Group Coping Intervention in Patients With Chronic Graft-Versus-Host Disease: A Pilot Randomized Clinical Trial.

BACKGROUND: More than half the long-term survivors of allogeneic hematopoietic cell transplantation develop chronic graft-versus-host disease (GVHD), a debilitating inflammatory syndrome. Supportive interventions to assist survivors in coping with chronic GVHD are critically needed. PATIENTS AND METHODS: We conducted a pilot randomized clinical trial of a multidisciplinary group intervention (Horizons Program; n=39) versus minimally enhanced usual care (n=41) for patients with moderate or severe chronic GVHD. Horizons participants received 8 weekly sessions about GVHD and coping co-led by a transplant clinician and a behavioral health expert via a secure videoconferencing platform. Participants completed the following surveys before randomization, at 10 weeks, and at 18 weeks: Functional Assessment of Cancer Therapy-Bone Marrow Transplant Scale (FACT-BMT) for quality of life (QoL), Lee Symptom Scale for symptom burden, and Hospital Anxiety and Depression Scale-Depression Symptoms (HADS) for mood. The primary endpoint was feasibility (≥50% enrollment, ≥80% attendance in half the sessions for the Horizons arm only, and ≥80% retention). We also explored preliminary efficacy of the Horizons intervention on changes in patient-reported outcomes with linear mixed effects models and estimates of effect size at 10 weeks. RESULTS: We enrolled and registered 80 (67.2%) of 119 eligible patients (mean age, 62 years; 48.8% female). Of the participants in the Horizons Program, 84.6% attended at least half the sessions. Of registered participants, 91.3% completed assessment follow-ups (Horizons, 35/39 [89.7%]; minimally enhanced usual care, 38/41 [92.7%]). Horizons participants reported improvements in QoL (b = 2.24; d=0.53), anxiety symptoms (b = -0.10; d=0.34), and depression symptoms (b = -0.71; d=0.44) compared with participants who received minimally enhanced usual care. CONCLUSIONS: Participation in a multidisciplinary group intervention study was feasible for patients with chronic GVHD, with promising signals for improving QoL and mood. A full-scale efficacy trial is needed to confirm effects on patient-reported outcomes.

Effects of captions on viewers' perceptions of images depicting human-primate interaction.

Promoting human contact with wildlife can be harmful to animal conservation and welfare by exposing animals to unsafe situations and driving demand for wildlife tourism and exotic pets. Conservationists and researchers justifiably use social media to raise awareness, but professionals posting pictures of themselves with animals can have unintended negative consequences for conservation. Though the International Union for Conservation of Nature Best Practice Guidelines for Responsible Images of Non-Human Primates suggests researchers and animal professionals provide context in captions of images of humans interacting with primates, there is little research investigating whether this approach is effective. We investigated whether informative captions affect viewers' desires to have primates as pets and attitudes toward wildlife conservation. Using 4 mock Instagram posts depicting human-gorilla and human-slender loris interactions, we surveyed 2977 respondents to assess the effect of captions on viewers' perceptions of the images and primate conservation. Likert scale response data were analyzed with ordered probit regression models. Captions clearly contextualizing an image as research resulted in a significantly higher agreement that posts depicted wildlife research (gorilla ß = 0.28 [SE 0.06], p < 0.001; loris ß = 0.18 [0.06], p = 0.002), but such captions resulted in no significant difference in responses regarding viewers' desires to own primates as pets or questions regarding the primates' conservation statuses. Although most participants agreed the primates were endangered, more than 56% and 59%, respectively, stated they would have a gorilla or loris as a pet, that they would make good pets, or both, further supporting the conclusion that captions do not minimize harmful impacts of images of human-primate interactions.

