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Extant great apes are characterized by a wide range of locomotor, postural and manipulative behaviours that each require the limbs to be used in different ways. In addition to external bone morphology, comparative investigation of trabecular bone, which (re‐)models to reflect loads incurred during life, can provide novel insights into bone functional adaptation. Here, we use canonical holistic morphometric analysis (cHMA) to analyse the trabecular morphology in the distal femoral epiphysis of Homo sapiens (n = 26), Gorilla gorilla (n = 14), Pan troglodytes (n = 15) and Pongo sp. (n = 9). We test two predictions: (1) that differing locomotor behaviours will be reflected in differing trabecular architecture of the distal femur across Homo, Pan, Gorilla and Pongo; (2) that trabecular architecture will significantly differ between male and female Gorilla due to their different levels of arboreality but not between male and female Pan or Homo based on previous studies of locomotor behaviours. Results indicate that trabecular architecture differs among extant great apes based on their locomotor repertoires. The relative bone volume and degree of anisotropy patterns found reflect habitual use of extended knee postures during bipedalism in Homo, and habitual use of flexed knee posture during terrestrial and arboreal locomotion in Pan and Gorilla. Trabecular architecture in Pongo is consistent with a highly mobile knee joint that may vary in posture from extension to full flexion. Within Gorilla, trabecular architecture suggests a different loading of knee in extension/flexion between females and males, but no sex differences were found in Pan or Homo, supporting our predictions. Inter‐ and intra‐specific variation in trabecular architecture of distal femur provides a comparative context to interpret knee postures and, in turn, locomotor behaviours in fossil hominins. [ABSTRACT FROM AUTHOR]

Strong, affiliative relationships are important across social mammals, and in many species, relationships between female kin form the basis of group life. Relationships are expected to be weaker in cases where females disperse or do not cooperatively defend resources. Mountain gorillas, Gorilla beringei beringei , seem to support this, as females can emigrate multiple times throughout their life and do not jointly defend the abundant vegetation they feed on. Unsurprisingly, mountain gorillas have been reported to form variable or weak relationships with other females and seemingly prioritize relationships with adult males. But prior studies may have misinterpreted relationships due to a focus on grooming and understandable limitations of small sample sizes and short study periods. Here, we examine proximity and grooming between 47 adult female mountain gorillas in five groups over 5–13 years. We analyse proximity data (2 m, 5 m) and grooming relationships between 366 individual dyads to determine (1) whether proximity and grooming relationships are preferential and (2) whether they endure across time. Most females formed at least one preferential 2 m and 5 m proximity relationship (43 of 47), which both lasted a mean of 2.1 years. Additionally, 3.6% of dyads (N = 13/366) formed enduring 2 m proximity preferences that exceeded 4 years, with the longest lasting at least 12 years. Maternal kin had the most enduring proximity and grooming relationships, although grooming was rare overall. The enduring proximity relationships between some female gorillas in our sample are similar in length to those of female yellow baboons, Papio cynocephalus , and male chimpanzees, Pan troglodytes , which are considered social bonds. Mountain gorillas provide a system in which factors influencing bonds can be better understood, and our study highlights a need to refine definitions of social bonds while potentially reassessing their evolutionary function. • We examined proximity (2 m, 5 m) and grooming in female mountain gorilla dyads. • Most females formed one long-term (2–12 years) preferential proximity relationship. • Proximity relationships were akin to social bonds in baboons and chimpanzees. • Maternal kin were more likely to have preferential 2 m proximity relationships. • Dispersal patterns may allow adult females to remain with maternal kin longer. [ABSTRACT FROM AUTHOR]

Because senescence impairs the ability of older males to compete successfully for mates, male reproductive strategies are expected to change with age. The terminal investment hypothesis proposes that older males, who could die soon, should take greater risks to obtain mating opportunities. Another possibility is that older males avoid such risks, adopting alternative reproductive tactics, such as increased affiliation with females, increased reliance on coalitions or sexual coercion to continue to compete with younger animals. We tested these hypotheses in wild chimpanzees, Pan troglodytes schweinfurthii , of the Kanyawara community, Kibale National Park, Uganda, where old males sire offspring at relatively high rates. Our data set included >40 000 incidents of male aggression and >5800 copulations observed between 2005 and 2017. We found that, even as their dominance status declined, old males maintained relatively high copulation rates, especially with established mothers. There was no evidence for terminal investment in response to ageing. Males became generally less aggressive as they aged. Neither did old males form affiliative bonds with females, nor use sexual coercion more frequently, as alternative reproductive tactics. Old males did, however, participate in coalitionary aggression at higher rates than young males and increased the proportion of their aggression that was coalitionary over time. Coalitions were positively associated with mating success, particularly for low- and middle-ranking males. These results support the hypothesis that ageing male chimpanzees use coalitions as an alternative reproductive tactic. The lack of evidence for terminal investment in response to ageing appears to reflect a broader mammalian pattern in which males who rely on fighting to secure mating opportunities avoid excessive risk taking as their formidability wanes. • Old male chimpanzees mated frequently with attractive females. • Old males were less aggressive and did not take greater risks in mating competition. • Old males did not groom females at high rates. • Old males were not more sexually coercive towards females. • Old males formed coalitions at high rates and these predicted mating success. [ABSTRACT FROM AUTHOR]

Objectives: Low‐energy vertebral fractures are a common health concern, especially in elderly people. Interestingly, African apes do not seem to experience as many vertebral fractures and the low‐energy ones are even rarer. One potential explanation for this difference is the lower bone density in humans. Yet, only limited research has been done on the vertebral bone density of the great apes and these have mainly included only single vertebrae. Hence the study aim is to expand our understanding of the vertebral microstructure of African apes in multiple spinal segments. Materials: Bone density in the vertebral body of C7, T12, and L3 was measured from 32 Pan troglodytes and 26 Gorilla gorilla using peripheral quantitative computed tomography (pQCT). Results: There was a clear difference between the three individual vertebrae and consequently the spinal segments in terms of trabecular density and cortical density and thickness. The variation of these bone parameters between the vertebrae differed between the apes but was also different from those reported for humans. The chimpanzees were observed to have overall higher trabecular density, but gorillas had higher cortical density and thickness. Cortical thickness had a relatively strong association with the vertebral size. Discussion: Despite the similarity in locomotion and posture, the results show slight differences in the bone parameters and their variation between spinal segments in African apes. This variation also differs from humans and appears to indicate a complex influence of locomotion, posture, and body size on the different spinal segments. [ABSTRACT FROM AUTHOR]

Field-to-susceptibility inversion in quantitative susceptibility mapping (QSM) is ill-posed and needs numerical stabilization through either regularization or oversampling by acquiring data at three or more object orientations. Calculation Of Susceptibility through Multiple Orientations Sampling (COSMOS) is an established oversampling approach and regarded as QSM gold standard. It achieves a well-conditioned inverse problem, requiring rotations by 0°, 60° and 120° in the yz -plane. However, this is impractical in vivo , where head rotations are typically restricted to a range of ±25°. Non-ideal sampling degrades the conditioning with residual streaking artifacts whose mitigation needs further regularization. Moreover, susceptibility anisotropy in white matter is not considered in the COSMOS model, which may introduce additional bias. The current work presents a thorough investigation of these effects in primate brain. Gradient-recalled echo (GRE) data of an entire fixed chimpanzee brain were acquired at 7 T (350 μm resolution, 10 orientations) including ideal COSMOS sampling and realistic rotations in vivo. Comparisons of the results included ideal COSMOS, in-vivo feasible acquisitions with 3–8 orientations and single-orientation iLSQR QSM. In-vivo feasible and optimal COSMOS yielded high-quality susceptibility maps with increased SNR resulting from averaging multiple acquisitions. COSMOS reconstructions from non-ideal rotations about a single axis required additional L2-regularization to mitigate residual streaking artifacts. In view of unconsidered anisotropy effects, added complexity of the reconstruction, and the general challenge of multi-orientation acquisitions, advantages of sub-optimal COSMOS schemes over regularized single-orientation QSM appear limited in in-vivo settings. [ABSTRACT FROM AUTHOR]

