long-studied communities of chimpanzees in western tanzania (pan troglodytes schweinfurthii) and in west africa (p. t. verus), but not central african populations (p. t. troglodytes). this report adds to the patchwork of evidence of termite-fishing tool use behaviour by chimpanzees across africa.	2014	23720026
what limits tool use in nonhuman primates? insights from tufted capuchin monkeys (sapajus spp.) and chimpanzees (pan troglodytes) aligning three-dimensional objects to a surface.	perceptuomotor functions that support using hand tools can be examined in other manipulation tasks, such as alignment of objects to surfaces. we examined tufted capuchin monkeys' and chimpanzees' performance at aligning objects to surfaces while managing one or two spatial relations to do so. we presented six subjects of each species with a single stick to place into a groove, two sticks of equal length to place into two grooves, or two sticks joined as a t to place into a t-shaped groove. tufte ...	2014	23820935
a nonverbal false belief task: the performance of children and great apes.	a nonverbal task of false belief understanding was given to 4- and 5-year-old children (n = 28) and to two species of great ape: chimpanzees and orangutans (n = 7). the task was embedded in a series of finding games in which an adult (the hider) hid a reward in one of two identical containers, and another adult (the communicator) observed the hiding process and attempted to help the participant by placing a marker on the container that she believed to hold the reward. an initial series of contro ...	2014	10218261
[utilization of the chimpanzee in experimental medicine: origin, success, failure, abandonment. is a return possible?].		2014	15420234
the effects of antifreeze peptide iii (afp) and insulin transferrin selenium (its) on cryopreservation of chimpanzee (pan troglodytes) spermatozoa.	we investigated the effects of antifreeze peptides (afp) and insulin transferrin selenium (its) on the motility and membrane integrity of chimpanzee (pan troglodytes) spermatozoa after chilling (0-5 degrees c) and thawing. the effects of three thawing procedures, in the presence or absence of afp and its, on sperm motility and on the status of the plasma membrane and acrosome were also examined. during chilling, afp and its seem mildly cytotoxic, as the progressive motility and velocity (curvili ...	2013	9570745