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From the recent genome assembly NHGRI_mPonAbe1-v2.0_NCBI (GCF_028885655.2) of orangutan chromosome 13, we computed the precise alpha satellite higher-order repeat (HOR) structure using the novel high-precision GRM2023 algorithm with Global Repeat Map (GRM) and Monomer Distance (MD) diagrams. This study rigorously identified alpha satellite HORs in the centromere of orangutan chromosome 13, discovering a novel 59mer HOR—the longest HOR unit identified in any primate to date. Additionally, it revealed the first intertwined sequence of three HORs, 18mer/27mer/45mer HORs, with a common aligned "backbone" across all HOR copies. The major 7mer HOR exhibits a Willard's-type canonical copy, although some segments of the array display significant irregularities. In contrast, the 14mer HOR forms a regular Willard's-type HOR array. Surprisingly, the GRM2023 high-precision analysis of chromosome 13 of human genome assembly T2T-CHM13v2.0 reveals the presence of only a 7mer HOR, despite both the orangutan and human genome assemblies being derived from whole genome shotgun sequences. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Threatened Taxa is the property of Wildlife Information Liaison Development and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Simple Summary: Histiocytic sarcoma (HS), a rare and highly aggressive cancer of histiocytic origin, has been identified across various animal species, including sporadic cases in non-human primates. This research presents the initial documented instance of disseminated HS in a captive orangutan. The clinical presentation closely resembled symptoms observed in human HS cases. A thorough examination of tissue samples revealed typical features of this cancer through histopathology, and the diagnosis was confirmed using immunohistochemistry, employing markers such as Iba-1 and HLA-DR. Notably, the lack of expression of CD163 and CD204 challenges their effectiveness as diagnostic indicators in non-human primates. This investigation contributes to our comprehension of diagnosing HS in non-human primates, emphasizing the importance of standardized markers and diagnostic procedures. Histiocytic sarcoma (HS), an infrequent highly aggressive hematopoietic tumor, has been observed in diverse animal species, with isolated occurrences in non-human primates. This study describes the first case of disseminated HS in a 45-year-old female hybrid captive orangutan. The clinical profile mirrored symptoms seen in human HS cases, encompassing anorexia and ascites. Detailed histopathological examination demonstrated characteristic features of this tumor and immunohistochemistry, using markers such as Iba-1 and HLA-DR, confirmed the diagnosis. Significantly, the absence of CD163 and CD204 expression challenges their diagnostic utility in non-human primates. This investigation enhances our understanding of HS diagnosis in non-human primates, underscoring the necessity for standardized markers and diagnostic protocols. [ABSTRACT FROM AUTHOR]

Recursive procedures that allow placing a vocal signal inside another of a similar kind provide a neuro-computational blueprint for syntax and phonology in spoken language and human song. There are, however, no known vocal sequences among nonhuman primates arranged in selfembedded patterns that evince vocal recursion or potential incipient or evolutionary transitional forms thereof, suggesting a neuro-cognitive transformation exclusive to humans. Here, we uncover that wild flanged male orangutan long calls feature rhythmically isochronous call sequences nested within isochronous call sequences, consistent with two hierarchical strata. Remarkably, three temporally and acoustically distinct call rhythms in the lower stratum were not related to the overarching rhythm at the higher stratum by any low multiples, which suggests that these recursive structures were neither the result of parallel non-hierarchical procedures nor anatomical artifacts of bodily constraints or resonances. Findings represent a case of temporally recursive hominid vocal combinatorics in the absence of syntax, semantics, phonology, or music. Second-order combinatorics, ‘sequences within sequences’, involving hierarchically organized and cyclically structured vocal sounds in ancient hominids may have preluded the evolution of recursion in modern language-able humans. [ABSTRACT FROM AUTHOR]

Primate fingers are typically in direct contact with the environment during both locomotion and manipulation, and aspects of external phalangeal morphology are known to reflect differences in hand use. Since bone is a living tissue that can adapt in response to loading through life, the internal bone architecture of the manual phalanges should also reflect differences in manual behaviours. Here, we use the R package Morphomap to analyse high‐resolution microCT scans of hominid proximal phalanges of digits 2–5 to determine whether cortical bone structure reflects variation in manual behaviours between bipedal (Homo), knuckle‐walking (Gorilla, Pan) and suspensory (Pongo) taxa. We test the hypothesis that relative cortical bone distribution patterns and cross‐sectional geometric properties will differ both among extant great apes and across the four digits due to locomotor and postural differences. Results indicate that cortical bone structure reflects the varied hand postures employed by each taxon. The phalangeal cortices of Pongo are significantly thinner and have weaker cross‐sectional properties relative to the African apes, yet thick cortical bone under their flexor sheath ridges corresponds with predicted loading during flexed finger grips. Knuckle‐walking African apes have even thicker cortical bone under the flexor sheath ridges, as well as in the region proximal to the trochlea, but Pan also has thicker diaphyseal cortices than Gorilla. Humans display a distinct pattern of distodorsal thickening, as well as relatively thin cortices, which may reflect the lack of phalangeal curvature combined with frequent use of flexed fingered hand grips during manipulation. Within each taxon, digits 2–5 have a similar cortical distribution in Pongo, Gorilla and, unexpectedly, Homo, which suggest similar loading of all fingers during habitual locomotion or hand use. In Pan, however, cortical thickness differs between the fingers, potentially reflecting differential loading during knuckle‐walking. Inter‐ and intra‐generic variation in phalangeal cortical bone structure reflects differences in manual behaviours, offering a comparative framework for reconstructing hand use in fossil hominins. [ABSTRACT FROM AUTHOR]

Formosan macaque (Macaca cyclopis) is the only non-human primate in Taiwan Island. We performed de novo hybrid assembly for M. cyclopis using Illumina paired-end short reads, mate-pair reads and Nanopore long reads and obtained 5065 contigs with a N50 of 2.66 megabases. M. cyclopis contigs > = 10 kb were assigned to chromosomes using Indian rhesus macaque (Macaca mulatta mulatta) genome assembly Mmul_10 as reference, resulting in a draft of M. cyclopis genome of 2,846,042,475 bases, distributed in 21 chromosomes. The draft genome contains 23,462 transcriptional origins (genes), capable of expressing 716,231 exons in 59,484 transcripts. Genome-based phylogenetic study using the assembled M. cyclopis genome together with genomes of four other macaque species, human, orangutan and chimpanzee showed similar result as previously reported. However, the M. cyclopis species was found to diverge from Chinese M. mulatta lasiota about 1.8 million years ago. Fossil gene analysis detected the presence of gap and pol endogenous viral elements of simian retrovirus in all macaques tested, including M. fascicularis, M. m. mulatta and M. cyclopis. However, M. cyclopis showed ~ 2 times less in number and more uniform in chromosomal locations. The constrain in foreign genome disturbance, presumably due to geographical isolation, should be able to simplify genomics-related investigations, making M. cyclopis an ideal primate species for medical research. [ABSTRACT FROM AUTHOR]

