Publications

molecular identification of oesophagostomum spp. from 'village' chimpanzees in uganda and their phylogenetic relationship with those of other primates.	oesophagostomum spp. are parasitic nematodes of mammals, including humans and other primates. to identify species and determine phylogeny, we analysed dna sequences of adult and larval oesophagostomum from wild chimpanzees in bulindi, uganda, which inhabit degraded forest fragments amid villages. oesophagostome larvae and/or eggs from baboons in tanzania and south africa and from a japanese macaque were also sequenced. based on the internal transcribed spacer 2 (its2) of nuclear ribosomal dna an ...	2015	26716002
ring-tailed lemurs: a species re-imagined.	for over 50 years, ring-tailed lemurs have been studied continuously in the wild. as one of the most long-studied primate species, the length and breadth of their study is comparable to research on japanese macaques, baboons and chimpanzees. they are also one of the most broadly observed of all primates, with comprehensive research conducted on their behaviour, biology, ecology, genetics, palaeobiology and life history. however, over the last decade, a new generation of lemur scholars, working i ...	2015	26022295
unconstrained cranial evolution in neandertals and modern humans compared to common chimpanzees.	a variety of lines of evidence support the idea that neutral evolutionary processes (genetic drift, mutation) have been important in generating cranial differences between neandertals and modern humans. but how do neandertals and modern humans compare with other species? and how do these comparisons illuminate the evolutionary processes underlying cranial diversification? to address these questions, we used 27 standard cranial measurements collected on 2524 recent modern humans, 20 neandertals a ...	2015	26468243
strong selective sweeps on the x chromosome in the human-chimpanzee ancestor explain its low divergence.	the human and chimpanzee x chromosomes are less divergent than expected based on autosomal divergence. we study incomplete lineage sorting patterns between humans, chimpanzees and gorillas to show that this low divergence can be entirely explained by megabase-sized regions comprising one-third of the x chromosome, where polymorphism in the human-chimpanzee ancestral species was severely reduced. we show that background selection can explain at most 10% of this reduction of diversity in the ances ...	2015	26274919
transposable elements and dna methylation create in embryonic stem cells human-specific regulatory sequences associated with distal enhancers and noncoding rnas.	despite significant progress in the structural and functional characterization of the human genome, understanding of the mechanisms underlying the genetic basis of human phenotypic uniqueness remains limited. here, i report that transposable element-derived sequences, most notably ltr7/herv-h, ltr5_hs, and l1hs, harbor 99.8% of the candidate human-specific regulatory loci (hsrl) with putative transcription factor-binding sites in the genome of human embryonic stem cells (hesc). a total of 4,094 ...	2015	25956794
insights into hominin phenotypic and dietary evolution from ancient dna sequence data.	nuclear genome sequence data from neandertals, denisovans, and archaic anatomically modern humans can be used to complement our understanding of hominin evolutionary biology and ecology through i) direct inference of archaic hominin phenotypes, ii) indirect inference of those phenotypes by identifying the effects of previously-introgressed alleles still present among modern humans, or iii) determining the evolutionary timing of relevant hominin-specific genetic changes. here we review and reanal ...	2015	25563409
recent origin of low trabecular bone density in modern humans.	humans are unique, compared with our closest living relatives (chimpanzees) and early fossil hominins, in having an enlarged body size and lower limb joint surfaces in combination with a relatively gracile skeleton (i.e., lower bone mass for our body size). some analyses have observed that in at least a few anatomical regions modern humans today appear to have relatively low trabecular density, but little is known about how that density varies throughout the human skeleton and across species or ...	2015	25535354
size and placement of developing anterior teeth in immature neanderthal mandibles from dederiyeh cave, syria: implications for emergence of the modern human chin.	evolutionary and functional significance of the human chin has long been explored from various perspectives including masticatory biomechanics, speech, and anterior tooth size. recent ontogenetic studies have indicated that the spatial position of internally forming anterior teeth partially constrains adult mandibular symphyseal morphology. the present study therefore preliminarily examined the size and placement of developing anterior teeth in immature neanderthal mandibles of dederiyeh 1 and 2 ...	2015	25388672
functional morphology of the neandertal scapular glenoid fossa.	neandertals and homo sapiens are known to differ in scapular glenoid fossa morphology. functional explanations may be appropriate for certain aspects of glenoid fossa morphology; however, other factors--e.g., allometry, evolutionary development--must be addressed before functional morphology is considered. using three-dimensional geometric morphometrics, shape of the scapular glenoid fossa was compared among neandertals, early and recent modern humans, chimpanzees, orangutans, australopithecus a ...	2015	25339238
virtual reconstruction of modern and fossil hominoid crania: consequences of reference sample choice.	most hominin cranial fossils are incomplete and require reconstruction prior to subsequent analyses. missing data can be estimated by geometric morphometrics using information from complete specimens, for example, by using thin-plate splines. in this study, we estimate missing data in several virtually fragmented models of hominoid crania (homo, pan, pongo) and fossil hominins (e.g., australopithecus africanus, homo heidelbergensis). the aim is to investigate in which way different references in ...	2015	25689596
np9, a cellular protein of retroviral ancestry restricted to human, chimpanzee and gorilla, binds and regulates ubiquitin ligase mdm2.	humans and primates are long-lived animals with long reproductive phases. one factor that appears to contribute to longevity and fertility in humans, as well as to cancer-free survival, is the transcription factor and tumor suppressor p53, controlled by its main negative regulator mdm2. however, p53 and mdm2 homologs are found throughout the metazoan kingdom from trichoplacidae to hominidae. therefore the question arises, if p53/mdm2 contributes to the shaping of primate features, then through w ...	2015	26103464
function of loud calls in wild bonobos.	under the social origins hypothesis, human language is thought to have evolved within the framework of non-human primate social contexts and relationships. our two closest relatives, chimpanzees and bonobos, however, have very different social relationships and this may be reflected in their use of loud calls. much of loud calling in the male-bonded and aggressive chimpanzee functions for male alliance formation and intercommunity aggression. bonobos, however, are female bonded and less aggressi ...	2015	25324464
