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Anatomical Record (Hoboken, N.J. : 2007) May 2017Elucidating the pelvic morphology of the Pan-Homo last common ancestor (LCA) is crucial for understanding ape and human evolution. The pelvis of Ardipithecus ramidus has...
Elucidating the pelvic morphology of the Pan-Homo last common ancestor (LCA) is crucial for understanding ape and human evolution. The pelvis of Ardipithecus ramidus has been the basis of controversial interpretations of the LCA pelvis. In particular, it was proposed that the lower ilium became elongate independently in the orangutan and chimpanzee clades, making these taxa poor analogues for the pelvis of the LCA. This study examines the variation in relative lower ilium height between and within living and fossil hominoid species (and other anthropoids), and models its evolution using available fossil hominoids as calibration points. We find nuanced differences in relative lower ilium height among living hominoids, particularly in regards to gorillas, which do not have elongate lower ilia (because they are likely to represent the plesiomorphic hominoid condition for this trait). We also show that differences in relative lower ilium height among hominoid taxa are not readily explained by differences in size between species. Our maximum likelihood ancestral state reconstructions support inferences that chimpanzees (Pan troglodytes in particular) and orangutans evolved their elongate lower ilia independently. We also find that the predicted lower ilium height of the Pan-Homo LCA is shorter than all great apes except gorillas. This study adds to a growing body of evidence that finds different regions of the body show different evolutionary histories in different hominoids, and underscores that the unique combinations of morphologies of each modern and fossil hominoid species should be considered when reconstructing the mosaic nature of the Pan-Homo LCA. Anat Rec, 300:828-844, 2017. © 2017 Wiley Periodicals, Inc.
Topics: Animals; Biological Evolution; Fossils; Hominidae; Ilium; Pan troglodytes; Phylogeny
PubMed: 28406561
DOI: 10.1002/ar.23545 -
Journal of Comparative Psychology... Aug 2020Eye gaze is widespread in nonhuman primate taxa and important for social cognition and communicative signaling. Bonobos and chimpanzees, two closely related primate...
Eye gaze is widespread in nonhuman primate taxa and important for social cognition and communicative signaling. Bonobos and chimpanzees, two closely related primate species, differ in social organization, behavior, and cognition. Chimpanzees' eye gaze and gaze following has been studied extensively, whereas less is known about bonobos' eye gaze. To examine species differences using a more ecologically relevant measure than videos or pictures, the current study compared bonobo and chimpanzee mutual eye gaze with a human observer. A multivariate analysis of variance revealed significant species differences in frequency and total duration, but not bout length, of mutual eye gaze ( < .001). Specifically, bonobos engage in mutual eye gaze more frequently and for longer total duration than chimpanzees. These results are likely related to species differences in social behavior and temperament and are consistent with eye-tracking studies in which bonobos looked at the eye region of conspecifics (in pictures and videos) longer than chimpanzees. Future research should examine the relationship between mutual eye gaze and gaze following, as well as examine its genetic and neurological correlates. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
Topics: Animals; Behavior, Animal; Female; Fixation, Ocular; Humans; Pan paniscus; Pan troglodytes; Social Behavior; Species Specificity
PubMed: 32804530
DOI: 10.1037/com0000247 -
Molecular Biology and Evolution Jan 2020Novel sequences (NSs), not present in the human reference genome, are abundant and remain largely unexplored. Here, we utilize de novo assembly to study NS in 1,000...
Novel sequences (NSs), not present in the human reference genome, are abundant and remain largely unexplored. Here, we utilize de novo assembly to study NS in 1,000 Swedish individuals first sequenced as part of the SweGen project revealing a total of 46 Mb in 61,044 distinct contigs of sequences not present in GRCh38. The contigs were aligned to recently published catalogs of Icelandic and Pan-African NSs, as well as the chimpanzee genome, revealing a great diversity of shared sequences. Analyzing the positioning of NS across the chimpanzee genome, we find that 2,807 NS align confidently within 143 chimpanzee orthologs of human genes. Aligning the whole genome sequencing data to the chimpanzee genome, we discover ancestral NS common throughout the Swedish population. The NSs were searched for repeats and repeat elements: revealing a majority of repetitive sequence (56%), and enrichment of simple repeats (28%) and satellites (15%). Lastly, we align the unmappable reads of a subset of the thousand genomes data to our collection of NS, as well as the previously published Pan-African NS: revealing that both the Swedish and Pan-African NS are widespread, and that the Swedish NSs are largely a subset of the Pan-African NS. Overall, these results highlight the importance of creating a more diverse reference genome and illustrate that significant amounts of the NS may be of ancestral origin.
