Personality Structure and Social Style in Macaques Adams, Mark James; Majolo, Bonaventura; Ostner, Julia ...
Journal of personality and social psychology,
08/2015, Volume:
109, Issue:
2
Journal Article
Peer reviewed
Open access
Why regularities in personality can be described with particular dimensions is a basic question in differential psychology. Nonhuman primates can also be characterized in terms of personality ...structure. Comparative approaches can help reveal phylogenetic constraints and social and ecological patterns associated with the presence or absence of specific personality dimensions. We sought to determine how different personality structures are related to interspecific variation in social style. Specifically, we examined this question in 6 different species of macaques, because macaque social style is well characterized and can be categorized on a spectrum of despotic (Grade 1) versus tolerant (Grade 4) social styles. We derived personality structures from adjectival ratings of Japanese (Macaca fuscata; Grade 1), Assamese (M. assamensis; Grade 2), Barbary (M. sylvanus; Grade 3), Tonkean (M. tonkeana; Grade 4), and crested (M. nigra; Grade 4) macaques and compared these species with rhesus macaques (M. mulatta; Grade 1) whose personality was previously characterized. Using a nonparametric method, fuzzy set analysis, to identify commonalities in personality dimensions across species, we found that all but 1 species exhibited consistently defined Friendliness and Openness dimensions, but that similarities in personality dimensions capturing aggression and social competence reflect similarities in social styles. These findings suggest that social and phylogenetic relationships contribute to the origin, maintenance, and diversification of personality.
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The heritability of human personality is well-established. Recent research indicates that nonadditive genetic effects, such as dominance and epistasis, play a large role in personality variation. One ...possible explanation for the latter finding is that there has been recent selection on human personality. To test this possibility, we estimated additive and nonadditive genetic variance in personality and subjective well-being of zoo-housed orangutans. More than half of the genetic variance in these traits could be attributed to nonadditive genetic effects, modeled as dominance. Subjective well-being had genetic overlap with personality, though less so than has been found in humans or chimpanzees. Since a large portion of nonadditive genetic variance in personality is not unique to humans, the nonadditivity of human personality is not sufficient evidence for recent selection of personality in humans. Nonadditive genetic variance may be a general feature of the genetic structure of personality in primates and other animals.
The heritability of Major Depressive Disorder (MDD) has been estimated at 37% based largely on twin studies that rely on contested assumptions. More recently, the heritability of MDD has been ...estimated on large populations from registries such as the Swedish, Finnish, and Chinese cohorts. Family-based designs utilise a number of different relationships and provide an alternative means of estimating heritability. Generation Scotland: Scottish Family Health Study (GS:SFHS) is a large (n = 20,198), family-based population study designed to identify the genetic determinants of common diseases, including Major Depressive Disorder. Two thousand seven hundred and six individuals were SCID diagnosed with MDD, 13.5% of the cohort, from which we inferred a population prevalence of 12.2% (95% credible interval: 11.4% to 13.1%). Increased risk of MDD was associated with being female, unemployed due to a disability, current smokers, former drinkers, and living in areas of greater social deprivation. The heritability of MDD in GS:SFHS was between 28% and 44%, estimated from a pedigree model. The genetic correlation of MDD between sexes, age of onset, and illness course were examined and showed strong genetic correlations. The genetic correlation between males and females with MDD was 0.75 (0.43 to 0.99); between earlier (≤ age 40) and later (> age 40) onset was 0.85 (0.66 to 0.98); and between single and recurrent episodic illness course was 0.87 (0.72 to 0.98). We found that the heritability of recurrent MDD illness course was significantly greater than the heritability of single MDD illness course. The study confirms a moderate genetic contribution to depression, with a small contribution of the common family environment (variance proportion = 0.07, CI: 0.01 to 0.15), and supports the relationship of MDD with previously identified risk factors. This study did not find robust support for genetic differences in MDD due to sex, age of onset, or illness course. However, we found an intriguing difference in heritability between recurrent and single MDD illness course. These findings establish GS:SFHS as a valuable cohort for the genetic investigation of MDD.
A general intelligence factor in dogs Arden, Rosalind; Adams, Mark James
Intelligence (Norwood),
March-April 2016, 2016-03-00, 20160301, Volume:
55
Journal Article
Peer reviewed
Hundreds of studies have shown that, in people, cognitive abilities overlap yielding an underlying ‘g’ factor, which explains much of the variance. We assessed individual differences in cognitive ...abilities in 68 border collies to determine the structure of intelligence in dogs. We administered four configurations of a detour test and repeated trials of two choice tasks (point-following and quantity-discrimination). We used confirmatory factor analysis to test alternative models explaining test performance. The best-fitting model was a hierarchical model with three lower-order factors for the detour time, choice time, and choice score and a higher order factor; these accounted jointly for 68% of the variance in task scores. The higher order factor alone accounted for 17% of the variance. Dogs that quickly completed the detour tasks also tended to score highly on the choice tasks; this could be explained by a general intelligence factor. Learning about g in non human species is an essential component of developing a complete theory of g; this is feasible because testing cognitive abilities in other species does not depend on ecologically relevant tests. Discovering the place of g among fitness-bearing traits in other species will constitute a major advance in understanding the evolution of intelligence.
•The structure of cognitive abilities in dogs is similar to that found in people.•Dogs that solved problems more quickly were also more accurate.•Dogs' cognitive abilities can be tested quickly, like those of people.•Bigger individual differences studies on dog cognition will contribute to cognitive epidemiology.
