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Journal of Comparative Psychology... Feb 2024Delay of gratification and inhibitory control are generally considered measures of self-control. In humans, individual differences in measures of self-control are...
Delay of gratification and inhibitory control are generally considered measures of self-control. In humans, individual differences in measures of self-control are associated with a host of behavioral, neurological, cognitive, and health-related outcomes. Self-control is not unique to humans and has been demonstrated in a variety of nonhuman species using a variety of paradigms. In this study, the effect of sex and age on delay of gratification performance, as measured by the hybrid delay task, was tested in a sample of 88 chimpanzees. Additionally, whether individual differences in hybrid delay task performance were associated with different aspects of personality was examined in this study. Contrary to reports in human subjects, geriatric male chimpanzees were found to perform more efficiently than adult males, while no age differences were found between geriatric and adult females. Indeed, delay of gratification efficiency was positively associated with age in males and negatively associated with age in females. Chimpanzees that performed more efficiently on the hybrid delay task were also found to be rated as more intelligent, more extraverted, and less impulsive. These findings suggest that objective measures of efficiency in delay of gratification tasks are associated with different dimensions of personality, which have some overlapping construct validity. (PsycInfo Database Record (c) 2024 APA, all rights reserved).
PubMed: 38407079
DOI: 10.1037/com0000373 -
PeerJ 2024Using field observations from a sanctuary, Oña and colleagues (DOI: 10.7717/peerj.7623) investigated the semantics of face-gesture combinations in chimpanzees (). The...
Using field observations from a sanctuary, Oña and colleagues (DOI: 10.7717/peerj.7623) investigated the semantics of face-gesture combinations in chimpanzees (). The response of the animals to these signals was encoded as a binary measure: positive interactions such as approaching or grooming were considered affiliative; ignoring or attacking was considered non-affiliative. The relevant signals are illustrated in Fig. 1 (https://doi.org/10.7717/peerj.7623/fig-1), together with the outcome in terms of average affiliativeness. The authors observe that there seems to be no systematicity in the way the faces modify the responses to the gestures, sometimes reducing affiliativeness, sometimes increasing it. A strong interpretation of this result would be that the meaning of a gesture-face combination cannot be derived from the meaning of the gesture and the meaning of the face, that is, the interpretation of chimpanzees' face-gesture combinations are non compositional in nature. We will revisit this conclusion: we will exhibit simple compositional systems which, after all, may be plausible. At the methodological level, we argue that it is critical to lay out the theoretical options explicitly for a complete comparison of their pros and cons.
Topics: Animals; Pan troglodytes; Gestures; Hominidae; Semantics
PubMed: 38406280
DOI: 10.7717/peerj.16800 -
Animals : An Open Access Journal From... Feb 2024The 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...
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, , 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.
PubMed: 38396522
DOI: 10.3390/ani14040553 -
In Vitro Cellular & Developmental... May 2024As humans' closest living relatives, chimpanzees offer valuable insights into human evolution. However, technical and ethical limitations hinder investigations into the... (Comparative Study)
Comparative Study
As humans' closest living relatives, chimpanzees offer valuable insights into human evolution. However, technical and ethical limitations hinder investigations into the molecular and cellular foundations that distinguish chimpanzee and human traits. Recently, induced pluripotent stem cells (iPSCs) have emerged as a novel model for functional comparative studies and provided a non-invasive alternative for studying embryonic phenomena. In this study, we generated five new chimpanzee iPSC lines from peripheral blood cells and skin fibroblasts with SeV vectors carrying four reprogramming factors (human OCT3/4, SOX2, KLF4, and L-MYC) and characterized their pluripotency and differentiation potential. We also examined the expression of a human-specific non-coding RNA, HSTR1, which is predicted to be involved in human brain development. Our results show that the chimpanzee iPSCs possess pluripotent characteristics and can differentiate into various cell lineages. Moreover, we found that HSTR1 is expressed in human iPSCs and their neural derivatives but not in chimpanzee counterparts, supporting its possible role in human-specific brain development. As iPSCs are inherently variable due to genetic and epigenetic differences in donor cells or reprogramming procedures, it is essential to expand the number of chimpanzee iPSC lines to comprehensively capture the molecular and cellular properties representative of chimpanzees. Hence, our cells provide a valuable resource for investigating the function and regulation of human-specific transcripts such as HSTR1 and for understanding human evolution more generally.
