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Objectives: Orangutans are found in tropical rainforests of Borneo (Pongo pygmaeus) and Sumatra (Pongo abelii and Pongo tapanuliensis), and they are primarily considered frugivorous species. However, ecological studies reported differences in feeding behavior between these species. P. pygmaeus spend more time feeding on low‐quality foods, such as bark and tough vegetation than do P. abelii. The aim of this study is to investigate if there is any geographic variation in molar macrowear pattern between the two species. Methods: We analyzed the macrowear pattern of second mandibular molars of 58 orangutan specimens combining dental topographic measurements (occlusal relief index, percentage of dentine exposure, and percentage of enamel wear) with the occlusal fingerprint analysis method. Results: The molar macrowear patterns of P. abelii and P. pygmaeus show no significant differences in most of the variables examined in this study. While P. pygmaeus molars are generally characterized by flatter occlusal morphology with slightly larger crushing and grinding areas than those of P. abelii, these differences are not statistically significant. However, we do observe a more variable wear in P. pygmaeus. Conclusions: Similarities in molar macrowear patterns between the two species could be linked to overlapping long‐term diets, primarily composed of ripe and pulpy fruits. Dental macrowear is a cumulative process that occurs during the individual's lifetime, and it may be difficult to detect seasonal changes through its examination. Future studies could integrate tooth micro‐ and macrowear data for a better understanding of primate dental ecology. [ABSTRACT FROM AUTHOR]

Objectives: Reconstruction of life histories for fossil and living primates draws on rate of enamel layering, termed Retzius periodicity (RP in days) expressed as surface perikymata, during dental crown formation. Disclosure of RP through thin sectioning is destructive; consequently, sample sizes are inadequate to detect the range of RPs present in discrete taxa. We propose an additional method to detect RPs at the population level based on twice‐yearly average recurrence of linear enamel hypoplasia (rLEH) in apes shown by prior studies. Materials and Methods: Casts of teeth from orangutans (Pongo pygmaeus) (n = 40) and Lufengpithecus lufengensis (n = 57) from Late Miocene Shihuiba, China, (133 and 138 LEH, respectively) were recorded with scanning electron microscope (SEM) and confocal microscopy to yield perikymata counts between episodes of LEH. Frequency distributions of aggregated perikymata counts between LEH were compared to frequency distribution of tooth‐specific ratios of perikymata counts between successive LEH (this latter step removes effects of RP differences within a sample). Results: Drawing on prior research, two successive intervals between LEH span 1 year on average. Ratios of successive to previous intervals between LEH show that orangutans and Lufengpithecus exhibit two asymmetric intervals centered on 5.3 and 6.7 months, likely reflecting the effect of axial tilt insolation on phenology. Estimated RPs are not unimodal but show a range from 7 to 12 in Lufenpithecus and 8 to 11 in Pongo, comparable to published values. Discussion: Repetitive LEH is sufficiently regular to detect additional RPs which, in the case of Lufengpithecus, have yet to be demonstrated histologically. [ABSTRACT FROM AUTHOR]

Laugh faces of humans play a key role in everyday social interactions as a pervasive tool of communication across contexts. Humans often vary the degree of mouth opening and teeth exposure when producing these facial expressions, which may depend on who their social partner is (e.g., their gender and age as well as their social relationship), serving this way different functions. Although it was found that laugh faces show evolutionary continuity across humans and non-human great apes according to the Principle of Maximum Parsimony, little is known about the function of laugh face variations from an evolutionary perspective. Hence, the present work examined the morphology of laugh faces in orangutan and chimpanzee dyadic play to test if they are modified with dependence on the playmate's characteristics (sex, age and social relationship). In total, we analysed over 600 facial expressions of 14 orangutans and 17 chimpanzees by coding the specific muscle activations (Action Units, i.e. AUs) contributing to these expressions, using OrangFACS and ChimpFACS, respectively. Our results suggest that age difference and, to a lesser extent, playmate sex influence laugh face morphology in both taxa, but in opposite ways. While the orangutans of our study seem to expose their upper teeth (with AU10) and to pull the mouth corners (with AU12) more towards weaker partners (younger and female), possibly to communicate non-hostility, the chimpanzees showed both upper and lower teeth exposure (with AU10 and AU16) more often when interacting with the stronger partners (older individuals), possibly to communicate submissiveness. These findings suggest that the ability of humans to modify laugh faces with dependence on social partner characteristics has most likely evolved from pre-existing traits, going back at least to the last common ancestor of today's great apes, including humans. [ABSTRACT FROM AUTHOR]