Efectos de los pies de foto sobre la percepción del público de imágenes de la interacción humano-primate Resumen La promoción del contacto humano con la fauna puede ser dañina para la conservación y el bienestar animal al exponer a la fauna a situaciones poco seguras e incrementar la demanda por el turismo de fauna y las mascotas exóticas. Los conservacionistas y los investigadores usan con justificación las redes sociales para generar conciencia, pero los profesionales que publican imágenes de sí mismos con los animales pueden generar sin intención consecuencias negativas para la conservación. Aunque la Guía de Buenas Prácticas de la Unión Internacional para la Conservación de la Naturaleza para la Obtención Responsable de Imágenes de Primates No Humanos sugiere que los investigadores y profesionales de fauna proporcionen contexto en los pies de foto de las imágenes de humanos interactuando con primates, hay muy poca investigación sobre si esta estrategia es efectiva. Investigamos si los pies de foto informativos afectan el deseo del público de tener primates como mascotas y la actitud hacia la conservación de la fauna. Usamos cuatro publicaciones simuladas de Instagram representando interacciones humano-gorila y humano-loris para encuestar a 2,977 respondientes y estudiar el efecto de los pies de foto sobre la percepción del público de las imágenes y la conservación de primates. Analizamos los datos de respuesta de escala Likert con modelos de regresión probit ordenada. Los pies de foto que contextualizaban con claridad una imagen como trabajo de investigación resultaron en mayor aceptación de que las publicaciones representaban investigación sobre la fauna (gorila ß = 0.28 [SE 0.06], p < 0.001; loris ß = 0.18 [0.06], p = 0.002), pero dichos textos resultaron en una diferencia no significativa en las respuestas con respecto al deseo del público de tener primates como mascota o preguntas sobre el estado de conservación de los primates. Mientras que la mayoría de los participantes estuvo de acuerdo en que los primates están en peligro de extinción, más del 56% y 59%, respectivamente, afirmaron que tendrían un gorila o un loris como mascota, que serían buenas mascotas, o ambas. Esto suma a la conclusión de que los pies de foto no minimizan el impacto dañino de las imágenes de interacciones humano-primate.

Do zoo-housed primates retreat from crowds? A simple study of five primate species.

An animal's welfare state is directly influenced by the mental state, which is shaped by experiences within the environment throughout the animal's life. For zoo-housed animals, visitors to the zoo are a large part of that environment and a fluctuating influence within it. This study examines the impact of zoo visitors on the space use of five species of zoo-housed primates (Eastern black-and-white colobus monkeys, Colobus guereza, n = 5, Allen's swamp monkeys, Allenopithecus nigroviridis, n = 2, DeBrazza's monkeys, Cercopithecus neglectus, n = 3, Bolivian gray titi monkeys, Callicebus donacophilus, n = 3, and crowned lemurs, Eulemur coronatus, n = 3). Specifically, we considered whether primates' distance from visitor areas changed as crowd sizes increased. Data were collected using the ZooMonitor app. Observers recorded spatial coordinates for each animal over periods ranging from 12 to 32 months. Data were analyzed using two types of regression models (linear and logistic) to examine the influence of visitors on the location of the primates. Both analyses revealed a statistically significant but small decrease in primate distance from visitor viewing glass as the number of visitors increased. Behavioral indicators of welfare were also unaffected by the presence of visitors. These results suggest that, with additional validation, distance from visitors may be one promising, simple way to evaluate the influence of visitors on primate welfare.

The relationship between personality, season, and wounding receipt in zoo-housed Japanese macaques (Macaca fuscata): A multi-institutional study.

It is important to those managing Japanese macaques (Macaca fuscata) in captive settings to understand predictors of wounding. While studies have demonstrated that season (breeding or nonbreeding) and sex predict rates of wounding received by zoo-housed Japanese macaques, we investigated whether individual differences in personality ratings also might explain some of the observed interindividual variance in wounding. Such patterns were previously observed in rhesus macaques (M. mulatta), such that individuals rated higher on Anxiety and Confidence received greater wounding. Here, we collected wounding data over 24 months on 48 Japanese macaques from eight AZA-accredited zoos. Each macaque was also rated by keepers using a 26-item personality questionnaire. Principle components analysis of these ratings revealed four personality components: Openness, Friendliness, Dominance, and Anxiety/Reactivity. The model with the best fit revealed an interaction effect between season (breeding vs. nonbreeding) and the personality component Friendliness, such that individuals rated higher on Friendliness incurred fewer wounds in the nonbreeding season. The second-best model revealed both a main effect of the season as well as an interaction effect between season and Openness, such that macaques rated higher in Openness received more wounds in the nonbreeding season than those rated lower in Openness. Thus, as with rhesus macaques, personality mediated wounding receipt rate in Japanese macaques, although different personality components explained interindividual variance in wounding for these two species. These differences likely reflect species differences in behavior and personality structure, as well as the influence of differing management practices, highlighting the importance of species-specific approaches for captive primate care and welfare. This study provides further support for understanding primate personality to create individualized strategies for their care.

Population-specific social dynamics in chimpanzees.

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.

Food Cleaning by Japanese Macaques: Innate, Innovative or Cultural?