Wild chimpanzees consume a variety of plants to meet their dietary needs and maintain wellbeing. While some plants have obvious value, others are nutritionally poor and/or contain bioactive toxins which make ingestion costly. In some cases, these nutrient-poor resources are speculated to be medicinal, thought to help individuals combat illness. In this study, we observed two habituated chimpanzee communities living in the Budongo Forest, Uganda, and collected 17 botanical samples associated with putative self-medication behaviors (e.g., bark feeding, dead wood eating, and pith-stripping) or events (e.g., when consumer had elevated parasite load, abnormal urinalysis, or injury). In total, we selected plant parts from 13 species (nine trees and four herbaceous plants). Three extracts of different polarities were produced from each sample using n-hexane, ethyl acetate, and methanol/water (9/1, v/v) and introduced to antibacterial and anti-inflammatory in vitro models. Extracts were evaluated for growth inhibition against a panel of multidrug-resistant clinical isolates of bacteria, including ESKAPE strains and cyclooxygenase-2 (COX-2) inhibition activity. Pharmacological results suggest that Budongo chimpanzees consume several species with potent medicinal properties. In the antibacterial library screen, 45 out of 53 extracts (88%) exhibited ≥40% inhibition at a concentration of 256 μg/mL. Of these active extracts, 41 (91%) showed activity at ≤256μg/mL in subsequent dose-response antibacterial experiments. The strongest antibacterial activity was achieved by the n-hexane extract of Alstonia boonei dead wood against Staphylococcus aureus (IC50: 16 μg/mL; MIC: 32 μg/mL) and Enterococcus faecium (IC50: 16 μg/mL; MIC: >256 μg/mL) and by the methanol-water extract of Khaya anthotheca bark and resin against E. faecium (IC50: 16 μg/mL; MIC: 32 μg/mL) and pathogenic Escherichia coli (IC50: 16 μg/mL; MIC: 256 μg/mL). We observed ingestion of both these species by highly parasitized individuals. K. anthotheca bark and resin were also targeted by individuals with indicators of infection and injuries. All plant species negatively affected growth of E. coli. In the anti-inflammatory COX-2 inhibition library screen, 17 out of 51 tested extracts (33%) showed ≥50% COX-2 inhibition at a concentration of 5 μg/mL. Several extracts also exhibited anti-inflammatory effects in COX-2 dose-response experiments. The K. anthotheca bark and resin methanol-water extract showed the most potent effects (IC50: 0.55 μg/mL), followed by the fern Christella parasitica methanol-water extract (IC50: 0.81 μg/mL). This fern species was consumed by an injured individual, a feeding behavior documented only once before in this population. These results, integrated with associated observations from eight months of behavioral data, provide further evidence for the presence of self-medicative resources in wild chimpanzee diets. This study addresses the challenge of distinguishing preventative medicinal food consumption from therapeutic self-medication by integrating pharmacological, observational, and health monitoring data—an essential interdisciplinary approach for advancing the field of zoopharmacognosy. [ABSTRACT FROM AUTHOR]

The known diversity of European middle and late Miocene hominids has increased significantly during the last decades. Most of these great apes were frugivores in the broadest sense, ranging from soft fruit frugivores most like chimpanzees to hard/tough object feeders like orangutans, varying in size from larger than siamangs (over 17 kg) to larger than most chimpanzees (~60–70 kg). In contrast to the frequent sympatry of hominoids in the early-to-middle Miocene of Africa, in no European Miocene locality more than one hominid taxon has been identified. Here we describe the first case of hominid sympatry in Europe from the 11.62 Ma old Hammerschmiede HAM 5 level, best known from its excellent record of Danuvius guggenmosi. The new fossils are consistent in size with larger pliopithecoids but differ morphologically from any pliopithecoid and from Danuvius. They are also distinguished from early and middle Miocene apes, share affinities with late Miocene apes, and represent a small hitherto unknown late Miocene ape Buronius manfredschmidi. With an estimated body mass of about 10 kg it represents the smallest known hominid taxon. The relative enamel thickness of Buronius is thin and contrasts with Danuvius, whose enamel is twice as thick. The differences between Buronius and Danuvius in tooth and patellar morphology, enamel thickness and body mass are indicative of differing adaptations in each, permitting resource partitioning, in which Buronius was a more folivorous climber. [ABSTRACT FROM AUTHOR]

Morphological studies typically avoid using osteological samples that derive from captive animals because it is assumed that their morphology is not representative of wild populations. Rearing environments indeed differ between wild and captive individuals. For example, mechanical properties of the diets provided to captive animals can be drastically different from the food present in their natural habitats, which could impact cranial morphology and dental health. Here, we examine morphological differences in the maxillae of wild versus captive chimpanzees (Pan troglodytes) given the prominence of this species in comparative samples used in human evolution research and the key role of the maxilla in such studies. Size and shape were analysed using three‐dimensional geometric morphometric methods based on computed tomography scans of 94 wild and 30 captive specimens. Captive individuals have on average larger and more asymmetrical maxillae than wild chimpanzees, and significant differences are present in their maxillary shapes. A large proportion of these shape differences are attributable to static allometry, but wild and captive specimens still differ significantly from each other after allometric size adjustment of the shape data. Levels of shape variation are higher in the captive group, while the degree of size variation is likely similar in our two samples. Results are discussed in the context of ontogenetic growth trajectories, changes in dietary texture, an altered social environment, and generational differences. Additionally, sample simulations show that size and shape differences between chimpanzees and bonobos (Pan paniscus) are exaggerated when part of the wild sample is replaced with captive chimpanzees. Overall, this study confirms that maxillae of captive chimpanzees should not be included in morphological or taxonomic analyses when the objective is to characterise the species. [ABSTRACT FROM AUTHOR]

A 40‐year old female chimpanzee (Pan troglodytes) developed hyporexia, weight loss, followed by progressive and complete blindness. Tomography demonstrated an intracranial mass in the rostroventral brain involving the optic chiasm, with a presumptive diagnosis of neoplasm. However, histopathology revealed a granulomatous meningoencephalitis, and tissue samples tested positive for Mycobacterium tuberculosis. [ABSTRACT FROM AUTHOR]