Sexually‐selected infanticide by males is widespread across primates. Maternal protection is one of many infanticide avoidance strategies employed by female primates. Bornean orangutan (Pongo pygmaeus wurmbii) mothers with younger offspring are less social with males than mothers with older offspring. Additionally, the distance between a mother and offspring decreases in the presence of male conspecifics, but not female conspecifics. We hypothesized that mothers are responsible for the change in mother‐offspring proximity when males are present. Using a year of behavioral data from orangutans in Gunung Palung National Park, we tested whether the Hinde Index, a ratio of the number of approaches and leaves between two individuals, was indicative of mother or offspring proximity maintenance across different social groupings. The semi‐solitary social organization of orangutans allows us to observe different social groupings. We found that the mother‐offspring Hinde Index was typically indicative of offspring maintenance of proximity. However, the presence of male conspecifics was associated with an increase in the Hinde Index which indicates that mothers are responsible for the decrease in mother‐offspring distance when males are present. The decrease in mother‐offspring distances and increase in Hinde Index when males are present indicates that mothers react to the presence of males in a protective manner. We suggest this may be an infanticide avoidance behavior by mother orangutans. RESEARCH HIGHLIGHTS: Male presence is associated with a change in mother‐offspring distance and proximity maintenance in Bornean orangutansThe Hinde Index shows that mother orangutans reduce the distance between themselves and their offspring when males are presentProximity maintenance is maternal protection from a potential infanticidal threat [ABSTRACT FROM AUTHOR]

Research in primate nutritional ecology uses concepts of quality, preference, and energy content to explain food choice: a primate consumes high-quality, preferred, and/or high-energy foods when available, and moves to other foods when they are not. Many frugivorous primates are thought to maximize energy, suggesting that high-energy fruit is a quality/preferred resource. However, recent research suggests a more complicated picture, including nutrient balancing and state-dependent foraging decisions. This brings into question whether a food is inherently high- or low-quality or whether this depends on previous feeding choices of the consumer. We tested whether a frugivorous primate, Pongo pygmaeus wurmbii, selects nonfruit foods when fruit is available. To test selectivity, we looked for three behaviors: (1) orangutans leaving available fruit for nonfruit foods, (2) evidence of orangutans navigating to nonfruit foods, and (3) orangutans selecting nonfruit when fruit was available and nearby. We use data from 51 focal follows (611 feeding bouts, 15 animals) in Gunung Palung National Park, Indonesia. We found when orangutans leave available fruit, it often is for nonfruit foods. We found evidence of orangutans navigating for nonfruit foods. GPS data show that orangutans leave or pass by fruit to consume other foods. When orangutans consumed nonfruit resources, 26% of the time, there was at least one available fruit resource within a 50-m radius. These data suggest that orangutans select nonfruit foods, strengthening the argument that feeding choice is consumer state-dependent, and leading us to argue for a revision of the use of "quality" as a descriptor of primate foods. [ABSTRACT FROM AUTHOR]

The primate scapula has been studied widely since its shape has been shown to correlate with how the forelimb is used in daily activities. In this study, we expand on the existing literature and use an image‐based methodology that was originally developed for orthopaedic practice to quantify and compare the three‐dimensional (3D) morphology of the scapula across humans and great apes. We expect that this image‐based approach will allow us to identify differences between great apes and humans that can be related to differences in mobility and loading regime of the shoulder. We hypothesize that gorillas and chimpanzees will have a similar scapular morphology, geared towards stability and weight‐bearing in knuckle‐walking, whilst the scapular morphology of orangutans is expected to be more similar to that of humans given their high glenohumeral mobility associated with their suspensory lifestyle. We made 3D reconstructions of computed tomography scans of 69 scapulae from four hominid genera (Pongo, Gorilla, Pan and Homo). On these 3D bone meshes, the inferior glenoid plane was determined, and subsequently, a set of bony landmarks on the scapular body, coracoid, and acromion were defined. These landmarks allowed us to measure a set of functionally relevant angles which represent acromial overhang, subacromial space and coracoacromial space. The angles that were measured are: the delto‐fulcral triangle (DFT), comprising the alpha, beta, and delta angle, the acromion‐glenoid angle (AGA), the coracoid‐glenoid centre‐posterior acromial angle (CGA), the anterior tilt (TA CGA) and the posterior tilt of the CGA (PT CGA). Three observers placed the landmarks on the 3D bone meshes, allowing us to calculate the inter‐observer error. The main differences in the DFT were found between humans and the great apes, with small differences between the great apes. The DFT of humans was significantly lower compared to that of the great apes, with the smallest alpha (32.7°), smallest delta (45.7°) and highest beta angle (101.6°) of all genera. The DFT of chimpanzees was significantly higher compared to that of humans (p < 0.01), with a larger alpha (37.6°) and delta angle (54.5°) and smaller beta angle (87.9°). The mean AGA of humans (59.1°) was significantly smaller (p < 0.001) than that of gorillas (68.8°). The mean CGA of humans (110.1°) was significantly higher (p < 0.001) than in orangutans (92.9°). Humans and gorillas showed mainly a posterior tilt of their coracoacromial complex whilst chimpanzees showed mainly an anterior tilt. The coracoacromial complex of the orangutans was not tilted anteriorly or posteriorly. With our image‐based method, we were able to identify morphological features of the scapula that differed significantly between hominid genera. However, we did not find an overall dichotomy in scapular morphology geared towards high stability (Pan/Gorilla) or high mobility (Homo/Pongo). Further research is needed to investigate the functional implications of these differences in scapular morphology. [ABSTRACT FROM AUTHOR]

Across species, communication systems may differ in their levels of flexibility, but comparisons are challenging, because flexibility is not operationalized in a consistent way. In this study, we investigated different aspects of flexibility in the gestural communication systems of 7 groups of captive apes (N = 53), including 19 chimpanzees (Pan troglodytes), 16 Sumatran orangutans (Pongo abelii), and 18 siamangs (Symphalangus syndactylus). We operationalized flexibility in four different ways: (i) the use of one gesture type across several contexts (i.e., contextual flexibility), (ii) the use of many gesture types in the same context (i.e., pragmatic flexibility), (iii) the production of one gesture type with different limbs and/or toward different target locations (i.e., morphological flexibility), and (iv) the ability to combine different signals into a sequence in different orders (i.e., combinational flexibility). Comparisons across individuals and species revealed variation in contextual and morphological flexibility. In particular, contextual flexibility increased with age and was overall higher in chimpanzees than siamangs. Moreover, morphological flexibility increased with social integration and was highest in siamangs and lowest in orangutans. Overall, variation largely reflected differences in social experience and possibly in the socioecological characteristics of the species. Our findings suggest that contextual and morphological flexibility might be good candidates to study interindividual and interspecific variation in primate gestural production. [ABSTRACT FROM AUTHOR]

