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American Journal of Biological... Sep 2023Morphological intraspecific variation is due to the balance between skeletal plasticity and genetic constraint on the skeleton. Osteogenic responses to external stimuli,...
OBJECTIVES
Morphological intraspecific variation is due to the balance between skeletal plasticity and genetic constraint on the skeleton. Osteogenic responses to external stimuli, such as locomotion, have been well documented interspecifically across the primate order, but less so at the intraspecific level. Here, we examine the differences in cross-sectional variability of the femur, humerus, radius, and tibia in Pan troglodytes troglodytes versus Gorilla gorilla gorilla. We investigate whether there are sex, species, bone, and trait differences in response to variable body size and locomotion.
MATERIALS AND METHODS
Adult male and female P. t. troglodytes and G. g. gorilla long bones from the Cleveland Museum of Natural History were scanned with a peripheral quantitative computer tomography system. Scans were taken at the midshaft of each bone according to functional bone length. Coefficients of variation were used to provide a size-independent measure of variation. We applied a Bonferroni correction to account for the multiple pairwise tests.
RESULTS
There were limited significant differences between males and females, however, females tended to be more variable than males. Variation in Gorilla, when significant, was greater than in Pan, although significant differences were limited. There were no differences between bone variability in male and female Gorilla, and female Pan.
DISCUSSION
Increased female variability may be due to more variable locomotor behavior, particularly during periods of pregnancy, lactation, and caring for an offspring compared to consistent locomotion over the life course by males. Body size may be a contributing factor to variability; more work is needed to understand this relationship.
Topics: Animals; Male; Female; Gorilla gorilla; Pan troglodytes; Hominidae; Bone and Bones; Locomotion
PubMed: 37504383
DOI: 10.1002/ajpa.24823 -
Journal of Human Evolution Sep 2023Quantifying and characterizing the pattern of trait covariances is crucial for understanding how population-level patterns of integration might constrain or facilitate...
Quantifying and characterizing the pattern of trait covariances is crucial for understanding how population-level patterns of integration might constrain or facilitate craniofacial evolution related to the feeding system. This study addresses an important gap in our knowledge by investigating magnitudes and patterns of morphological integration of biomechanically informative traits in the skulls of Homo sapiens, Pan troglodytes, and Gorilla gorilla. We predicted a lower magnitude of integration among human biomechanical traits since humans eat a softer, less biomechanically challenging diet than apes. Indeed, compared to African apes, the magnitudes of integration were lower in H. sapiens skulls for form data (raw dimensions) but were similar or higher for shape data (raw dimensions scaled by geometric mean). Patterns of morphological integration were generally similar, but not identical, across the three species, particularly for the form data compared to the shape data. Traits that load heavily on the primary axis of variation in morphospace are generally associated with size and/or shape of the temporalis and masseter muscles and with dimensions related to the constrained lever model of jaw biomechanics. Given the conserved nature of morphological integration, skull adaptations for food processing in African apes and humans may have been constrained to occur along certain paths of high evolvability. The conserved pattern of functional integration also indicates that extant hominine species can operate as reasonable analogues for extinct hominins in studies that require population-level patterns of trait variance/covariance.
Topics: Humans; Animals; Biomechanical Phenomena; Skull; Pan troglodytes; Acclimatization; Food Handling
PubMed: 37647749
DOI: 10.1016/j.jhevol.2023.103401 -
American Journal of Biological... Mar 2024Current evidence suggests that flaked stone tool technologies did not emerge until ~3.3-2.6 million-years-ago (Ma). It is often hypothesized that early hominin...
OBJECTIVES
Current evidence suggests that flaked stone tool technologies did not emerge until ~3.3-2.6 million-years-ago (Ma). It is often hypothesized that early hominin (principally Ardipithecus and early Australopithecus) manual anatomy may have prevented an earlier emergence, as the forceful precision grips essential to flake tool-use may have been ineffectively performed by these species. Marzke, Marchant, McGrew, and Reece (2015) observed potentially forceful pad-to-side precision grips being recruited by wild chimpanzees (Pan troglodytes) during feeding behaviors, indicating that Pan-like manual anatomy, and therefore potentially early hominin anatomy, may be capable of effectively securing flake stone tools during their use.
MATERIALS AND METHODS
Here, we report on the grips recruited by four captive, human-trained, bonobos (Pan paniscus) during the use of stone and organic tools, including flake stone tools during cutting behaviors.
