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Scientific Reports May 2024Differences in the tool use of non-human primates and humans are subject of ongoing debate. In humans, representations of object functions underpin efficient tool use....
Differences in the tool use of non-human primates and humans are subject of ongoing debate. In humans, representations of object functions underpin efficient tool use. Yet, representations of object functions can lead to functional fixedness, which describes the fixation on a familiar tool function leading to less efficient problem solving when the problem requires using the tool for a new function. In the current study, we examined whether chimpanzees exhibit functional fixedness. After solving a problem with a tool, chimpanzees were less efficient in solving another problem which required using the same tool with a different function compared to a control group. This fixation effect was still apparent after a period of nine months and when chimpanzees had learned about the function of a tool by observation of a conspecific. These results suggest that functional fixedness in our closest living relatives likely exists and cast doubt on the notion that stable function representations are uniquely human.
Topics: Animals; Pan troglodytes; Male; Female; Problem Solving; Tool Use Behavior; Learning; Humans
PubMed: 38802445
DOI: 10.1038/s41598-024-62685-w -
NeuroImage Jul 2024Accurate processing and analysis of non-human primate (NHP) brain magnetic resonance imaging (MRI) serves an indispensable role in understanding brain evolution,...
Accurate processing and analysis of non-human primate (NHP) brain magnetic resonance imaging (MRI) serves an indispensable role in understanding brain evolution, development, aging, and diseases. Despite the accumulation of diverse NHP brain MRI datasets at various developmental stages and from various imaging sites/scanners, existing computational tools designed for human MRI typically perform poor on NHP data, due to huge differences in brain sizes, morphologies, and imaging appearances across species, sites, and ages, highlighting the imperative for NHP-specialized MRI processing tools. To address this issue, in this paper, we present a robust, generic, and fully automated computational pipeline, called non-human primates Brain Extraction and Segmentation Toolbox (nBEST), whose main functionality includes brain extraction, non-cerebrum removal, and tissue segmentation. Building on cutting-edge deep learning techniques by employing lifelong learning to flexibly integrate data from diverse NHP populations and innovatively constructing 3D U-NeXt architecture, nBEST can well handle structural NHP brain MR images from multi-species, multi-site, and multi-developmental-stage (from neonates to the elderly). We extensively validated nBEST based on, to our knowledge, the largest assemblage dataset in NHP brain studies, encompassing 1,469 scans with 11 species (e.g., rhesus macaques, cynomolgus macaques, chimpanzees, marmosets, squirrel monkeys, etc.) from 23 independent datasets. Compared to alternative tools, nBEST outperforms in precision, applicability, robustness, comprehensiveness, and generalizability, greatly benefiting downstream longitudinal, cross-sectional, and cross-species quantitative analyses. We have made nBEST an open-source toolbox (https://github.com/TaoZhong11/nBEST) and we are committed to its continual refinement through lifelong learning with incoming data to greatly contribute to the research field.
Topics: Animals; Deep Learning; Brain; Magnetic Resonance Imaging; Image Processing, Computer-Assisted; Macaca mulatta; Neuroimaging; Pan troglodytes; Aging
PubMed: 38797384
DOI: 10.1016/j.neuroimage.2024.120652 -
Primates; Journal of Primatology May 2024Wild chimpanzees (Pan troglodytes) are caught in snares set for other animals and sometimes injure or lose body parts. Snaring can compromise the health, growth,...
Wild chimpanzees (Pan troglodytes) are caught in snares set for other animals and sometimes injure or lose body parts. Snaring can compromise the health, growth, survival, and behavior of chimpanzees and, thus, represents a threat for the conservation of this endangered species. During a long-term study of chimpanzees at Ngogo in Kibale National Park, Uganda, we started a project to remove snares in and around their territory. We compared the number of times chimpanzees were snared during the 12.75 years after the start of this project with the number of times individuals were snared during the previous 14 years. Only one chimpanzee was snared after we began removing snares compared with 12 individuals caught during the period before. This represents a clear reduction in the risk created by snaring at this site and suggests that removing snares can be employed to protect chimpanzees.
PubMed: 38787490
DOI: 10.1007/s10329-024-01139-3 -
American Journal of Primatology May 2024Heart rate is a crucial vital sign and a valuable indicator for assessing the physical and psychological condition of a target animal. Heart rate contributes to (1)...