Simple Summary: Understanding drawing features is a complex task, particularly concerning non-human primates, where the relevant features may not be the same as those for humans. Here, we propose a methodology for objectively analyzing drawings. To do so, we used deep learning, which allows for automated feature selection and extraction, to classify a female orangutan's drawings according to the seasons they were produced. We found evidence of seasonal variation in her drawing behavior according to the extracted features, and our results support previous findings that features linked to colors can partly explain seasonal variation. Using grayscale images, we demonstrate that not only do colors contain relevant information but also the shape of the drawings. In addition, this study demonstrates that both the style and content of drawings partly explain seasonal variations. Drawings have been widely used as a window to the mind; as such, they can reveal some aspects of the cognitive and emotional worlds of other animals that can produce them. The study of non-human drawings, however, is limited by human perception, which can bias the methodology and interpretation of the results. Artificial intelligence can circumvent this issue by allowing automated, objective selection of features used to analyze drawings. In this study, we use artificial intelligence to investigate seasonal variations in drawings made by Molly, a female orangutan who produced more than 1299 drawings between 2006 and 2011 at the Tama Zoological Park in Japan. We train the VGG19 model to first classify the drawings according to the season in which they are produced. The results show that deep learning is able to identify subtle but significant seasonal variations in Molly's drawings, with a classification accuracy of 41.6%. We use VGG19 to investigate the features that influence this seasonal variation. We analyze separate features, both simple and complex, related to color and patterning, and to drawing content and style. Content and style classification show maximum performance for moderately complex, highly complex, and holistic features, respectively. We also show that both color and patterning drive seasonal variation, with the latter being more important than the former. This study demonstrates how deep learning can be used to objectively analyze non-figurative drawings and calls for applications to non-primate species and scribbles made by human toddlers. [ABSTRACT FROM AUTHOR]

Gestures play an essential role in primate communication. However, little is known about how complexity of gestural use (in terms of repertoire size, intentional use, flexibility and use of gestural sequences) relates to individual and dyadic measures of sociality and whether more complex gestural use is more effective in eliciting a response. We observed 19 captive chimpanzees (Pan troglodytes), 16 Sumatran orangutans (Pongo abelii) and 18 siamangs (Symphalangus syndactylus) to assess the complexity and effectiveness of their gestural use. We found that, beyond interspecies variation, the number of gesture types used in a dyad was higher when individuals had stronger social bonds; the probability of accounting for others' attention increased with age, especially for visual gestures; and sequences were more likely used by younger or socially less integrated individuals. In terms of effectiveness, older individuals and those using fewer sequences were more likely to be responded to, while across dyads, the probability of obtaining a response was higher when both individuals accounted for the other's attention and when they used fewer sequences. Overall, this confirms the link between sociality and complex gestural use and suggests that more complex forms of communication, at least in terms of intentional use, may be more effective at achieving communicative goals. This article is part of the theme issue 'Cognition, communication and social bonds in primates'. [ABSTRACT FROM AUTHOR]

Tuberculosis (TB) is a globally important reemerging disease that is chronic, multi host infection caused by Mycobacterium tuberculosis complex (MTBC), which causes disease in livestock, wildlife and zoonotic TB in humans. Twelve (n=12) different species of NHPs were screened for MTBC and MAC in Zoo Melaka, Malaysia. The surveillance of MTBC and MAC was through the application of skin test, serology and PCR. The results showed two orangutan Pongo spp. (16.7%) were reactive to skin test with orangutan A showing obvious swelling of eyelids with drooping and varying degrees of erythema and orangutan B with moderate swelling of the eyelids with drooping and without erythema. For the antibody detection against MTBC, these two orangutans were positive by serology (16.7%), all other NHPs were antibody negative. Polymerase chain reaction from the blood of all NHPs was negative for the MTBC, however, all samples from blood and pharyngeal swab were PCR positive for MAC. In conclusion MAC was detected in captive NHPs population probably due to exposure to the environment without completely discriminating MTBC. [ABSTRACT FROM AUTHOR]

Univentricular heart malformations are rarely described in the veterinary literature. This case report describes a single‐inlet univentricular heart with persistent truncus arteriosus as a cause of death of a captive‐bred, 2‐day‐old, female Sumatran orangutan (Pongo abelii), a critically endangered species. [ABSTRACT FROM AUTHOR]

Between-individual variation in behavioural expression, such as social responsiveness, has been shown to have important eco-evolutionary consequences. However, most comparative research on non-human primate communication has focused on species- or population-level variation, while among- and within-individual variation has been largely ignored or considered as noise. Here, we apply a behavioural reaction norm framework to repeated observations of mother–offspring interactions in wild and zoo-housed orang-utans (Pongo abelii, P. pygmaeus) to tease apart variation on the individual level from population-level and species-level differences. Our results showed that mothers not only differed in the composition of their infant-directed gestural repertoires, but also in communicative tactics, such as gestural redoings (i.e. persistence) and responsiveness to infants' requests. These differences remained after controlling for essential moderators, including species, setting, parity and infant age. Importantly, mothers differed in how they adjusted their behaviour across social contexts, making a strong case for investigating within-individual variation. Our findings highlight that partitioning behavioural variation into its within-individual, between-individual and environmental sources allows us to estimate the extent of plastic responses to the immediate environment in great ape communication. [ABSTRACT FROM AUTHOR]

Vertebrate predation and consumption by wild Bornean orangutans (Pongo pygmaeus spp.) is rare. In contrast to recorded observations of slow loris consumption by Sumatran orangutans (Pongo abelii), no cases of this have been previously published for Bornean orangutans in the wild. In 2017, we observed the capture and consumption of a slow loris (Nycticebus borneanus) by an adult unflanged male Bornean orangutan at Tuanan Orangutan Research Station, which is located in the Kapuas region of Central Kalimantan. The unflanged male was together with an adult female and her 3.5-year-old offspring throughout the event. However, despite the mother and her offspring watching the male closely and occasionally begging while he consumed the loris, he resisted all food-taking attempts. This study reports, to the best of our knowledge, the first documented case of slow loris predation and consumption by a Bornean orangutan, and thus provides an important data point for understanding primate predation on other primate species. [ABSTRACT FROM AUTHOR]

Copyright of People & Nature is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Estimating stable isotopic offset values is crucial for dietary reconstructions. Although research into stable isotope ecology of wild nonhuman primates is increasing overall, only a minority of studies involve laboratory experiments. This study is the first to report the carbon and nitrogen stable isotopic offset values in hair and feces of orangutans. During an experiment lasting 1 week, the weight of each consumed food item was recorded for each of six captive Bornean orangutan (Pongo pygmaeus) individuals. The food, hair, and fecal samples were collected for a few days, and their stable carbon and nitrogen isotope ratios were measured using an elemental analyzer/isotope ratio mass spectrometer. Subsamples of feces were treated with ethanol during the preservation process. Monte Carlo analyses showed that the 95% confidence intervals (CIs) of the carbon and nitrogen offset values between hair and diet were +0.9‰ to +3.9‰ and +2.3‰ to +4.5‰, respectively. The 95% CIs of the carbon and nitrogen offset values between feces and diet were −3.7‰ to −0.9‰ and +0.3‰ to +2.7‰, respectively. The effect of ethanol treatment on the stable isotope ratios of feces was unclear and inconclusive. The computed offset values of hair in captive orangutans are similar to those reported in other nonhuman primates, although those of feces showed greater interspecies variations. The offset values estimated in this study contribute to isotopic studies into the feeding ecology of free-ranging orangutans who are critically endangered in most wild settings. [ABSTRACT FROM AUTHOR]

