Age, but not hand preference, is related to personality traits in common marmosets (Callithrix jacchus).

The proximate mechanisms underlying animal personalities, i.e. consistent inter-individual differences in behaviour, are a matter of discussion. Brain lateralization, expressed as the preferred use of the contralateral limb, has been suggested as one of these mechanisms. In this study, we measured a proxy of brain lateralization in captive common marmosets (N = 28) by testing hand preference in a simple food-reaching task and evaluated personality by coding a wide range of behaviours observed in daily situations. We explored the links between personality and both direction and strength of hand preference, as well as age and sex, using linear models. Principal component analysis revealed that the stable behavioural variables were organized in three personality dimensions: Agreeableness, Extraversion and Neuroticism. Regarding hand preference, 14 individuals were left-handed, seven were right-handed and seven were ambilateral. Contrary to our predictions, we did not find any relationship between personality scores and hand preference or sex. Instead, age was a significant predictor of personality scores, with older individuals being more agreeable and less extraverted. The link between brain lateralization and personality seems to be equivocal and dependent on personality and brain lateralization assessment methods. Further examinations of other proximate mechanisms, such as physiology or (epi)genetics, may elucidate what drives personality variation in common marmosets.

Linking personality traits and reproductive success in common marmoset (Callithrix jacchus).

Animal personality can affect individual fitness and population growth. Personality traits of either parent or parents' combination may facilitate reproduction and offspring survival across species. However, previous studies focused mainly on the role of only one sex, and the link between personality and fitness has not been confirmed in primates. We examined this link in both sexes of captive common marmosets (Callithrix jacchus), a cooperatively breeding primate with extensive paternal care. We studied the effects of five personality traits of the parents (Agreeableness, Assertiveness, Conscientiousness, Inquisitiveness, and Patience), including their absolute and directional differences within pairs, on key components of reproductive performance. We expected pairs with more similar personality scores to have higher reproductive success as found in other species with long-term pairs and biparental care, but found no evidence for this hypothesis. Instead, we detected strong effects of female traits on inter-birth intervals, which were shorter in more agreeable females, and fecundity rates, which were higher in more inquisitive females. Male traits appeared to have only a limited effect on reproductive success of the pair. Our study demonstrates that various aspects of animal personality underpin reproductive performance in captive common marmosets and provides novel insights into the possible ultimate causes of personality in cooperatively breeding species.

Health service needs and perspectives of remote forest communities in Papua New Guinea: study protocol for combined clinical and rapid anthropological assessments with parallel treatment of urgent cases.

INTRODUCTION: Our project follows community requests for health service incorporation into conservation collaborations in the rainforests of Papua New Guinea (PNG). This protocol is for health needs assessments, our first step in coplanning medical provision in communities with no existing health data. METHODS AND ANALYSIS: The study includes clinical assessments and rapid anthropological assessment procedures (RAP) exploring the health needs and perspectives of partner communities in two areas, conducted over 6 weeks fieldwork. First, in Wanang village (population c.200), which is set in lowland rainforest. Second, in six communities (population c.3000) along an altitudinal transect up the highest mountain in PNG, Mount Wilhelm. Individual primary care assessments incorporate physical examinations and questioning (providing qualitative and quantitative data) while RAP includes focus groups, interviews and field observations (providing qualitative data). Given absence of in-community primary care, treatments are offered alongside research activity but will not form part of the study. Data are collected by a research fellow, primary care clinician and two PNG research technicians. After quantitative and qualitative analyses, we will report: ethnoclassifications of disease, causes, symptoms and perceived appropriate treatment; community rankings of disease importance and service needs; attitudes regarding health service provision; disease burdens and associations with altitudinal-related variables and cultural practices. To aid wider use study tools are in online supplemental file, and paper and ODK versions are available free from the corresponding author. ETHICS AND DISSEMINATION: Challenges include supporting informed consent in communities with low literacy and diverse cultures, moral duties to provide treatment alongside research in medically underserved areas while minimising risks of therapeutic misconception and inappropriate inducement, and PNG research capacity building. Brighton and Sussex Medical School (UK), PNG Institute of Medical Research and PNG Medical Research Advisory Committee have approved the study. Dissemination will be via journals, village meetings and plain language summaries.

Comparative assessment of behaviorally derived personality structures in golden-handed tamarins (Saguinus midas), cotton-top tamarins (Saguinus oedipus), and common marmosets (Callithrix jacchus).