long-term balancing selection in lad1 maintains a missense trans-species polymorphism in humans, chimpanzees, and bonobos.	balancing selection maintains advantageous genetic and phenotypic diversity in populations. when selection acts for long evolutionary periods selected polymorphisms may survive species splits and segregate in present-day populations of different species. here, we investigate the role of long-term balancing selection in the evolution of protein-coding sequences in the homo-pan clade. we sequenced the exome of 20 humans, 20 chimpanzees, and 20 bonobos and detected eight coding trans-species polymo ...	2015	25605789
non-adjacent visual dependency learning in chimpanzees.	humans have a strong proclivity for structuring and patterning stimuli: whether in space or time, we tend to mentally order stimuli in our environment and organize them into units with specific types of relationships. a crucial prerequisite for such organization is the cognitive ability to discern and process regularities among multiple stimuli. to investigate the evolutionary roots of this cognitive capacity, we tested chimpanzees-which, along with bonobos, are our closest living relatives-for ...	2015	25604423
delimiting species-poor data sets using single molecular markers: a study of barcode gaps, haplowebs and gmyc.	most single-locus molecular approaches to species delimitation available to date have been designed and tested on data sets comprising at least tens of species, whereas the opposite case (species-poor data sets for which the hypothesis that all individuals are conspecific cannot by rejected beforehand) has rarely been the focus of such attempts. here we compare the performance of barcode gap detection, haplowebs and generalized mixed yule-coalescent (gmyc) models to delineate chimpanzees and bon ...	2015	25601944
experimental studies illuminate the cultural transmission of percussive technologies in homo and pan.	the complexity of stone age tool-making is assumed to have relied upon cultural transmission, but direct evidence is lacking. this paper reviews evidence bearing on this question provided through five related empirical perspectives. controlled experimental studies offer special power in identifying and dissecting social learning into its diverse component forms, such as imitation and emulation. the first approach focuses on experimental studies that have discriminated social learning processes i ...	2015	26483537
how did bonobos come to range south of the congo river? reconsideration of the divergence of pan paniscus from other pan populations.	while investigating the genetic structure in wild bonobos,(1) we realized that the widely accepted scenario positing that the pleistocene appearance of the congo river separated the common ancestor of chimpanzees (pan troglodytes) and bonobos (p. paniscus) into two species is not supported by recent geographical knowledge about the formation of the congo river. we explored the origin of bonobos using a broader biogeographical perspective by examining local faunas in the central african region. t ...	2015	26478139
sex differences in object manipulation in wild immature chimpanzees (pan troglodytes schweinfurthii) and bonobos (pan paniscus): preparation for tool use?	sex differences in immatures predict behavioural differences in adulthood in many mammal species. because most studies have focused on sex differences in social interactions, little is known about possible sex differences in 'preparation' for adult life with regards to tool use skills. we investigated sex and age differences in object manipulation in immature apes. chimpanzees use a variety of tools across numerous contexts, whereas bonobos use few tools and none in foraging. in both species, a ...	2015	26444011
great apes make anticipatory looks based on long-term memory of single events.	everyday life poses a continuous challenge for individuals to encode ongoing events, retrieve past events, and predict impending events [1-4]. attention and eye movements reflect such online cognitive and memory processes [5, 6], especially through "anticipatory looks" [7-10]. previous studies have demonstrated the ability of nonhuman animals to retrieve detailed information about single events that happened in the distant past [11-20]. however, no study has tested whether nonhuman animals emplo ...	2015	26387711
personality in bonobos.	to better understand human and chimpanzee personality evolution, we obtained trait ratings of personality for 154 captive bonobos (~80% of the u.s. and european population). we found factors that we labeled assertiveness, conscientiousness, openness, agreeableness, attentiveness, and extraversion. the interrater reliabilities and test-retest reliabilities for these factors were comparable to those found in humans and other species. using orthogonal targeted procrustes rotations, we compared the ...	2015	26209530
human rather than ape-like orbital morphology allows much greater lateral visual field expansion with eye abduction.	while convergent, the human orbit differs from that of non-human apes in that its lateral orbital margin is significantly more rearward. this rearward position does not obstruct the additional visual field gained through eye motion. this additional visual field is therefore considered to be wider in humans than in non-human apes. a mathematical model was designed to quantify this difference. the mathematical model is based on published computed tomography data in the human neuro-ocular plane (no ...	2015	26190625
correction: social attention in the two species of pan: bonobos make more eye contact than chimpanzees.		2015	26176749
preparation and use of varied natural tools for extractive foraging by bonobos (pan paniscus).	the tool-assisted extractive foraging capabilities of captive (zoo) and semi-captive (sanctuary) bonobo (pan paniscus) groups were compared to each other and to those known in wild chimpanzee (pan troglodytes) cultures.	2015	26119360
unique human orbital morphology compared with that of apes.	humans' and apes' convergent (front-facing) orbits allow a large overlap of monocular visual fields but are considered to limit the lateral visual field extent. however, humans can greatly expand their lateral visual fields using eye motion. this study aimed to assess whether the human orbital morphology was unique compared with that of apes in avoiding lateral visual field obstruction. the orbits of 100 human skulls and 120 ape skulls (30 gibbons; 30 orangutans; 30 gorillas; 30 chimpanzees and ...	2015	26111067
chimpanzees and bonobos differ in intrinsic motivation for tool use.	tool use in nonhuman apes can help identify the conditions that drove the extraordinary expansion of hominin technology. chimpanzees and bonobos are our closest living relatives. whereas chimpanzees are renowned for their tool use, bonobos use few tools and none in foraging. we investigated whether extrinsic (ecological and social opportunities) or intrinsic (predispositions) differences explain this contrast by comparing chimpanzees at kalinzu (uganda) and bonobos at wamba (drc). we assessed ec ...	2015	26079292