Mammalian mothers flexibly invest in their offspring to maximize their lifetime fitness. Flexible maternal investment may be particularly important in large-brained species with prolonged maternal care, e.g., in great apes. We investigated the effects of socioecological factors and mother–offspring characteristics on nine maternal behaviors in wild Sumatran orangutans (Pongo abelii; N = 22 mother-offspring pairs; >11,200 hr of focal data from 2007–2022) using generalized linear mixed models. The behaviors fall under four maternal functions: locomotory support (carrying), skill acquisition support (feeding in proximity, food transfer), protective proximity maintenance (body contact and proximity initiation, following), and independence promotion (body contact and proximity termination, avoiding). Mother's parity was not significantly associated with any maternal behavior. Mothers were more likely to show locomotory support, skill acquisition support, and protective proximity maintenance toward younger than older offspring, whereas they were more likely to promote independence in older than younger offspring. Mothers with male offspring were more likely to show skill acquisition support to their offspring than those with female offspring. With increasing food availability, skill acquisition support reduced. With increasing association size (i.e., the number of individuals within 50 m of each other), mothers were more likely to show protective proximity maintenance and less likely to promote independence. When males were present, mothers were more likely to show locomotory support to their offspring. Sumatran orangutan mothers thus flexibly adjust offspring-directed behavior in response to prevailing socioecological factors and mother–offspring characteristics. Our findings add support to the evolutionary theory that mammalian mothers flexibly invest in their offspring. [ABSTRACT FROM AUTHOR]

Glyptothorax pongoensis, sp. n. is described from the Yongmon River in Nagaland, India. The new species can be distinguished from its congeners in the Indian subcontinent by the following combination of characters: an ovate-shaped thoracic adhesive apparatus with skin ridges present over the entire apparatus, including the subulate-shaped median depression; presence of plicae on the ventral surface of the pectoral fin spine and the first ray of the pelvic fin; W-shaped anterior nuchal plate element; dorsal-fin origin nearer to the snout tip than to the origin of the adipose fin; posterior margin of dorsal spine rugose with 4–5 ridges, tuberculate skin, and nasal barbel not reaching eye when adpressed. [ABSTRACT FROM AUTHOR]

Abstract Laugh faces of humans play a key role in everyday social interactions as a pervasive tool of communication across contexts. Humans often vary the degree of mouth opening and teeth exposure when producing these facial expressions, which may depend on who their social partner is (e.g., their gender and age as well as their social relationship), serving this way different functions. Although it was found that laugh faces show evolutionary continuity across humans and non-human great apes according to the Principle of Maximum Parsimony, little is known about the function of laugh face variations from an evolutionary perspective. Hence, the present work examined the morphology of laugh faces in orangutan and chimpanzee dyadic play to test if they are modified with dependence on the playmate’s characteristics (sex, age and social relationship). In total, we analysed over 600 facial expressions of 14 orangutans and 17 chimpanzees by coding the specific muscle activations (Action Units, i.e. AUs) contributing to these expressions, using OrangFACS and ChimpFACS, respectively. Our results suggest that age difference and, to a lesser extent, playmate sex influence laugh face morphology in both taxa, but in opposite ways. While the orangutans of our study seem to expose their upper teeth (with AU10) and to pull the mouth corners (with AU12) more towards weaker partners (younger and female), possibly to communicate non-hostility, the chimpanzees showed both upper and lower teeth exposure (with AU10 and AU16) more often when interacting with the stronger partners (older individuals), possibly to communicate submissiveness. These findings suggest that the ability of humans to modify laugh faces with dependence on social partner characteristics has most likely evolved from pre-existing traits, going back at least to the last common ancestor of today’s great apes, including humans.

Abstract When presented with the option of either an immediate benefit or a larger, later reward, we may behave impatiently by choosing instant gratification. Nonetheless, when we can make the same decision ahead of time and plan for the future, we tend to make more patient choices. Here, we explored whether great apes share this core feature of human decision-making, often referred to as dynamic inconsistency. We found that orangutans, bonobos, and gorillas tended to act impatiently and with considerable variability between individuals when choosing between an immediate reward and a larger-later reward, which is a commonly employed testing method in the field. However, with the inclusion of a front-end delay for both alternatives, their decisions became more patient and homogeneous. These results show that great apes are dynamically inconsistent. They also suggest that, when choosing between future outcomes, they are more patient than previously reported. We advocate for the inclusion of diverse time ranges in comparative research, especially considering the intertwinement of intertemporal choices and future-oriented behavior.

