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Behavior Research Methods Mar 2024Parsing signals from noise is a general problem for signallers and recipients, and for researchers studying communicative systems. Substantial efforts have been invested...
Parsing signals from noise is a general problem for signallers and recipients, and for researchers studying communicative systems. Substantial efforts have been invested in comparing how other species encode information and meaning, and how signalling is structured. However, research depends on identifying and discriminating signals that represent meaningful units of analysis. Early approaches to defining signal repertoires applied top-down approaches, classifying cases into predefined signal types. Recently, more labour-intensive methods have taken a bottom-up approach describing detailed features of each signal and clustering cases based on patterns of similarity in multi-dimensional feature-space that were previously undetectable. Nevertheless, it remains essential to assess whether the resulting repertoires are composed of relevant units from the perspective of the species using them, and redefining repertoires when additional data become available. In this paper we provide a framework that takes data from the largest set of wild chimpanzee (Pan troglodytes) gestures currently available, splitting gesture types at a fine scale based on modifying features of gesture expression using latent class analysis (a model-based cluster detection algorithm for categorical variables), and then determining whether this splitting process reduces uncertainty about the goal or community of the gesture. Our method allows different features of interest to be incorporated into the splitting process, providing substantial future flexibility across, for example, species, populations, and levels of signal granularity. Doing so, we provide a powerful tool allowing researchers interested in gestural communication to establish repertoires of relevant units for subsequent analyses within and between systems of communication.
PubMed: 38438657
DOI: 10.3758/s13428-024-02368-6 -
American Journal of Primatology Oct 2023Body condition, a measure for relative fat mass, is associated with primate health, fitness, and overall welfare. Body condition is often influenced by dietary factors,...
Body condition, a measure for relative fat mass, is associated with primate health, fitness, and overall welfare. Body condition is often influenced by dietary factors, age, and/or sex, but several body condition measures (body weight, weight-to-height ratios, and so on) also show high heritability across primate species, indicating a role of genetic effects. Although different measures for body condition exist, many require direct handling of animals, which is invasive, time-consuming, and expensive, making them impractical in wild and captive settings. Therefore, noninvasive visual body condition score (BCS) systems were developed for various animal species, including macaques and chimpanzees, to visually assess relative fat mass. Here we evaluate the utility of a visual BCS system in bonobos by assessing (1) inter-rater reliability, (2) links with body mass, a traditional hands-on measure of condition, and (3) the factors driving individual variation in BCS. We adapted the chimpanzee BCS system to rate 76 bonobos in 11 European zoos (92% of the adult population). Inter-rater reliability was high (s* = 0.948), BCSs were positively associated with body mass (β = 0.075) and not predicted by diet, sex, or age, nor were they associated with a higher abundance of obesity-related diseases. Instead, BCSs showed high levels of heritability (h = 0.637), indicating that a majority of body condition variation in bonobos is attributable to genetic similarity of the individuals. This is in line with reported h -values for traditional body condition measures in primates and provides support for the reliability of visual BCS systems in great apes. The results of this study emphasize an often unanticipated role of genetics in determining primate body fat and health that has implications for the management of captive primates. Application of this tool in wild populations would aid to unravel environmental from genetic drivers of body condition variation in primates.
Topics: Animals; Pan paniscus; Reproducibility of Results; Hominidae; Pan troglodytes; Body Weight
PubMed: 37507232
DOI: 10.1002/ajp.23540 -
Biology Letters Mar 2024During pregnancy, the mammalian immune system must simultaneously protect against pathogens while being accommodating to the foreign fetal tissues. Our current...