social attention in the two species of pan: bonobos make more eye contact than chimpanzees.	humans' two closest primate living relatives, bonobos and chimpanzees, differ behaviorally, cognitively, and emotionally in several ways despite their general similarities. while bonobos show more affiliative behaviors towards conspecifics, chimpanzees display more overt and severe aggression against conspecifics. from a cognitive standpoint, bonobos perform better in social coordination, gaze-following and food-related cooperation, while chimpanzees excel in tasks requiring extractive foraging ...	2015	26075710
share your sweets: chimpanzee (pan troglodytes) and bonobo (pan paniscus) willingness to share highly attractive, monopolizable food sources.	all over the world, humans (homo sapiens) display resource-sharing behavior, and common patterns of sharing seem to exist across cultures. humans are not the only primates to share, and observations from the wild have long documented food sharing behavior in our closest phylogenetic relatives, chimpanzees (pan troglodytes) and bonobos (pan paniscus). however, few controlled studies have been made in which groups of pan are introduced to food items that may be shared or monopolized by a first foo ...	2015	26075515
on the apparent rarity of epithelial cancers in captive chimpanzees.	malignant neoplasms arising from epithelial cells are called carcinomas. such cancers are diagnosed in about one in three humans in 'developed' countries, with the most common sites affected being lung, breast, prostate, colon, ovary and pancreas. by contrast, carcinomas are said to be rare in captive chimpanzees, which share more than 99% protein sequence homology with humans (and possibly in other related 'great apes'-bonobos, gorillas and orangutans). simple ascertainment bias is an unlikely ...	2015	26056369
feeding ecology of bonobos living in forest-savannah mosaics: diet seasonal variation and importance of fallback foods.	primates along with many other animal taxa are forced to cope with large shifts in basic ecological conditions because of rapid anthropogenically induced changes of their habitats. one of the coping strategies for primates is to adjust their diet to these changes, and several studies have demonstrated the importance of fallback resources for this. bonobos, like chimpanzees, might be particularly vulnerable to habitat fragmentation because of their high dependence on fruit availability. little is ...	2015	25974229
bonobos show limited social tolerance in a group setting: a comparison with chimpanzees and a test of the relational model.	social tolerance is a core aspect of primate social relationships with implications for the evolution of cooperation, prosociality and social learning. we measured the social tolerance of bonobos in an experiment recently validated with chimpanzees to allow for a comparative assessment of group-level tolerance, and found that the bonobo group studied here exhibited lower social tolerance on average than chimpanzees in this paradigm. furthermore, following the relational model of de waal, we inve ...	2015	25926027
de novo assembly of the chimpanzee transcriptome from nextgen mrna sequences.	common chimpanzees (pan troglodytes) and bonobos (pan paniscus) are the species most closely related to humans. for this reason, it is especially important to have complete and accurate chimpanzee nucleotide and protein sequences to understand how humans evolved their unique capabilities. we provide transcriptome data from four untransformed cell types derived from the reference pan troglodytes, "clint", to better annotate the chimpanzee genome and provide empirical validation for proposed gene ...	2015	25897398
body language: the interplay between positional behavior and gestural signaling in the genus pan and its implications for language evolution.	the gestural repertoires of bonobos and chimpanzees are well documented, but the relationship between gestural signaling and positional behavior (i.e., body postures and locomotion) has yet to be explored. given that one theory for language evolution attributes the emergence of increased gestural communication to habitual bipedality, this relationship is important to investigate.	2015	25851528
behavioural, hormonal and neurobiological mechanisms of aggressive behaviour in human and nonhuman primates.	aggression is a key component for social behaviour and can have an adaptive value or deleterious consequences. here, we review the role of sex-related differences in aggressive behaviour in both human and nonhuman primates. first, we address aggression in primates, which varies deeply between species, both in intensity and in display, ranging from animals that are very aggressive, such as chimpanzees, to the nonaggressive bonobos. aggression also influences the hierarchical structure of gorillas ...	2015	25749197
bonobos and chimpanzees exhibit human-like framing effects.	humans exhibit framing effects when making choices, appraising decisions involving losses differently from those involving gains. to directly test for the evolutionary origin of this bias, we examined decision-making in humans' closest living relatives: bonobos (pan paniscus) and chimpanzees (pan troglodytes). we presented the largest sample of non-humans to date (n = 40) with a simple task requiring minimal experience. apes made choices between a 'framed' option that provided preferred food, an ...	2015	25672997
do tufted capuchin monkeys play the odds? flexible risk preferences in sapajus spp.	as humans, several non-human animal species avoid risk, defined as "variability in rate of gain". however, non-human primate studies revealed a more complicated picture, with different species ranging from risk aversion to risk proneness. within an ecological rationality framework, a species' feeding ecology should influence its risk preferences, as it has been shown in bonobos and chimpanzees. although the feeding ecology hypothesis is promising, it has not been yet verified in species other th ...	2015	24993065
apes produce tools for future use.	there is now growing evidence that some animal species are able to plan for the future. for example great apes save and exchange tools for future use. here we raise the question whether chimpanzees, orangutans, and bonobos would produce tools for future use. subjects only had access to a baited apparatus for a limited duration and therefore should use the time preceding this access to create the appropriate tools in order to get the rewards. the apes were tested in three conditions depending on ...	2015	25236323
grips and hand movements of chimpanzees during feeding in mahale mountains national park, tanzania.	it has long been assumed that stone tool making was a major factor in the evolution of derived hominin hand morphology. however, stresses on the hand associated with food retrieval and processing also have been recognized as relevant early hominin behaviors that should be investigated. to this end, chimpanzee food manipulation was videotaped in the mahale mountains national park, tanzania. grips and hand movements by 39 chimpanzees were analyzed for arboreal and terrestrial feeding involving 10 ...	2015	25363236