Nut‐cracking with hammer tools (henceforth: nut‐cracking) has been argued to be one of the most complex tool‐use behaviors observed in nonhuman animals. So far, only chimpanzees, capuchins, and macaques have been observed using tools to crack nuts in the wild (Boesch and Boesch, 1990; Gumert et al., 2009; Mannu and Ottoni, 2009). However, the learning mechanisms behind this behavior, and the extent of nut‐cracking in other primate species are still unknown. The aim of this study was two‐fold. First, we investigated whether another great ape species would develop nut‐cracking when provided with all the tools and appropriate conditions to do so. Second, we examined the mechanisms behind the emergence of nut‐cracking by testing a naïve sample. Orangutans (Pongo abelii and Pongo pygmaeus) have the second most extensive tool‐use repertoire among the great apes (after chimpanzees) and show flexible problem‐solving capacities. Orangutans have not been observed cracking nuts in the wild, however, perhaps because their arboreal habits provide limited opportunities for nut‐cracking. Therefore, orangutans are a valid candidate species for the investigation of the development of this behavior. Four nut‐cracking‐naïve orangutans at Leipzig zoo (P. abelii; Mage = 16; age range = 10–19; 4F; at the time of testing) were provided with nuts and hammers but were not demonstrated the nut‐cracking behavioral form. Additionally, we report data from a previously unpublished study by one of the authors (Martina Funk) with eight orangutans housed at Zürich zoo (six P. abelii and two P. pygmaeus; Mage = 14; age range = 2–30; 5F; at the time of testing) that followed a similar testing paradigm. Out of the twelve orangutans tested, at least four individuals, one from Leipzig (P. abelii) and three from Zürich (P. abelii and P. pygmaeus), spontaneously expressed nut‐cracking using wooden hammers. These results demonstrate that nut‐cracking can emerge in orangutans through individual learning and certain types of non‐copying social learning. Research highlights: Nut‐cracking with a tool by wild chimpanzees has been argued to be one of the most complex non‐human animal tool‐use behaviors.To test the extent of this behavior in other great apes, and the learning mechanisms underlying it, 12 naïve orangutans (Pongo abelii and P. pygmaeus) across two testing institutions (Leipzig zoo and Zürich zoo) were provided with the materials of nut‐cracking (hammer tool and shelled nuts) but no demonstrations.At least four of the naïve orangutans spontaneously cracked nuts with the hammer tools, demonstrating a similar behavior to wild primate nut‐cracking.These findings suggest that orangutans can acquire nut‐cracking with hammer tools via a combination of individual learning and non‐copying social learning. [ABSTRACT FROM AUTHOR]

Polyspecific associations, in which individuals of multiple species move together, have not been reported in Asian primates. However, only one study in India has shown this lack of association quantitatively. We collected data on interspecific encounters among 5 species of diurnal primates in Danum Valley by censusing 4 predetermined routes of 9.9 km, covering 1544.3 km, and tracking red leaf monkeys (Presbytis rubicunda) for 423 h over 25 mo. We tested the null hypothesis that the frequency and duration of encounters did not differ from chance levels. During censuses, we detected primates 373 times and found 2 species on the same 100-m segment only 6 times. This frequency was not significantly different from the chance level. While following red leaf monkeys, the frequency of encounters was lower than expected by chance with Müeller's gibbons (Hylobates muelleri) but higher than expected by chance with Bornean orangutans (Pongo pygmaeus) in the nonfruiting season. Interspecific encounters accounted for 6.4% of tracking time, and the encounter duration was significantly longer than expected by chance for orangutans. Red leaf monkeys did not change their rate or direction of travel on meeting another species. We could not distinguish the association between red leaf monkeys and orangutans in the nonfruiting season from the possibility that the two species were independently attracted to the same place. In conclusion, we show the absence of active and consistent polyspecific association and identify avoidance in some species pairs in an Asian primate community. [ABSTRACT FROM AUTHOR]

The body proportions of extant animals help inform inferences about the behaviors of their extinct relatives, but relationships between body proportions, behavior, and phylogeny in extant primates remain unclear. Advances in behavioral data, molecular phylogenies, and multivariate analytical tools make it an opportune time to perform comprehensive comparative analyses of primate traditional limb length proportions (e.g., intermembral, humerofemoral, brachial, and crural indices), body size-adjusted long bone proportions, and principal components. In this study we used a mix of newly-collected and published data to investigate whether and how the limb length proportions of a diverse sample of primates, including monkeys, apes, and modern humans, are influenced by behavior and phylogeny. We reconfirm that the intermembral index, followed by the first principal component of traditional limb length proportions, is the single most effective variable distinguishing hominoids and other anthropoids. Combined limb length proportions and positional behaviors are strongly correlated in extant anthropoid groups, but phylogeny is a better predictor of limb length proportion variation than of behavior. We confirm convergences between members of the Atelidae and extant apes (especially Pan), members of the Hylobatidae and Pongo , and a potential divergence of Presbytis limb proportions from some other cercopithecoids, which correlate with adaptations for forelimb-dominated behaviors in some colobines. Collectively, these results substantiate hypotheses indicating that extinct hominins and other hominoid taxa can be distinguished by analyzing combinations of their limb length proportions at different taxonomic levels. From these results, we hypothesize that fossil skeletons characterized by notably disparate limb length proportions are unlikely to have exhibited similar behavioral patterns. [ABSTRACT FROM AUTHOR]

Decision outcomes in unpredictable environments may not have exact known probabilities. Yet the predictability level of outcomes matters in decisions, and animals, including humans, generally avoid ambiguous options. Managing ambiguity may be more challenging and requires stronger cognitive skills than decision-making under risk, where decisions involve known probabilities. Here we compare decision-making in capuchins, macaques, orangutans, gorillas, chimpanzees and bonobos in risky and ambiguous contexts. Subjects were shown lotteries (a tray of potential rewards, some large, some small) and could gamble a medium-sized food item to obtain one of the displayed rewards. The odds of winning and losing varied and were accessible in the risky context (all rewards were visible) or partially available in the ambiguous context (some rewards were covered). In the latter case, the level of information varied from fully ambiguous (individuals could not guess what was under the covers) to predictable (individuals could guess). None of the species avoided gambling in ambiguous lotteries and gambling rates were high if at least two large rewards were visible. Capuchins and bonobos ignored the covered items and gorillas and macaques took the presence of potential rewards into account, but only chimpanzees and orangutans could consistently build correct expectations about the size of the covered rewards. Chimpanzees and orangutans combined decision rules according to the number of large visible rewards and the level of predictability, a process resembling conditional probabilities assessment in humans. Despite a low sample size, this is the first evidence in non-human primates that a combination of several rules can underlie choices made in an unpredictable environment. Our finding that non-human primates can deal with the uncertainty of an outcome when exchanging one food item for another is a key element to the understanding of the evolutionary origins of economic behaviour. [ABSTRACT FROM AUTHOR]