Japanese macaques (Macaca fuscata) display a number of cultural behaviours including food washing, stone handling and certain grooming techniques. These are deemed cultural behaviours because it is presumed that they are socially learned and, importantly, that social learning is essential for their emergence. Recently, however, research has revealed that culturally naïve primates can re-innovate presumed cultural behaviours. These behaviours are said to fall within that species' "zone of latent solutions" (ZLS). A notable cultural behaviour of Japanese macaques is food washing, first reported by Japanese researchers studying wild Japanese macaques in the 1950s. To test whether culturally naïve Japanese macaques would spontaneously wash food and also, therefore, whether food-washing behaviour is within their ZLS, we presented 12 zoo-housed macaques with sweet potato covered in sand near a pool in their exhibit. Over 11 days we recorded the macaques' behaviour. While 11 of the 12 macaques ate the potato pieces, none washed them. However, 4 macaques cleaned their food, brushing off the sand using their hand or rubbing the potato against their body or another food item, using three distinct techniques. We found no change over time in the rate at which monkeys cleaned or consumed potato, but there was a significant positive correlation between the number of potato pieces a monkey ate and the number of cleaning behaviours performed. We conclude that, minimally, food-cleaning behaviour is within macaques' ZLS.

Sex and season predict wounds in zoo-housed Japanese macaques (Macaca fuscata): A multi-institutional study.

Japanese macaque societies are characterized by frequent intragroup conflict both in free-ranging and zoo-housed conditions. In zoos, understanding the factors that contribute to wounding is of interest because this knowledge can aid in proactive husbandry and management planning that can minimize the negative impacts wounding can have on individual welfare. This study sought to determine whether the variables sex, season and age predicted wounding rates. Data were collected for 24 months on 119 Japanese macaques living in 10 zoos, and we analyzed the contribution of variables using generalized linear mixed models. A total of 1,007 wounds were reported, and the best model included the interaction between sex and season. Follow-up analyses revealed that females incurred more wounds than males, and this sex difference was more pronounced during the breeding compared to the nonbreeding season. On average, individuals received 4.67 (±SEM: 0.55) wounds per year and 77.31% of the population incurred at least one wound in the study period. The majority of wounds were superficial and did not require veterinary intervention. Wound locations were not randomly distributed across body regions and were most often reported on the face. Finally, macaques living in larger social groups experienced more wounds, on average. This study represents the first quantification of wounding in this species and may provide insight to help inform husbandry and management strategies in zoos.

A multi-institutional assessment of a short-form personality questionnaire for use with macaques.

There are two commonly-used methods for calculating primates' personality dimensions, behavioral assessments and surveys, which can be used separately or in conjunction. However, these methods have limitations. Behavioral assessments, such as the novel object test or human intruder test, often require subjects to be separated and demand highly-controlled conditions. This is likely not feasible in many zoological institutions. Furthermore, it may be difficult to replicate methods across institutions. While surveys are easier to implement, the most commonly used one - the Hominoid Personality Questionnaire (HPQ) - is long and can be time consuming to complete, especially if multiple individuals need assessing. Therefore, we developed a short-form personality questionnaire for use with macaques. We aimed to retain elements of published scales while creating a tool that would be less time consuming to complete. After creating a novel 26-item scale (28 fewer items than the HPQ), we gathered ratings for 63 Japanese macaques (Macaca fuscata) living in eight zoos accredited by the Association of Zoos and Aquariums. Using principal components analysis, we identified four components to describe the Japanese macaque personality: Openneness, Friendliness, Dominance, and Anxiety/Reactivity. While further testing is required to fully validate this scale, we tested for the convergent validity of our questionnaire by correlating the responses of a subset of the monkeys to a novel object and assessed the face validity of our scale in comparison to previously-published scales.

Chimpanzees' responses to the dead body of a 9-year-old group member.

The social behavior of chimpanzees has been extensively studied, yet not much is known about how they behave in response to the death of a group member. Here, we provide a detailed report of the reactions of a group of chimpanzees to finding the dead body of a 9-year-old male group member. The behavior of the group was characterized by quiet attendance and close inspections punctuated by rare displays. Moreover, the body was continuously attended and closely inspected by several adults and juveniles, including an adult male who formed a close social bond with the deceased individual after the deceased individual's mother died 4 years earlier. When considered with observations of how chimpanzees respond to dead infants and adults in this group and in others, these observations suggest that chimpanzees' responses to death may be mediated by social bonds with the deceased individual. The results are discussed in light of recent reports on chimpanzees' reactions to dead community members and more general primate thanatology. Am. J. Primatol. 78:914-922, 2016. © 2016 Wiley Periodicals, Inc.