Heart rate is a crucial vital sign and a valuable indicator for assessing the physical and psychological condition of a target animal. Heart rate contributes to (1) fundamental information for cognitive research, (2) an indicator of psychological and physical stress, and (3) improving the animal welfare of captive animals, especially in nonhuman primate studies. Heart rate has been measured using a contact-type device; however, the device burdens the target animals and that there are risks associated with anesthesia during installation. This study explores the application of heartbeat measurement techniques using millimeter-wave radar, primarily developed for humans, as a remote and noninvasive method for measuring the heart rate of nonhuman primates. Through a measurement test conducted on two chimpanzees, we observed a remarkable correspondence between the peak frequency spectrum of heart rate estimated using millimeter-wave radar and the mean value obtained from electrocardiograph data, thereby validating the accuracy of the method. To the best of our knowledge, this is the first demonstration of the precise measurement of great apes' heart rate using millimeter-wave radar technology. Compared to heart rate measurement using video analysis, the method using millimeter-wave radar has the advantage that it is less susceptible to weather and lighting conditions and that measurement techniques for multiple individuals have been developed for human subjects, while its disadvantage is that validation of measurement from long distances has not been completed. Another disadvantage common to both methods is that measurement becomes difficult when the movement of the target individual is large. The possibility of noncontact measurement of heart rate in wild and captive primates will undoubtedly open up a new research area while taking animal welfare into consideration.
PubMed: 38775638
DOI: 10.1002/ajp.23633 -
In Vitro Cellular & Developmental... May 2024The comparative analysis between humans and non-human primates is an instrumental approach for elucidating the evolutional traits and disease propensity of humans....
The comparative analysis between humans and non-human primates is an instrumental approach for elucidating the evolutional traits and disease propensity of humans. However, in primates, cross-species analyses of their developmental events have encountered constraints because of the ethical and technical limitations in available sample collection, sequential monitoring, and manipulations. In an endeavor to surmount these challenges, in recent years, induced pluripotent stem cells (iPSCs) have garnered escalating interest as an in vitro tool for cross-species analyses between humans and non-human primates. Meanwhile, compared to humans, there is less information on in vitro differentiation of non-human primate iPSCs, and their genetic diversity including subspecies may cause different eligibility to in vitro differentiation methods. Therefore, antecedent to embarking on a comparative analysis to humans, it is a prerequisite to develop the efficacious methodologies for in vitro differentiation regardless of the intraspecies genetic background in non-human primates. In this study, we executed the in vitro differentiation of cardiomyocytes from four chimpanzee iPSC lines with different subspecies and individual backgrounds. To induce cardiomyocytes from chimpanzee iPSCs, we evaluated our methodology for in vitro cardiac differentiation of human iPSCs. Eventually, with minor alterations, our cardiac differentiation method was applicable to all chimpanzee iPSC lines tested as assessed by the expression of cardiac marker genes and the beating ability. Hence, our in vitro differentiation method will advance iPSC-based research of chimpanzee cardiac development and also hold possible utility to cross-species analyses among primate species.
Topics: Induced Pluripotent Stem Cells; Animals; Cell Differentiation; Myocytes, Cardiac; Pan troglodytes; Cell Line; Humans; Species Specificity
PubMed: 38753247
DOI: 10.1007/s11626-024-00914-2 -
Proceedings of the National Academy of... May 2024The aryl hydrocarbon receptor (AHR) is a transcription factor that has many functions in mammals. Its best known function is that it binds aromatic hydrocarbons and...
The aryl hydrocarbon receptor (AHR) is a transcription factor that has many functions in mammals. Its best known function is that it binds aromatic hydrocarbons and induces the expression of cytochrome P450 genes, which encode enzymes that metabolize aromatic hydrocarbons and other substrates. All present-day humans carry an amino acid substitution at position 381 in the AHR that occurred after the divergence of modern humans from Neandertals and Denisovans. Previous studies that have expressed the ancestral and modern versions of AHR from expression vectors have yielded conflicting results with regard to their activities. Here, we use genome editing to modify the endogenous gene so that it encodes to the ancestral, Neandertal-like AHR protein in human cells. In the absence of exogenous ligands, the expression of AHR target genes is higher in cells expressing the ancestral AHR than in cells expressing the modern AHR, and similar to the expression in chimpanzee cells. Furthermore, the modern human AHR needs higher doses of three ligands than the ancestral AHR to induce the expression of target genes. Thus, the ability of AHR to induce the expression of many of its target genes is reduced in modern humans.