• Facial Action Coding Systems (FACS) are useful tools for facial behaviour measurement. • FACS is objective, anatomically based and systematic. • FACS have been created to facilitate cross-species comparison. • Homology is indicated by stereotypy, physical and anatomical similarity, and presence across multiple species. • FACS can help determine homology of facial behaviour across species. Darwin observed that form, and in his view, meaning, of facial behaviour (observable changes in the appearance of the face, often termed facial 'expression') is similar between a wide range of species and concluded that this must be due to a shared ancestral origin. Yet, as with all social behaviours, exactly how to define similarity and determine homology is debated. Facial behaviour is linked to specific facial muscle movements, so one important factor in determining homology is the anatomical basis of facial behaviours that appear similar in both appearance and social function. The Facial Action Coding System (FACS) was developed for the scientific measurement of human facial behaviour and is based on individual facial muscle movements (Ekman and Friesen, 1978). FACS has since been modified for use with various non-human primate species (chimpanzees, macaques, hylobatids, orangutans) and domestic species (dogs, cats, horses). These FACS can be used to trace continuity of form in facial behaviour across species and build a better understanding of the evolution of facial communication in mammals. [ABSTRACT FROM AUTHOR]

The article focuses on the study of primates, including humans, to better understand the diverse forms, behaviors, and evolutionary history of this taxon, offering insights into primate intelligence, social behaviors, and the interface between humans and non-human primates.

"Attention-getters" are proposed to be gestures that function to attract the attention of a recipient and therefore allow further communication to take place. Their use is an indicator of intentional communication and thus of great interest to researchers in the field of language evolution. However, there is conflicting evidence as to whether nonhuman primates use attention-getters, both in conspecific interactions and in interactions with humans. We examined whether zoo-housed orangutans (Pongo pygmaeus and hybrid [Pongo pygmaeus × Pongo abelii]) and gorillas (Gorilla gorilla gorilla) used auditory signals to initiate visual communication with a human. To test this, a human experimenter stood with food in her hand and her back to the ape. If the ape produced an auditory signal, the experimenter either turned to face the ape or, in the control condition, away from the ape. We found that condition had no significant effect on whether the apes followed their initial auditory signal with a visual signal. Furthermore, the apes did not show greater persistence with, or elaboration of, their auditory signals when the human did not turn to face them, than when she did. In contrast, the apes showed significantly more persistence and elaboration of visual signals when the experimenter turned to face them. Our results suggest that while the orangutans and gorillas were able to discriminate human visual attention and use visual gestures accordingly, they did not attempt to manipulate this attention through the use of auditory behaviors to initiate visual communication. [ABSTRACT FROM AUTHOR]

Orangutan pelves commonly exhibit a large, projecting tubercle in the iliopubic region, historically assumed to homologous to the pubic tubercle in humans. However, it is not clear whether this tubercle is a unique feature of Pongo, or if it is anatomically homologous with the human pubic tubercle when considered as a soft tissue attachment point. To clarify this issue, we dissected orangutan and other ape cadaveric specimens to evaluate the pelvic brim soft tissues and how they may relate to the tubercle (when present). We additionally conducted a broad osteological survey of pelvic brim morphology across 28 primate genera (n = 294 specimens) to document the presence of the tubercle in primate pelves. Cadaveric dissections revealed that the tubercle is exclusively associated with the proximal attachment of the adductor longus muscle tendon in orangutans. Our osteological survey confirms that the tubercle is both constantly present and very prominent in orangutans. We observed that the tubercle is consistently situated along the pectineal line, lateral to where the pubic tubercle in humans is found, thereby making its structural homology unlikely. The osteological survey documented the tubercle at polymorphic frequencies in all hominoid taxa, though generally less protuberant than observed in Pongo. We argue that this further excludes its possibility of homology with the pubic tubercle, and that it may therefore be more appropriately be considered an adductor longus tubercle. We discuss possible functional and phylogenetic implications for this feature. [ABSTRACT FROM AUTHOR]

The Bornean orangutan is critically endangered and monitoring its population is needed to inform effective conservation management. In this paper, we present results of 2014–17 aerial nest surveys of the major orangutan populations in Sabah and compare them with baseline data produced during surveys conducted in 2002–03 using similar methods. Our results show three important points: a) by increasing the survey effort (estimated at 15–25% cover), sparsely scattered orangutan sub-populations not recorded in the previous aerial surveys were located and the accuracy of the nest count estimates is expected to improve; b) large populations in the interior forests of Sabah, occupying sustainably managed logged and unlogged forests, have been stable over 15 years and are of vital importance for the species’ conservation; c) fragmented populations located in eastern Sabah, that are surrounded by extensive oil palm plantations, have declined at varying rates. [ABSTRACT FROM AUTHOR]

The most mineralized tissue of the mammalian body is tooth enamel. Especially in species with thick enamel, three-dimensional (3D) tomography data has shown that the distribution of enamel varies across the occlusal surface of the tooth crown. Differences in enamel thickness among species and within the tooth crown have been used to examine taxonomic affiliations, life history, and functional properties of teeth. Before becoming fully mineralized, enamel matrix is secreted on the top of a dentine template, and it remains to be explored how matrix thickness is spatially regulated. To provide a predictive framework to examine enamel distribution, we introduce a computational model of enamel matrix secretion that maps the dentine topography to the enamel surface topography. Starting from empirical enamel-dentine junctions, enamel matrix deposition is modeled as a diffusion-limited free boundary problem. Using laboratory microCT and synchrotron tomographic data of pig molars that have markedly different dentine and enamel surface topographies, we show how diffusion-limited matrix deposition accounts for both the process of matrix secretion and the final enamel distribution. Simulations reveal how concave and convex dentine features have distinct effects on enamel surface, thereby explaining why the enamel surface is not a straightforward extrapolation of the dentine template. Human and orangutan molar simulations show that even subtle variation in dentine topography can be mapped to the enamel surface features. Mechanistic models of extracellular matrix deposition can be used to predict occlusal morphologies of teeth. [ABSTRACT FROM AUTHOR]

Wildlife restoration is one of the key components of conservation strategies, and this includes the rehabilitation and release of animals confiscated from wildlife traffickers. When primates are re-introduced, most individuals need a pre-release training to acquire the skills needed to survive in the wild. Pre-release training may either negatively or positively affect primate post-release behavior and survival. Post-release behavior, however, has rarely been monitored even though it is the only means to assess the survival of released individuals. Here, we present a thorough analysis of data from a 3-year radio tracking study on 32 orangutans (Pongo abelii) released in Sumatra after their rehabilitation. We investigated whether and how the age at release, the duration of the pre-release rehabilitation and training, and the release location affected the post-release individual spatial behavior. Orangutans released at older age exhibited post-release habitat selection patterns that were more comparable to that shown by wild conspecifics, i.e., they chose areas closer to rivers and at lower elevations (150–250 meters a.s.l.) where previous research had documented greater food availability. In contrast, individuals released at younger age showed a stronger spatial dependency on the rehabilitation station and exhibited disrupted habitat selection patterns; although after several months after the release all individuals tended to decrease their spatial reliance on the rehabilitation facility. This study indicates that the rehabilitation of individuals for a longer period and their release further from the rehabilitation station have facilitated the subsequent development of more natural spatial behavior, i.e. driven by food availability rather than by the dependence on care-giving human facility. Our study provides indications on how to improve the rehabilitation and release of confiscated orangutans, highlighting the importance of the age at release, the length of the rehabilitation program, and the location of the release site. [ABSTRACT FROM AUTHOR]

