Primate social organization evolved from a flexible pair-living ancestor.

Explaining the evolution of primate social organization has been fundamental to understand human sociality and social evolution more broadly. It has often been suggested that the ancestor of all primates was solitary and that other forms of social organization evolved later, with transitions being driven by various life history traits and ecological factors. However, recent research showed that many understudied primate species previously assumed to be solitary actually live in pairs, and intraspecific variation in social organization is common. We built a detailed database from primary field studies quantifying the number of social units expressing different social organizations in each population. We used Bayesian phylogenetic models to infer the probability of each social organization, conditional on several socioecological and life history predictors. Here, we show that when intraspecific variation is accounted for, the ancestral social organization of primates was inferred to be variable, with the most common social organization being pair-living but with approximately 10 to 20% of social units of the ancestral population deviating from this pattern by being solitary living. Body size and activity patterns had large effects on transitions between types of social organizations. As in other mammalian clades, pair-living is closely linked to small body size and likely more common in ancestral species. Our results challenge the assumption that ancestral primates were solitary and that pair-living evolved afterward emphasizing the importance of focusing on field data and accounting for intraspecific variation, providing a flexible statistical framework for doing so.

Comparative approaches in social network ecology.

Social systems vary enormously across the animal kingdom, with important implications for ecological and evolutionary processes such as infectious disease dynamics, anti-predator defence, and the evolution of cooperation. Comparing social network structures between species offers a promising route to help disentangle the ecological and evolutionary processes that shape this diversity. Comparative analyses of networks like these are challenging and have been used relatively little in ecology, but are becoming increasingly feasible as the number of empirical datasets expands. Here, we provide an overview of multispecies comparative social network studies in ecology and evolution. We identify a range of advancements that these studies have made and key challenges that they face, and we use these to guide methodological and empirical suggestions for future research. Overall, we hope to motivate wider publication and analysis of open social network datasets in animal ecology.

Ecological and genetic variables co-vary with social group identity to shape the gut microbiome of a pair-living primate.

Primates exhibit diverse social systems that are intricately linked to their biology, behavior, and evolution, all of which influence the acquisition and maintenance of their gut microbiomes (GMs). However, most studies of wild primate populations focus on taxa with relatively large group sizes, and few consider pair-living species. To address this gap, we investigate how a primate's social system interacts with key environmental, social, and genetic variables to shape the GM in pair-living, red-bellied lemurs (Eulemur rubriventer). Previous research on this species suggests that social interactions within groups influence interindividual microbiome similarity; however, the impacts of other nonsocial variables and their relative contributions to gut microbial variation remain unclear. We sequenced the 16S ribosomal RNA hypervariable V4-V5 region to characterize the GM from 26 genotyped individuals across 11 social groups residing in Ranomafana National Park, Madagascar. We estimated the degree to which sex, social group identity, genetic relatedness, dietary diversity, and home range proximity were associated with variation in the gut microbial communities residing in red-bellied lemurs. All variables except sex played a significant role in predicting GM composition. Our model had high levels of variance inflation, inhibiting our ability to determine which variables were most predictive of gut microbial composition. This inflation is likely due to red-bellied lemurs' pair-living, pair-bonded social system that leads to covariation among environmental, social, and genetic variables. Our findings highlight some of the factors that predict GM composition in a tightly bonded, pair-living species and identify variables that require further study. We propose that future primate microbiome studies should simultaneously consider environmental, social, and genetic factors to improve our understanding of the relationships among sociality, the microbiome, and primate ecology and evolution.

Individual and social system factors influencing evidence-based practices among nurses in general hospitals: A cross-sectional multi-institutional study.

AIMS AND OBJECTIVES: To investigate evidence-based practices and examine the influence of individual and social system factors on evidence-based practices among nurses in general hospitals. BACKGROUND: Evidence-based practice is essential for improving healthcare quality. However, a challenge for nursing worldwide is nurses' limited use of evidence-based practices. It is crucial to determine the individual and social system factors affecting nurses' use of evidence-based practices. DESIGN: This study employs a multi-institutional cross-sectional design. METHODS: With a multistage random sampling method, 336 registered nurses were recruited from 17 general hospitals in the Republic of the Union of Myanmar. Data were collected through a seven-part questionnaire, including the Evidence-Based Practice Implementation Scale and individual and social system factors. Data were analyzed using descriptive statistics and multiple linear regression. RESULTS: Nurses in general hospitals perceived low levels of evidence-based practices. Individual factors, such as perceived barriers (p < .001), knowledge (p < .001) and attitudes (p = .001), were related to EBP as well as social system factors, including the work environment (p < .001) which influence nurses' practice, explaining 34% variance among nurses. CONCLUSION: Nurses perceived the work environment as the most influencing factor related to evidence-based practices. Individual characteristics, including perceived knowledge, attitudes and barriers, were critical factors in performing evidence-based practices in Myanmar. RELEVANCE TO CLINICAL PRACTICE: Nurse administrators and policymakers can develop strategies and interventions for improving knowledge, attitudes and work environment towards evidence-based practice. Minimizing the barriers to evidence-based practice will promote evidence-based practices in Myanmar general hospitals. IMPACT: In addressing the individual and social system factors influencing the evidence-based practices of nurses, this study contributes to enhancing healthcare quality and outcomes. REPORTING METHOD: This study adhered to the STROBE checklist. PATIENT OR PUBLIC CONTRIBUTION: There was no patient or public contribution.