One way to address questions about the origins and adaptive significance of personality dimensions is by comparing the personality structures of closely related species that differ in their socioecological circumstances. For the present study, we compared the personalities of captive golden-handed tamarins (Saguinus midas; N = 28), cotton-top tamarins (Saguinus oedipus; N = 20), and common marmosets (Callithrix jacchus; N = 17). All 3 species are New World monkeys of the family Callitrichidae. They thus share reproductive and behavioral characteristics but differ some in terms of their diet, habitat, and social organization. We expected that personality structures of closely related tamarin species would overlap more, both in terms of number of dimensions and their content, than either would overlap with the personality structure of common marmosets. We assessed personality using behavioral observations and compared the personality structures by means of cross-species correlations and fuzzy set analyses. Principal component analyses identified components that we labeled Agreeableness, Assertiveness, and Extraversion in golden-handed tamarins and common marmosets and components labeled Confidence and Extraversion in cotton-top tamarins. The greater personality similarities of the two phylogenetically more distant species suggest that differences in social organization, and in both habitat diversity and complexity, contributed to the evolution of personality. However, we also found that behaviors clustered in similar ways in the two tamarin species, suggesting that phylogenetic relatedness and genus-specific socioecological characteristics, such as the degree of reproductive competition, shaped personality structure in this primate family. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Complex patterns of grooming and sexual activity in Barbary macaques (Macaca sylvanus).

Grooming in primates is often considered a "currency" that can be exchanged for other "services" or "commodities" such as reciprocal grooming, coalitionary support, infant handling, tolerance around food sources, active food sharing, or mating opportunities. Previous studies on primate grooming-for-sex exchange viewed the males as the demanding class, with the females as suppliers of mating opportunities. In this study, we examine the broader context of grooming-for-mating exchange in Barbary macaques in Gibraltar. Our data show that Barbary macaque males groom females with whom they are mating more frequently and for longer periods than other females, and the relationship between grooming and mating remains significant in both sexual and nonsexual contexts. In addition, females groomed males with whom they were mating more frequently and for longer periods than other males. In both sexes, grooming was observed to be far more frequent and to occur for longer durations in sexual compared to nonsexual contexts. We did not find any difference in grooming behavior between presexual and postsexual contexts. Our data suggest that there is no simple model to describe Barbary macaque grooming patterns in sexual contexts. Although our results are partly consistent with male use of grooming as payment for mating, broadly assessed grooming-mating patterns cannot be solely explained by a male-driven grooming-for-mating exchange.

How long does it take? Reliable personality assessment based on common behaviour in cotton-top tamarins (Saguinus oedipus).

Individual variation in behaviour has been shown to have important ecological and evolutionary consequences. Research on animal personality has therefore received considerable attention, yet some methodological issues remain unresolved. We tested whether assessing personality by coding common behaviours is as time-consuming method as some researchers believe it to be. Altogether, 300 hours of observation were collected on 20 captive cotton-top tamarins (Saguinus oedipus). We first examined the repeatability of behavioural indices that represented the behavioural repertoire of cotton-top tamarins. We then compared the personality structures, based on different lengths of observation time, of these behavioural indices. The minimum observational time necessary to obtain a stable personality structure was 5 to 7 hours per individual. This stable structure included two components: Extraversion and Confidence, which were similar to those described in great apes, Old World monkeys, and other New World monkeys. Our findings suggest that, at least in the case of cotton-top tamarins, behavioural coding over relatively short periods of time can be used to assess personality and that longer observation periods may yield diminishing returns.

Global variation in diurnal cortisol rhythms: evidence from Garisakang forager-horticulturalists of lowland Papua New Guinea.

The hypothalamic-pituitary-adrenal (HPA) axis represents an important and evolutionarily ancient biological pathway linking physical and psychological stressors with human health. Despite considerable research exploring the physiological stress response among developed populations, few studies have examined HPA activity in non-industrialized contexts, restricting understanding of variation in human stress reactivity across global socio-ecological diversity. The present study addresses this shortcoming by investigating diurnal cortisol rhythms among Garisakang forager-horticulturalists of remote, lowland Papua New Guinea. Using a large sample of repeated salivary cortisol measurements from 169 participants (age 4-70 years), multilevel growth curve models were constructed to assess Garisakang waking cortisol concentrations and diurnal cortisol slopes. As predicted, results demonstrate identifiable but substantially diminished diurnal cortisol rhythms relative to those of industrialized populations. Sample-wide, Garisakang cortisol concentrations are highest upon waking (mean = 4.86 nmol/L) and decrease throughout the day at a mean rate of only -0.18 nmol/L/h or -6.20%/h. Age and sex significantly predict evaluated cortisol parameters in ways not consistently reported among industrialized populations, suggesting that Garisakang diurnal cortisol rhythms are defined by distinct ontogenetic trajectories across the lifespan. These findings highlight cross-cultural diversity in HPA activity and have important implications for understanding basic mechanisms of the physiological stress response in contexts of chronic physical stressors such as limited nutrition, heavy burden of infectious disease, and high levels of physical activity.

Triadic awareness predicts partner choice in male-infant-male interactions in Barbary macaques.

Social knowledge beyond one's direct relationships is a key in successfully manoeuvring the social world. Individuals gather information on the quality of social relationships between their group companions, which has been termed triadic awareness. Evidence of the use of triadic awareness in natural contexts is limited mainly to conflict management. Here we investigated triadic awareness in wild Barbary macaques (Macaca sylvanus) in the context of bridging interactions defined as male-infant-male interactions whereby a male (initiator, holder) presents an infant to another male (receiver, non-holder) in order to initiate an affiliative interaction with that male. Analyses based on 1263 h of focal observations on ten infants of one wild social group in Morocco supported the hypothesis that males use their knowledge of the relationship between infants and other adult males when choosing a male as a partner for bridging interactions. Specifically, (i) the number of bridging interactions among holder-infant-receiver triads was positively affected by the strength of the infant-receiver relationship and (ii) when two males were available as bridging partners, a male was more likely to be chosen as the receiver the stronger his social relationship with the infant relative to the other available male. This demonstrates that non-human primates establish triadic awareness of temporary infant-male relationships and use it in a naturally occurring affiliative context. Our results contribute to the discussion about the mechanism underlying the acquisition of triadic awareness and the benefits of its usage, and lend support to hypotheses linking social complexity to the evolution of complex cognition.