Eastern New Mexico, part of the Great Plains in the USA, has often been neglected for its studies of butterfly diversity because of its arid climate and flat landscape. This study was conducted to assess the current species richness and abundance of butterflies in two sub-ecoregions of the Great Plains in central eastern NM, including the Semiarid Canadian Breaks and the Llano Estacado. The survey was conducted at selected focal sites in each sub-ecoregion from January to November 2023. A modified Pollard walk technique was employed to collect cumulative monthly data on the diversity of adult butterflies. A total of 856 individuals belonging to 46 species were counted for the Semiarid Canadian breaks, while a total of 812 individuals belonging to 65 species were counted for the Llano Estacado sub-ecoregion. The Shannon diversity index, Shannon equitability index, and relative abundance were calculated for each sub-ecoregion and a local abundance index was designed to rank the density of butterflies. Checklists of butterflies were prepared, along with information related to their residential status, phenology, and local abundance. Six new locality distributions were recorded from Llano Estacado, including Cupido amyntula (Boisduval, 1852), Gesta tristis tatius (W. H. Edwards, 1883), Polites carus (W. H. Edwards, 1883), Celastrina sp., Ministrymon leda (W. H. Edwards, 1882), and Polygonia satyrus satyrus (W. H. Edwards, 1869). The extensions of their ranges are discussed. A comparison of the diversity of butterflies between the two sub-ecoregions revealed a significant difference in the species abundances. Additionally, a significant difference was found among different families and their species abundances and among the different months and their species abundances in both sub-ecoregions. A total of 206 voucher specimens were collected during this study and were deposited at the Natural History Museum of Eastern New Mexico University, Portales. Overall, this study has helped to quantify the diversity of butterflies for 2023 in central eastern New Mexico. The baseline data generated from this study can be subjected to various ecological analyses for additional diversity analysis, and this research can also be replicated over years to observe the changes in diversity with changing environmental conditions. [ABSTRACT FROM AUTHOR]

Objectives: Metatarsal bones constitute a key functional unit of the foot in primates. While the form‐function relationships of metatarsals have been extensively studied, particularly in relation to the loss of the grasping ability of the foot in humans in contrast to apes, the effect of phyletic history on the metatarsal morphology and its variability remains largely unknown. Materials and Methods: Here, we evaluate how the strength of the phylogenetic signal varies from the first to the fifth metatarsal in humans, chimpanzees, gorillas, orangutans, gibbons, and Japanese macaques. We use computed tomography imaging and morphometric mapping to quantify the second moment of area around and along the metatarsal shaft and evaluate the strength of the phylogenetic signal with multivariate K‐statistics. Results: The shaft structure of the first metatarsal, but not the others, correlates well with the phylogeny of apes and humans. Discussion: Given the importance of the first metatarsal for grasping and bipedal/quadrupedal locomotion, the strong phylogenetic but weak functional signal in its structure is unexpected. These findings suggest that the evolutionary diversification of hominoid locomotor behaviors, including human bipedality, is only partly reflected in form‐function relationships of key skeletal elements, and that phylogenetic history acted as a major evolutionary constraint. [ABSTRACT FROM AUTHOR]

When presented with the option of either an immediate benefit or a larger, later reward, we may behave impatiently by choosing instant gratification. Nonetheless, when we can make the same decision ahead of time and plan for the future, we tend to make more patient choices. Here, we explored whether great apes share this core feature of human decision-making, often referred to as dynamic inconsistency. We found that orangutans, bonobos, and gorillas tended to act impatiently and with considerable variability between individuals when choosing between an immediate reward and a larger-later reward, which is a commonly employed testing method in the field. However, with the inclusion of a front-end delay for both alternatives, their decisions became more patient and homogeneous. These results show that great apes are dynamically inconsistent. They also suggest that, when choosing between future outcomes, they are more patient than previously reported. We advocate for the inclusion of diverse time ranges in comparative research, especially considering the intertwinement of intertemporal choices and future-oriented behavior. [ABSTRACT FROM AUTHOR]

Play is thought to serve different purposes at different times during ontogeny. The nature and frequency of play are expected to change accordingly over the developmental trajectory and with socio-ecological context. Orangutans offer the opportunity to disentangle the ontogenetic trajectories of solitary and social play with their extended immature phase, and socio-ecological variation among populations and species. We evaluated the frequency of play in 39 immature individuals across two populations (Pongo pygmaeus wurmbii, at Tuanan, Borneo, and P. abelii at Suaq, Sumatra), age (0–11 years), sex, and social context, using more than 11 500 h of full-day focal observation data. We found independent age trajectories of different play types, with solitary object and solitary locomotor peaking before social play. Social play partners changed during ontogeny, and male immatures were more likely to engage in non-mother social play than females. Overall, social play was more frequent at Suaq than Tuanan, linked to the more frequent availability of partners. Furthermore, per time in association with conspecifics, Tuanan immatures were as likely to engage in social play as their peers at Suaq, suggesting similar intrinsic motivation. Increasing fruit availability correlated with both longer associations and increased social play frequency in the less sociable population of Tuanan, but not at Suaq. Our findings on orangutans support evidence from other species that different play types follow different developmental trajectories, vary with sex, social opportunities, and ecological context. Although drawing functional inferences is challenging, the distinct developmental trajectories reflecting adult sociability and behavioral repertoires may indicate that play serves several, non-mutually exclusive functions during ontogeny. [ABSTRACT FROM AUTHOR]

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]