calcaneal robusticity in plio-pleistocene hominins: implications for locomotor diversity and phylogeny.	a key pedal adaptation to bipedality is a relatively large, weight-bearing calcaneus. the earliest evidence for a human-like, robust calcaneus is at 3.2 ma in australopithecus afarensis (a.l. 333-8, a.l. 333-55, a.l. 333-37) from hadar, ethiopia. australopithecus sediba at 1.98 ma from malapa, south africa displays a unique combination of primitive australopith features and more derived homo-like features, but surprisingly is characterized by a gracile, chimpanzee-like calcaneus. the differences ...	2015	25440133
developmental defects in the teeth of three wild chimpanzees from the taï forest.	developmental defects in teeth (accentuated lines and hypoplasias) have played a critical role in studies of childhood disease, nutrition, weaning, environmental variation, and early mortality. while these enigmatic structures have been lauded for their potential insights into human evolution, few studies have examined defects in individuals of known histories.	2015	25820182
center of mass mechanics of chimpanzee bipedal walking.	center of mass (com) oscillations were documented for 81 bipedal walking strides of three chimpanzees. full-stride ground reaction forces were recorded as well as kinematic data to synchronize force to gait events and to determine speed. despite being a bent-hip, bent-knee (bhbk) gait, chimpanzee walking uses pendulum-like motion with vertical oscillations of the com that are similar in pattern and relative magnitude to those of humans. maximum height is achieved during single support and minimu ...	2015	25407636
footprints of ancient-balanced polymorphisms in genetic variation data from closely related species.	when long-lasting, balancing selection can lead to "trans-species" polymorphisms that are shared by two or more species identical by descent. in such cases, the gene genealogy at the selected site clusters by allele instead of by species, and nearby neutral sites also have unusual genealogies because of linkage. while this scenario is expected to leave discernible footprints in genetic variation data, the specific patterns remain poorly characterized. motivated by recent findings in primates, we ...	2015	25403856
great ape origins of personality maturation and sex differences: a study of orangutans and chimpanzees.	human personality development evinces increased emotional stability, prosocial tendencies, and responsibility. one hypothesis offered to explain this pattern is social-investment theory, which posits that culturally defined social roles, including marriage and employment, are responsible for the increased maturity. alternatively, five-factor theory emphasizes the role of biological factors, such as those governing physical development, which may predate the emergence of humans. five-factor theor ...	2015	25402680
species-specific exon loss in human transcriptomes.	changes in exon-intron structures and splicing patterns represent an important mechanism for the evolution of gene functions and species-specific regulatory networks. although exon creation is widespread during primate and human evolution and has been studied extensively, much less is known about the scope and potential impact of human-specific exon loss events. historically, transcriptome data and exon annotations are significantly biased toward humans over nonhuman primates. this ascertainment ...	2015	25398629
adaptive evolution at immune system genes and deep pregnancy implantation in primates.	a major evolutionary change in the lineage ancestral to humans, chimpanzee and gorilla (hcg) has been the embedding of the embryo into maternal tissue. thus, the first layer of cells (trophoblast) to differentiate after fertilization must adapt to invade the uterus. such event would likely leave signatures of positive selection at genes with roles in embryo implantation. here, 163 pregnancy implantation genes are tested for evidence of adaptive diversification in the ancestral lineage to hcg. tw ...	2015	25451741
identification of human-specific alus elements through comparative genomics.	mobile elements are responsible for ~45% of the human genome. among them is the alu element, accounting for 10% of the human genome (>1.1million copies). several studies of alu elements have reported that they are frequently involved in human genetic diseases and genomic rearrangements. in this study, we investigated the alus subfamily, which is a relatively old alu subfamily and has the highest copy number in primate genomes. previously, a set of 263 human-specific alus insertions was identifie ...	2015	25447892
defining value through quantity and quality-chimpanzees (pan troglodytes) undervalue food quantities when items are broken.	decision-making largely is influenced by the relative value of choice options, and the value of such options can be determined by a combination of different factors (e.g., the quantity, size, or quality of a stimulus). in this study, we examined the competing influences of quantity (i.e., the number of food items in a set) and quality (i.e., the original state of a food item) of choice items on chimpanzees' food preferences in a two-option natural choice paradigm. in experiment 1, chimpanzees ch ...	2015	25447509
the importance of witnessed agency in chimpanzee social learning of tool use.	social learning refers to individuals learning from others, including information gained through indirect social influences, such as the results of others' actions and changes in the physical environment. one method to determine the relative influence of these varieties of information is the 'ghost display', in which no model is involved, but subjects can watch the results that a model would produce. previous research has shown mixed success by chimpanzees (pan troglodytes) learning from ghost d ...	2015	25444770
an intentional vocalization draws others' attention: a playback experiment with wild chimpanzees.	a vital step in the evolution of language is likely to have been when signalers explicitly intended to direct recipients' attention to external objects with the use of referential signals. although animal signals can direct the attention of others to external events, such as in monkey predator alarm calls, there is little evidence that this is the result of an intention to inform the recipient. two recent studies, however, indicate that the production of chimpanzee quiet alarm calls, given to sn ...	2015	25537683
virtual dissection and comparative connectivity of the superior longitudinal fasciculus in chimpanzees and humans.	many of the behavioral capacities that distinguish humans from other primates rely on fronto-parietal circuits. the superior longitudinal fasciculus (slf) is the primary white matter tract connecting lateral frontal with lateral parietal regions; it is distinct from the arcuate fasciculus, which interconnects the frontal and temporal lobes. here we report a direct, quantitative comparison of slf connectivity using virtual in vivo dissection of the slf in chimpanzees and humans. slf i, the superi ...	2015	25534109
