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Psychological Science Sep 2015To better understand human and chimpanzee personality evolution, we obtained trait ratings of personality for 154 captive bonobos (~80% of the U.S. and European...
To better understand human and chimpanzee personality evolution, we obtained trait ratings of personality for 154 captive bonobos (~80% of the U.S. and European population). We found factors that we labeled Assertiveness, Conscientiousness, Openness, Agreeableness, Attentiveness, and Extraversion. The interrater reliabilities and test-retest reliabilities for these factors were comparable to those found in humans and other species. Using orthogonal targeted Procrustes rotations, we compared the bonobo dimensions with those of three samples of captive chimpanzees. Overall congruence coefficients indicated a fair degree of similarity; at the factor level, there was good evidence for Assertiveness, Conscientiousness, Openness, and Agreeableness in the chimpanzee samples; evidence for Attentiveness and Extraversion was poor. These findings suggest that, as expected given their close phylogenetic relationship, bonobo personality structure resembles chimpanzee personality structure in some respects. However, divergent evolution, perhaps as a result of socioecological differences between bonobos and chimpanzees, also appears to have shaped personality structure in these species.
Topics: Animals; Behavior, Animal; Biological Evolution; Female; Male; Pan paniscus; Pan troglodytes; Personality; Phylogeny
PubMed: 26209530
DOI: 10.1177/0956797615589933 -
Science (New York, N.Y.) Nov 2023Bonobos provide insight into the origins of partner-specific cooperation in human groups.
Bonobos provide insight into the origins of partner-specific cooperation in human groups.
Topics: Animals; Humans; Pan paniscus; Pan troglodytes; Mass Behavior; Cooperative Behavior; Grooming
PubMed: 37972176
DOI: 10.1126/science.adl1813 -
American Journal of Physical... Apr 2021The Giles hypothesis posits that differences in the cranial morphology of Pan troglodytes and Gorilla gorilla are largely the result of allometric scaling. However,...
OBJECTIVES
The Giles hypothesis posits that differences in the cranial morphology of Pan troglodytes and Gorilla gorilla are largely the result of allometric scaling. However, previous support for the Giles hypothesis was based on bivariate plots of linear measurements. This investigation uses geometric morphometric methods to retest this hypothesis and its prediction that extending the ontogenetic trajectory of a chimpanzee would produce an adult gorilla-like cranial morphology.
MATERIALS AND METHODS
Forty-three 3D cranial landmarks were collected from an ontogenetic series of 76 Pan troglodytes and 58 Gorilla gorilla specimens. Ontogenetic trajectories of cranial shape change were computed via multivariate regression of Procrustes aligned coordinates against LnCS (size vector) and molar eruption stage (developmental vector). These two vectors were then used in developmental simulations to extend the ontogenetic trajectories of adult chimpanzees. Allometric trajectories of chimpanzees and gorillas were also directly compared using Procrustes ANOVA.
RESULTS
Pan and Gorilla significantly differ in their allometric trajectories, and none of the Pan developmental simulations resembled actual adult gorillas. Additionally, the more the Pan developmental vector was extended, the more morphologically distinct the simulations became from actual adult gorillas.
DISCUSSION
Taken together, these results do not support the Giles hypothesis that allometric scaling is primarily responsible for observed morphological differences between chimpanzee and gorilla crania. This investigation demonstrates that neither "growing" a chimpanzee to the size of a gorilla, nor extending a chimpanzee's developmental shape trajectory will result in an adult gorilla-like cranial morphology as they differ in their patterns of allometry.
Topics: Animals; Anthropology, Physical; Biological Evolution; Cephalometry; Female; Gorilla gorilla; Male; Pan troglodytes; Skull
PubMed: 33393687
DOI: 10.1002/ajpa.24219 -
Nature Communications Sep 2020Large brains and behavioural innovation are positively correlated, species-specific traits, associated with the behavioural flexibility animals need for adapting to...