The ability to judge the visual attention of others is a key aspect of human social cognition and communication. While evidence has shown that chimpanzees can discriminate human attention based on eye cues alone, findings for gorillas and orangutans have been less consistent. In addition, it is currently unclear whether these gorillas and orangutans attempt to attract the visual attention of inattentive recipients using "attention-getting" behaviors. We replicated and extended previous work by testing whether six orangutans (Pongo pygmaeus and hybrid) and six gorillas (Gorilla gorilla gorilla) modified the use of their visual and auditory signals based on the attentional state of a human experimenter. We recorded all communicative behaviors produced by the apes for 30 s while a human experimenter stood in front of them with a food reward in a variety of postures, both visually attentive (facing the apes) and inattentive (body and/or head facing away or eyes covered). Both species produced visual behaviors more often when the experimenter was looking at them than when she had her face turned away, but only the orangutans discriminated attention based on eye cues alone. When we removed human-reared apes from the analyses (N = 3), mother-reared apes showed sensitivity to eye cues from the experimenter. However, further analyses found that the orangutans and gorillas relied more heavily on the body and head orientation of the experimenter than on her eye cues. Neither species produced more vocalizations or nonvocal auditory behaviors, such as mesh and object banging, mesh rubbing, or clapping, in the inattentive, than attentive, conditions. Our results reveal that while orangutans and gorillas preferentially use visual gestures when a human is attending to them, they do not appear to produce auditory behaviors, including vocalizations, with the intention of manipulating the recipient's attention state. [ABSTRACT FROM AUTHOR]

Human chromosome 15q25 is involved in several disease-associated structural rearrangements, including microdeletions and chromosomal markers with inverted duplications. Using comparative fluorescence in situ hybridization, strand-sequencing, single-molecule, real-time sequencing and Bionano optical mapping analyses, we investigated the organization of the 15q25 region in human and nonhuman primates. We found that two independent inversions occurred in this region after the fission event that gave rise to phylogenetic chromosomes XIV and XV in humans and great apes. One of these inversions is still polymorphic in the human population today and may confer differential susceptibility to 15q25 microdeletions and inverted duplications. The inversion breakpoints map within segmental duplications containing core duplicons of the GOLGA gene family and correspond to the site of an ancestral centromere, which became inactivated about 25 million years ago. The inactivation of this centromere likely released segmental duplications from recombination repression typical of centromeric regions. We hypothesize that this increased the frequency of ectopic recombination creating a hotspot of hominid inversions where dispersed GOLGA core elements now predispose this region to recurrent genomic rearrangements associated with disease. [ABSTRACT FROM AUTHOR]

Making economic decisions in a natural foraging situation that involves the use of tools may require an animal to consider more levels of relational complexity than merely deciding between an immediate and a delayed food option. We used the same method previously used with Goffin´s cockatoos to investigate the orangutans’ flexibility for making the most profitable decisions when confronted with five different settings that included one or two different apparatuses, two different tools and two food items (one more preferred than the other). We found that orangutans made profitable decisions relative to reward quality, when the task required the subjects to select a tool over an immediately accessible food reward. Furthermore, most subjects were sensitive to work-effort when the immediate and the delayed option (directly accessible by using a tool) led to the same outcome. Most subjects continued to make profitable decisions that required taking into account the tool functionality. In a final multidimensional task design in which subjects had to simultaneously focus on two apparatuses, two reward qualities and two different tools, the orangutans chose the functional tool to access the high quality reward. [ABSTRACT FROM AUTHOR]

That great ape endocranial shape development persists into adolescence indicates that the splanchnocranium succeeds brain growth in driving endocranial development. However, the extent of this splanchnocranial influence is unknown. We applied two-block partial least squares analyses of Procrustes shape variables on an ontogenetic series of great ape crania to explore the covariation of the endocranium (the internal braincase) and splanchnocranium (face, or viscerocranium). We hypothesized that a transition between brain growth and splanchnocranial development in the establishment of final endocranial form would be manifest as a change in the pattern of shape covariation between early and adolescent ontogeny. Our results revealed a strong pattern of covariation between endocranium and splanchnocranium, indicating that chimpanzees, gorillas, and orangutans share a common tempo and mode of morphological integration from the eruption of the deciduous dentition onwards to adulthood: a reflection of elongating endocranial shape and continuing splanchnocranial prognathism. Within this overarching pattern, we noted that species variation exists in magnitude and direction, and that the covariation between the splanchnocranium and endocranium is somewhat weaker in early infancy compared to successive age groups. When correcting our covariation analyses for allometry, we found that an ontogenetic signal remains, signifying that allometric variation alone is insufficient to account for all endocranial-splanchnocranial developmental integration. Finally, we assessed the influence of the cranial base, which acts as the interface between the face and endocranium, on the shape of the vault using thin-plate spline warping. We found that not all splanchnocranial shape changes during development are tightly integrated with endocranial shape. This suggests that while the developmental expansion of the brain is the main driver of endocranial shape during early ontogeny, endocranial development from infancy onwards is moulded by the splanchnocranium in conjunction with the neurocranium. [ABSTRACT FROM AUTHOR]

2): gray woolly monkeys are large-bodied, opportunistic frugivorous primates that occur in the Amazon forests of Brazil, Peru, and Bolivia. 1): upper left: gray woolly monkey ( I Lagothrix lagotricha cana i ), upper right: Borneo orangutan ( I Pongo pygmaeus morio i ), bottom: baboon ( I Papio ursinus griseipes i ). [Extracted from the article]

Background The rise of nature-based ecotourism in the past decade has introduced unprecedented challenges in managing the increasing interaction between humans and animals. The potential transmission of antibiotic resistant microbes between humans and non-human primate populations is a concern due to their genetic similarity. Malaysia is well known for hotspots of wildlife diversity where non-human primates like monkeys and orangutans have become popular tourist attractions. In this study, we assessed the prevalence of antimicrobial resistant Staphylococcus aureus, Enterococcus species, and other Enterobacteriaceae in the faeces of human (HS) and two non-human primates (NHP) in Malaysia, the Long-tailed macaque (Macaca fascicularis, MF) and Silvered leaf monkey (Trachypithecus cristatus, TC). In addition, the faecal bacterial composition was profiled to evaluate the potential association between antibiotic resistant profiles and composition of gut microbiota. Results We tested the isolated bacteria using a selection of antibiotics. The results showed that both the number of antibiotic resistant strains and resistance level were higher in humans than NHPs. Overall, the composition of gut microbiome and pattern of antibiotic resistance showed that there was higher similarity between MF and TC, the two NHPs, than with HS. In addition, samples with higher levels of antibiotic resistance showed lower bacterial richness. Homo sapiens had the lowest bacterial diversity and yet it had higher abundance of Bacteroides. In contrast, NHPs displayed higher bacterial richness and greater prevalence of Firmicutes such as Ruminococceae and Oscillospira. Conclusion Higher antibiotic susceptibility in NHPs is likely related to low direct exposure to antibiotics. The lack of resistance may also suggest limited antimicrobial resistance transmission between humans and NHP. Nonetheless, continued monitoring over a long period will help mitigate the risk of anthropozoonosis and zooanthroponosis. Keywords: Ecotourism, Non-human primates, Human animal interaction, Antibiotic resistance, Author(s): C. W. Chong[sup.1], A. H. S. Alkatheeri[sup.2], N. Ali[sup.3], Z. H. Tay[sup.3], Y. L. Lee[sup.3], S. J. Paramasivam[sup.4,7], K. Jeevaratnam[sup.4], W. Y. Low[sup.5,6] and S. H. E. Lim[sup.2,3] Background [...]