Bonobos show limited social tolerance in a group setting: a comparison with chimpanzees and a test of the relational model.

Social tolerance is a core aspect of primate social relationships with implications for the evolution of cooperation, prosociality and social learning. We measured the social tolerance of bonobos in an experiment recently validated with chimpanzees to allow for a comparative assessment of group-level tolerance, and found that the bonobo group studied here exhibited lower social tolerance on average than chimpanzees in this paradigm. Furthermore, following the Relational Model of de Waal, we investigated whether bonobos responded to an increased potential for social conflict with tolerance, conflict avoidance or conflict escalation, and found that only behaviours indicative of conflict escalation differed across conditions. Taken together, these findings contribute to the current debate over the level of social tolerance of bonobos and lend support to the position that the social tolerance of bonobos may not be notably high compared with other primates.

A group-specific arbitrary tradition in chimpanzees (Pan troglodytes).

Social learning in chimpanzees has been studied extensively and it is now widely accepted that chimpanzees have the capacity to learn from conspecifics through a multitude of mechanisms. Very few studies, however, have documented the existence of spontaneously emerged traditions in chimpanzee communities. While the rigour of experimental studies is helpful to investigate social learning mechanisms, documentation of naturally occurring traditions is necessary to understand the relevance of social learning in the real lives of animals. In this study, we report on chimpanzees spontaneously copying a seemingly non-adaptive behaviour ("grass-in-ear behaviour"). The behaviour entailed chimpanzees selecting a stiff, straw-like blade of grass, inserting the grass into one of their own ears, adjusting the position, and then leaving it in their ear during subsequent activities. Using a daily focal follow procedure, over the course of 1 year, we observed 8 (out of 12) group members engaging in this peculiar behaviour. Importantly, in the three neighbouring groups of chimpanzees (n = 82), this behaviour was only observed once, indicating that ecological factors were not determiners of the prevalence of this behaviour. These observations show that chimpanzees have a tendency to copy each other's behaviour, even when the adaptive value of the behaviour is presumably absent.

Choice, control, and animal welfare: definitions and essential inquiries to advance animal welfare science.

The ways in which humans can support good welfare for animals in their care is an ongoing subject of debate: some place emphasis on the animals' physical health; others, on animals' ability to live "natural lives"; and others on animals' affective states or psychological wellbeing. Recently, there has been an increase in interest in how an animal's ability to exercise control over its environment could impact their welfare. In this article, we take the stance that the relevant aspects of the first two concepts of animal welfare (physical health, natural lives) are largely addressed when an animal's psychological wellbeing is prioritized. Through that lens, we review the current state of the literature regarding the psychology of control, and the intersection between choice, control, and welfare. We clarify terms to support future work, and propose future directions that could lead to a better understanding of the psychological benefits of choice and control and ultimately inform animal care decisions.

Clinical Outcomes and Health Care Utilization in Patients With Burkitt Lymphoma.

PURPOSE: Burkitt lymphoma is an aggressive B-cell lymphoma requiring intensive therapy, which places patients at risk for severe toxicity. However, few studies have described these patients' clinical outcomes and health care utilization, particularly among older adults. METHODS: We conducted a retrospective analysis of adults 40 years and older with Burkitt lymphoma at Massachusetts General Hospital and Dana-Farber Cancer Institute from February 1999 to December 2020 (N = 97). We abstracted patient characteristics, clinical outcomes, and health care utilization (unplanned hospitalizations, intensive care unit [ICU] admissions) during therapy from the electronic health record. Using univariate logistic regression, we examined factors associated with rates of unplanned hospitalization and ICU admission during therapy. RESULTS: Among evaluable patients (median age, 69 years; 23.7% female; 19.3% with bone marrow involvement), 45.8% (38 of 83) experienced unplanned hospitalization and 23.2% (19 of 82) experienced ICU admission during therapy. Among those 70 years and older, rates of unplanned hospitalization and ICU admission were 36.8% (14 of 38) and 29.0% (11 of 38), respectively. Bone marrow involvement (odds ratio [OR], 3.00; P = .069) was associated with a nonsignificantly greater likelihood of unplanned hospitalization. Older age (OR, 1.06; P = .039), Charlson comorbidity index >0 (OR, 3.14; P = .038), and hypoalbuminemia (OR, 3.22; P = .035) were associated with greater likelihood of ICU admission. Overall, 8.7% (8 of 92) of patients died during treatment, all of whom were 70 years and older. CONCLUSION: Adults with Burkitt lymphoma experience substantial rates of unplanned hospitalizations and ICU admissions, with older adults at especially high risk for ICU admission and death during treatment. Our findings underscore the need to develop supportive care interventions for patients with Burkitt lymphoma to help improve clinical outcomes and health care utilization.