During pregnancy, the mammalian immune system must simultaneously protect against pathogens while being accommodating to the foreign fetal tissues. Our current understanding of this immune modulation derives predominantly from industrialized human populations and laboratory animals. However, their environments differ considerably from the pathogen-rich, resource-scarce environments in which pregnancy and the immune system co-evolved. For a better understanding of immune modulation during pregnancy in challenging environments, we measured urinary neopterin, a biomarker of cell-mediated immune responses, in 10 wild female bonobos () before, during and after pregnancy. Bonobos, sharing evolutionary roots and pregnancy characteristics with humans, serve as an ideal model for such investigation. Despite distinct environments, we hypothesized that cell-mediated immune modulation during pregnancy is similar between bonobos and humans. As predicted, neopterin levels were higher during than outside of pregnancy, and highest in the third trimester, with a significant decline post-partum. Our findings suggest shared mechanisms of cell-mediated immune modulation during pregnancy in bonobos and humans that are robust despite distinct environmental conditions. We propose that these patterns indicate shared immunological processes during pregnancy among hominins, and possibly other primates. This finding enhances our understanding of reproductive immunology.
Topics: Pregnancy; Animals; Humans; Female; Pan paniscus; Neopterin; Immunity, Cellular; Biological Evolution; Pan troglodytes; Mammals
PubMed: 38471567
DOI: 10.1098/rsbl.2023.0548 -
Anatomical Science International Sep 2023Flexor digitorum superficialis (FDS) shows diverse muscle-tendon arrangements among primates. The intramuscular nerve distribution pattern is a criterion for discussing...
Muscle-tendon arrangement and intramuscular nerve distribution of flexor digitorum superficialis in the siamang (Symphalangus syndactylus), western lowland gorilla (Gorilla gorilla gorilla), western chimpanzee (Pan troglodytes verus), and Japanese macaque (Macaca fuscata).
Flexor digitorum superficialis (FDS) shows diverse muscle-tendon arrangements among primates. The intramuscular nerve distribution pattern is a criterion for discussing the homology of FDS. In this study, the muscle-tendon arrangement and intramuscular nerve distribution of FDS were examined in the siamang, western lowland gorilla, western chimpanzee, and Japanese macaques. The FDS had muscle bellies to digits II-V. FDS had proximal belly and intermediate tendon except for siamang. Distal belly to digit II (in the western lowland gorilla and western chimpanzees) or distal bellies to digits II and V (in Japanese macaque) originated from the intermediate tendon. In all specimens, nerve branches within digit III belly extended into digit IV belly, and nerve branch(es) within digit IV belly extended into digit V belly. This consistent pattern suggested that each muscle belly to digits III-V is interspecifically homologous. The digit II belly in the siamang and the distal belly to digit II in the western lowland gorilla, western chimpanzees, and Japanese macaques could be homologous based on their similar innervating patterns. The proximal belly was innervated by branches from the communicating nerve between median and ulnar nerves in the western lowland gorilla or branches from median and ulnar nerves in western chimpanzees. In the siamang and Japanese macaque, the whole FDS was innervated by median nerve. The proximal belly in the western lowland gorilla, western chimpanzees, and Japanese macaques could be classified into different groups from the other part of the FDS.
Topics: Animals; Pan troglodytes; Macaca fuscata; Gorilla gorilla; Hylobatidae; Muscle, Skeletal; Tendons
PubMed: 36943670
DOI: 10.1007/s12565-023-00713-x -
American Journal of Primatology Oct 2023Measuring the relative contributions of milk and non-milk foods in the diets of primate infants is difficult from observations. Stable carbon (δ C) and nitrogen (δ N)...
Measuring the relative contributions of milk and non-milk foods in the diets of primate infants is difficult from observations. Stable carbon (δ C) and nitrogen (δ N) isotopes in hair can be used to physiologically track infant feeding through development, but few wild studies have done so, likely due to the difficulty in collecting hair non-invasively. We assessed infant feeding at different ages in wild chimpanzees (Pan troglodytes) at Ngogo, Uganda using δ C and δ N of keratin in 164 naturally shed hairs from 29 infants (61 hairs), 6 juveniles (7 hairs), 28 mothers (67 hairs) and 14 adult males (29 hairs). Hairs were collected when they stuck to feces during defecation or from the ground after chimpanzees groomed or rested. We could not distinguish between the hairs of infants and mothers using strand length and diameter. Infants 1-2 years old were most enriched in C and N and showed means of 1.1‰ in δ C and 2.1‰ in δ N above their mothers. Infants at 2 years had hair δ C values like those of their mothers, which suggests infants began relying more heavily on plants around this age. While mother-infant δ C and δ N differences generally decreased with offspring age, as is expected when infants rely increasingly more on independent foraging through development, milk seemed to remain an important dietary component for infants older than 2.5 years, as evidenced by continuing elevated δ N. We showed that stable carbon and nitrogen isotopes in naturally shed hairs can feasibly detect trophic level differences between chimpanzee infants and mothers. Since it can mitigate some of the limitations associated with behavioral and fecal stable isotope data, the use of hair stable isotopes is a useful, non-invasive tool for assessing infant feeding development in wild primates.