Large brains and behavioural innovation are positively correlated, species-specific traits, associated with the behavioural flexibility animals need for adapting to seasonal and unpredictable habitats. Similar ecological challenges would have been important drivers throughout human evolution. However, studies examining the influence of environmental variability on within-species behavioural diversity are lacking despite the critical assumption that population diversification precedes genetic divergence and speciation. Here, using a dataset of 144 wild chimpanzee (Pan troglodytes) communities, we show that chimpanzees exhibit greater behavioural diversity in environments with more variability - in both recent and historical timescales. Notably, distance from Pleistocene forest refugia is associated with the presence of a larger number of behavioural traits, including both tool and non-tool use behaviours. Since more than half of the behaviours investigated are also likely to be cultural, we suggest that environmental variability was a critical evolutionary force promoting the behavioural, as well as cultural diversification of great apes.
Topics: Animals; Behavior, Animal; Ecosystem; Environment; Female; Forests; Male; Pan troglodytes; Tool Use Behavior
PubMed: 32934202
DOI: 10.1038/s41467-020-18176-3 -
Current Biology : CB Aug 2019Garcia and Dunn [1] raise some interesting and valuable points regarding our recent paper in Current Biology[2]. As Garcia and Dunn [1] point out, cross-species...
Garcia and Dunn [1] raise some interesting and valuable points regarding our recent paper in Current Biology[2]. As Garcia and Dunn [1] point out, cross-species variation in vocal and anatomical relations allows for the identification of relevant outliers from the body size - fundamental frequency (f) regression. However, this depends on the premise that the chosen or available f and body size values are typical of the species. A motivation for our study [2] was in part to improve the accuracy of such estimates by providing more data per species compared to previous studies. We address each point of their critique by controlling for cross-species body size variation using body weights for chimpanzees (Pan troglodytes) and bonobos (Pan paniscus), addressing potential call variation in different subspecies of Pan troglodytes, measuring minimum f as well as maximum f and possible effects caused by different larynx fixation methods.
Topics: Animals; Larynx; Pan paniscus; Pan troglodytes
PubMed: 31386846
DOI: 10.1016/j.cub.2019.06.023 -
The Veterinary Record Nov 2023Georgina Mills discusses new research that investigates if the hormonal changes seen in women in later life are reflected in chimpanzees.
Georgina Mills discusses new research that investigates if the hormonal changes seen in women in later life are reflected in chimpanzees.
Topics: Female; Animals; Pan troglodytes; Menopause
PubMed: 37975459
DOI: 10.1002/vetr.3683 -
American Journal of Biological... Feb 2022Craniofacial fluctuating asymmetry (FA) refers to the random deviations from symmetry exhibited across the craniofacial complex and can be used as a measure of...
OBJECTIVES
Craniofacial fluctuating asymmetry (FA) refers to the random deviations from symmetry exhibited across the craniofacial complex and can be used as a measure of developmental instability for organisms with bilateral symmetry. This article addresses the lack of data on craniofacial FA in nonhuman primates by analyzing FA magnitude and variation in chimpanzees, gorillas, and macaques. We offer a preliminary investigation into how FA, as a proxy for developmental instability, varies within and among nonhuman primates.
MATERIALS AND METHODS
We generated 3D surface models of 121 crania from Pan troglodytes troglodytes, Gorilla gorilla gorilla, and Macaca fascicularis fascicularis. Using geometric morphometric techniques, the magnitude of observed FA was calculated and compared for each individual, sex, and taxon, along with the variation of FA across cranial regions and for each bilateral landmark.
RESULTS
Gorillas and macaques exhibited higher and more similar magnitudes of FA to each other than either taxon did to chimpanzees; variation in magnitude of FA followed this same trend. No significant differences were detected between sexes using pooled data across species, but sex did influence FA magnitude within taxa in gorillas. Further, variation in FA variance across cranial regions and by landmark was not distributed in any particular pattern.
CONCLUSION
Possible environmentally induced causes for these patterns of FA magnitude include differences in growth rate and physiological stress experienced during life. Developmental stability may be greatest in chimpanzees in this sample. Additionally, these results point to appropriate landmarks for future FA analyses and may help suggest more urgent candidate taxa for conservation efforts.
Topics: Animals; Gorilla gorilla; Pan troglodytes; Macaca; Hominidae; Skull; Facial Asymmetry
PubMed: 36790754
DOI: 10.1002/ajpa.24432 -
Proceedings of the National Academy of... Nov 2018Understanding intraspecific variation in sociality is essential for characterizing the flexibility and evolution of social systems, yet its study in nonhuman animals is...