RESULTS
It is revealed that pad-to-side precision grips are frequently recruited by these bonobos when securing stone flakes during cutting actions. In some instances, high forces could have been resisted and applied by the thumb and fingers.
DISCUSSION
While our analyzes are preliminary and limited to captive individuals, and Pan is not suggested to secure flakes with the same efficacy as Homo or Australopithecus, it points to early hominins potentially being able to perform the precision grips required to use flake stone tools. In turn, the ability to gain tangible benefits from the effective use of flake tools (i.e., gain energetic returns from processing food resources) may have been - at least anatomically - possible in early Australopithecus and other pre-Early Stone Age hominin species. In turn, hominin manual anatomy may not be a leading restriction on the emergence of the earliest stone tool technologies.
Topics: Humans; Animals; Pan paniscus; Hominidae; Pan troglodytes; Thumb; Hand Strength
PubMed: 37218536
DOI: 10.1002/ajpa.24759 -
Journal of Human Evolution Aug 2023Living nonhuman primates have long served as a referential framework for understanding various aspects of hominin biological and cultural evolution. Comparing the...
Living nonhuman primates have long served as a referential framework for understanding various aspects of hominin biological and cultural evolution. Comparing the cognitive, social, and ecological contexts of nonhuman primate and hominin tool use has allowed researchers to identify key adaptations relevant to the evolution of hominin behavior. Although the Oldowan is often considered to be a major evolutionary milestone, it has been argued that the Oldowan is rather an extension of behaviors already present in the ape lineage. This is based on the fact that while apes move tools through repeated, unplanned, short-distance transport bouts, they produce material patterning often associated with long-distance transport, planning, and foresight in the Oldowan. Nevertheless, remain fundamental differences in how Oldowan core and flake technology and nonhuman primate tools are used. The goal of the Oldowan hominins is to produce sharp-edged flakes, whereas nonhuman primates use stone tools primarily as percussors. Here, we present an agent-based model that investigates the explanatory power of the ape tool transport model in light of these differences. The model simulates the formation of the Oldowan record under the conditions of an accumulated short-distance transport pattern, as seen in extant chimpanzees. Our results show that while ape tool transport can account for some of the variation observed in the archaeological record, factors related to use-life duration severely limit how far an Oldowan core can be moved through repeated short-distance transport bouts. Thus, the ape tool transport has limitations in its ability to explain patterns in the Oldowan. These results provide a basis for discussing adaptive processes that would have facilitated the development of the Oldowan.
Topics: Animals; Tool Use Behavior; Hominidae; Primates; Pan troglodytes; Archaeology
PubMed: 37356333
DOI: 10.1016/j.jhevol.2023.103399 -
Scientific Reports Nov 2023The anatomy of the auditory region of fossil hominins may shed light on the emergence of human spoken language. Humans differ from other great apes in several features...
The anatomy of the auditory region of fossil hominins may shed light on the emergence of human spoken language. Humans differ from other great apes in several features of the external, middle and inner ear (e.g., short external ear canal, small tympanic membrane, large oval window). However, the functional implications of these differences remain poorly understood as comparative audiometric data from great apes are scarce and conflicting. Here, we measure the sound transfer function of the external and middle ears of humans, chimpanzees and bonobos, using laser-Doppler vibrometry and finite element analysis. This sound transfer function affects auditory thresholds, which relate to speech reception thresholds in humans. Unexpectedly we find that external and middle ears of chimpanzees and bonobos transfer sound better than human ones in the frequency range of spoken language. Our results suggest that auditory thresholds of the last common ancestor of Homo and Pan were already compatible with speech reception as observed in humans. Therefore, it seems unlikely that the morphological evolution observed in the bony auditory region of fossil hominins was driven by the emergence of spoken language. Instead, the peculiar human configuration may be a by-product of morpho-functional constraints linked to brain expansion.
Topics: Animals; Humans; Pan troglodytes; Auditory Threshold; Pan paniscus; Speech; Hominidae
PubMed: 38007561
DOI: 10.1038/s41598-023-47778-2 -
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 -
Behavioural Processes Aug 2023Questionnaires based on human models can be used to reliably assess personality also in non-human primates. In this study, we used an adapted version of Eysenck's...