In apes and humans, neutrophil to lymphocyte ratio (NLR) can be used as a predictive indicator of a variety of clinical conditions, longevity, and physiological stress. In chimpanzees specifically, NLR systematically varies with age, rearing, sex, and premature death, indicating that NLR may be a useful diagnostic tool in assessing primate health. To date, just one very recent study has investigated NLR in old world monkeys and found lower NLR in males and nursery‐reared individuals, as well as a negative relationship between NLR and disease outcomes. Given that baboons are increasingly used as research models, we aimed to characterize NLR in baboons by providing descriptive data and examinations of baboon NLR heritability, and of the relationships between NLR, age, rearing, and sex in 387 olive baboons (Papio anubis) between 6 months and 19 years of age. We found that (1) mother‐reared baboons had higher NLRs than nursery‐reared baboons; (2) females had higher NLRs than males; and (3) there was a quadratic relationship between NLR and age, such that middle‐aged individuals had the highest NLR values. We also examined NLR as a function of transport to a new facility using a subset of the data. Baboons exhibited significantly higher transport NLRs compared to routine exam NLRs. More specifically, adult baboons had higher transport NLRs than routine NLRs, whereas juveniles showed no such difference, suggesting that younger animals may experience transport stress differently than older animals. We also found that transport NLR was heritable, whereas routine NLR was not, possibly suggesting that stress responses (as indicated in NLR) have a strong genetic component. Consistent with research in humans and chimpanzees, these findings suggest that NLR varies with important biological and life history variables and that NLR may be a useful health biomarker in baboons. Research highlights: To date, only a handful of studies have been published examining neutrophil‐lymphocyte ratio (NLR) in nonhuman primates, including in chimpanzees (Pan troglodytes) and infant rhesus monkeys (Macaca mulatta).In the current study, we found that mother‐reared baboons (Papio anubis) showed higher NLRs than nursery‐reared individuals, females had higher NLRs than males, and there was a quadratic relationship between NLR and age.Following transport to a new facility, baboons also exhibited elevated NLRs, and these post‐transport NLR values were significantly heritable.These results suggest that NLR varies with important biological and life history variables and that NLR may be a useful health biomarker in baboons. [ABSTRACT FROM AUTHOR]

Summary: Dual interactive Wasserstein generative adversarial networks optimized with hybrid Archimedes optimization and chimp optimization algorithm‐based channel estimation in OFDM (DiWGAN‐Hyb AOA‐COA‐MIMO‐OFDM) is proposed in this manuscript. In OFDM, there is a non‐stationary channel physical appearance during channel estimation (CE). Therefore in this work, Hyb AOA‐COA is employed to enhance the DiWGAN weight parameters. The proposed DiWGAN‐Hyb AOA‐COA‐MIMO‐OFDM technique is executed in network simulator (NS2) tool. The proposed technique attains lower computational cost 99.67%, 92.34%, and 97.45%; lesser bit error rate 98.33%, 83.12%, and 88.96%; and lesser mean square error 93.15%, 79.90%, and 92.88% compared with existing methods, like MIMO‐OFDM system using deep neural network and MN‐based improved AMO model (DNN‐IAMO‐MIMO‐OFDM), MIMO‐OFDM systems using the deep learning and optimization (RBFNN‐PSO‐MIMO‐OFDM), and MIMO‐OFDM systems using hybrid neural network (HNN‐CSI‐MIMO‐OFDM) respectively. [ABSTRACT FROM AUTHOR]

Tool use is considered a driving force behind the evolution of brain expansion and prolonged juvenile dependency in the hominin lineage. However, it remains rare across animals, possibly due to inherent constraints related to manual dexterity and cognitive abilities. In our study, we investigated the ontogeny of tool use in chimpanzees (Pan troglodytes), a species known for its extensive and flexible tool use behavior. We observed 70 wild chimpanzees across all ages and analyzed 1,460 stick use events filmed in the Taï National Park, Côte d'Ivoire during the chimpanzee attempts to retrieve high-nutrient, but difficult-to-access, foods. We found that chimpanzees increasingly utilized hand grips employing more than 1 independent digit as they matured. Such hand grips emerged at the age of 2, became predominant and fully functional at the age of 6, and ubiquitous at the age of 15, enhancing task accuracy. Adults adjusted their hand grip based on the specific task at hand, favoring power grips for pounding actions and intermediate grips that combine power and precision, for others. Highly protracted development of suitable actions to acquire hidden (i.e., larvae) compared to non-hidden (i.e., nut kernel) food was evident, with adult skill levels achieved only after 15 years, suggesting a pronounced cognitive learning component to task success. The prolonged time required for cognitive assimilation compared to neuromotor control points to selection pressure favoring the retention of learning capacities into adulthood. Tool use is considered a driving force behind the evolution of brain expansion and prolonged juvenile dependency in the hominin lineage. A study of stick tool use in wild chimpanzees reveals a prolonged time for cognitive assimilation, suggesting selection pressure that favors retention of learning capacities into adulthood. [ABSTRACT FROM AUTHOR]

Modern humans and chimpanzees share a common ancestor on the phylogenetic tree, yet chimpanzees do not spontaneously produce speech or speech sounds. The lab exercise presented in this paper was developed for undergraduate students in a course entitled "What's Special About Human Speech?" The exercise is based on acoustic analyses of the words "cup" and "papa" as spoken by Viki, a home-raised, speech-trained chimpanzee, as well as the words spoken by a human. The analyses allow students to relate differences in articulation and vocal abilities between Viki and humans to the known anatomical differences in their vocal systems. Anatomical and articulation differences between humans and Viki include (1) potential tongue movements, (2) presence or absence of laryngeal air sacs, (3) presence or absence of vocal membranes, and (4) exhalation vs inhalation during production. [ABSTRACT FROM AUTHOR]

Primate archaeology is a field that studies the material remains left by past and present primates, including humans. The field aims to bridge the gap between researchers studying human origins and primatologists studying living primates. However, a recent review by Pascual-Garrido et al. titled "Primate archaeology 3.0" overlooks important primate genera that use tools, such as the gracile capuchin monkey (Cebus) and baboons (Papio). The review also fails to consider the emergence and loss of tool use among non-human animals and the potential for genetic analysis to track tool-use patterns. The author suggests that primate archaeology should avoid using cladograms to represent behavioral traits unless they account for independent inventions and loss of tool activities. Overall, the review by Pascual-Garrido et al. is valuable but could benefit from considering these additional perspectives. [Extracted from the article]

Objectives: Morphological variation among extant primates in the lumbar vertebral column is well studied. However, knowledge concerning the thoracic spine, an important region responsible for supporting and facilitating movement in the upper trunk, remains relatively scarce. Consequently, our comprehension of the functional differentiation exhibited throughout the thoracolumbar vertebral column among various primate species remains constrained. In this study, we examined patterns of morphological variation in the thoracolumbar vertebral column of extant hominoids, cercopithecoids, and Ateles. Materials and Methods: We collected external shape data on 606 thoracic and lumbar vertebrae from Homo sapiens, Pan troglodytes, Hylobates lar, Macaca fuscata, Chlorocebus aethiops, Colobus guereza, Ateles geoffroyi, and A. belzebuth. Forty‐four landmarks were obtained on the three‐dimensional surface. Geometric morphometrics was used to quantify the centroid size and variation of the shapes of thoracic and lumbar vertebrae. Results: Cercopithecoids exhibited greater variation in the size and shape of their thoracic and lumbar vertebrae compared to hominoids and Ateles. Although many vertebral features contributed to the observed variation throughout the thoracolumbar vertebral column within the taxon, the transverse and spinous processes exhibited relatively major contributions. Discussion: Our results suggest that quadrupedal locomotion requires the functional differentiation between thoracic and lumbar vertebrae, and for hominoids, functional adaptation to orthograde posture necessitates a relatively more uniform shape of thoracic and lumbar vertebrae. [ABSTRACT FROM AUTHOR]

