Repeatability of measures of behavioral organization over two years in captive infant rhesus macaques, Macaca mulatta.

Individual differences of infant temperament have been associated with future health outcomes that provide explanatory power beyond adult personality. Despite the importance of such a metric, our developmental understanding of personality-like traits is poor. Therefore, we examined whether young primates show consistency in personality traits throughout development. We replicated a Biobehavioral Assessment (BBA) at three time periods: 3-4 months, 1 year, and 2 years of age in 47 rhesus macaque (Macaca mulatta) subjects from large mixed-sex outdoor social housing units at the California National Primate Research Center. We report results for tests focused on responses and adaptation to the temporary separation and relocation, responses to a threatening stimulus, and ratings of overall temperament. We found consistently repeatable associations in measures of Emotionality; these associations were stronger in males, but also present in females, and broadly consistent between Years 1 and 2. We also explored whether behavioral responses to this experimental relocation might be influenced by their experience being relocated for other reasons (i.e., hospitalizations) as individuals' responses might be influenced by similar experiences to the BBA procedure. Only locomotion, during one of the assessments, was associated with past hospitalization events. Overall, repeatability in Emotionality-associated behaviors was evident across the 2 years, in both sexes. We did, however, find evidence of the emergence of sex differences via differentiated expression of behavioral responses during the BBA. We emphasize that there is likely contextual nuance in the use of these BBA factor-associated behaviors. Further research is required to determine whether and how shifts occur in underlying factor structure and the expression of associated behaviors.

Social stability via management of natal males in captive rhesus macaques (Macaca mulatta).

Keystone individuals are expected to disproportionately contribute to group stability. For instance, rhesus macaques (Macaca mulatta) who police conflict contribute towards stability. Not all individuals' motivations align with mechanisms of group stability. In wild systems, males typically disperse at maturity and attempt to ascend via contest competition. In a captive system, dispersal is not naturally enabled - individuals attempt to ascend in their natal groups, which can be enabled by matrilineal kin potentially destabilizing group dynamics. We relocated select high-ranking natal males from five groups and assessed group stability before and after. We quantified hierarchical metrics at the individual and group level. After removal, we found significantly higher aggression against the established hierarchy (reversals), indicative of opportunistic attempts to change the hierarchy. Mixed-sex social signaling became more hierarchical, but the strength of this effect varied. Stable structure was not uniformly reached across the groups and alpha males did not all benefit. Indiscriminate natal male removal is an unreliable solution to group instability. Careful assessment of how natal males are embedded within their group is necessary to balance individual and group welfare.

Hair and plasma cortisol throughout the first 3 years of development in infant rhesus macaques, Macaca mulatta.

Cortisol expression has been demonstrated to have variation across development in rhesus macaques (Macaca mulatta). There exists contradictory evidence for the nature of this change, and age at which it occurs, across biological sample types. Consequently, we lack a cohesive understanding for cortisol concentrations across the development of a major human health translational model. We examined hair cortisol concentrations over the first 3 years of life for 49 mother-reared infant macaques from mixed-sex outdoor units at the California National Primate Research Center. For 48 of these subjects at infancy, 1 year, and 2 years, we obtained plasma cortisol samples for response to a stressor, adjustment to prolonged stress, and response to dexamethasone injection. Hair cortisol concentrations decreased dramatically between 3 and 10 months, followed by relative stability up to the final sampling event at around 34 months of age. Plasma cortisol showed within-year consistency, and consistency between infancy and year 1. We document variability in the infant plasma cortisol samples, especially in percent change between samples 1 and 2. Our plasma cortisol results indicate that infants possess the physiological capacity to effectively inhibit the release of cortisol when stimulated, as effectively as later responses in juveniles. Age-related changes in hair cortisol parallel findings indicating a large decline in the weeks following postparturation.

The interplay of social constraints and individual variation in risk tolerance in the emergence of superspreaders.

Individual host behaviours can drastically impact the spread of infection through a population. Differences in the value individuals place on both socializing with others and avoiding infection have been shown to yield emergent homophily in social networks and thereby shape epidemic outcomes. We build on this understanding to explore how individuals who do not conform to their social surroundings contribute to the propagation of infection during outbreaks. We show how non-conforming individuals, even if they do not directly expose a disproportionate number of other individuals themselves, can become functional superspreaders through an emergent social structure that positions them as the functional links by which infection jumps between otherwise separate communities. Our results can help estimate the potential success of real-world interventions that may be compromised by a small number of non-conformists if their impact is not anticipated, and plan for how best to mitigate their effects on intervention success.

Influence of Lived Experiences on Public Responses to Future Diseases via (De)Sensitization of Concern.

OBJECTIVES: Public responses to a future novel disease might be influenced by a subset of individuals who are either sensitized or desensitized to concern-generating processes through their lived experiences during the coronavirus disease 2019 (COVID-19) pandemic. Such influences may be critical for shaping public health messaging during the next emerging threat. METHODS: This study explored the potential outcomes of the influence of lived experiences by using a dynamic multiplex network model to simulate a COVID-19 outbreak in a population of 2000 individuals, connected by means of disease and communication layers. Then a new disease was introduced, and a subset of individuals (50% or 100% of hospitalized during the COVID-19 outbreak) was assumed to be either sensitized or desensitized to concern-generating processes relative to the general population, which alters their adoption of non-pharmaceutical interventions (social distancing). RESULTS: Altered perceptions and behaviors from lived experiences with COVID-19 did not necessarily result in a strong mitigating effect for the novel outbreak. When public disease response is already strong or sensitization is assumed to be a robust effect, then a sensitized subset may enhance public mitigation of an outbreak through social distancing. CONCLUSIONS: In preparing for future outbreaks, assuming an experienced and disease-aware public may compromise effective design of effective public health messaging and mitigative action.