Ratings of chimpanzee, Pan troglodytes, and orang-utan, Pongo pygmaeus and Pongo abelii, personality reveal dimensions resembling those found in humans. Critics have argued that this similarity ...derives from anthropomorphic projection or other rater-based effects. We developed two forms of data reduction analyses to determine whether these dimensions can best be explained by the inherent tendencies of the animals (e.g. orang-utans that are curious are playful) or anthropomorphic projections of raters (e.g. believing that orang-utans that are curious should be playful). We found that personality dimensions derived after differences between rater means and rater*item interactions had been removed from ratings replicated the previously discovered dimensions. Conversely, we found a different set of dimensions when analysing items from which differences between animal means and animal*item interactions had been removed. Finally, we used multilevel factor analysis to examine whether the published structure was replicated when we extracted factors based on the within-level animal differences in item scores effects while allowing between-rater differences to covary freely. Again, the personality dimensions were similar to those described in previous studies. These analyses can be used in combination with interrater reliability, temporal stability, and correlations between personality and other external variables to validate animal personality ratings. These analyses confirmed that personality similarities between humans and great apes are best explained by genetic and phylogenetic affinity and not by anthropomorphic artefacts.
► We tested whether personality ratings are anthropomorphic projections. ► Anthropomorphism could not explain chimpanzee or orang-utan personality dimensions. ► Anthropomorphic dimensions differed from subject-based dimensions. ► Personality ratings are a valid approach to studying animal personality.
The analysis of phenotypic covariances among genetically related individuals is the basis for estimations of genetic and phenotypic effects on phenotypes. Beyond heritability, there are several other ...estimates that can be made with behavior genetic models of interest to primatologists. Some of these estimates are feasible with primate samples because they take advantage of the types of relatives available to compare in primate species and because most behaviors are expressed orders of magnitude more often and in a greater variety of contexts than morphological or life-history traits. The hypotheses that can be tested with these estimates are contrasted with hypotheses that will be difficult to achieve in primates because of sample size limitations. Feasible comparisons include the proportion of variance from interaction effects, the variation of genetic effects across environments, and the genetics of growth and development. Simulation shows that uncertainty of genetic parameters can be reduced by sampling each individual more than once. Because sample sizes are likely to remain relatively small in most primate behavior genetics, expressing uncertainty in parameter estimates is needed to move our inferences forward.
Personality dimensions capturing individual differences in behavior, cognition, and affect have been described in several species, including humans, chimpanzees, and orangutans. However, comparisons ...between species are limited by the use of different questionnaires. We asked raters to assess free-ranging rhesus macaques at two time points on personality and subjective well-being questionnaires used earlier to rate chimpanzees and orangutans. Principal-components analysis yielded domains we labeled Confidence, Friendliness, Dominance, Anxiety, Openness, and Activity. The presence of Openness in rhesus macaques suggests it is an ancestral characteristic. The absence of Conscientiousness suggests it is a derived characteristic in African apes. Higher Confidence and Friendliness, and lower Anxiety were prospectively related to subjective well-being, indicating that the connection between personality and subjective well-being in humans, chimpanzees, and orangutans is ancestral in catarrhine primates. As demonstrated here, each additional species studied adds another fold to the rich, historical story of primate personality evolution.
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Phenotypes expressed in a social context are not only a function of the individual, but can also be shaped by the phenotypes of social partners. These social effects may play a major role in the ...evolution of cooperative breeding if social partners differ in the quality of care they provide and if individual carers adjust their effort in relation to that of other carers. When applying social effects models to wild study systems, it is also important to explore sources of individual plasticity that could masquerade as social effects. We studied offspring provisioning rates of parents and helpers in a wild population of long-tailed tits Aegithalos caudatus using a quantitative genetic framework to identify these social effects and partition them into genetic, permanent environment and current environment components. Controlling for other effects, individuals were consistent in their provisioning effort at a given nest, but adjusted their effort based on who was in their social group, indicating the presence of social effects. However, these social effects differed between years and social contexts, indicating a current environment effect, rather than indicating a genetic or permanent environment effect. While this study reveals the importance of examining environmental and genetic sources of social effects, the framework we present is entirely general, enabling a greater understanding of potentially important social effects within any ecological population.
► We tested whether there was a general factor of personality (GFP) in chimpanzees, orangutans, or rhesus macaques. ► In each of these species we tried extracting a GFP using confirmatory factor ...analysis (CFA) and two principal axis factor analyses (PFA). ► If a GFP exists, we would expect good model fit, loadings consistent with a GFP, and/or two correlated higher-order factors. ► We found no evidence of a GFP in chimpanzees, orangutans, or rhesus macaques.
We examined whether a general factor of personality (GFP) was present in chimpanzees, orangutans, or rhesus macaques. We used confirmatory factor analysis (CFA) to model correlations among first-order factors as arising from a GFP. We then conducted principal axis factor analyses (PFA) of the first-order factors to extract a single higher-order factor and then to extract two oblique higher-order factors. The CFA model fit was poor for chimpanzees and orangutans, but not rhesus macaques. The single higher-order factors extracted via PFA did not resemble the GFP in all three species. The oblique higher-order factors extracted via PFA were only weakly correlated in all three species. These results do not support the existence of a GFP in nonhuman primates.
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