In the process of using natural caving mining, it is necessary to accurately predict the caving behavior of rock masses to ensure safe production operations. The aim of this study is to explore the spatiotemporal evolution law of natural caving mining and rock caving through numerical simulation methods. Based on FLAC3D software, a three-dimensional model of the actual strata of Peru Pampa de Pongo Iron Mine was constructed, and combined with the Burgers Mohr constitutive model, key technical parameters such as the initial and continuous caving undercut area, the continuous caving velocity, the entire process of undercut surface subsidence, and the amount of ore rock caving were studied. The research results indicate that the initial and continuous caving and undercut areas of Pampa de Pongo Iron Mine are between 864 m²~1350 m² and 5400 m²~6534 m², respectively; The continuous caving velocity is 0.3112 m/d; After all undercutting is completed, the total amount of ore rock caving is 630.12 million tons, which can meet the design production capacity requirements. The results of this study provide new ideas and methods for the study of key technical parameters of block caving method. [ABSTRACT FROM AUTHOR]

Orang-utans are well-known for their vocal flexibility. However, the described vocal repertoire of female orang-utans is relatively limited. This anecdotal report discusses the occurrence of long call-like vocalisations in two zoo-housed Bornean orang-utan females. While Temmy demonstrated these vocalisations in response to playbacks of male long calls, Eloise proactively produced vocalisations during her ovulation before her reproductive senescence. The vocalisations produced by Temmy and Eloise seem to differ in many aspects from known orang-utan calls, although they bear some similarities to male long calls. Thus, the vocal repertoire of female orang-utans may be more extensive than previously thought. We carefully suggest that these calls might indicate proceptivity, while also discussing methodological limitations and theoretical considerations. [ABSTRACT FROM AUTHOR]

Simple Summary: This study investigates the application of machine learning in the form of image classification and object detection to video material to automate behavior recognition in captive orangutans (Pongo pygmaeus). A machine learning model was constructed using a 2 min video consisting of 30 s clips of each selected behavior. The machine learning model had a 13% detection rate and showed potential for future expansion, with the goal of automating behavioral studies, but also notable issues that should be considered when using such methods. This article applies object detection to CCTV video material to investigate the potential of using machine learning to automate behavior tracking. This study includes video tapings of two captive Bornean orangutans and their behavior. From a 2 min training video containing the selected behaviors, 334 images were extracted and labeled using Rectlabel. The labeled training material was used to construct an object detection model using Create ML. The use of object detection was shown to have potential for automating tracking, especially of locomotion, whilst filtering out false positives. Potential improvements regarding this tool are addressed, and future implementation should take these into consideration. These improvements include using adequately diverse training material and limiting iterations to avoid overfitting the model. [ABSTRACT FROM AUTHOR]

The surveillance and treatment of parasites are important features of preventative healthcare plans in zoological institutes. The parasite control strategies employed in temperate regions often involve prophylactic anthelmintic treatments during seasons where the burden of gastrointestinal parasites in fecal testing is high. These strategies are, however, not applicable in the tropics, where temperatures remain high throughout the year, allowing continuous parasitic development. A risk-based parasite management strategy was adopted by a tropical zoological institute. For parasite surveillance, routine fecal direct smears and magnesium sulfate flotations were performed to determine parasitic prevalence. The frequency of fecal checks for the year was determined by the frequency at which clinically relevant parasitism (fecal tests that resulted in the animal being treated) was detected during routine fecal checks in the previous year. A yearly anthelmintic drug-class rotation schedule was also implemented. The total number of fecal tests performed per year and the number of animals with clinically significant parasitic disease decreased by 30.0% (637/2126) and 46.9% (207/451), respectively, over the four-year period of the study. Anthelmintic class rotation also improved the efficacy of fenbendazole in treating Strongyloides spp. infecting the group of orangutans. This parasite control strategy is a targeted approach to managing preventative healthcare, reducing the work required to perform routine surveillance tests whilst maintaining the health of the collection of animals. [ABSTRACT FROM AUTHOR]

Objectives: We perform a comparative assessment of shape variation of the proximal fibula in extant humans and great apes, intending to investigate the possible link between proximal fibular shape and locomotor patterns. Methods: Our sample includes 94 fibulae of 37 Homo sapiens, 15 Gorilla, 17 Pongo, and 25 Pan. Fibular morphology was investigated through three‐dimensional (semi)landmark‐based geometric morphometric methods. Results: We found unique features of the human fibular head compared to that of great apes (i.e., oblique articular surface, the presence of the styloid process, specific morphology of muscle attachment sites), supporting the functional role of this bone in relation to human obligate bipedalism. Great apes also showed distinctive traits in their proximal fibula morphology, in agreement with differences in locomotor behavior. Conclusion: The morphology of the proximal fibula in extant humans and great apes is indicative of locomotor behavior, offering the potential for the comparative analysis of fossil hominin remains. [ABSTRACT FROM AUTHOR]