population diversity and adaptive evolution in keratinization genes: impact of environment in shaping skin phenotypes.	several studies have demonstrated the role of climatic factors in shaping skin phenotypes, particularly pigmentation. keratinization is another well-designed feature of human skin, which is involved in modulating transepidermal water loss (tewl). although this physiological process is closely linked to climate, presently it is not clear whether genetic diversity is observed in keratinization and whether this process also responds to the environmental pressure. to address this, we adopted a multi ...	2015	25534032
commentary: is alzheimer's disease uniquely human?	that alzheimer's disease (ad) might be a human-specific disease was hypothesized by rapoport in 1989. apes and humans share an identical amyloid beta (aβ) peptide amino acid sequence and accumulate considerable aβ deposits after age 40 years, an age when amyloid plaques are uncommon in humans. despite their early aβ buildup, ape brains have not shown evidence dystrophic neurites near plaques. aging great ape brains also have few neurofibrillary tangles, with one exception of 1 obese chimpanzee e ...	2015	25533426
an intrahepatic transcriptional signature of enhanced immune activity predicts response to peginterferon in chronic hepatitis b.	differences in intrahepatic gene expression patterns may be associated with therapy response in peginterferon-treated chronic hepatitis b (chb) patients.	2015	25533046
epiphyseal fusion in pan troglodytes relative to dental age.	previous studies on different aspects of chimpanzee growth and development have documented dental eruption and development, long bone and somatic growth, and to a lesser extent, skeletal fusion. such data are useful in comparative and evolutionary studies of growth and some aspects of life history evolution in apes and early hominids. however, few studies have integrated dental development and other aspects of skeletal development, and none of these have been able to incorporate a large study sa ...	2015	25532866
two cases of cleft lip and other congenital anomalies in wild chimpanzees living in kibale national park, uganda.	observations of wild chimpanzees ( pan troglodytes schweinfurthii) were conducted in kibale national park, uganda, at the sites of sebitoli and ngogo.	2015	25531736
uniquely human self-control begins at school age.	human beings have remarkable skills of self-control, but the evolutionary origins of these skills are unknown. here we compare children at 3 and 6 years of age with one of humans' two nearest relatives, chimpanzees, on a battery of reactivity and self-control tasks. three-year-old children and chimpanzees were very similar in their abilities to resist an impulse for immediate gratification, repeat a previously successful action, attend to a distracting noise, and quit in the face of repeated fai ...	2015	25529764
the feeding biomechanics and dietary ecology of paranthropus boisei.	the african plio-pleistocene hominins known as australopiths evolved derived craniodental features frequently interpreted as adaptations for feeding on either hard, or compliant/tough foods. among australopiths, paranthropus boisei is the most robust form, exhibiting traits traditionally hypothesized to produce high bite forces efficiently and strengthen the face against feeding stresses. however, recent mechanical analyses imply that p. boisei may not have been an efficient producer of bite for ...	2015	25529240
biomechanical implications of intraspecific shape variation in chimpanzee crania: moving toward an integration of geometric morphometrics and finite element analysis.	in a broad range of evolutionary studies, an understanding of intraspecific variation is needed in order to contextualize and interpret the meaning of variation between species. however, mechanical analyses of primate crania using experimental or modeling methods typically encounter logistical constraints that force them to rely on data gathered from only one or a few individuals. this results in a lack of knowledge concerning the mechanical significance of intraspecific shape variation that lim ...	2015	25529239
craniocerebral gunshot wound in a baby chimpanzee--an uncommon experience of neurosurgical treatment conducted in the guinean forest.	an orphan female chimpanzee was wounded by a left craniocerebral gunshot complicated with a right hemiparesis. local treatment and long-term antibiotherapy failed to lead to healing. a neurosurgical procedure was planned and achieved. she fully recovered, and 2 years after the procedure, there is no evidence of infection.	2015	25523755
genetic basis in motor skill and hand preference for tool use in chimpanzees (pan troglodytes).	chimpanzees are well known for their tool using abilities. numerous studies have documented variability in tool use among chimpanzees and the role that social learning and other factors play in their development. there are also findings on hand use in both captive and wild chimpanzees; however, less understood are the potential roles of genetic and non-genetic mechanisms in determining individual differences in tool use skill and laterality. here, we examined heritability in tool use skill and h ...	2015	25520351
application of the human intestinal tract chip to the non-human primate gut microbiota.	the human intestinal microbiota is responsible for various health-related functions, and its diversity can be readily mapped with the 16s ribosomal rna targeting human intestinal tract (hit) chip. here we characterise distal gut samples from chimpanzees, gorillas and marmosets, and compare them with human gut samples. our results indicated applicability of the hitchip platform can be extended to chimpanzee and gorilla faecal samples for analysis of microbiota composition and enterotypes, but not ...	2015	25519524
different patterns of a*80:01:01:01 allele generation based on exon or intron sequences.	generation of the hla-a*80:01:01:01 allele has been analysed using its complete sequence. direct comparison of the sequences and phylogenetic trees using the human leukocyte antigen (hla)-a representative alleles and the major histocompatibility complex (mhc)-a sequences of non-human primates has been made. results based on exon sequences confirm previously published, but considering only the sequences of the introns, two distinct regions can be differentiated. the first one comprises from the 5 ...	2015	25515742
new era for chimpanzee research: broad implications of chimpanzee research decisions.	the unprecedented recent decision-making about chimpanzees supported for biomedical science by the us national institutes of health attracted international attention and significantly changed many dimensions of chimpanzee research. many public and media portrayals incorrectly generalized the nih findings to conclude that chimpanzee research itself was no longer necessary. in fact, the broader question of the necessity and value of the full range of chimpanzee research was never asked, evaluated, ...	2015	25783188
high spatial resolution proteomic comparison of the brain in humans and chimpanzees.	we performed high-throughput mass spectrometry at high spatial resolution from individual regions (anterior cingulate and primary motor, somatosensory, and visual cortices) and layers of the neocortex (layers iii, iv, and v) and cerebellum (granule cell layer), as well as the caudate nucleus in humans and chimpanzees. a total of 39 mass spectrometry peaks were matched with probable protein identifications in both species, allowing for comparison in expression. we explored how the pattern of prot ...	2015	25779868