Molar and incisor microwear reflect aspects of food choice and ingestive behaviors in living primates and have both been used to infer the same for fossil samples. Canine microwear, however, has received less attention, perhaps because of the prominent role canines play in social display and because they are used as weapons–while outside of a few specialized cases, their involvement in diet related behaviors has not been obvious. Here, we posit that microwear can also provide glimpses into canine tooth use in ingestion. Canines of Sumatran long‐tailed macaques (Macaca fascicularis), agile gibbons (Hylobates agilis), lar gibbons (Hylobates lar), Thomas' leaf monkeys (Presbytis thomasi), and orangutans (Pongo abelii), and two African great apes, bonobos (Pan paniscus) and common chimpanzees (Pan troglodytes schweinfurthii), were considered. The labial tips of maxillary canine replicas were scanned using a white‐light confocal profiler, and both feature and texture analyses were used to characterize microwear surface patterning. The taxa exhibited significant differences in canine microwear. In some cases, these were consistent with variation in reported anterior tooth use such that, for example, the orangutans, known to use their front teeth extensively in ingestion, had the highest median number of microwear features on their canines, whereas the gibbons, reported to use their front teeth infrequently in food acquisition, had the lowest. Research Highlights: Canine microwear patterns of catarrhine primates are independent of the shapes of these teeth (i.e., "stubby" vs. "stabby").Variation in canine microwear patterns among Sumatran anthropoid primates, especially gibbons and orangutans, reflect broad differences in anterior tooth use reported in the literature.Canine microwear holds the potential to reveal insights into ingestive behaviors in past primates. [ABSTRACT FROM AUTHOR]

Humans spontaneously and consistently map information coming from different sensory modalities. Surprisingly, the phylogenetic origin of such cross‐modal correspondences has been under‐investigated. A notable exception is the study of Ludwig et al. (Visuoauditory mappings between high luminance and high pitch are shared by chimpanzees [Pan troglodytes] and humans. Proceedings of the National Academy of Sciences, 108(51), 20661–20665) which reports that both humans and chimpanzees spontaneously map high‐pitched sounds with bright objects and low‐pitched sounds with dark objects. Our pre‐registered study aimed to directly replicate this research on both humans and baboons (Papio papio), an old world monkey which is more phylogenetically distant from humans than chimpanzees. Following Ludwig et al. participants were presented with a visual classification task where they had to sort black and white square (low and high luminance), while background sounds (low or high‐pitched tones) were playing. Whereas we replicated the finding that humans' performance on the visual task was affected by congruency between sound and luminance of the target, we did not find any of those effects on baboons' performance. These results question the presence of a shared cross‐modal pitch‐luminance mapping in other nonhuman primates. Research highlights: Humans and chimpanzees spontaneously associate high‐pitched sounds with bright objects and low‐pitched sounds with dark objects.This effect was not seen in baboons (Papio papio).This result questions the presence of a shared cross‐modal pitch‐luminance mapping between humans and all nonhuman primates. [ABSTRACT FROM AUTHOR]

Identifying novel medicinal resources in chimpanzee diets has historically presented challenges, requiring extensive behavioral data collection and health monitoring, accompanied by expensive pharmacological analyses. When putative therapeutic self‐medicative behaviors are observed, these events are often considered isolated occurrences, with little attention paid to other resources ingested in combination. For chimpanzees, medicinal resource combinations could play an important role in maintaining well‐being by tackling different symptoms of an illness, chemically strengthening efficacy of a treatment, or providing prophylactic compounds that prevent future ailments. We call this concept the self‐medicative resource combination hypothesis. However, a dearth of methodological approaches for holistically investigating primate feeding ecology has limited our ability to identify nonrandom resource combinations and explore potential synergistic relationships between medicinal resource candidates. Here we present two analytical tools that test such a hypothesis and demonstrate these approaches on feeding data from the Sonso chimpanzee community in Budongo Forest, Uganda. Using 4 months of data, we establish that both collocation and APRIORI analyses are effective exploratory tools for identifying binary combinations, and that APRIORI is effective for multi‐item rule associations. We then compare outputs from both methods, finding up to 60% agreement, and propose APRIORI as more effective for studies requiring control over confidence intervals and those investigating nonrandom associations between more than two resources. These analytical tools, which can be extrapolated across the animal kingdom, can provide a cost‐effective and efficient method for targeting resources for further pharmacological investigation, potentially aiding in the discovery of novel medicines. Highlights: New methods needed for holistically evaluating chimpanzee diets.Collocation and APRIORI analyses are effective tools for finding nonrandom resource combinations.Relatively high level of agreement between methods.Effective tool for exploring feeding ecology data sets and discovering novel self‐medicative resources. [ABSTRACT FROM AUTHOR]

Compared to their closest ape relatives, humans walk bipedally with lower metabolic cost (C) and less mechanical work to move their body center of mass (external mechanical work, WEXT). However, differences in WEXT are not large enough to explain the observed lower C: humans may also do less work to move limbs relative to their body center of mass (internal kinetic mechanical work, WINT,k). From published data, we estimated differences in WINT,k, total mechanical work (WTOT), and efficiency between humans and chimpanzees walking bipedally. Estimated WINT,k is ~ 60% lower in humans due to changes in limb mass distribution, lower stride frequency and duty factor. When summing WINT,k to WEXT, between-species differences in efficiency are smaller than those in C; variations in WTOT correlate with between-species, but not within-species, differences in C. These results partially support the hypothesis that the low cost of human walking is due to the concerted low WINT,k and WEXT. [ABSTRACT FROM AUTHOR]

Monkeypox virus (MPXV) is a reemerging virus of global concern. An outbreak of clade I MPXV affected 20 captive chimpanzees in Cameroon in 2016. We describe the epidemiology, virology, phylogenetics, and clinical progression of this outbreak. Clinical signs included exanthema, facial swelling, perilaryngeal swelling, and eschar. Mpox can be lethal in captive chimpanzees, with death likely resulting from respiratory complications. We advise avoiding anesthesia in animals with respiratory signs to reduce the likelihood of death. This outbreak presented a risk to animal care staff. There is a need for increased awareness and a One Health approach to preparation for outbreaks in wildlife rescue centers in primate range states where MPXV occurs. Control measures should include quarantining affected animals, limiting human contacts, surveillance of humans and animals, use of personal protective equipment, and regular decontamination of enclosures. [ABSTRACT FROM AUTHOR]

As environmental contamination becomes more and more severe, enterprises need to consider optimizing environmental criteria while optimizing production criteria. In this study, a multi-objective green flexible job shop scheduling problem (MO_GFJSP) is established with two objective functions: the makespan and the carbon emission. To effectively solve the MO_GFJSP, an improved chimp optimization algorithm (IChOA) is designed. The proposed IChOA has four main innovative aspects: 1) the fast non-dominated sorting (FDS) method is introduced to compare the individuals with multiple objectives and strengthen the solution accuracy. 2) a dynamic convergence factor (DCF) is introduced to strengthen the capabilities of exploration and exploitation. 3) the position weight (PW) is used in the individual position updating to enhance the search efficiency. 4) the variable neighborhood search (VNS) is developed to strengthen the capacity to escape the local optimum. By executing abundant experiments using 20 benchmark instances, it was demonstrated that the developed IChOA is efficient to solve the MO_GFJSP and effective for reducing carbon emission in the flexible job shop. [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 process of habituation in moor macaques (Macaca maura) and how it is affected by changes in group composition. The researchers conducted a study on a wild group of moor macaques in Indonesia, observing their responses to human researchers during two habituation phases. They found that the macaques were less likely to show neutral responses and be tolerant of researcher proximity at the start of the second habituation phase compared to the first. However, the macaques in the second phase habituated more quickly overall, suggesting that previous experience of neutral exposure to researchers facilitated the habituation process. The researchers also noted the need for further study on social learning and individual differences in habituation, as well as the potential risks for habituated groups. [Extracted from the article]