Quality of Life, Physical Functioning, and Psychological Distress of Older Adults Undergoing Hematopoietic Stem Cell Transplantation.

With advances in therapies for hematologic cancers, older adults increasingly undergo hematopoietic stem cell transplantation (HSCT). Older adults may potentially experience an exaggerated burden of toxicity from HSCT. Studies examining the quality of life (QOL), physical functioning, and psychological symptom trajectory for older adults undergoing HSCT are limited. Our primary aim was to describe the trajectory of QOL, physical functioning, and psychological distress of older adults undergoing HSCT. Secondarily, we aimed to compare the trajectory of QOL, physical functioning, and psychological distress of older and younger adults undergoing HSCT and to evaluate factors associated with QOL trajectory in older adults undergoing HSCT. We conducted secondary analyses of two prospective studies conducted at Massachusetts General Hospital. From 2011 to 2016, we enrolled 250 adults undergoing allogeneic or autologous HSCT. Older age was defined as age ≥65 years. We collected patient-reported outcomes (PROs) within 72 hours of admission for HSCT, at hematologic nadir (2 weeks), and at 6 months after HSCT. To assess QOL, physical functioning, and psychological symptoms, we used the Functional Assessment of Cancer Therapy (FACT)-Bone Marrow Transplant, FACT-Trial Outcome Index, and Patient Health Questionnaire-9, respectively. We used the post-traumatic stress disorder (PTSD) Checklist-Civilian Version to assess PTSD symptoms. We fit linear mixed effects models to characterize trajectories of changes in PROs across timepoints and to evaluate baseline factors associated with QOL trajectories in older adults. Overall 30.4% (76/250) of our cohort was 65 years or older. All older adults undergoing allogeneic HSCT received a reduced intensity conditioning regimen. At 2 weeks after HSCT, older patients experienced a decline in QOL (Δ = -16.6, P < .001), physical functioning (Δ = -15.4, P < .001) and an increase in depression symptoms (Δ = 3.8, P < .001). At 6 months after HSCT, QOL (Δ = 1.4, P = .7), physical functioning (Δ = 1.7, P = .5), and depression symptoms (Δ = 0.4, P = .6) recovered to baseline values. At 6 months after HSCT, the proportion of older patients with PTSD symptoms increased from 5.3% (4/76) at baseline to 13.2% (10/76). There was no significant difference in slopes or trajectories of PROs between older and younger patients. In older adults, baseline psychological distress was associated with significantly worse QOL trajectory (Δ= -21.6, P ≤ .001). Older adults experienced a sharp decline in QOL and physical functioning and an increase in depression symptoms within 2 weeks of HSCT hospitalization. Baseline psychological distress was associated with a pronounced worsening in post-HSCT QOL trajectory. These findings underscore the need for supportive care interventions to improve the experience of older adults undergoing HSCT.

Delirium and Healthcare Utilization in Patients Undergoing Hematopoietic Stem Cell Transplantation.