Understanding intraspecific variation in sociality is essential for characterizing the flexibility and evolution of social systems, yet its study in nonhuman animals is rare. Here, we investigated whether chimpanzees exhibit population-level differences in sociality that cannot be easily explained by differences in genetics or ecology. We compared social proximity and grooming tendencies across four semiwild populations of chimpanzees living in the same ecological environment over three consecutive years, using both linear mixed models and social network analysis. Results indicated temporally stable, population-level differences in dyadic-level sociality. Moreover, group cohesion measures capturing network characteristics beyond dyadic interactions (clustering, modularity, and social differentiation) showed population-level differences consistent with the dyadic indices. Subsequently, we explored whether the observed intraspecific variation in sociality could be attributed to cultural processes by ruling out alternative sources of variation including the influences of ecology, genetics, and differences in population demographics. We conclude that substantial variation in social behavior exists across neighboring populations of chimpanzees and that this variation is in part shaped by cultural processes.
Topics: Animals; Competitive Behavior; Cooperative Behavior; Female; Grooming; Male; Models, Statistical; Pan troglodytes; Population Dynamics; Social Conformity; Social Dominance; Zambia
PubMed: 30397113
DOI: 10.1073/pnas.1722614115 -
ELife Oct 2018Life history strategies for optimizing individual fitness fall on a spectrum between maximizing reproductive efforts and maintaining physical health over time....
Life history strategies for optimizing individual fitness fall on a spectrum between maximizing reproductive efforts and maintaining physical health over time. Strategies across this spectrum are viable and different suites of personality traits evolved to support these strategies. Using data from 538 captive chimpanzees () we tested whether any of the dimensions of chimpanzee personality - agreeableness, conscientiousness, dominance, extraversion, neuroticism, and openness - were associated with longevity, an attribute of slow life history strategies that is especially important in primates given their relatively long lives. We found that higher agreeableness was related to longevity in males, with weaker evidence suggesting that higher openness is related to longer life in females. Our results link the literature on human and nonhuman primate survival and suggest that, for males, evolution has favored the protective effects of low aggression and high quality social bonds.
Topics: Aggression; Animals; Extraversion, Psychological; Female; Humans; Longevity; Male; Pan troglodytes; Personality; Sex Characteristics
PubMed: 30296994
DOI: 10.7554/eLife.33781 -
Philosophical Transactions of the Royal... Apr 2018Major routes to identifying individual differences (in diverse species) include studies of behaviour patterns as represented in language and neurophysiology. But results... (Review)
Review
Major routes to identifying individual differences (in diverse species) include studies of behaviour patterns as represented in language and neurophysiology. But results from these approaches appear not to converge on some major dimensions. Identifying dimensions of human variation least applicable to non-human species may help to partition human-specific individual differences of recent evolutionary origin from those shared across species. Human culture includes learned, enforced social-norm systems that are symbolically reinforced and referenced in displays signalling adherence. At a key juncture in human evolution bullying aggression and deception-based cheating apparently became censured in the language of a moral community, enabling mutual observation coordinated in gossip, associated with external sanctions. That still-conserved cultural paradigm moralistically regulates selfish advantage-taking, with shared semantics and explicit rules. Ethics and moral codes remain critical and universal components of human culture and have a stronger imprint in language than most aspects of the currently popular Big-Five taxonomy, a model that sets out five major lines of individual-differences variation in human personality. In other species (e.g. chimpanzees), human observers might see apparent individual differences in morality-relevant traits, but not because the animals have human-analogue sanctioning systems. Removing the moral dimension of personality and other human-specific manifestations (e.g. religion) may aid in identifying those other bases of individual differences more ubiquitous across species.This article is part of the theme issue 'Diverse perspectives on diversity: multi-disciplinary approaches to taxonomies of individual differences'.
Topics: Animals; Biological Evolution; Bullying; Culture; Deception; Humans; Individuality; Language; Morals; Pan troglodytes; Punishment; Religion; Social Norms; Species Specificity
PubMed: 29483353
DOI: 10.1098/rstb.2017.0170