Chimpanzees (Pan troglodytes) and humans cooperate in reciprocal patterns, but it is unclear whether these interactions are based on the same psychological foundations. While there is evidence suggesting that both species engage in long‐term forms of reciprocity, there is very little work exploring their short‐term behavioural contingencies with suitable methods. Here, we present a direct comparative study on short‐term reciprocity in chimpanzees and human children using a novel, low‐cost instrumental helping task. We investigated whether participants help a conspecific partner to obtain a tool for accessing a reward, and whether the level of helping depends on the partner's previous helpful or unhelpful behaviour. In line with prior research, both chimpanzees and children demonstrated helping behaviour towards their partner. However, the extent to which the two species showed short‐term reciprocity differed considerably. After receiving help, tested children always helped in return. They helped substantially less when interacting with an unhelpful partner. Chimpanzees showed a higher tendency to help when interacting with a helpful compared to an unhelpful partner only in the first half the experiment. With increasing trial number, chimpanzees stopped discriminating between helpful and unhelpful partners. This study provides evidence for short‐term reciprocity in human children and, to a lesser extent, in our closest living relatives. Our findings demonstrate that helping paradigms provide a useful context to investigate reciprocal motives in humans and chimpanzees alike. [ABSTRACT FROM AUTHOR]

Primate social organizations, or grouping patterns, vary significantly across species. Behavioral strategies that allow for flexibility in grouping patterns offer a means to reduce the costs of group living. Chimpanzees (Pan troglodytes) have a fission‐fusion social system in which temporary subgroups ("parties") change in composition because of local socio‐ecological conditions. Notably, western chimpanzees (P. t. verus) are described as showing a higher degree of bisexual bonding and association than eastern chimpanzees, and eastern female chimpanzees (P. t. schweinfurthii) are thought to be more solitary than western female chimpanzees. However, reported comparisons in sociality currently depend on a small number of study groups, particularly in western chimpanzees, and variation in methods. The inclusion of additional communities and direct comparison using the same methods are essential to assess whether reported subspecies differences in sociality hold in this behaviorally heterogeneous species. We explored whether sociality differs between two communities of chimpanzees using the same motion‐triggered camera technology and definitions of social measures. We compare party size and composition (party type, sex ratio) between the western Gahtoy community in the Nimba Mountains (Guinea) and the eastern Waibira community in the Budongo Forest (Uganda). Once potential competition for resources such as food and mating opportunities were controlled for, subspecies did not substantially influence the number of individuals in a party. We found a higher sex‐ratio, indicating more males in a party, in Waibira; this pattern was driven by a greater likelihood in Gahtoy to be in all‐female parties. This finding is the opposite of what was expected for eastern chimpanzees, where female‐only parties are predicted to be more common. Our results highlight the flexibility in chimpanzee sociality, and caution against subspecies level generalizations. Research highlights: Party size in western and eastern chimpanzees did not differ between our two study communities suggesting that the number of individuals in a party is shaped by similar socio‐ecological pressures.In our sample, eastern chimpanzees were found to have more males in a party compared to western chimpanzees, contrary to the expectation of more female‐only parties in eastern compared to western chimpanzees.Our findings highlight the flexibility in chimpanzee grouping patterns and caution against subspecies level generalizations from limited data points and/or heterogeneous methods. [ABSTRACT FROM AUTHOR]

Feature selection is a critical component of machine learning and data mining to remove redundant and irrelevant features from a dataset. The Chimp Optimization Algorithm (CHoA) is widely applicable to various optimization problems due to its low number of parameters and fast convergence rate. However, CHoA has a weak exploration capability and tends to fall into local optimal solutions in solving the feature selection process, leading to ineffective removal of irrelevant and redundant features. To solve this problem, this paper proposes the Enhanced Chimp Hierarchy Optimization Algorithm for adaptive lens imaging (ALI-CHoASH) for searching the optimal classification problems for the optimal subset of features. Specifically, to enhance the exploration and exploitation capability of CHoA, we designed a chimp social hierarchy. We employed a novel social class factor to label the class situation of each chimp, enabling effective modelling and optimization of the relationships among chimp individuals. Then, to parse chimps' social and collaborative behaviours with different social classes, we introduce other attacking prey and autonomous search strategies to help chimp individuals approach the optimal solution faster. In addition, considering the poor diversity of chimp groups in the late iteration, we propose an adaptive lens imaging back-learning strategy to avoid the algorithm falling into a local optimum. Finally, we validate the improvement of ALI-CHoASH in exploration and exploitation capabilities using several high-dimensional datasets. We also compare ALI-CHoASH with eight state-of-the-art methods in classification accuracy, feature subset size, and computation time to demonstrate its superiority. [ABSTRACT FROM AUTHOR]

The chimp optimization algorithm (ChOA) is a nature-inspired algorithm that imitates chimpanzees' individual intelligence and hunting behaviors. In this algorithm, the hunting process consists of four steps: driving, blocking, chasing, and attacking. Because of the novelty of ChOA, the steps of the hunting process have been modeled in the simplest possible way, leading to slow and premature convergence similar to other iterative algorithms. This paper proposes six spiral functions and introduces two novel hybrid spiral functions (SEB-ChOA) to rectify the abovementioned deficiencies. The SEB-ChOAs' performance is evaluated on 23 standard benchmarks, 20 benchmarks of IEEE CEC-2005, 10 cases of IEEE CEC06-2019 test-suite, and 12 constrained real-world engineering problems of IEEE CEC-2020. The SEB-ChOAs are compared with three groups of optimization algorithms, including Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) as the most well-known optimization algorithms, Slime Mould Algorithm (SMA), Marine Predators Algorithm (MPA), Ant Lion Optimization (ALO), Henry Gas Solubility Optimization (HGSO), as almost novel optimization algorithms, and jDE100 and DISHchain1e+12, as winners of IEEE CEC06-2019 competition, and also EBOwithCMAR and CIPDE as superior secondary optimization algorithms. The SEB-ChOAs reached the first rank among almost all benchmarks and demonstrated very competitive results compared to jDE100 and DISHchain1e+12 as the best-performing optimizers. Statistical evidence shows that the SEB-ChOA outperforms the PSO, GA, SMA, MPA, ALO, and HGSO optimizers while producing results comparable to those of the jDE100 and DISHchain1e+12 algorithms. [ABSTRACT FROM AUTHOR]

Earthquakes are complex phenomena that generate various forms of clusters that are highly correlated in the space and time domains. To study the dynamic properties of seismicity and estimate risk, the earthquake catalog needs to be separated into clustered and background events. Here, seismicity de-clustering is formulated as a binary many-objective optimization problem. A swarm-based many-objective chimp optimization algorithm (MaOChOA) is proposed to segregate the earthquake catalog into aftershocks and background events. The reference point-based leader selection strategy is adopted to update the solution. The proposed MaOChOA is evaluated on many objective benchmark test functions. The results are compared with existing many-objective techniques using performance metrics such as generational distance, inverse generational distance, spacing metric, hyper-volume distance, and runtime. Further, de-clustering the earthquake catalog is performed using a binary version of many-objective Chimp optimization algorithms (BMaChOA), where the sigmoid function is used in the position update mechanism. The BMaChOA is applied to 32-year historical earthquake catalogs of the Japan, California, Indonesia, and Himalayan regions. The potential of the proposed algorithm is reported by comparing it to five benchmark de-clustering techniques. The results are validated using the epicenter plot, inter-event time Vs. inter-event distance plot, cumulative plot, λ -plot, and statistical parameters such as the m-Morisita index, coefficient of variance, average nearest neighbor, and nearest neighbor distance. [ABSTRACT FROM AUTHOR]