Primates have evolved to rapidly detect and respond to danger in their environment. However, the mechanisms involved in attending to threatening stimuli are not fully understood. The dot-probe task is one of the most widely used experimental paradigms to investigate these mechanisms in humans. However, to date, few studies have been conducted in non-human primates. The aim of this study was to investigate whether the dot-probe task can measure attentional biases towards threatening faces in chimpanzees. Eight adult chimpanzees participated in a series of touch screen dot-probe tasks. We predicted faster response times towards chimpanzee threatening faces relative to neutral faces and faster response times towards faces of high threat intensity (scream) than low threat intensity (bared teeth). Contrary to prediction, response times for chimpanzee threatening faces relative to neutral faces did not differ. In addition, we found no difference in response times for faces of high and low threat intensity. In conclusion, we found no evidence that the touch screen dot-probe task can measure attentional biases specifically towards threatening faces in our chimpanzees. Methodological limitations of using the task to measure emotional attention in human and non-human primates, including stimulus threat intensity, emotional state, stimulus presentation duration and manual responding are discussed. [ABSTRACT FROM AUTHOR]

Scholars have debated the taxonomic identity of isolated primate teeth from the Asian Pleistocene for over a century, which is complicated by morphological and metric convergence between orangutan (Pongo) and hominin (Homo) molariform teeth. Like Homo erectus, Pongo once showed considerable dental variation and a wide distribution throughout mainland and insular Asia. In order to clarify the utility of isolated dental remains to document the presence of hominins during Asian prehistory, we examined enamel thickness, enamel-dentine junction shape, and crown development in 33 molars from G. H. R. von Koenigswald's Chinese Apothecary collection (11 Sinanthropus officinalis [= Homo erectus], 21 “Hemanthropus peii,” and 1 “Hemanthropus peii” or Pongo) and 7 molars from Sangiran dome (either Homo erectus or Pongo). All fossil teeth were imaged with non-destructive conventional and/or synchrotron micro-computed tomography. These were compared to H. erectus teeth from Zhoukoudian, Sangiran and Trinil, and a large comparative sample of fossil Pongo, recent Pongo, and recent human teeth. We find that Homo and Pongo molars overlap substantially in relative enamel thickness; molar enamel-dentine junction shape is more distinctive, with Pongo showing relatively shorter dentine horns and wider crowns than Homo. Long-period line periodicity values are significantly greater in Pongo than in H. erectus, leading to longer crown formation times in the former. Most of the sample originally assigned to S. officinalis and H. erectus shows greater affinity to Pongo than to the hominin comparative sample. Moreover, enamel thickness, enamel-dentine junction shape, and a long-period line periodicity value in the “Hemanthropus peii” sample are indistinguishable from fossil Pongo. These results underscore the need for additional recovery and study of associated dentitions prior to erecting new taxa from isolated teeth. [ABSTRACT FROM AUTHOR]

Background. Peaceful conflict resolution strategies have been identified as effective mechanisms for minimising the potential costs of group life in many gregarious species, especially in primates. The knowledge of conflict-management in orangutans, though, is still extremely limited. Given their semi-solitary lives in the wild, there seems to be barely a need for orangutans to apply conflict management strategies other than avoidance. However, because of the rapid loss of orangutan habitat due to deforestation, opportunities to prevent conflicts by dispersion are shrinking. Additionally, more and more orangutans are brought into rehabilitation centres where they are bound to live in close contact with conspecifics. This raises the questions of whether and how orangutans are able to cope with conflicts, which are inevitably connected with group life. Methods. Observational zoo-studies provide a valuable method to investigate such potential: in zoos, orangutans usually live in permanent groups and face the challenges of group life every day. Therefore, we observed a group of six socially-housed Sumatran orangutans at the Dortmund Zoo, Germany, both in their spacious outdoor enclosure in the summer and in the less spacious indoor enclosure in the winter. During 157.5 h of observation, we collected data on aggressive interactions, third-party interventions and post-conflict affiliations. We applied the post-conflict/matched-control observation (PC/MC) and the time rule method to investigate the occurrence of reconciliation and post-conflict third-party affiliations. Results. We recorded a total of 114 aggressive interactions (including conflicts in the context of weaning and of male sexual coercion). As expected, we found an increase of both open conflicts and peaceful conflict resolution under less spacious conditions. In accordance with previous reports, we observed interventions by initially uninvolved individuals. Whereas we found no clear evidence for post-conflict thirdparty affiliations, we were able to demonstrate the occurrence of reconciliation among orangutans. Discussion. Notwithstanding the small sample size and the explorative character of our study, we found evidence that orangutans possess a potential for prosocial conflict resolution. When living in groups and under conditions in which dispersion is no longer an option, orangutans are capable to flexibly apply strategies of conflict resolution to cease open conflicts and to repair the potential social damage of aggressive interactions. These strategies are similar to those of other great apes. [ABSTRACT FROM AUTHOR]

Metacognition refers to thinking about one’s thinking or knowing what one knows. Research suggests that this ability is not unique to humans and may be shared with nonhuman animals. In particular, great apes have shown behaviors on a variety of tasks that are suggestive of metacognitive ability. Here we combine a metacognitive task, the information-seeking task, with tool use and variable forms of initial information provided to chimpanzees to explore how informational states impact behavioral responses in these apes. Three chimpanzees were presented with an apparatus that contained five locations where food could be hidden. If they pointed to the correct location, they received the reward, but otherwise they did not. We first replicated several existing findings using this method, and then tested novel hypotheses. The chimpanzees were given different types of information across the experiments. Sometimes, they were shown the location of the food reward. Other times, they were shown only one empty location, which was not useful information. The chimpanzees also could use a tool to search any of those locations before making a selection. Chimpanzees typically used the tool to search out the location of the reward when they could not already know where it was, but they did not use the tool when they already had been given that information. One chimpanzee made inferences about the location of hidden food, even when that food was never shown in that location. The final experiment involved hiding foods of differing preference values, and then presenting the chimpanzees with different initial knowledge states (i.e., where the best food was located, where the less-preferred food was located, or where no food was located). All chimpanzees used the tool when they needed to use it to find the best possible item on that trial, but responded by choosing a location immediately when they did not need the tool. This finding highlights that their behavior was not the result of a simple rule following such as pointing to where any food had been seen. [ABSTRACT FROM AUTHOR]