Topics: Receptors, Aryl Hydrocarbon; Humans; Gene Editing; Animals; Basic Helix-Loop-Helix Transcription Factors; Evolution, Molecular; Pan troglodytes; Neanderthals; Ligands
PubMed: 38739836
DOI: 10.1073/pnas.2402159121 -
The Journal of the Acoustical Society... May 2024Modern humans and chimpanzees share a common ancestor on the phylogenetic tree, yet chimpanzees do not spontaneously produce speech or speech sounds. The lab exercise... (Comparative Study)
Comparative Study
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.
Topics: Humans; Animals; Pan troglodytes; Speech Acoustics; Speech; Tongue; Vocalization, Animal; Species Specificity; Speech Production Measurement; Larynx; Phonetics
PubMed: 38738937
DOI: 10.1121/10.0026020 -
Scientific Reports May 2024Reverse zoonotic respiratory diseases threaten great apes across Sub-Saharan Africa. Studies of wild chimpanzees have identified the causative agents of most respiratory...
Reverse zoonotic respiratory diseases threaten great apes across Sub-Saharan Africa. Studies of wild chimpanzees have identified the causative agents of most respiratory disease outbreaks as "common cold" paediatric human pathogens, but reverse zoonotic transmission pathways have remained unclear. Between May 2019 and August 2021, we conducted a prospective cohort study of 234 children aged 3-11 years in communities bordering Kibale National Park, Uganda, and 30 adults who were forest workers and regularly entered the park. We collected 2047 respiratory symptoms surveys to quantify clinical severity and simultaneously collected 1989 nasopharyngeal swabs approximately monthly for multiplex viral diagnostics. Throughout the course of the study, we also collected 445 faecal samples from 55 wild chimpanzees living nearby in Kibale in social groups that have experienced repeated, and sometimes lethal, epidemics of human-origin respiratory viral disease. We characterized respiratory pathogens in each cohort and examined statistical associations between PCR positivity for detected pathogens and potential risk factors. Children exhibited high incidence rates of respiratory infections, whereas incidence rates in adults were far lower. COVID-19 lockdown in 2020-2021 significantly decreased respiratory disease incidence in both people and chimpanzees. Human respiratory infections peaked in June and September, corresponding to when children returned to school. Rhinovirus, which caused a 2013 outbreak that killed 10% of chimpanzees in a Kibale community, was the most prevalent human pathogen throughout the study and the only pathogen present at each monthly sampling, even during COVID-19 lockdown. Rhinovirus was also most likely to be carried asymptomatically by adults. Although we did not detect human respiratory pathogens in the chimpanzees during the cohort study, we detected human metapneumovirus in two chimpanzees from a February 2023 outbreak that were genetically similar to viruses detected in study participants in 2019. Our data suggest that respiratory pathogens circulate in children and that adults become asymptomatically infected during high-transmission times of year. These asymptomatic adults may then unknowingly carry the pathogens into forest and infect chimpanzees. This conclusion, in turn, implies that intervention strategies based on respiratory symptoms in adults are unlikely to be effective for reducing reverse zoonotic transmission of respiratory viruses to chimpanzees.
Topics: Animals; Pan troglodytes; Humans; Child; Female; Male; Child, Preschool; Common Cold; Adult; Uganda; Prospective Studies; Zoonoses; COVID-19; Ape Diseases; Respiratory Tract Infections; Rhinovirus; SARS-CoV-2; Incidence
PubMed: 38714841
DOI: 10.1038/s41598-024-61236-7 -
Current Biology : CB May 2024A 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...
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.
Topics: Animals; Pan paniscus; Aggression; Male; Female; Pan troglodytes; Behavior, Animal; Social Behavior
PubMed: 38714164
DOI: 10.1016/j.cub.2024.03.056 -
PLoS Biology May 2024Tool 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...
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.
Topics: Animals; Pan troglodytes; Tool Use Behavior; Female; Male; Hand Strength; Cote d'Ivoire; Cognition; Feeding Behavior
PubMed: 38713644
DOI: 10.1371/journal.pbio.3002609