Delirium, a common neuropsychiatric syndrome among hospitalized patients, has been associated with significant morbidity and mortality in patients undergoing hematopoietic stem cell transplantation (HSCT). Although delirium is often reversible with prompt diagnosis and appropriate management, timely screening of hospitalized patients, including HSCT recipients at risk for delirium, is lacking. The association between delirium symptoms and healthcare utilization among HSCT recipients is also limited. We conducted a retrospective analysis of 502 hospitalized patients admitted for allogeneic or autologous HSCT at 2 tertiary care hospitals between April 2016 and April 2021. We used Natural Language Processing (NLP) to identify patients with delirium symptoms, as defined by an NLP-assisted chart review of the electronic health record (EHR). We used multivariable regression models to examine the associations between delirium symptoms, clinical outcomes, and healthcare utilization, adjusting for patient-, disease-, and transplantation-related factors. Overall, 44.4% (124 of 279) of patients undergoing allogeneic HSCT and 39.0% (87 of 223) of those undergoing autologous HSCT were identified as having delirium symptoms during their index hospitalization. Two-thirds (139 of 211) of the patients with delirium symptoms were prescribed treatment with antipsychotic medications. Among allogeneic HSCT recipients, delirium symptoms were associated with longer hospital length of stay (ß = 7.960; P < .001), fewer days alive and out of the hospital (ß = -23.669; P < .001), and more intensive care unit admissions (odds ratio, 2.854; P = .002). In autologous HSCT recipients, delirium symptoms were associated with longer hospital length of stay (ß = 2.204; P < .001). NLP-assisted EHR review is a feasible approach to identifying hospitalized patients, including HSCT recipients at risk for delirium. Because delirium symptoms are negatively associated with health care utilization during and after HSCT, our findings underscore the need to efficiently identify patients hospitalized for HSCT who are at risk of delirium to improve their outcomes. © 2023 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Coping in caregivers of patients with hematologic malignancies undergoing hematopoietic stem cell transplantation.

Caregivers of patients with hematologic malignancies undergoing hematopoietic stem cell transplantation (HSCT) must cope with substantial caregiving burden, high rates of psychological distress, and diminished quality of life (QOL). However, data describing coping strategies before HSCT and the association between coping, QOL, and psychological outcomes in this population are lacking. We conducted a secondary analysis of data collected during a multisite randomized clinical trial of a supportive care intervention in HSCT recipients and their caregivers. Caregivers completed the Brief COPE, Hospital Anxiety and Depression Scale, and the Caregiver Oncology Quality of Life Questionnaire to measure coping strategies, psychological distress, and QOL, respectively. We grouped coping into 2 higher-order domains: approach-oriented (ie, emotional support and active coping) and avoidant (ie, self-blame and denial). We used the median split method to describe the distribution of coping and multivariate linear regression models to assess the relationship between coping and caregiver outcomes. We enrolled 170 caregivers, with a median (range) age of 53 (47-64) years. Most were White (87%), non-Hispanic (96%), and female (77%). Approach-oriented coping was associated with less anxiety (ß = -0.210, P = .003), depression symptoms (ß = -0.160, P = .009), and better QOL (ß = 0.526, P = .002). In contrast, avoidant coping was associated with more anxiety (ß = 0.687, P<.001), depression symptoms (ß = 0.579, P < .001), and worse QOL (ß = -1.631, P < .001). Our findings suggest that coping is related to distress and QOL among caregivers of HSCT recipients even before transplant. Hence, caregivers of patients with hematologic malignancies undergoing HSCT may benefit from resources that facilitate adaptive coping with the demands of caregiving.

Neighbouring chimpanzee communities show different preferences in social grooming behaviour.

Grooming handclasp (GHC) behaviour was originally advocated as the first evidence of social culture in chimpanzees owing to the finding that some populations engaged in the behaviour and others do not. To date, however, the validity of this claim and the extent to which this social behaviour varies between groups is unclear. Here, we measured (i) variation, (ii) durability and (iii) expansion of the GHC behaviour in four chimpanzee communities that do not systematically differ in their genetic backgrounds and live in similar ecological environments. Ninety chimpanzees were studied for a total of 1029 h; 1394 GHC bouts were observed between 2010 and 2012. Critically, GHC style (defined by points of bodily contact) could be systematically linked to the chimpanzee's group identity, showed temporal consistency both within and between groups, and could not be accounted for by the arm-length differential between partners. GHC has been part of the behavioural repertoire of the chimpanzees under study for more than 9 years (surpassing durability criterion) and spread across generations (surpassing expansion criterion). These results strongly indicate that chimpanzees' social behaviour is not only motivated by innate predispositions and individual inclinations, but may also be partly cultural in nature.

Chimpanzees organize their social relationships like humans.

Human relationships are structured in a set of layers, ordered from higher (intimate relationships) to lower (acquaintances) emotional and cognitive intensity. This structure arises from the limits of our cognitive capacity and the different amounts of resources required by different relationships. However, it is unknown whether nonhuman primate species organize their affiliative relationships following the same pattern. We here show that the time chimpanzees devote to grooming other individuals is well described by the same model used for human relationships, supporting the existence of similar social signatures for both humans and chimpanzees. Furthermore, the relationship structure depends on group size as predicted by the model, the proportion of high-intensity connections being larger for smaller groups.