Questionnaires based on human models can be used to reliably assess personality also in non-human primates. In this study, we used an adapted version of Eysenck's Psychoticism-Extraversion-Neuroticism (PEN) model that focuses on three higher-order personality traits. Extending previous work on a small group of chimpanzees (Pan troglodytes), we tested 37 chimpanzees housed at Fundació Mona (Girona, Spain) and the Leipzig Zoo (Germany). We assessed personality with a 12-item questionnaire, which raters scored using a 7-point Likert scale. To identify the personality traits, we conducted data reduction with Principal Components Analysis and Robust Unweighted Least Squares. The ICCs for the single (3, 1) and average (3, k) ratings indicated substantial agreement between raters. Parallel analyses identified two factors to retain, whereas the scree plot inspection and eigenvalues larger than one rule identified three factors. Factor 1 and 2 in our study were identical to the ones previously described for this species (labelled Extraversion and Neuropsychoticism, respectively) and we also obtained a third factor that could be related to Dominance (Fearless Dominance). Thus, our results confirm the potential of the PEN model to describe chimpanzee personality structure.
Topics: Animals; Pan troglodytes; Extraversion, Psychological; Neuroticism; Personality; Surveys and Questionnaires
PubMed: 37364625
DOI: 10.1016/j.beproc.2023.104909 -
Scientific Reports Jul 2023Humans are adept at extracting affective information from vocalizations of humans and other animals. However, the extent to which human recognition of vocal affective...
Humans are adept at extracting affective information from vocalizations of humans and other animals. However, the extent to which human recognition of vocal affective cues of other species is due to cross-taxa similarities in acoustic parameters or the phylogenetic closeness between species is currently unclear. To address this, we first analyzed acoustic variation in 96 affective vocalizations, taken from agonistic and affiliative contexts, of humans and three other primates-rhesus macaques (Macaca mulatta), chimpanzees and bonobos (Pan troglodytes and Pan paniscus). Acoustic analyses revealed that agonistic chimpanzee and bonobo vocalizations were similarly distant from agonistic human voices, but chimpanzee affiliative vocalizations were significantly closer to human affiliative vocalizations, than those of bonobos, indicating a potential derived vocal evolution in the bonobo lineage. Second, we asked 68 human participants to categorize and also discriminate vocalizations based on their presumed affective content. Results showed that participants reliably categorized human and chimpanzee vocalizations according to affective content, but not bonobo threat vocalizations nor any macaque vocalizations. Participants discriminated all species calls above chance level except for threat calls by bonobos and macaques. Our results highlight the importance of both phylogenetic and acoustic parameter level explanations in cross-species affective perception, drawing a more complex picture to the origin of vocal emotions.
Topics: Animals; Humans; Phylogeny; Pan troglodytes; Macaca mulatta; Cues; Pan paniscus; Acoustics
PubMed: 37407601
DOI: 10.1038/s41598-023-37558-3 -
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 -
Nutrition Research Reviews Feb 2024The main cause of mortality in great apes in zoological settings is cardiovascular disease (CVD), affecting all four taxa: chimpanzee (), bonobo (), gorilla ( spp.) and... (Review)
Review
The main cause of mortality in great apes in zoological settings is cardiovascular disease (CVD), affecting all four taxa: chimpanzee (), bonobo (), gorilla ( spp.) and orangutan ( spp.). Myocardial fibrosis, the most typical histological characterisation of CVD in great apes, is non-specific, making it challenging to understand the aetiopathogenesis. A multifactorial origin of disease is assumed whereby many potential causative factors are directly or indirectly related to the diet, which in wild-living great apes mainly consists of high-fibre, low-carbohydrate and very low-sodium components. Diets of great apes housed in zoological settings are often different compared with the situation in the wild. Moreover, low circulating vitamin D levels have recently been recognised in great apes housed in more northern regions. Evaluation of current supplementation guidelines shows that, despite implementation of different dietary strategies, animals stay vitamin D insufficient. Therefore, recent hypotheses designate vitamin D deficiency as a potential underlying factor in the pathogenesis of myocardial fibrosis. The aim of this literature review is to: (i) examine important differences in nutritional factors between zoological and wild great ape populations; (ii) explain the potential detrimental effects of the highlighted dietary discrepancies on cardiovascular function in great apes; and (iii) elucidate specific nutrition-related pathophysiological mechanisms that may underlie the development of myocardial fibrosis. This information may contribute to understanding the aetiopathogenesis of myocardial fibrosis in great apes and pave the way for future clinical studies and a more preventive approach to great ape CVD management.
PubMed: 38343129
DOI: 10.1017/S0954422424000076