We identified five distinct full-length human mineralocorticoid receptor (MR) genes containing either 984 amino acids (MR-984) or 988 amino acids (MR-988), which can be distinguished by the presence or absence of Lys, Cys, Ser, and Trp (KCSW) in their DNA-binding domain (DBD) and mutations at codons 180 and 241 in their amino-terminal domain (NTD). Two human MR-KCSW genes contain either (Val-180, Val-241) or (Ile-180, Val-241) in their NTD, and three human MR-984 genes contain either (Ile-180, Ala-241), (Val-180, Val-241), or (Ile-180, Val-241). Human MR-KCSW with (Ile-180, Ala-241) has not been cloned. In contrast, chimpanzees contain four MRs: two MR-988s with KCSW in their DBD, or two MR-984s without KCSW in their DBD. Chimpanzee MRs only contain (Ile180, Val-241) in their NTD. A chimpanzee MR with either (Val-180, Val-241) or (Ile-180, Ala-241) in the NTD has not been cloned. Gorillas and orangutans each contain one MR-988 with KCSW in the DBD and one MR-984 without KCSW, and these MRs only contain (Ile-180, Val-241) in their NTD. A gorilla MR or orangutan MR with either (Val-180, Val-241) or (Ile-180, Ala-241) in the NTD has not been cloned. Together, these data suggest that human MRs with (Val-180, Val-241) or (Ile-180, Ala-241) in the NTD evolved after humans and chimpanzees diverged from their common ancestor. Considering the multiple functions in human development of the MR in kidney, brain, heart, skin, and lungs, as well as MR activity in interaction with the glucocorticoid receptor, we suggest that the evolution of human MRs that are absent in chimpanzees may have been important in the evolution of humans from chimpanzees. Investigation of the physiological responses to corticosteroids mediated by the MR in humans, chimpanzees, gorillas, and orangutans may provide insights into the evolution of humans and their closest relatives. [ABSTRACT FROM AUTHOR]

Primate mandibular morphology is often associated with jaw functionality of the masticatory complex in the context of variation in diets. Recent research into the disparities between the diet and jaw functionality in male and female hominoids is inconclusive and suggests that sexual dimorphism in the mandible may be influenced by external factors such as temporalis and masseter muscle morphology, which in turn may be influenced by sexual selection. As the muscles associated with mastication (i.e., the type of chewing exhibited by primates and other mammals) encompass the mandible as well as the neurocranium, including the sagittal crest among some individuals, this study investigates sex‐specific associations between regions of the mandibular ramus and neurocranium associated with mastication in a dentally mature sample of Gorilla and Pongo. A total of four cranial and mandibular variables were measured in two Gorilla taxa (Gorilla gorilla gorilla and Gorilla beringei graueri) and one Pongo taxon (Pongo pygmaeus pygmaeus) (n = 220). For all three taxa, we investigate (a) whether the degree of sexual dimorphism in cranial regions associated with sagittal cresting (sagittal crest size (SCS) and temporalis muscle attachment area (TMAA)) is proportional to the degree of mandibular ramus area (MRA) and coronoid process height (CPH) sexual dimorphism, (b) whether there are sex differences in scaling relationships between TMAA and MRA, and (c) whether there are sex differences in the strength of association between TMAA and CPH. We show that for G. g. gorilla, variables associated with sagittal cresting show higher sexual dimorphism values than our two mandibular ramus variables, which is not the case for G. b. graueri or for P. p. pygmaeus. All three taxa show similar sex‐specific scaling relationships between TMAA and MRA, where for males this relationship does not diverge from isometry, and for females there is a negative allometric relationship. Our findings also show intraspecific sex differences in allometric slopes between MRA and TMAA for all three taxa. Only G. g. gorilla shows a significant association between TMAA and CPH, which is observed in both sexes. Although there are some statistical associations between the cranial and mandibular regions associated with mastication, our results show that among male gorillas and orangutans, patterns of variation in the sagittal crest, TMAA, mandibular ramus and the coronoid process cannot be explained by the muscle attachment hypothesis alone. These findings have implications surrounding the associations between social behaviour and the morphology of the craniofacial complex. [ABSTRACT FROM AUTHOR]

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Objectives: Reconstruction of fossil hominin manual behaviors often relies on comparative analyses of extant hominid hands to understand the relationship between hand use and skeletal morphology. In this context, the intermediate phalanges remain understudied. Thus, here we investigate cortical bone morphology of the intermediate phalanges of extant hominids and compare it to the cortical structure of the proximal phalanges, to investigate the relationship between cortical bone structure and inferred loading during manual behaviors. Materials and Methods: Using micro‐CT data, we analyze cortical bone structure of the intermediate phalangeal shaft of digits 2–5 in Pongo pygmaeus (n = 6 individuals), Gorilla gorilla (n = 22), Pan spp. (n = 23), and Homo sapiens (n = 23). The R package morphomap is used to study cortical bone distribution, cortical thickness and cross‐sectional properties within and across taxa. Results: Non‐human great apes generally have thick cortical bone on the palmar shaft, with Pongo only having thick cortex on the peaks of the flexor sheath ridges, while African apes have thick cortex along the entire flexor sheath ridge and proximal to the trochlea. Humans are distinct in having thicker dorsal shaft cortex as well as thick cortex at the disto‐palmar region of the shaft. Discussion: Variation in cortical bone distribution and properties of the intermediate phalanges is consistent with differences in locomotor and manipulative behaviors in extant great apes. Comparisons between the intermediate and proximal phalanges reveals similar patterns of cortical bone distribution within each taxon but with potentially greater load experienced by the proximal phalanges, even in knuckle‐walking African apes. This study provides a comparative context for the reconstruction of habitual hand use in fossil hominins and hominids. [ABSTRACT FROM AUTHOR]