Topics: Pan troglodytes; Animals; Induced Pluripotent Stem Cells; Kruppel-Like Factor 4; Cell Differentiation; Humans; Cell Line; Species Specificity; Fibroblasts; Cellular Reprogramming
PubMed: 38386235
DOI: 10.1007/s11626-024-00853-y -
Journal of Human Evolution Mar 2024Since the initial discovery of Paranthropus robustus at the site of Kromdraai in 1938, the hypodigm of this species has been expanded by subsequent work at the...
Since the initial discovery of Paranthropus robustus at the site of Kromdraai in 1938, the hypodigm of this species has been expanded by subsequent work at the localities of Swartkrans and Drimolen, with a few fossils also known from Cooper's D, Gondolin and Sterkfontein Member 5. Beginning in 2014, systematic excavations at Kromdraai uncovered a large and previously unknown fossiliferous area, shedding light on Units O and P in the earliest part of the site's stratigraphic sequence. The aim of this paper is to provide detailed descriptions and illustrations of 30 P. robustus craniodental specimens recovered between 2014 and 2017 within the Unit P deposits at Kromdraai. This new sample predates all prior conspecific specimens found at this site (including the holotype of P. robustus from Kromdraai, TM 1517). Its basic dental morphology dimensions and cranial features are compared in a preliminary analysis with other P. robustus samples. The P. robustus sample from Kromdraai Unit P documents previously unknown portions of the P. robustus juvenile cranium. The new dental and cranial remains aid in the exploration of potential morphological distinctions between site-specific P. robustus samples and are compared favorably in size and morphology with the small P. robustus specimens from Drimolen (e.g., DNH 7). These findings do not support the hypothesis that the specimens from Drimolen belong to a different taxonomic group. Instead, they reinforce the presence of a significant degree of sexual dimorphism within P. robustus. The Kromdraai Unit P specimens also contribute to the biodemographic profile of P. robustus. The notable prevalence of infants (i.e., juvenile individuals before the emergence of their first permanent molars) mirrors the natural mortality profiles observed in wild chimpanzees. This suggests a closer resemblance in the processes of accumulation in Kromdraai Unit P and Drimolen than at Swartkrans.
Topics: Humans; Animals; Fossils; Hominidae; South Africa; Molar; Pan troglodytes
PubMed: 38382132
DOI: 10.1016/j.jhevol.2023.103481 -
Journal of Anatomy Jul 2024Extant 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...
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.
Topics: Animals; Male; Female; Femur; Hominidae; Humans; Cancellous Bone; Locomotion; Gorilla gorilla; Pan troglodytes
PubMed: 38381116
DOI: 10.1111/joa.14026 -
Nature Human Behaviour Apr 2024The great apes-bonobos, chimpanzees, gorillas and orangutans-are critically threatened by human activities. We have destroyed their habitats, hunted them and transmitted... (Review)
Review
The great apes-bonobos, chimpanzees, gorillas and orangutans-are critically threatened by human activities. We have destroyed their habitats, hunted them and transmitted fatal diseases to them. Yet we also conduct research on them, try to protect them and live alongside them. They are endangered, and time is running out. Here we outline what must be done to ensure that future generations continue to share this planet with great apes. We urge dialogue with those who live with great apes and interact with them often. We advocate conservation plans that acknowledge the realities of climate change, economic drivers and population growth. We encourage researchers to use technology to minimize risks to great apes. Our proposals will require substantial investment, and we identify ways to generate these funds. We conclude with a discussion of how field researchers might alter their work to protect our closest living relatives more effectively.