Effect of chewing betel nut (Areca catechu) on salivary cortisol measurement.

OBJECTIVES: Cultural practices may compromise the accuracy of salivary hormone measurements and must be considered when designing human biology research protocols. This study aims to evaluate the acute effect of one common human practice-chewing betel nut-on the measurement of salivary cortisol levels under field conditions. MATERIALS AND METHODS: Data were collected from 17 adult habitual betel nut users (males = 11; females = 6; mean age = 32.8 years) from a small rural community in Papua New Guinea. Saliva was collected in time series from each participant before and at 0, 15, 30, 45, 60, and 75 min after chewing betel nut. Samples were analyzed by radioimmunoassay and cortisol levels were compared across time using linear mixed effects modeling. RESULTS: Measured mean cortisol concentration fell nearly 40% immediately following betel nut use and remained significantly below baseline levels for the following 45 min (all P < 0.05). Cortisol concentrations measured at 60 min and 75 min were indistinguishable from baseline levels (all P > 0.16). DISCUSSION: Chewing betel nut is associated with a transient but significant reduction in measured levels of salivary cortisol. Future research must take this into account in populations where betel nut use is prevalent.

Whom to groom and for what? Patterns of grooming in female Barbary macaques (Macaca sylvanus).

Grooming is one of the most conspicuous social interactions among nonhuman primates. The selection of grooming partners can provide important clues about factors relevant for the distribution of grooming within a social group. We analyzed grooming behavior among 17 semi-free ranging female Barbary macaques (Macaca sylvanus). We tested whether grooming is related to kinship, rank and friendship. Furthermore, we tested whether grooming is reciprocated or exchanged for rank related benefits (i.e. lower aggression and increased tolerance whilst feeding). We found that in general grooming was reciprocally exchanged, directed up the hierarchy and at the same time affected by friendship and kinship. Grooming was more frequent among individuals with higher friendship values as well as amongst related individuals. We also divided our data set on the basis of rank difference and tested if different power asymmetries between individuals affected the tendency to exchange grooming for rank related benefits and grooming reciprocation. In support of our initial hypothesis our results show that the reciprocation of grooming was a significant predictor of grooming interactions between individuals of similar rank, but not between those individuals more distantly separated in the social hierarchy. However, we did not find any evidence for grooming being exchanged for rank related benefits in either data set. Our results, together with previously published studies, illustrate the behavioral flexibility of macaques. It is clear that multiple studies of the same species are necessary to gather the data required for the solid comparative studies needed to shed light on patterns of grooming behavior in primates.

Puberty as a life history transition.

BACKGROUND: James Tanner's landmark publication, Growth at Adolescence, was not only the first and most comprehensive treatise on the subject of human pubertal development of its time, its core insights have held up remarkably well over time. REVIEW: This review connects Tanner's contributions to contemporary understanding of puberty as a process fundamentally driven by neuroendocrine maturation. It introduces the concepts of the 'hour-glass of puberty' and 'somatic strategy' as heuristic constructs. The 'hour-glass of puberty' describes the converging pathways of information flow influencing the timing of the neuroendocrine events of puberty and its ramifying consequences throughout the body. Somatic strategy refers to the pattern of sex-specific, adult body morphology that develops at puberty as the individual undergoes a life history transition from juvenile to adult.

Personality in free-ranging Hanuman langur (Semnopithecus entellus) males: subjective ratings and recorded behavior.

The authors obtained behavioral observations and personality ratings for 27 free-ranging Hanuman langur males. Subjects were rated using a questionnaire based on the human Five-Factor Model (FFM). Behavioral observations were taken over 5 months using an ethogram that included 50 behaviors. Principal Component Analysis (PCA) of ratings revealed Agreeableness_(R), Confidence_(R), and Extraversion_(R) components. Each personality dimension was associated with a unique set of observed behaviors. PCA of 36 behavioral indices revealed Dominance_(B), Involvement_(B), and Activity_(B) components. Bivariate correlations showed that Agreeableness_(R) was negatively correlated with Dominance_(B); Confidence_(R) was positively correlated with Dominance_(B) and Involvement_(B) but negatively correlated with Activity_(B); and Extraversion_(R) was positively correlated with Activity_(B). Dominance rank was positively correlated with Confidence_(R) and Dominance_(B) but negatively correlated with Agreeableness_(R) and Activity_(B). These results highlight the comparability of behavioral coding and personality ratings and suggest that some aspects of personality structure were present in the common ancestor of Old World monkeys.