Nest building is an important subsistence behaviour that young great apes must learn to become competent adults. Orang-utans show a remarkable degree of variability and selectivity for a broad range of features in their nest building. However, the details of when different aspects of nest-building skills emerge remain unclear. We used data on 27 immature Sumatran orang-utans and 20 mothers collected over a decade at Suaq Balimbing, Sumatra to investigate when immatures develop their nest-building skills and examine when nest tree species preferences emerge. We found that young orang-utans showed interest in nest building from 6 months of age and begin to construct day nests at around 1 year of age, whereas night nests were not practised until close to the third year of life. Nest-building practice peaked around age 3–4 years and then steadily decreased as immatures approached the age of nutritional independence, around age 8 years. By then, immature orang-utans were competent nest-builders, but their nests differed from adult nests in several aspects, such as fewer multitree nests and additional comfort elements, which seemed to be mastered later in development. All age classes demonstrated stronger selectivity towards tree species used for night nests and immatures eventually had similar preferences to mothers. We conclude that the ontogeny of nest-building behaviour and the selection of nest tree species in Sumatran orang-utans is a multiyear learning process that requires intense practice. • Orang-utans gradually acquire nest-building skills over around 7 years. • Day nests are practised and mastered earlier and quicker than night nests. • Multistep features of nest building appear late in development. • Orang-utans show greater tree species selectivity for night than day nests. • Development of nest tree species selection suggests these are learnt socially. [ABSTRACT FROM AUTHOR]

The genus Languidipes is currently represented by three species distributed in southeastern Asia, India, and Sri Lanka. Languidipes corporaali is the most widely distributed species, and both, male and female imagos, as well as nymphs, are known. In contrast, the other species, L. taprobanes and L. lithophagus, are only known from nymphs. Here, we describe a new species, Languidipes janae sp nov, based on male imagos collected from Borneo, Indonesia. This new species is characterized by the presence of ommation on mesonotum, and penis almost completely divided, with sub-quadrate base and a small outer projection basal to the long and slender distal arms. This constitutes the first record of the genus for Borneo. A cladistic analysis of the subfamily Asthenopodinae supports its taxonomic status. [ABSTRACT FROM AUTHOR]

Vocal complexity is central to many evolutionary hypotheses about animal communication. Yet, quantifying and comparing complexity remains a challenge, particularly when vocal types are highly graded. Male Bornean orangutans (Pongo pygmaeus wurmbii) produce complex and variable "long call" vocalizations comprising multiple sound types that vary within and among individuals. Previous studies described six distinct call (or pulse) types within these complex vocalizations, but none quantified their discreteness or the ability of human observers to reliably classify them. We studied the long calls of 13 individuals to: (1) evaluate and quantify the reliability of audio-visual classification by three well-trained observers, (2) distinguish among call types using supervised classification and unsupervised clustering, and (3) compare the performance of different feature sets. Using 46 acoustic features, we used machine learning (i.e., support vector machines, affinity propagation, and fuzzy c-means) to identify call types and assess their discreteness. We additionally used Uniform Manifold Approximation and Projection (UMAP) to visualize the separation of pulses using both extracted features and spectrogram representations. Supervised approaches showed low inter-observer reliability and poor classification accuracy, indicating that pulse types were not discrete. We propose an updated pulse classification approach that is highly reproducible across observers and exhibits strong classification accuracy using support vector machines. Although the low number of call types suggests long calls are fairly simple, the continuous gradation of sounds seems to greatly boost the complexity of this system. This work responds to calls for more quantitative research to define call types and quantify gradedness in animal vocal systems and highlights the need for a more comprehensive framework for studying vocal complexity vis-à-vis graded repertoires. [ABSTRACT FROM AUTHOR]

Faunus ater is a pachychilid gastropod known to inhabit brackish water habitats of Western Indo-Pacific countries. This study aimed to analyse the morphometric relationships and condition factor of F. ater collected from the Edava-Nadayara brackish water lake of Kerala, India. Hydrographic parameters of sampling stations were recorded. A total of 1,522 specimens were collected every month from March 2019 to February 2020. The mean values recorded for total length, shell width, body whorl length, opercular length, opercular width, and total weight were 45.38±13.44 mm, 14.47±3.88 mm, 20.81±5.83 mm, 7.71±3.08 mm, 4.62±1.62 mm, and 6.97±3.72 g, respectively. The length-weight relation was obtained as Log W= -1.005+2.871 Log L. The b value (<3) indicated a negative allometric growth of the organism. Regression analysis of other morphometric measurements also showed a positive correlation (P<0.001). The analysis of Fulton's condition factor indicated a state of wellbeing of F. ater in this habitat, with condition factors ranging from 5.87 to 6.99 spatially and 5.48 to 7.00 temporally. This study provides the first detailed investigation of morphometric relationships and condition factors in F. ater. [ABSTRACT FROM AUTHOR]