To address the issue of poor performance in the chimp optimization (ChOA) algorithm, a new algorithm called the manta ray-based chimpa optimization algorithm (MChOA) was developed. Introducing the Latin hypercube method to construct the initial population so that the individuals of the initial population are evenly distributed in the solution space, increasing the diversity of the initial population. Introducing nonlinear convergence factors based on positive cut functions to changing the convergence of algorithms, the early survey capabilities and later development capabilities of the algorithm are balanced. The manta ray foraging strategy is introduced at the position update to make up for the defect that the algorithm is prone to local optimization, which effectively improves the optimization performance of the algorithm. To evaluate the performance of the proposed algorithm, 27 well-known test reference functions were selected for experimentation, which showed significant advantages compared to other algorithms. Finally, in order to further verify the algorithm's applicability in actual production processes, it was applied to solve scheduling problems in three flexible workshop scenarios and an aviation engine job shop scheduling in an enterprise. This confirmed its efficacy in addressing complex real-world problems. [ABSTRACT FROM AUTHOR]

Cardiac measures such as heart rate measurements are important indicators of both physiological and psychological states. However, despite their extraordinary potential, their use is restricted in comparative psychology because traditionally cardiac measures involved the attachment of sensors to the participant's body, which, in the case of undomesticated animals such as nonhuman primates, is usually only possible during anesthesia or after extensive training. Here, we validate and apply a camera-based system that enables contact-free detection of animals' heart rates. The system automatically detects and estimates the cardiac signals from cyclic change in the hue of the facial area of a chimpanzee. In Study 1, we recorded the heart rate of chimpanzees using the new technology, while simultaneously measuring heart rate using classic PPG (photoplethysmography) finger sensors. We found that both methods were in good agreement. In Study 2, we applied our new method to measure chimpanzees' heart rate in response to seeing different types of video scenes (groupmates in an agonistic interaction, conspecific strangers feeding, nature videos, etc.). Heart rates changed during video presentation, depending on the video content: Agonistic interactions and conspecific strangers feeding lead to accelerated heart rate relative to baseline, indicating increased emotional arousal. Nature videos lead to decelerated heart rate relative to baseline, indicating a relaxing effect or heightened attention caused by these stimuli. Our results show that the new contact-free technology can reliably assess the heart rate of unrestrained chimpanzees, and most likely other primates. Furthermore, our technique opens up new avenues of research within comparative psychology and facilitates the health management of captive individuals. [ABSTRACT FROM AUTHOR]

The article is a review of the book "Stuff: Humanity's Epic Journey from Naked Ape to Nonstop Shopper" by Chip Colwell. The book explores the history of human interaction with material culture and our relationship with "stuff." It discusses the evolution of toolmaking, the emergence of art and religion, and the rise of consumerism. The author examines how our dependence on material possessions has shaped our society and raises questions about the future of our relationship with "stuff." The review praises the book for its comprehensive approach but notes that it lacks discussion on certain perspectives and the role of museums in addressing overconsumption. [Extracted from the article]

Despite zoonotic potential, data are lacking on enteric infection diversity in wild apes. We employed a novel molecular diagnostic platform to detect enteric infections in wild chimpanzees and gorillas. Prevalent Cryptosporidium parvum, adenovirus, and diarrheagenic Escherichia coli across divergent sites and species demonstrates potential widespread circulation among apes in Africa. [ABSTRACT FROM AUTHOR]

Compassion fatigue (CF) refers to the exhaustion and distress caused by the demands of caring for others. CF occurs in a variety of helping professions, including physicians, nurses, educators, social workers and animal caregivers, and is known to adversely impact both caregivers' quality of life and the care they provide. This study assessed the prevalence, risk and protective factors, coping strategies and support programs for CF in chimpanzee caregivers (N = 123) at accredited sanctuaries and zoos in the United States. Online survey results revealed that 91.06% of chimpanzee caregivers experienced CF at some point in their careers. Common CF symptoms were exhaustion, frustration, anxiety, depression, and apathy. Perceived factors influencing CF included being understaffed, lacking resources and training, poor relationships with coworkers and supervisors, and financial insecurity. Commonly reported coping strategies were talking to someone, having pets, self-care, and getting away from work. 20.33% of caregivers reported having institutional support programs available to them, however they were rarely viewed as helpful and 32.52% of respondents were unsure about program availability. Overall, our findings suggest that, like other caregiving professionals, chimpanzee caregivers are susceptible to CF and may benefit from new or updated support programs that continue to build a 'culture of care' that meets employee, animal, and facility needs. [ABSTRACT FROM AUTHOR]

Simple Summary: The aim of protected areas is to conserve nature. However, the wild animal populations they shelter are not immune to extinction. It is, therefore, important for researchers to provide regular information on the ecology of these populations in order to guide management actions and enhance knowledge. From studies based on chimpanzee nests, we revealed that chimpanzees in Niokolo Koba National Park nest more in closed habitats than in open ones, and that certain plant species are preferentially chosen for nest construction. Diospyros mespiliformis and Pterocarpus erinaceus are the trees most used by chimpanzees for bearing their nests. In addition, we found that chimpanzee nest height and nest life were influenced by the environmental factors. We conclude that the preservation of nesting sites of chimpanzees is crucial for the conservation of this great ape, considered to be on the border of extinction in Senegal. The Niokolo Koba National Park (NKNP) is the largest protected area in Senegal and lies at the northern limit of the chimpanzee's range in West Africa. Recent information on nesting behavior and factors influencing nesting behavior is available for several sites outside NKNP. However, the information available for NKNP is obsolete. Considering that the adequate management of chimpanzee populations cannot be achieved without strong scientific knowledge, it is essential to update data on chimpanzee, Pan troglodytes verus, nesting behavior in NKNP. For this reason, we surveyed their habitat in Mt. Assirik and recorded 626 chimpanzee nests. The results of the study showed that chimpanzees nest more often in closed-canopy habitats such as gallery forests. The average nest height observed in this study was 8.07 ± 0.36 m, varying between 2 and 20 m, which is well below the heights described in most sites where chimpanzees cohabit with large carnivores. Botanical surveys confirmed that chimpanzees select tree species bearing their nests. In Assirik, 12 of the 37 tree species bearing nests are the most used. The nest decay rate (or the time it takes for a nest to go from the fresh to the skeletal stage) at Assirik averaged 68.8 ± 5.8 days. [ABSTRACT FROM AUTHOR]