PubMed: 37779353
DOI: 10.1002/ajp.23552 -
American Journal of Primatology May 2024Humans spontaneously and consistently map information coming from different sensory modalities. Surprisingly, the phylogenetic origin of such cross-modal correspondences...
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.
Topics: Humans; Animals; Papio papio; Papio; Pan troglodytes; Phylogeny; Cognition
PubMed: 38475662
DOI: 10.1002/ajp.23613 -
American Journal of Primatology Sep 2023In primates, as well as in other mammals, play fighting (PF) is a complex form of playful activity that is structurally similar to real fighting (RF) and may also be...
In primates, as well as in other mammals, play fighting (PF) is a complex form of playful activity that is structurally similar to real fighting (RF) and may also be used in a competitive way. Here, we verify the structural key differences that can distinguish PF from RF in adult chimpanzees (Pan troglodytes). We collected 962 h of video recording on 30 adult individuals belonging to four chimpanzee groups (Mona Chimpanzee Sanctuary, Spain; La Vallée des Singes and ZooParc de Beauval, France). We applied different indices-two of which were borrowed from the ecological measures of biodiversity-to test for structural differences between PF (345 sessions) and RF (461 sessions) in the levels of behavior repetition (Repeatability of Same Behavior Index, RSBI), distribution uniformity (Pielou Index, J), variability (Shannon Index, H') and, symmetry (i.e., reciprocal exchange of offensive/defensive behaviors; Asymmetry Index, AI). Moreover, we compared the session duration between PF and RF. We found that duration and RSBI were higher in PF than RF while AI was higher in RF than PF. No difference was found between J and H'. Interestingly, both females and males maintained similar ranking positions (determined via Normalized David's scores) in RF and PF. Our study indicates that session duration, behavior repetition, and symmetry can be distinctive structural key features of PF whereas dominance role-reversal, behavior variability, and distribution uniformity were not. PF in adult chimpanzees may have elements of serious contexts (e.g., absence of role-reversal as in RF) which is in line with the view that play is a blended, multifunctional behavior deriving from the re-combination of different behavioral systems. Our findings highlight the need to investigate play structure and manifestation in a nuanced way to better understand the actual motivation that underlies what appears to be play.
Topics: Male; Female; Animals; Social Behavior; Pan troglodytes; France; Mammals
PubMed: 37461284
DOI: 10.1002/ajp.23537 -
Viruses May 2024Endogenous retroviruses (ERVs) are related to long terminal repeat (LTR) retrotransposons, comprising gene sequences of exogenous retroviruses integrated into the host...