Imitation is a social learning mechanism in humans but its relevance in nonhuman primates is controversial. Studies have suggested that some ape species, such chimpanzees and orangutans, may be able to imitate. However, records of true imitation in gorillas are scarce. This study was designed to evaluate the imitation ability of two female western lowland gorillas (Gorilla gorilla gorilla) by using the "do as I do" method, after 15 months of training. For the final evaluation, we tested the gorillas with 52 novel actions classified in four categories (Gestures, Object, Object-Object, and Object-Subject). To assess the difficulty of the novel actions, the lead researcher and two independent observers scored the responses from 0 to 3 based on how well they were done. During the training period, the two gorillas obtained similar success rates for imitation. During the evaluation, they achieved true imitation in 46% of transparent actions and 58% of the opaque actions. We identified "Gestures" as the easiest actions for one gorilla and "Object-Subject" for the other. "Object-Object" were the most difficult actions for both gorillas. Our findings show that female western lowland gorillas can imitate after a training period. [ABSTRACT FROM AUTHOR]

This article discusses the specimens of mammals and birds collected near Mount Kinabalu, Borneo, between 1887 and 1888, which are now housed in the World Museum, National Museums Liverpool. The naturalist John Whitehead was the first person to reach the summit of Mount Kinabalu in 1888 and his collections included over forty new species of birds and six new mammals. The specimens were examined and documented by Michael Rogers Oldfield Thomas and Richard Bowdler Sharpe of the British Museum (Natural History), London. The article provides information about specific bird and mammal specimens, including their collection dates and locations. [Extracted from the article]

The Tapanuli orangutan (Pongo tapanuliensis) is found only in the Tapanuli area. This species includes protected and endangered animals and has a very limited distribution. An important component of animal management is feed availability. This study aims to assess the diversity of food in the Tapanuli orangutan at the Tapanuli Research Station Plan, Batu Satail, Sipirok District. Research was carried out in November 2021 by conducting a vegetation analysis on 3 predetermined paths. The results showed that in this area, there were 91 plant species from 42 families, of which 29 species (31.87%) were orangutan food. However, the highest plant importance index value is dominated by nonfood plants. [ABSTRACT FROM AUTHOR]

The Katingan-Kahayan Corridor is currently one of the remaining habitats for Pongo pygmaeus wurmbii in Central Kalimantan, likely to be managed as an Essential Ecosystem Area. This area faces a high risk of deforestation in the future, as it is located outside protected or conservation zones. This study aims to project future deforestation in the Katingan-Kahayan Corridor from 2019 to 2050 and model its impact on orangutan habitat under two scenarios: (1) Business-as-Usual (BAU), and (2) implementation of an Essential Ecosystem Area (EEA). The deforestation risk model was built using the Random Forest Regression algorithm, while the orangutan habitat model was run using Maxent. The results of the deforestation projection model based on the two scenarios showed that by 2050, the Katingan Forest will become an isolated orangutan habitat with almost no connectivity to other large habitats around it. The secondary forest mosaic in the north of the Katingan Forest was likely to become highly vulnerable to deforestation and thus needs to be a conservation priority. The BAU deforestation scenario projected a decrease in the orangutan population in the Katingan-Kahayan Corridor by up to 68% by 2050, while the EEA implementation scenario can reduce the potential for population decline to 35%. [ABSTRACT FROM AUTHOR]

The Reuleng River is a mangrove area located in Aceh Besar district. Environmental changes that occur in the structure and composition of the mangrove ecosystem in the Reuleng River affect the macrozoobenthos conditions in the area. This study aims to determine the structure of the makrozoobenthos community as a biomomonitoring instrument in the mangrove ecosystem area. The study was conducted from February 2021 to May 2021. Determination of the sampling location was carried out using the purposive sampling technique and sampling was determined in three areas, namely upstream, middle stream, and downstream. The results showed that there were 19 species grouped into 4 genera and 12 families. The Macrozoobenthos Diversity Index in the Reuleng River area ranges from 2.62. The species that dominate the mangrove ecosystem area is the Faunus ater species with a dominant index value (0.16) and the lowest dominant species in the mangrove ecosystem is Thalassina anomala (0.01). No specific species were found that dominate the area. Based on descriptive observations, there is a group of Makrozoobenthos that has a relationship with the psychochemical quality of the air. The results show that the balance of the community in the area is still vulnerable and experiencing the impact of environmental pressures. [ABSTRACT FROM AUTHOR]

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]