a neonatal perspective on homo erectus brain growth.	the mojokerto calvaria has been central to assessment of brain growth in homo erectus, but different analytical approaches and uncertainty in the specimen's age at death have hindered consensus on the nature of h. erectus brain growth. we simulate average annual rates (ar) of absolute endocranial volume (ecv) growth and proportional size change (psc) in h. erectus, utilizing estimates of h. erectus neonatal ecv and a range of ages for mojokerto. these values are compared with resampled ars and p ...	2015	25771994
the association between imitation recognition and socio-communicative competencies in chimpanzees (pan troglodytes).	imitation recognition provides a viable platform from which advanced social cognitive skills may develop. despite evidence that non-human primates are capable of imitation recognition, how this ability is related to social cognitive skills is unknown. in this study, we compared imitation recognition performance, as indicated by the production of testing behaviors, with performance on a series of tasks that assess social and physical cognition in 49 chimpanzees. in the initial analyses, we found ...	2015	25767454
differences between chimpanzee and baboon gastrointestinal parasite communities.	cross-species infection among humans, chimpanzees (pan troglodytes) and baboons (papio spp.) is potentially a significant public health issue in africa, and of concern in the conservation of p. troglodytes. however, to date, no statistical comparisons have been made between the prevalence, richness and composition of parasite communities in sympatric populations of baboons and p. troglodytes. we compared parasite communities in sympatric p. troglodytes and papio papio living in a wilderness site ...	2015	25731985
progress in the diagnosis and control of ebola disease.	ebola hemorrhagic fever is one of numerous viral hemorrhagic fevers. it is a severe, often fatal disease in humans and nonhuman primates (gorillas and chimpanzees). this article discusses the history of ebola disease, already known routes of infection together with defining prevention methods and treatment trials. the importance of increasing awareness of the risk of disease among people who do not inhabit endemic regions is emphasized. this risk is associated especially with the increasing popu ...	2015	25724796
personality influences responses to inequity and contrast in chimpanzees.	several species besides humans respond negatively to inequity (i.e. receiving a less preferred outcome as compared to a social partner). among primates, the taxon for which inequity responses have been most comprehensively studied, there are large individual differences in responses that have, thus far, not been well explained by demographic features such as sex, rank and age. recent evidence shows that individuals' personalities are important in explaining differences in behavioural outcomes in ...	2015	25722495
human-specific gene arhgap11b promotes basal progenitor amplification and neocortex expansion.	evolutionary expansion of the human neocortex reflects increased amplification of basal progenitors in the subventricular zone, producing more neurons during fetal corticogenesis. in this work, we analyze the transcriptomes of distinct progenitor subpopulations isolated by a cell polarity-based approach from developing mouse and human neocortex. we identify 56 genes preferentially expressed in human apical and basal radial glia that lack mouse orthologs. among these, arhgap11b has the highest de ...	2015	25721503
pestle-pounding and nut-cracking by wild chimpanzees at kpala, liberia.	bossou in guinea is one of the longitudinal study sites of wild chimpanzees, and is located only a few kilometers away from the national border between guinea and liberia. the forests in the area spread over the national border of guinea, and the bossou chimpanzees have been found to use the neighboring liberian forest. local assistants and i started surveying these forests in liberia, and found that additional groups of chimpanzees lived in nimba county, liberia. the present study reports tool ...	2015	25721009
route-planning and the comparative study of future-thinking.		2015	25717315
impact of visual context on public perceptions of non-human primate performers.	prior research has shown that the use of apes, specifically chimpanzees, as performers in the media negatively impacts public attitudes of their conservation status and desirability as a pet, yet it is unclear whether these findings generalize to other non-human primates (specifically non-ape species). we evaluated the impact of viewing an image of a monkey or prosimian in an anthropomorphic or naturalistic setting, either in contact with or in the absence of a human. viewing the primate in an a ...	2015	25714101
single aggressive interactions increase urinary glucocorticoid levels in wild male chimpanzees.	a basic premise in behavioural ecology is the cost-benefit arithmetic, which determines both behavioural decisions and evolutionary processes. aggressive interactions can be costly on an energetic level, demanding increased energy or causing injuries, and on a psychological level, in the form of increased anxiety and damaged relationships between opponents. here we used urinary glucocorticoid (ugc) levels to assess the costs of aggression in wild chimpanzees of budongo forest, uganda. we collect ...	2015	25714095
a longitudinal assessment of vocabulary retention in symbol-competent chimpanzees (pan troglodytes).	a number of studies from the 1960s to 1990s assessed the symbolic competence of great apes and other animals. these studies provided varying forms of evidence that some species were capable of symbolically representing their worlds, both through productive symbol use and comprehension of symbolic stimuli. one such project at the language research center involved training chimpanzees (pan troglodytes) to use lexigram symbols (geometric visual stimuli that represented objects, actions, locations, ...	2015	25706561
human-chimpanzee differences in a fzd8 enhancer alter cell-cycle dynamics in the developing neocortex.	the human neocortex differs from that of other great apes in several notable regards, including altered cell cycle, prolonged corticogenesis, and increased size [1-5]. although these evolutionary changes most likely contributed to the origin of distinctively human cognitive faculties, their genetic basis remains almost entirely unknown. highly conserved non-coding regions showing rapid sequence changes along the human lineage are candidate loci for the development and evolution of uniquely human ...	2015	25702574
"missing perikymata"--fact or fiction? a study on chimpanzee (pan troglodytes verus) canines.	recently, a lower than expected number of perikymata between repetitive furrow-type hypoplastic defects has been reported in chimpanzee canines from the fongoli site, senegal (skinner and pruetz: am j phys anthropol 149 (2012) 468-482). based on an observation in a localized enamel fracture surface of a canine of a chimpanzee from the taï forest (ivory coast), these authors inferred that a nonemergence of striae of retzius could be the cause for the "missing perikymata" phenomenon in the fongoli ...	2015	25693508