Topics: Animals; Hominidae; Conservation of Natural Resources; Humans; Climate Change; Endangered Species; Ecosystem; Pan troglodytes; Pan paniscus
PubMed: 38374442
DOI: 10.1038/s41562-024-01830-x -
ELife Feb 2024Although gene expression divergence has long been postulated to be the primary driver of human evolution, identifying the genes and genetic variants underlying uniquely...
Although gene expression divergence has long been postulated to be the primary driver of human evolution, identifying the genes and genetic variants underlying uniquely human traits has proven to be quite challenging. Theory suggests that cell-type-specific -regulatory variants may fuel evolutionary adaptation due to the specificity of their effects. These variants can precisely tune the expression of a single gene in a single cell-type, avoiding the potentially deleterious consequences of -acting changes and non-cell type-specific changes that can impact many genes and cell types, respectively. It has recently become possible to quantify human-specific -acting regulatory divergence by measuring allele-specific expression in human-chimpanzee hybrid cells-the product of fusing induced pluripotent stem (iPS) cells of each species . However, these -regulatory changes have only been explored in a limited number of cell types. Here, we quantify human-chimpanzee -regulatory divergence in gene expression and chromatin accessibility across six cell types, enabling the identification of highly cell-type-specific -regulatory changes. We find that cell-type-specific genes and regulatory elements evolve faster than those shared across cell types, suggesting an important role for genes with cell-type-specific expression in human evolution. Furthermore, we identify several instances of lineage-specific natural selection that may have played key roles in specific cell types, such as coordinated changes in the -regulation of dozens of genes involved in neuronal firing in motor neurons. Finally, using novel metrics and a machine learning model, we identify genetic variants that likely alter chromatin accessibility and transcription factor binding, leading to neuron-specific changes in the expression of the neurodevelopmentally important genes and . Overall, our results demonstrate that integrative analysis of -regulatory divergence in chromatin accessibility and gene expression across cell types is a promising approach to identify the specific genes and genetic variants that make us human.
Topics: Humans; Animals; Chromatin; Pan troglodytes; Hybrid Cells; Motor Neurons; Gene Expression
PubMed: 38358392
DOI: 10.7554/eLife.89594 -
Developmental Psychobiology Feb 2024The motivational value of visual infant stimuli in humans is considered to encourage parental behavior. To explore the evolutionary roots of this preference for infants,...
The motivational value of visual infant stimuli in humans is considered to encourage parental behavior. To explore the evolutionary roots of this preference for infants, we examined the reward value of conspecific infant videos compared to adult ones in nine chimpanzees. We employed a novel approach, a simultaneous discrimination task with differential sensory reinforcement. In Experiments 1 and 2, we tested if watching conspecific infant videos is more rewarding than watching adult ones. Participants were required to discriminate between two visual stimuli by a touch panel task. In video reward trials, a video clip featuring a chimpanzee infant followed a correct choice, while one featuring an adult followed an incorrect choice. However, the percentage of correct choices did not significantly differ from chance except in one chimpanzee, indicating that chimpanzees did not exhibit a preference for watching infant videos over those of adult. In Experiment 3, we tested if chimpanzees prefer conspecific videos over a blank screen; however, we did not find evidence either at a group level. These results suggest that the incentive salience of infant stimuli may not be universally compelling across species. Additionally, we discuss the limitations of the task using sensory reinforcement.
Topics: Adult; Animals; Infant; Humans; Discrimination Learning; Pan troglodytes; Motivation; Reward; Reinforcement, Psychology
PubMed: 38356136
DOI: 10.1002/dev.22470 -
American Journal of Primatology May 2024Molar 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....
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.
Topics: Animals; Hylobates; Primates; Hominidae; Pan paniscus; Macaca fascicularis; Pongo pygmaeus; Diet
PubMed: 38353023
DOI: 10.1002/ajp.23608