Studies of climate variation commonly rely on chemical and isotopic changes recorded in sequentially produced growth layers, such as in corals, shells, and tree rings, as well as in accretionary deposits--ice and sediment cores, and speleothems. Oxygen isotopic compositions (δ18O) of tooth enamel are a direct method of reconstructing environmental variation experienced by an individual animal. Here, we utilize long-forming orangutan dentitions (Pongo spp.) to probe recent and ancient rainfall trends on a weekly basis over ~3-11 years per individual. We first demonstrate the lack of any consistent isotopic enrichment effect during exclusive nursing, supporting the use of primate first molar teeth as environmental proxies. Comparisons of δ18O values (n=2016) in twelve molars from six modern Bornean and Sumatran orangutans reveal a high degree of overlap, with more consistent annual and bimodal rainfall patterns in the Sumatran individuals. Comparisons with fossil orangutan δ18O values (n=955 measurements from six molars) reveal similarities between modern and late Pleistocene fossil Sumatran individuals, but differences between modern and late Pleistocene/early Holocene Bornean orangutans. These suggest drier and more open environments with reduced monsoon intensity during this earlier period in northern Borneo, consistent with other Niah Caves studies and long-term speleothem δ18O records in the broader region. This approach can be extended to test hypotheses about the paleoenvironments that early humans encountered in southeast Asia. [ABSTRACT FROM AUTHOR]

This essay reflects on the story of probably the world's most famous captive orangutan, Ah Meng, who died in 2008 but has since been "replaced" by her granddaughter, Ishta, who took over as the "new face" of Singapore Zoo in 2016. Ah Meng's story is interesting for what it conceals and what it reveals, including the recent history of wildlife trafficking in Southeast Asia, for which Singapore – despite its conservationist credentials – acts as an important hub. Ah Meng's rescue and rehabilitation also raises interesting questions about the Singapore Story, the popular name given to the heroic narrative of historical survival and economic development associated with Singapore's ruling party, the PAP (People's Action Party), and especially its former leader, Lee Kuan Yew. This essay considers the extent to which Ah Meng is more than just a national ambassador animal or a global conservation icon, but is also a multifaceted figure for Singapore's progress in an unevenly developed capitalist world order in which it insists on playing a leading part. [ABSTRACT FROM AUTHOR]

Objectives: The shape of the trapezium and first metacarpal (Mc1) markedly influence thumb mobility, strength, and the manual abilities of extant hominids. Previous research has typically focused solely on trapezium‐Mc1 joint shape. Here we investigate how morphological integration and shape covariation between the entire trapezium (articular and non‐articular surfaces) and the entire Mc1 reflect known differences in thumb use in extant hominids. Materials and Methods: We analyzed shape covariation in associated trapezia and Mc1s across a large, diverse sample of Homo sapiens (n = 40 individuals) and other extant hominids (Pan troglodytes, n = 16; Pan paniscus, n = 13; Gorilla gorilla gorilla, n = 27; Gorilla beringei, n = 6; Pongo pygmaeus, n = 14; Pongo abelii, n = 9) using a 3D geometric morphometric approach. We tested for interspecific significant differences in degree of morphological integration and patterns of shape covariation between the entire trapezium and Mc1, as well as within the trapezium‐Mc1 joint specifically. Results: Significant morphological integration was only found in the trapezium‐Mc1 joint of H. sapiens and G. g. gorilla. Each genus showed a specific pattern of shape covariation between the entire trapezium and Mc1 that was consistent with different intercarpal and carpometacarpal joint postures. Discussion: Our results are consistent with known differences in habitual thumb use, including a more abducted thumb during forceful precision grips in H. sapiens and a more adducted thumb in other hominids used for diverse grips. These results will help to infer thumb use in fossil hominins. [ABSTRACT FROM AUTHOR]

Male orangutans (Pongo spp.) exhibit bimaturism, an alternative reproductive tactic, with flanged and unflanged males displaying two distinct morphological and behavioral phenotypes. Flanged males are larger than unflanged males and display secondary sexual characteristics which unflanged males lack. The evolutionary explanation for alternative reproductive tactics in orangutans remains unclear because orangutan paternity studies to date have been from sites with ex-captive orangutans, provisioning via feeding stations and veterinary care, or that lack data on the identity of mothers. Here we demonstrate, using the first long-term paternity data from a site free of these limitations, that alternative reproductive tactics in orangutans are condition-dependent, not frequency-dependent. We found higher reproductive success by flanged males than by unflanged males, a pattern consistent with other Bornean orangutan (Pongo pygmaeus) paternity studies. Previous paternity studies disagree on the degree of male reproductive skew, but we found low reproductive skew among flanged males. We compare our findings and previous paternity studies from both Bornean and Sumatran orangutans (Pongo abelii) to understand why these differences exist, examining the possible roles of species differences, ecology, and human intervention. Additionally, we use long-term behavioral data to demonstrate that while flanged males can displace unflanged males in association with females, flanged males are unable to keep other males from associating with a female, and thus they are unable to completely mate guard females. Our results demonstrate that alternative reproductive tactics in Bornean orangutans are condition-dependent, supporting the understanding that the flanged male morph is indicative of good condition. Despite intense male-male competition and direct sexual coercion by males, female mate choice is effective in determining reproductive outcomes in this population of wild orangutans. [ABSTRACT FROM AUTHOR]