personality in sanctuary-housed chimpanzees: a comparative approach of psychobiological and penta-factorial human models.	we evaluate a sanctuary chimpanzee sample (n = 11) using two adapted human assessment instruments: the five-factor model (ffm) and eysenck's psychoticism-extraversion-neuroticism (pen) model. the former has been widely used in studies of animal personality, whereas the latter has never been used to assess chimpanzees. we asked familiar keepers and scientists (n = 28) to rate 38 (ffm) and 12 (pen) personality items. the personality surveys showed reliability in all of the items for both instrumen ...	2015	25692710
the genital prolapse of australopithecus lucy?	the female bony pelvis has to fulfil opposing functions: it has to be sufficiently closed to support the pelvic viscera in the upright position, while remaining sufficiently open to allow vaginal delivery. we aim to give an evolutionary perspective and the possible evolution of the bony pelvis from lucy to the modern female with the implications in terms of genital prolapse.	2015	25681037
vocal learning in the functionally referential food grunts of chimpanzees.	one standout feature of human language is our ability to reference external objects and events with socially learned symbols, or words. exploring the phylogenetic origins of this capacity is therefore key to a comprehensive understanding of the evolution of language. while non-human primates can produce vocalizations that refer to external objects in the environment, it is generally accepted that their acoustic structure is fixed and a product of arousal states. indeed, it has been argued that t ...	2015	25660548
the pattern of dna cleavage intensity around indels.	indels (insertions and deletions) are the second most common form of genetic variations in the eukaryotic genomes and are responsible for a multitude of genetic diseases. despite its significance, detailed molecular mechanisms for indel generation are still unclear. here we examined 2,656,597 small human and mouse germline indels, 16,742 human somatic indels, 10,599 large human insertions, and 5,822 large chimpanzee insertions and systematically analyzed the patterns of dna cleavage intensities ...	2015	25660536
age-related decline in ovarian follicle stocks differ between chimpanzees (pan troglodytes) and humans.	similarity in oldest parturitions in humans and great apes suggests that we maintain ancestral rates of ovarian aging. consistent with that hypothesis, previous counts of primordial follicles in postmortem ovarian sections from chimpanzees (pan troglodytes) showed follicle stock decline at the same rate that human stocks decline across the same ages. here, we correct that finding with a chimpanzee sample more than three times larger than the previous one, which also allows comparison into older ...	2015	25651885
positive reinforcement methods to train chimpanzees to cooperate with urine collection.	positive reinforcement training can be used in many ways to enhance the welfare of captive primates. training for biologic sample collection is one application of positive reinforcement training. in this study, 35 adult female chimpanzees were trained to cooperate with the collection of urine samples needed to facilitate a research study. a median of 35 training sessions was required for the subjects to reach reliable performance (4 of 5 sequential attempts successful) of the urine collection be ...	2015	25651093
antigen expression determines adenoviral vaccine potency independent of ifn and sting signaling.	recombinant adenoviral vectors (rads) are lead vaccine candidates for protection against a variety of pathogens, including ebola, hiv, tuberculosis, and malaria, due to their ability to potently induce t cell immunity in humans. however, the ability to induce protective cellular immunity varies among rads. here, we assessed the mechanisms that control the potency of cd8 t cell responses in murine models following vaccination with human-, chimpanzee-, and simian-derived rads encoding siv-gag anti ...	2015	25642773
cortical structure of hallucal metatarsals and locomotor adaptations in hominoids.	diaphyseal morphology of long bones, in part, reflects in vivo loads experienced during the lifetime of an individual. the first metatarsal, as a cornerstone structure of the foot, presumably expresses diaphyseal morphology that reflects loading history of the foot during stance phase of gait. human feet differ substantially from those of other apes in terms of loading histories when comparing the path of the center of pressure during stance phase, which reflects different weight transfer mechan ...	2015	25635768
the role of dna insertions in phenotypic differentiation between humans and other primates.	what makes us human is one of the most interesting and enduring questions in evolutionary biology. to assist in answering this question, we have identified insertions in the human genome which cannot be found in five comparison primate species: chimpanzee, gorilla, orangutan, gibbon, and macaque. a total of 21,269 nonpolymorphic human-specific insertions were identified, of which only 372 were found in exons. any function conferred by the remaining 20,897 is likely to be regulatory. many of thes ...	2015	25635043
maternal rank influences the outcome of aggressive interactions between immature chimpanzees.	for many long-lived mammalian species, extended maternal investment has a profound effect on offspring integration in complex social environments. one component of this investment may be aiding young in aggressive interactions, which can set the stage for offspring social position later in life. here we examined maternal effects on dyadic aggressive interactions between immature (<12 years) chimpanzees. specifically, we tested whether relative maternal rank predicted the probability of winning a ...	2015	25624528
species-specific influence of lithium on the activity of slc13a5 (nact): lithium-induced activation is specific for the transporter in primates.	nact (slc13a5) is a na(+)-coupled transporter for krebs cycle intermediates and is expressed predominantly in the liver. human nact is relatively specific for citrate compared with other krebs cycle intermediates. the transport activity of human nact is stimulated by li(+), whereas that of rat nact is inhibited by li(+). we studied the influence of li(+) on nacts cloned from eight different species. li(+) stimulated the activity of only nacts from primates (human, chimpanzee, and monkey); by con ...	2015	25617245
giant pandas failed to show mirror self-recognition.	mirror self-recognition (msr), i.e., the ability to recognize oneself in a mirror, is considered a potential index of self-recognition and the foundation of individual development. a wealth of literature on msr is available for social animals, such as chimpanzees, asian elephants and dolphins, yet little is known about msr in solitary mammalian species. we aimed to evaluate whether the giant panda can recognize itself in the mirror, and whether this capacity varies with age. thirty-four captive ...	2015	25609263