When viewing social scenes, humans and nonhuman primates focus on particular features, such as the models’ eyes, mouth, and action targets. Previous studies reported that such viewing patterns vary significantly across individuals in humans, and also across closely-related primate species. However, the nature of these individual and species differences remains unclear, particularly among nonhuman primates. In large samples of human and nonhuman primates, we examined species differences and the effects of experience on patterns of gaze toward social movies. Experiment 1 examined the species differences across rhesus macaques, nonhuman apes (bonobos, chimpanzees, and orangutans), and humans while they viewed movies of various animals’ species-typical behaviors. We found that each species had distinct viewing patterns of the models’ faces, eyes, mouths, and action targets. Experiment 2 tested the effect of individuals’ experience on chimpanzee and human viewing patterns. We presented movies depicting natural behaviors of chimpanzees to three groups of chimpanzees (individuals from a zoo, a sanctuary, and a research institute) differing in their early social and physical experiences. We also presented the same movies to human adults and children differing in their expertise with chimpanzees (experts vs. novices) or movie-viewing generally (adults vs. preschoolers). Individuals varied within each species in their patterns of gaze toward models’ faces, eyes, mouths, and action targets depending on their unique individual experiences. We thus found that the viewing patterns for social stimuli are both individual- and species-specific in these closely-related primates. Such individual/species-specificities are likely related to both individual experience and species-typical temperament, suggesting that primate individuals acquire their unique attentional biases through both ontogeny and evolution. Such unique attentional biases may help them learn efficiently about their particular social environments. [ABSTRACT FROM AUTHOR]

Spontaneous looking preferences were assessed in six zoo-housed orangutans. Orangutans were presented with two photographs simultaneously on two identical laptop computers. Preference was measured by calculating the relative looking time for photographs from each stimulus category, over three studies. Orangutans exhibited moderate interest in looking at photographs, with four orangutans participating in Study 1 and Study 2, and six orangutans participating in Study 3. The results of Study 1 showed that orangutans preferred photographs of unfamiliar orangutans over unfamiliar humans. Study 2 results showed that orangutans preferred photographs of familiar orangutans over unfamiliar orangutans. In Study 3, preferences were assessed using photographs of the nine members of the participants' own orangutan social group. Orangutans preferred photographs of adults over infants, and males over females. Similar studies have reported varied preferences, and we propose that variation is a result of complex demographic and social factors. [ABSTRACT FROM AUTHOR]

Humans mentally represent magnitudes spatially; we respond faster to one side of space when processing small quantities and to the other side of space when processing large quantities. We determined whether spatial representation of magnitude is a fundamental feature of primate cognition by testing for such space-magnitude correspondence in gorillas and orangutans. Subjects picked the larger quantity in a pair of dot arrays in one condition, and the smaller in another. Response latencies to the left and right sides of the screen were compared across the magnitude range. Apes showed evidence of spatial representation of magnitude. While all subjects did not adopt the same orientation, apes showed consistent tendencies for spatial representations within individuals and systematically reversed these orientations in response to reversal of the task instruction. Results suggest that spatial representation of magnitude is phylogenetically ancient and that consistency in the orientation of these representations in humans is likely culturally mediated. [ABSTRACT FROM AUTHOR]

Orangutans ( Pongo sp.) show among the highest occurrence of three types of developmental enamel defect. Two are attributed to nutritional factors that reduce bone growth in the infant's face early in development. Their timing and prevalence indicate that Sumatra provides a better habitat than does Borneo. The third type, repetitive linear enamel hypoplasia (rLEH) is very common but its etiology is not understood. Our objective is to draw attention to this enigmatic, episodic stressor in the lives of orangutans. We are concerned that neglect of this possible marker of ill health may be contributing, through inaction, to their alarming decline in numbers. Width and depth of an LEH are considered proxies for duration and intensity of stress. The hypothesis that Bornean orangutans would exhibit relatively wider and deeper LEH was tested on 163 independent episodes of LEH from 9 Sumatran and 26 Bornean orangutans measured with a NanoFocus AG 'µsurf Mobile Plus' scanner. Non-normally distributed data (depths) were converted to natural logs. No difference was found in width of LEH among the two island taxa; nor are their differences in width or depth between the sexes. After controlling for significant differences in LEH depths between incisors and canines, defects are, contrary to prediction, significantly deeper in Sumatran than Bornean animals (median = 28, 18 µm, respectively). It is concluded that repetitive LEH records an unknown but significant stressor present in both Sumatra and Borneo, with an average periodicity of 6 months (or multiples thereof) that lasts about 6-8 weeks. It is worse in Sumatra. Given this patterning, shared with apes from a wide range of ecological and temporal sources, rLEH is more likely attributable to disease than to malnutrition. [ABSTRACT FROM AUTHOR]

Wild orangutan populations exist in an increasingly fragile state. As numbers continue to decline and populations became fragmented, the overall health of remaining individuals becomes increasingly at risk. Parasitic infections can have a serious impact on the health of wild orangutans, and can be fatal. It has been reported that rehabilitated individuals demonstrate a higher prevalence of parasitic diseases, and it is possible that they may spread these infections to wild orangutans upon reintroduction. In order to ensure the success of reintroduction and conservation efforts, it is crucial to understand the potential risks by fully understanding what parasites they have been reported to be infected with. Using this knowledge, future conservation strategies can be adapted to minimize the risk and prevalence of parasite transmission in the remaining orangutan populations. There is still limited information available on orangutan parasites, with several still not identified to the species level. Based on comprehensive literature review, we found 51 parasite taxa known to infect wild, semi-wild, and captive orangutans, including newly reported species. Here, we summarize methods used to identify parasites and draw conclusions relative to their reported prevalence. We also recommend fecal sample preservation and analytical methods to obtain best result in the future. [ABSTRACT FROM AUTHOR]

Objectives Recently, studies have interpreted regular spacing and average number of perikymata between dental enamel defects in orangutans to reflect seasonal episodes of physiological stress. To estimate the amount of time between developmental defects (enamel hypoplasia), studies have relied on perikymata counts. Unfortunately, perikymata are frequently not continuously visible between defects, significantly reducing data sets. A method is presented here for estimating the number of perikymata between defects using standard perikymata profiles (SPP) that allow the number of perikymata between all pairs of defects across a tooth to be analyzed. The SPP method should allow the entire complement of defects to be analyzed within the context of an individual's crown formation time. Materials and methods The average number of perikymata were established per decile and charted to create male and female Pongo pygmaeus SPPs. The position of the beginning of each defect was recorded for lower canines from males ( n = 6) and females ( n = 17). The number of perikymata between defects estimated by the SPP was compared to the actual count (where perikymata were continuously visible). Results The number of perikymata between defects estimated by the SPPs was accurate within three perikymata and highly correlated with the actual counts, significantly increasing the number of analyzable defect pairs. Conclusion SPPs allow all defect pairs to be included in studies of defect timing, not just those with continuously visible perikymata. Establishing an individual's entire complement of dental defects makes it possible to calculate the regularity (and potential seasonality) of defects. [ABSTRACT FROM AUTHOR]