Partner choice promotes competition among individuals to be selected as a cooperative partner, a phenomenon referred to as competitive altruism. We explored whether chimpanzees engage in competitive altruism in a triadic Ultimatum Game where two proposers can send offers simultaneously or consecutively to a responder who can only accept one of the two competing offers. In a dyadic control condition only one proposer at a time could send an offer to the responder. Chimpanzees increased their offers across trials in the competitive triadic, but not in the dyadic control condition. Chimpanzees also increased their offers after being rejected in previous triadic trials. Furthermore, we found that chimpanzees, under specific conditions, outcompete first proposers in triadic consecutive trials before the responder could choose which offer to accept by offering more than what is expected if they acted randomly or simply offered the smallest possible amount. These results suggest that competitive altruism in chimpanzees did not emerge just as a by-product of them trying to increase over previous losses. Chimpanzees might consider how others' interactions affect their outcomes and engage in strategies to maximize their chances of being selected as cooperative partners. [ABSTRACT FROM AUTHOR]

Though there is consent that poaching is an important driver of wildlife declines in many African forests, we lack a deeper understanding of the factors behind population patterns in Afrotropical landscapes to inform conservation management. We surveyed line transects in four Cameroonian sites of different protection status in 2013/2014, namely Korup National Park, Banyang Mbo Wildlife Reserve, one timber concession and a section of an unprotected agroforestry matrix, and used data from 2007 for trend assessment. We used GLMs to identify predictors for mammal distribution based on a set of variables. While species compositions showed complex trend patterns, it is noteworthy that chimpanzee and elephant abundances declined significantly in the Banyang Mbo Wildlife Reserve. Although landscape management type affected the distribution of most mammal species, anthropogenic or environmental variables were strong predictors. Chimpanzee, elephant and drill abundances were higher at a larger distance to settlements. Vegetation density positively affected a number of species, including chimpanzee and red colobus. Several species were more abundant in rough terrain, probably because of reduced poaching. Our results suggest that protected areas in Southwest Cameroon had a mitigating effect on wildlife declines, mainly due to their remoteness and habitat quality, rather than management interventions. [ABSTRACT FROM AUTHOR]

The most common type of disease that is normal among women is lung cancer. It is one of the main reasons among women, despite great efforts to prevent it through trackers. An automatic disease detection system helps doctors identify and provide accurate results, thus minimizing the mortality rate. Computer Aided Diagnosis (CAD) has minimal human intervention and produces more accurate results than humans. It will be a difficult and lengthy task that depends on the experience of the pathologists. Deep learning methods have been shown to give better results when correlated with ML and extract the best highlights from images. The main objective of this article is to propose a deep learning technique in combination with a convolution neural network (CNN) with a chimpanzee optimization algorithm to diagnose lung cancer. Here, CNN is used for feature extraction and used for extracted feature detection. Experimental results show that the proposed system achieves 100% accuracy, 99% sensitivity, 99% recall, and 98% F1 score compared to other traditional models. As the system achieved correct results, it can help doctors easily investigate lung cancer. [ABSTRACT FROM AUTHOR]

The Chimp Optimization Algorithm (ChOA) is a cutting-edge swarm intelligence algorithm that models the social status ties and hunting behavior of chimps to solve complex optimization problems. Although ChOA is known for its simplicity and efficiency, it may encounter challenges such as convergence speed and local optima. This study presents a comprehensive and competitive multi-strategy-enhanced chimp optimization algorithm (SLDChOA), which comprehensively enhances the optimization performance of the algorithm through four strategies. Firstly, a low-difference Sobol sequence strategy is used to initialize the chimp population to increase the diversity of the initial population. Secondly, different location update strategies are adopted according to different iteration stages. The early iteration stage employs the Lévy flight-based location update strategy to help chimps explore the space more abundantly and improve the global search ability of the algorithm. In contrast, the proposed probability-based elitist operation strategy is used in the late iteration stage to help the chimps obtain higher-quality optimal solutions and improve the convergence accuracy and speed of the algorithm. Finally, the dimension learning-based hunting search strategy is introduced to facilitate information sharing among chimps and enable the algorithm to jump out of the local optimum effectively. To demonstrate its comprehensive performance, SLDChOA is compared with 17 state-of-the-art algorithms on 23 traditional benchmark functions, CEC 2014 and CEC 2019 test sets (totaling 63 test functions). Moreover, its efficacy and excellence are further demonstrated in 4 well-known engineering optimization issues and 2 feature selection problems of multimodal Parkinson's speech datasets. A series of simulations demonstrate that SLDChOA has good comprehensive merit-seeking ability and is extremely competitive. [ABSTRACT FROM AUTHOR]

Based on the invention and development of photography and movie in the 19th century, schools of contemporary art, such as Futurism, have emerged that express the dynamism of motion in painting. Painting techniques such as multiple stroboscopic images, motion blur, and motion lines are culturally based, but the biological basis of their perception has also been intensively investigated recently. Then what are the evolutionary origins of such pictorial representations of motion? Do nonhuman animals also have sensitivity to such representations? To address this question, we examined the effects of motion blur and motion lines on the judgments of global motion directions in chimpanzees. The results showed that the motion lines biased the chimpanzees' judgments toward the direction of motion implied by them, whereas the effect of the motion blur was either absent or weak (Experiment 1). In Experiment 2, we manipulated the length and number of motion lines to examine the effect of "speed" and "distance" in addition to the motion direction implied by the motion lines. The results showed that the effect of motion lines became stronger as the length and the number of lines increased within a specific range. These results indicate that the motion lines also imply the direction of motion in chimpanzees and provide a clue to the evolutionary basis for the pictorial representations of motion. [ABSTRACT FROM AUTHOR]

Primate facial musculature enables a wide variety of movements during bouts of communication, but how these movements contribute to signal construction and repertoire size is unclear. The facial mobility hypothesis suggests that morphological constraints shape the evolution of facial repertoires: species with higher facial mobility will produce larger and more complex repertoires. In contrast, the socio-ecological complexity hypothesis suggests that social needs shape the evolution of facial repertoires: as social complexity increases, so does communicative repertoire size. We tested these two hypotheses by comparing chimpanzees (Pan troglodytes) and gibbons (family Hylobatidae), two distantly related apes who vary in their facial mobility and social organization. While gibbons have higher facial mobility than chimpanzees, chimpanzees live in more complex social groups than gibbons. We compared the morphology and complexity of facial repertoires for both apes using Facial Action Coding Systems designed for chimpanzees and gibbons. Our comparisons were made at the level of individual muscle movements (action units [AUs]) and the level of muscle movement combinations (AU combinations). Our results show that the chimpanzee facial signaling repertoire was larger and more complex than gibbons, consistent with the socio-ecological complexity hypothesis. On average, chimpanzees produced AU combinations consisting of more morphologically distinct AUs than gibbons. Moreover, chimpanzees also produced more morphologically distinct AU combinations than gibbons, even when focusing exclusively on AUs present in both apes. Therefore, our results suggest that socio-ecological factors were more important than anatomical ones to the evolution of facial signaling repertoires in chimpanzees and gibbons. [ABSTRACT FROM AUTHOR]

We report the presence of habitual ground nesting in a newly studied East African chimpanzee (Pan troglodytes schweinfurthii) population in the Bugoma Central Forest Reserve, Uganda. Across a 2‐year period, we encountered 891 night nests, 189 of which were classified as ground nests, a rate of ~21%. We find no preliminary evidence of socio‐ecological factors that would promote its use and highlight local factors, such as high incidence of forest disturbance due to poaching and logging, which appear to make its use disadvantageous. While further study is required to establish whether this behavior meets the strict criteria for nonhuman animal culture, we support the argument that the wider use of population and group‐specific behavioral repertoires in flagship species, such as chimpanzees, offers a tool to promote the urgent conservation action needed to protect threatened ecosystems, including the Bugoma forest. Research highlights: Chimpanzees in the Bugoma Forest, Uganda, habitually employ overnight ground nests (21% of total nests, ground nests present in 25% of nest sites).We discuss a range of socio‐ecological and cultural explanations, highlighting local factors that appear to be disadvantageous for the behavior.While behavioral variation may offer a powerful tool for conservation, strict scientific thresholds for establishing cultural explanations may not be compatible with urgent conservation timelines. [ABSTRACT FROM AUTHOR]