Endogenous retroviruses (ERVs) are related to long terminal repeat (LTR) retrotransposons, comprising gene sequences of exogenous retroviruses integrated into the host genome and inherited according to Mendelian law. They are considered to have contributed greatly to the evolution of host genome structure and function. We previously characterized HERV-K HML-9 in the human genome. However, the biological function of this type of element in the genome of the chimpanzee, which is the closest living relative of humans, largely remains elusive. Therefore, the current study aims to characterize HML-9 in the chimpanzee genome and to compare the results with those in the human genome. Firstly, we report the distribution and genetic structural characterization of the 26 proviral elements and 38 solo LTR elements of HML-9 in the chimpanzee genome. The results showed that the distribution of these elements displayed a non-random integration pattern, and only six elements maintained a relatively complete structure. Then, we analyze their phylogeny and reveal that the identified elements all cluster together with HML-9 references and with those identified in the human genome. The HML-9 integration time was estimated based on the 2-LTR approach, and the results showed that HML-9 elements were integrated into the chimpanzee genome between 14 and 36 million years ago and into the human genome between 18 and 49 mya. In addition, conserved motifs, cis-regulatory regions, and enriched PBS sequence features in the chimpanzee genome were predicted based on bioinformatics. The results show that pathways significantly enriched for ERV LTR-regulated genes found in the chimpanzee genome are closely associated with disease development, including neurological and neurodevelopmental psychiatric disorders. In summary, the identification, characterization, and genomics of HML-9 presented here not only contribute to our understanding of the role of ERVs in primate evolution but also to our understanding of their biofunctional significance.
Topics: Animals; Pan troglodytes; Endogenous Retroviruses; Phylogeny; Humans; Terminal Repeat Sequences; Evolution, Molecular; Genome; Genome, Human; Proviruses; Virus Integration; Retroelements
PubMed: 38932184
DOI: 10.3390/v16060892 -
Communications Biology Jul 2023Identifying the evolutionary origins of human speech remains a topic of intense scientific interest. Here we describe a unique feature of adult human neuroanatomy...
Identifying the evolutionary origins of human speech remains a topic of intense scientific interest. Here we describe a unique feature of adult human neuroanatomy compared to chimpanzees and other primates that may provide an explanation of changes that occurred to enable the capacity for speech. That feature is the Prefrontal extent of the Frontal Operculum (PFOp) region, which is located in the ventrolateral prefrontal cortex, adjacent and ventromedial to the classical Broca's area. We also show that, in chimpanzees, individuals with the most human-like PFOp, particularly in the left hemisphere, have greater oro-facial and vocal motor control abilities. This critical discovery, when combined with recent paleontological evidence, suggests that the PFOp is a recently evolved feature of human cortical structure (perhaps limited to the genus Homo) that emerged in response to increasing selection for cognitive and motor functions evident in modern speech abilities.
Topics: Adult; Animals; Humans; Speech; Pan troglodytes; Frontal Lobe; Primates; Voice
PubMed: 37407769
DOI: 10.1038/s42003-023-05066-9 -
Neuropathology : Official Journal of... Dec 2023A 57-year-old female chimpanzee presented with a brief history of increasing lethargy and rapidly progressive lower-limb weakness that culminated in loss of use....
A 57-year-old female chimpanzee presented with a brief history of increasing lethargy and rapidly progressive lower-limb weakness that culminated in loss of use. Postmortem examination revealed no significant gross lesions in the nervous system or other organ systems. Histological analysis revealed round, basophilic to amphophilic polyglucosan bodies (PGBs) in the white and gray matter of the cervical, thoracic, lumbar, and coccygeal regions of spinal cord. Only rare PGBs were observed in forebrain samples. The lesions in the spinal cord were polymorphic, and they were positively stained with hematoxylin, periodic acid Schiff, Alcian blue, toluidine blue, Bielschowsky silver, and Grocott-Gomori methenamine-silver methods, and they were negative for von Kossa and Congo Red stains. Immunohistochemical evaluation revealed reactivity with antibodies to ubiquitin, but they were negative for glial fibrillary acidic protein, neuron-specific enolase, neurofilaments, tau protein, and Aβ protein. Electron microscopy revealed non-membrane-bound deposits composed of densely packed filaments within axons and in the extracellular space. Intra-axonal PGBs were associated with disruption of the axonal fine structure and disintegration of the surrounding myelin sheath. These findings are the first description of PGBs linked to neurological dysfunction in a chimpanzee. Clinicopathologically, the disorder resembled adult PGB disease in humans.
Topics: Adult; Female; Animals; Humans; Aged; Middle Aged; Pan troglodytes; Silver; Axons; Glucans
PubMed: 37086019
DOI: 10.1111/neup.12906