Topics: Animals; Genetic Variation; Genome, Human; Humans; Pan troglodytes; Sweden; Whole Genome Sequencing
PubMed: 31560401
DOI: 10.1093/molbev/msz176 -
NeuroImage Aug 2022Humans and chimpanzees both exhibit a diverse set of tool use skills which suggests selection for tool manufacture and use occurred in the common ancestors of the two...
Phenotypic and genetic associations between gray matter covariation and tool use skill in chimpanzees (Pan troglodytes): Repeatability in two genetically isolated populations.
Humans and chimpanzees both exhibit a diverse set of tool use skills which suggests selection for tool manufacture and use occurred in the common ancestors of the two species. Our group has previously reported phenotypic and genetic associations between tool use skill and gray matter covariation, as quantified by source-based morphometry (SBM), in chimpanzees. As a follow up study, here we evaluated repeatability in heritability in SBM components and their phenotypic association with tool use skill in two genetically independent chimpanzee cohorts. Within the two independent cohorts of chimpanzees, we identified 8 and 16 SBM components, respectively. Significant heritability was evident for multiple SBM components within both cohorts. Further, phenotypic associations between tool use performance and the SBM components were largely consistent between the two cohorts; the most consistent finding being an association between tool use performance and an SBM component including the posterior superior temporal sulcus (STS) and superior temporal gyrus (STG), and the interior and superior parietal regions (p < 0.05). These findings indicate that the STS, STG, and parietal cortices are phenotypically and genetically implicated in chimpanzee tool use abilities.
Topics: Animals; Follow-Up Studies; Gray Matter; Humans; Pan troglodytes; Temporal Lobe; Tool Use Behavior
PubMed: 35551989
DOI: 10.1016/j.neuroimage.2022.119292 -
Current Biology : CB Apr 2019Temperament and personality research in humans and nonhuman animals measures behavioral variation in individual, population, or species-specific traits with implications...
Temperament and personality research in humans and nonhuman animals measures behavioral variation in individual, population, or species-specific traits with implications for survival and fitness, such as social status, foraging, and mating success [1-5]. Curiosity and risk-taking tendencies have been studied extensively across taxa by measuring boldness and exploration responses to experimental novelty exposure [3, 4, 6-15]. Here, we conduct a natural field experiment using wildlife monitoring technology to test variation in the reaction of wild great apes (43 groups of naive chimpanzees, bonobos, and western gorillas across 14 field sites in Africa) to a novel object, the camera trap. Bonobo and gorilla groups demonstrated a stronger looking impulse toward the camera trap device compared to chimpanzees, suggesting higher visual attention and curiosity. Bonobos were also more likely to show alarm and other fearful behaviors, although such neophobic (and conversely, neophilic) responses were generally rare. Among all three species, individuals looked at cameras longer when they were young, were associating with fewer individuals, and did not live near a long-term research site. Overall, these findings partially validate results from great ape novelty paradigms in captivity [7, 8]. We further suggest that species-typical leadership styles [16] and social and environmental effects, including familiarity with humans, best explain novelty responses of wild great apes. In sum, this study illustrates the feasibility of large-scale field experiments and the importance of both intrinsic and extrinsic factors in shaping animal curiosity. VIDEO ABSTRACT.
Topics: Africa; Animals; Exploratory Behavior; Female; Gorilla gorilla; Male; Pan paniscus; Pan troglodytes; Photography; Species Specificity
PubMed: 30880013
DOI: 10.1016/j.cub.2019.02.024 -
Philosophical Transactions of the Royal... May 2022Group territory defence poses a collective action problem: individuals can free-ride, benefiting without paying the costs. Individual heterogeneity has been proposed to...
Group territory defence poses a collective action problem: individuals can free-ride, benefiting without paying the costs. Individual heterogeneity has been proposed to solve such problems, as individuals high in reproductive success, rank, fighting ability or motivation may benefit from defending territories even if others free-ride. To test this hypothesis, we analysed 30 years of data from chimpanzees () in the Kasekela community, Gombe National Park, Tanzania (1978-2007). We examined the extent to which individual participation in patrols varied according to correlates of reproductive success (mating rate, rank, age), fighting ability (hunting), motivation (scores from personality ratings), costs of defecting (the number of adult males in the community) and gregariousness (sighting frequency). By contrast to expectations from collective action theory, males participated in patrols at consistently high rates (mean ± s.d. = 74.5 ± 11.1% of patrols, = 23 males). The best predictors of patrol participation were sighting frequency, age and hunting participation. Current and former alpha males did not participate at a higher rate than males that never achieved alpha status. These findings suggest that the temptation to free-ride is low, and that a mutualistic mechanism such as group augmentation may better explain individual participation in group territorial behaviour. This article is part of the theme issue 'Intergroup conflict across taxa'.