the population genetics of wild chimpanzees in cameroon and nigeria suggests a positive role for selection in the evolution of chimpanzee subspecies.	chimpanzees (pan troglodytes) can be divided into four subspecies. substantial phylogenetic evidence suggests that these subspecies can be grouped into two distinct lineages: a western african group that includes p. t. verus and p. t. ellioti and a central/eastern african group that includes p. t. troglodytes and p. t. schweinfurthii. the geographic division of these two lineages occurs in cameroon, where the rages of p. t. ellioti and p. t. troglodytes appear to converge at the sanaga river. re ...	2015	25608610
chimpanzee population structure in cameroon and nigeria is associated with habitat variation that may be lost under climate change.	the nigeria-cameroon chimpanzee (pan troglodytes ellioti) is found in the gulf of guinea biodiversity hotspot located in western equatorial africa. this subspecies is threatened by habitat fragmentation due to logging and agricultural development, hunting for the bushmeat trade, and possibly climate change. although p. t. ellioti appears to be geographically separated from the neighboring central chimpanzee (p. t. troglodytes) by the sanaga river, recent population genetics studies of chimpanzee ...	2015	25608567
environmental variation and rivers govern the structure of chimpanzee genetic diversity in a biodiversity hotspot.	the mechanisms that underlie the diversification of tropical animals remain poorly understood, but new approaches that combine geo-spatial modeling with spatially explicit genetic data are providing fresh insights on this topic. data about the diversification of tropical mammals remain particularly sparse, and vanishingly few opportunities exist to study endangered large mammals that increasingly exist only in isolated pockets. the chimpanzees of cameroon represent a unique opportunity to examin ...	2015	25608511
let bone and muscle talk together: a study of real and virtual dissection and its implications for femoral musculoskeletal structure of chimpanzees.	proximal femoral morphology and associated musculature are of special relevance to the understanding of hominoid locomotor systems. knowledge of bone-muscle correspondence in extant hominoids forms an important comparative basis for inferring structure-function relationships in fossil hominids. however, there is still a lack of consensus on the correspondence between muscle attachment sites and surface morphology of the proximal femoral diaphysis in chimpanzees. two alternative observations have ...	2015	25601190
snakes as hazards: modelling risk by chasing chimpanzees.	snakes are presumed to be hazards to primates, including humans, by the snake detection hypothesis (isbell in j hum evol 51:1-35, 2006; isbell, the fruit, the tree, and the serpent. why we see so well, 2009). quantitative, systematic data to test this idea are lacking for the behavioural ecology of living great apes and human foragers. an alternative proxy is snakes encountered by primatologists seeking, tracking, and observing wild chimpanzees. we present 4 years of such data from mt. assirik, ...	2015	25600837
a method for calculating probabilities of fitness consequences for point mutations across the human genome.	we describe a new computational method for estimating the probability that a point mutation at each position in a genome will influence fitness. these 'fitness consequence' (fitcons) scores serve as evolution-based measures of potential genomic function. our approach is to cluster genomic positions into groups exhibiting distinct 'fingerprints' on the basis of high-throughput functional genomic data, then to estimate a probability of fitness consequences for each group from associated patterns o ...	2015	25599402
chimpanzees trust conspecifics to engage in low-cost reciprocity.	many of humans' most important social interactions rely on trust, including most notably among strangers. but little is known about the evolutionary roots of human trust. we presented chimpanzees (pan troglodytes) with a modified version of the human trust game--trust in reciprocity--in which subjects could opt either to obtain a small but safe reward on their own or else to send a larger reward to a partner and trust her to reciprocate a part of the reward that she could not access herself. in ...	2015	25589606
human locomotion and heat loss: an evolutionary perspective.	humans are unique in many respects including being furless, striding bipeds that excel at walking and running long distances in hot conditions. this review summarizes what we do and do not know about the evolution of these characteristics, and how they are related. although many details remain poorly known, the first hominins (species more closely related to humans than to chimpanzees) apparently diverged from the chimpanzee lineage because of selection for bipedal walking, probably because it i ...	2015	25589265
chimpanzees (pan troglodytes) and human children (homo sapiens) know when they are ignorant about the location of food.	over the last decade, the metacognitive abilities of nonhuman primates and the developmental emergence of metacognition in children have become topics of increasing research interest. in the current study, the performance of three adult chimpanzees (pan troglodytes; experiment 1) and forty-four 3.5- and 5.5-year-old human children (experiment 2) was assessed on a behavioral search paradigm designed to assess metacognition. subjects either directly observed the baiting of a large reward into one ...	2015	25586587
new human-specific brain landmark: the depth asymmetry of superior temporal sulcus.	identifying potentially unique features of the human cerebral cortex is a first step to understanding how evolution has shaped the brain in our species. by analyzing mr images obtained from 177 humans and 73 chimpanzees, we observed a human-specific asymmetry in the superior temporal sulcus at the heart of the communication regions and which we have named the "superior temporal asymmetrical pit" (stap). this 45-mm-long segment ventral to heschl's gyrus is deeper in the right hemisphere than in t ...	2015	25583500
egalitarian despots: hierarchy steepness, reciprocity and the grooming-trade model in wild chimpanzees, pan troglodytes.	biological market theory models the action of natural selection as a marketplace in which animals are viewed as traders with commodities to offer and exchange. studies of female old world monkeys have suggested that grooming might be employed as a commodity to be reciprocated or traded for alternative services, yet previous tests of this grooming-trade model in wild adult male chimpanzees have yielded mixed results. here we provide the strongest test of the model to date for male chimpanzees: we ...	2015	25580017
selective and contagious prosocial resource donation in capuchin monkeys, chimpanzees and humans.	prosocial acts benefitting others are widespread amongst humans. by contrast, chimpanzees have failed to demonstrate such a disposition in several studies, leading some authors to conclude that the forms of prosociality studied evolved in humans since our common ancestry. however, similar prosocial behavior has since been documented in other primates, such as capuchin monkeys. here, applying the same methodology to humans, chimpanzees, and capuchins, we provide evidence that all three species wi ...	2015	25559658