Oral health is a crucial aspect of overall well‐being in both humans and nonhuman primates. Understanding the oral pathologies and dental conditions in apes can provide valuable insights into their evolutionary history, dietary habits, and overall health. The present study evaluates dental findings in wild great apes from museum specimens to gain insights into the influence of natural nutrition on dental health. Complete macerated skulls of wild, adult great apes from the collection of the Museum of Natural History, Berlin, Germany, were examined. We analyzed skulls of 53 gorillas (Gorilla gorilla), 63 chimpanzees (Pan troglodytes), and 41 orangutans (Pongo spp.). For each skull, we recorded wear of dental hard tissues (Lussi and Ganss index), carious lesions, and periodontal bone loss. Incisal and occlusal dental hard tissue defects were found in all skulls, as well as considerable external staining. In all species, incisors and canines showed the greatest loss of tissue, followed by molars. The wear of molars decreased from the first to the third molars, premolars showed the least pronounced defects. Some individuals had apical osteolytic defects along with severe dental hard tissue loss with pulp involvement or after dental trauma, respectively (n = 5). Our study did not observe any carious lesions among the examined great ape skulls. However, we did find evidence for localized or generalized periodontal bone loss in a subset of the specimens (n = 3 chimpanzees, n = 7 orangutans). The natural diet and foraging behavior of great apes induces abrasion and attrition of dental hard tissue but does not yield carious lesions. The occurrence of periodontitis in individual apes indicates that the natural circumstances can induce periodontal bone loss even in the wild, despite physiological nutrition. Research Highlights: The natural diet and foraging behavior of great apes induces wear of dental hard tissues but not carious lesions.The occurrence of periodontitis in individual apes indicates that the natural microbiome, in conjunction with the host's defense, can induce periodontal bone loss even in the wild. [ABSTRACT FROM AUTHOR]

Precise estimates of population dynamics and social grouping patterns are required for effective conservation of wild animal populations. It is difficult to obtain such information on non‐human great apes as they have slow reproductive rates. To gain a better understanding of demography in these populations, previous research has typically involved habituation\, a process that requires years. Here, we collected data continuously over year‐long periods to monitor an unhabituated population of critically endangered Western chimpanzees (Pan troglodytes verus) in the Moyen Bafing National Park, Guinea. We used two arrays of 100 camera traps that were placed opportunistically in two distinct 100 km2 sites, named Bakoun and Koukoutamba. We identified 227 individuals in Bakoun and 207 in Koukoutamba through their unique facial features. Our camera trap data make clear that these individuals belong to six and seven closed groups, respectively. Six of those groups were near‐completely sampled with an average minimum size of 46.8 individuals (range: 37–58), and a mean adult sex ratio of 1.32 (range: 0.93–2.10). We described the demographic composition of these groups and use Bayesian social network analysis to understand population structure. The network analyses suggested that the social bonds within the two populations were structured by sex homophily, with male chimpanzees being more or equally likely to be observed together than other adult associations. Through estimation of minimum convex polygons, we described the minimum home range for those groups. Compared to other chimpanzee groups living in a similar environment (mosaic savanna‐forest), the Moyen Bafing region seems to host a high‐density of chimpanzees with small home ranges for their group size. Our research highlights the potential of camera traps for studying the demographic composition of chimpanzee populations with high resolution and obtaining crucial information on several groups in a time‐efficient and cost‐effective way. Research highlights: Using an array of 100 camera traps for a year in two different 100 km2 study sites, we were able to identify individually more than 400 chimpanzees and assigned them in 13 different closed groups.From the identification, we could study demography, social structure, and home range of six unhabituated groups in a savanna‐forest mosaic landscape where few chimpanzee studies took place.From the identification, we could study demography, social structure, and home range of six unhabituated groups in a savanna‐forest mosaic landscape where few chimpanzee studies took place. [ABSTRACT FROM AUTHOR]

One way mammalian mothers support offspring is by intervening on their behalf when they receive conspecific aggression. Maternal intervention protects offspring and facilitates mother–offspring rank correlation in several female-philopatric species. We tested the hypothesis that maternal intervention during development similarly facilitates mother–offspring rank correlation in one of our two male-philopatric closest living relatives: bonobos, Pan paniscus , for whom male ranks have been described as matrifocal but mechanisms of status transmission are unclear. We predicted mothers would intervene at higher rates in bonobos compared to chimpanzees, Pan troglodytes , where sons earn adult ranks independently. We expected this difference would be especially pronounced for sons as they reached reproductive age (∼8 years) and when aggressors were adult males, which female bonobos, but not female chimpanzees, often dominate. However, for both sons and daughters of all ages (0.5–16 years) and against aggressors of varying age and sex, bonobo mothers in Kokolopori, DRC (N = 22 pairs, 210 conflicts) intervened less frequently than did chimpanzee mothers at Ngogo, Uganda (N = 66 pairs, 221 conflicts), doing so in 8% versus 49% of all conflicts. These differences persisted regardless of the severity of aggression offspring received and the distress they demonstrated. Our results provide no support for our hypothesis that conflict intervention facilitates mother–son rank correlation in bonobos. Nor are patterns explained by additional alternative hypotheses related to species variation in costs of retaliation, quality of female–female relationships or infanticide risk. We introduce two new hypotheses: (1) that success in aggressive competition is less important for male bonobos than for male chimpanzees and (2) proclivities for support are heightened in chimpanzees compared to bonobos because of increased ingroup protectiveness in chimpanzees. The latter hypothesis arises from our unexpected, preliminary observation that nonmother bonobo bystanders intervened less often than nonmother chimpanzee bystanders during these events. • Bonobo vs chimpanzee mothers intervened less often when offspring were aggressed. • Maternal likelihood of intervening increased with severity of inflicted aggression. • Bonobo mothers intervened less often regardless of severity of aggression. • Bonobo mothers intervened less often regardless of aggressor or offspring age or sex. • Bonobos mothers received less retaliation than chimpanzee mothers for intervening. [ABSTRACT FROM AUTHOR]

Tool use by animals, traditionally studied mainly in captive primates due to its relevance to human evolution, has been investigated in both free-ranging and captive mammals. Here, I present a report on tree bark and branch use behaviours by a free-ranging Japanese marten (Martes melampus). The marten put its face in a water-filled container, looking for something, and then it proceeded to make a scooping motion with a bark held in its mouth. Subsequently, it picked up a branch with its mouth and tried to scoop something from the water with it. Upon inspecting the container approximately 2 weeks later, I found a larva belonging to the family Syrphidae. While it is unclear if the marten was trying to catch this larva, its behaviour resembled reach extension behaviour seen in chimpanzees. The use of bark or branches may provide an advantage by allowing access to objects in hard-to-reach positions. [ABSTRACT FROM AUTHOR]

A new paper shows that rates of aggression are higher, and rates of coalition formation are lower, among male bonobos than among male chimpanzees. These findings are noteworthy because they challenge the view that female bonobos' preferences for less aggressive males favored a reduction in male aggression and an increase in social tolerance. [ABSTRACT FROM AUTHOR]