Topics: Animals; Humans; Male; Motivation; Pan troglodytes; Personality; Reproduction; Territoriality
PubMed: 35369753
DOI: 10.1098/rstb.2021.0151 -
Psychological Science Mar 2023Risk preference impacts how people make key life decisions related to health, wealth, and well-being. Systematic variations in risk-taking behavior can be the result of...
Risk preference impacts how people make key life decisions related to health, wealth, and well-being. Systematic variations in risk-taking behavior can be the result of differences in fitness expectations, as predicted by life-history theory. Yet the evolutionary roots of human risk-taking behavior remain poorly understood. Here, we studied risk preferences of chimpanzees (86 ; 47 females; age = 2-40 years) using a multimethod approach that combined observer ratings with behavioral choice experiments. We found that chimpanzees' willingness to take risks shared structural similarities with that of humans. First, chimpanzees' risk preference manifested as a traitlike preference that was consistent across domains and measurements. Second, chimpanzees were ambiguity averse. Third, males were more risk prone than females. Fourth, the appetite for risk showed an inverted-U-shaped relation to age and peaked in young adulthood. Our findings suggest that key dimensions of risk preference appear to emerge independently of the influence of human cultural evolution.
Topics: Animals; Female; Humans; Male; Pan troglodytes; Risk-Taking; Biological Evolution
PubMed: 36595467
DOI: 10.1177/09567976221140326 -
Anatomical Record (Hoboken, N.J. : 2007) Feb 2021The facial muscles have significant roles for vocalization, feeding, and facial expression in both human and non-human primates. Of these, the anatomy of the incisivus...
The facial muscles have significant roles for vocalization, feeding, and facial expression in both human and non-human primates. Of these, the anatomy of the incisivus labii superioris (ILS) and incisivus labii inferioris (ILI), which are considered as the accessory bundle of the orbicularis oris (OO) in humans, has rarely been documented in the literature. Our current understanding of the function of the ILS and ILI is that they probably retract the upper and lower lips. Also, there is no account of these muscles in non-human primates in the current literature. The aim of this study was to reveal the ILS and ILI in non-human primates. Five Macaca fascicularis, one Macaca fuscata, one Macaca fuscata yakui, and one Pan troglodytes were dissected. Seven formalin-fixed cadavers and one fresh cadaver were included. Both the ILS and ILI were observed in all specimens. The ILS originated from the incisive fossa of the maxilla and inserted into the OO. The mentalis (MT) and ILI arose from the incisive fossa of the mandible and inserted into the OO and the skin of the chin area. The MT and ILI in the P. troglodytes examined were thicker than in the other three non-human species, and the ILS and ILI in the three macaques were similar in shape to those of humans. The difference of these muscles may result in different functions of the lip such as during vocalization, feeding, and facial expression.
Topics: Animals; Facial Expression; Facial Muscles; Lip; Macaca; Pan troglodytes; Vocalization, Animal
PubMed: 32420698
DOI: 10.1002/ar.24406 -
Philosophical Transactions of the Royal... Mar 2021Non-human primates evaluate choices based on quantitative information and subjective valuation of options. Non-human primates can learn to value tokens as placeholders... (Review)
Review
Non-human primates evaluate choices based on quantitative information and subjective valuation of options. Non-human primates can learn to value tokens as placeholders for primary rewards (such as food). With those tokens established as a potential form of 'currency', it is then possible to examine how they respond to opportunities to earn and use tokens in ways such as accumulating tokens or exchanging tokens with each other or with human experimenters to gain primary rewards. Sometimes, individuals make efficient and beneficial choices to obtain tokens and then exchange them at the right moments to gain optimal reward. Sometimes, they even accumulate such rewards through extended delay of gratification, or through other exchange-based interactions. Thus, non-human primates are capable of associating value to arbitrary tokens that may function as currency-like stimuli, but there also are strong limitations on how non-human primates can integrate such tokens into choice situations or use such tokens to fully 'symbolize' economic decision-making. These limitations are important to acknowledge when considering the evolutionary emergence of currency use in our species. This article is part of the theme issue 'Existence and prevalence of economic behaviours among non-human primates'.
Topics: Animals; Biological Evolution; Cebinae; Choice Behavior; Learning; Macaca; Pan troglodytes; Reward
PubMed: 33423633
DOI: 10.1098/rstb.2019.0675 -
Current Biology : CB Nov 2020Animals use a variety of strategies to navigate their world, but few are thought to have detailed mental maps of their landscapes. New research with our closest...
Animals use a variety of strategies to navigate their world, but few are thought to have detailed mental maps of their landscapes. New research with our closest relatives suggests chimpanzees may use cognitive maps to find the most energy efficient routes.
Topics: Animals; Ecology; Goals; Pan troglodytes
PubMed: 33202239
DOI: 10.1016/j.cub.2020.09.029