Survey-rated personality traits and experimentally measured coping style and stress reactivity, in wild baboons.

The coping style and stress reactivity framework for individual differences in the stress response has been of increasing utility within primatological research. Such differences are often quantified using an experimental approach, but many primatological studies have historically been reliant on a personality-like framework. The personality-like research is derived from human personality literature using survey ratings, while approaches focused on coping styles are often used to interpret differences in small rodents and birds. Experimental approaches benefit from a constrained situation that facilitates control, but sacrifice utility via the generalizability afforded via ratings. Resolving how these two theoretical and methodological approaches intersect is paramount to establishing a biological synthesis between two robust fields of research on individual differences. We applied these frameworks to adult wild olive baboons (Papio anubis) at a field site in Laikipia, Kenya. We quantified coping style and stress reactivity using individually targeted field experiments. We quantified personality trait differences using observer ratings of the monkeys. We isolated three personality trait factors: Neuroticism, Assertiveness, and Friendliness. Personality trait differences showed little association with coping style, but Neuroticism was predicted by stress reactivity.

How reported outbreak data can shape individual behavior in a social world.

Agencies reporting on disease outbreaks face many choices about what to report and the scale of its dissemination. Reporting impacts an epidemic by influencing individual decisions directly, and the social network in which they are made. We simulated a dynamic multiplex network model-with coupled infection and communication layers-to examine behavioral impacts from the nature and scale of epidemiological information reporting. We explored how adherence to protective behaviors (social distancing) can be facilitated through epidemiological reporting, social construction of perceived risk, and local monitoring of direct connections, but eroded via social reassurance. We varied reported information (total active cases, daily new cases, hospitalizations, hospital capacity exceeded, or deaths) at one of two scales (population level or community level). Total active and new case reporting at the population level were the most effective approaches, relative to the other reporting approaches. Case reporting, which synergizes with test-trace-and-isolate and vaccination policies, should remain a priority throughout an epidemic.

Balancing timeliness of reporting with increasing testing probability for epidemic data.

Reporting of epidemiological data requires coordinated action by numerous agencies, across a multitude of logistical steps. Using collated and reported information to inform direct interventions can be challenging due to associated delays. Mitigation can, however, occur indirectly through the public generation of concern, which facilitates adherence to protective behaviors. We utilized a coupled-dynamic multiplex network model with a communication- and disease-layer to examine how variation in reporting delay and testing probability are likely to impact adherence to protective behaviors, such as reducing physical contact. Individual concern mediated adherence and was informed by new- or active-case reporting, at the population- or community-level. Individuals received information from the communication layer: direct connections that were sick or adherent to protective behaviors increased their concern, but absence of illness eroded concern. Models revealed that the relative benefit of timely reporting and a high probability of testing was contingent on how much information was already obtained. With low rates of testing, increasing testing probability was of greater mitigating value. With high rates of testing, maximizing timeliness was of greater value. Population-level reporting provided advanced warning of disease risk from nearby communities; but we explore the relative costs and benefits of delays due to scale against the assumption that people may prioritize community-level information. Our findings emphasize the interaction of testing accuracy and reporting timeliness for the indirect mitigation of disease in a complex social system.

Measuring behavioral coping style and stress reactivity experimentally in wild olive baboons.

Many nonhuman animals have been used as subjects to elucidate intra-individual variation in the stress response - understood via coping styles and stress reactivity. Given the evidence and theory supporting evolutionary trade-offs associated with such differences, it is surprising, then, how few studies have used wild nonhuman primates to develop this theoretical framework. In the current study, we evaluated this framework using a combination of behaviours from focal follows and an experimental method, novel to the field - collected during a 17 month project on olive baboons (Papio anubis) in Laikipia, Kenya. Our experimental design simultaneously introduces a risk with an incentive: a model snake with a real chicken egg, respectively. Such an approach facilitates multiple solutions to a stressor, a key element of coping style theory. General behavioral tendencies did not associate with the experimental measures of coping style and stress reactivity. These results, however, demonstrated the utility and validity of this experimental approach for measuring coping style and stress reactivity in wild nonhumans. Fear grimaces represented stress reactivity. A factor solution represented coping style - summarizing decision making under stress. The treatment experiment, with a snake and egg, elicited a behavioral stress response, relative to control trials with just an egg.

Park Rangers' Behaviors and Their Effects on Tourists and Tibetan Macaques (Macaca thibetana) at Mt. Huangshan, China.

Previous studies have reported the negative impacts of tourism on nonhuman primates (NHPs) and tourists and advocated the improvement of tourism management, yet what constitutes good quality management remains unclear. We explored whether rates of macaque aggression and self-directed behaviors (SDBs) differed under the supervision of two park ranger teams at the Valley of the Wild Monkeys (VWM) in Mt. Huangshan, Anhui Province, China. The two ranger teams provisioned and managed a group of macaques on an alternating monthly basis. Monkey, tourist and ranger behaviors were collected from August 16-September 30, 2012. Macaque aggression and SDB rates did not differ significantly under the management of the two teams. Overall, there was little intervention in tourist-macaque interactions by park rangers, and even when rangers discouraged tourists' undesirable behaviors, tourist interactions with monkeys persisted. Furthermore, only one or sometimes two park rangers managed monkeys and tourists, and rangers established dominance over the monkeys to control them. In order to effectively manage tourists and monkeys by a single park ranger, we recommend that rangers: (1) prohibit tourists from feeding; (2) move around the viewing platform more frequently; and (3) limit the number of tourists each visiting session.