Effects of social tolerance on stress: hair cortisol concentrations in the tolerant Tonkean macaques (Macaca tonkeana) and the despotic long-tailed macaques (Macaca fascicularis).

Group living is a source of stress and an individuals' social environment has been shown to have a significant effect on its health and well-being. However, little is known about how different social organizations affect the stress levels of their members. Is living in a hierarchical society more or less stressful than living in a more tolerant structure? Here, we assess cortisol concentrations in the hair of two macaque species with radically different dominance styles: the egalitarian Tonkean macaque (Macaca Tonkeana) and the despotic long-tailed macaques (Macaca fascicularis). Hair was sampled in winter and again in late spring in two mixed-sex groups of 22 Tonkean macaques and 9 long-tailed macaques; Hair cortisol concentrations were significantly higher in the egalitarian Tonkean macaques than in the despotic long-tailed macaques, ranging from 161.13 to 938.8 pg/mg (mean ± SD 349.67 ± 126.22) and from 134.46 to 339.86 pg/mg (mean ± SD 231.2 ± 44.24), respectively. There was no difference between male and female cortisol concentrations, but hair cortisol increased with age in males. Dominance rank certainty was lower among female Tonkean macaques compared to long-tailed macaques. Our results suggest that species differences in dominance styles may translate into differences in long-term cortisol concentrations. We suggest that the higher cortisol concentrations in Tonkean macaques could be linked to the instability and lack of predictability and control around social relationships.

LAY SUMMARYBeing part of a social group can be very stressful, depending on the social structure of this group. We found that the more socially tolerant Tonkean macaques exhibited on average higher hair cortisol concentrations than more despotic long-tailed macaques. Males and females exhibited similar concentrations of hair cortisol in both species, but in male Tonkean macaques concentrations increased with age. The finding that overall cortisol levels were higher in the more tolerant species suggests that psychological arousal due to unpredictable social relations and mating competition may be an important driver of cortisol release in this species despite its overall tolerant social organization.

Fostering Cyber-Physical Social Systems through an Ontological Approach to Personality Classification Based on Social Media Posts.

The exponential increase in social networks has led to emergent convergence of cyber-physical systems (CPS) and social computing, accelerating the creation of smart communities and smart organizations and enabling the concept of cyber-physical social systems. Social media platforms have made a significant contribution to what we call human behavior modeling. This paper presents a novel approach to developing a users' segmentation tool for the Romanian language, based on the four DISC personality types, based on social media statement analysis. We propose and design the ontological modeling approach of the specific vocabulary for each personality and its mapping with text from posts on social networks. This research proposal adds significant value both in terms of scientific and technological contributions (by developing semantic technologies and tools), as well as in terms of business, social and economic impact (by supporting the investigation of smart communities in the context of cyber-physical social systems). For the validation of the model developed we used a dataset of almost 2000 posts retrieved from 10 social medial accounts (Facebook and Twitter) and we have obtained an accuracy of over 90% in identifying the personality profile of the users.

Investigating tradeoffs between supply, use and demand of ecosystem services and their effective drivers for sustainable environmental management.

Ecosystems have a huge impact on social systems through providing diverse services. Sustainable management of social and ecological systems requires the quantification of spatial relationships between the supply, demand, and use of these ecosystem services. The main purpose of this paper was to provide a framework addressing all the complicated relationships of ecosystem services between ecological and social systems. Sustainable management cannot be achieved without considering these complex relationships. To simplify these complexities, management priorities must be identified. In this study, spatial changes of supply, use, and demand of ecosystem services and their main drivers were investigated. A Public Participation Geographic Information System was used to map the supply, demand and use of 19 ecosystem services in semiarid landscapes of Iran. Multi Criteria Decision Making methods were also used to link ecosystem services to social well-being. The main drivers of tradeoffs between supply, use, and demand of ecosystem services were determined using General Linear Method. The results showed that there was a synergy between supply, demand and use of ecosystem services in highlands. The deficit zones of ecosystem services were concentrated in lowlands. Provisioning services were the most important services for social well-being. The framework presented in this paper revealed all the complex relationships that the environmental management is faced with in ecosystem and social systems. Simplifying integrated relationships in both ecosystems (supply) and social systems (demand and use) helps sustainable management of ecosystems under environmental and social changes.

Possible Infanticidal Event of an Aye-Aye (Daubentonia madagascariensis) in Torotorofotsy, Madagascar.

Infanticide occurs in an array of mammalian species, especially primates. Most infanticidal events occur in polygynous societies, though they sometimes happen in nongregarious populations. We witnessed a possible infanticidal event of a 3-month-old male aye-aye, a species that exhibits a dispersed multimale social system, in Torotorofotsy, Madagascar. Though firsthand killing of the infant was not observed, physical injuries to the infant, vocalizations of the adult female, and her subsequent chase of the adult male aye-aye strongly indicates infanticide. If true, this would be the first recorded incident of an infanticidal event in a noyau primate. The evidence for three different explanations of infanticide is evaluated.

Personal identification systems for persons with dementia: a systematic review.

People with dementia can become missing and unable to be identified due to their cognitive decline and may not have belongings, including personally identifiable information. The aim of this systematic review was to summarise and discuss the current status of personal identification systems for missing and unidentified persons with dementia. An electronic systematic literature search was conducted by using PubMed, Web of Science, Cochrane Library, and CINAHL. By performing an electronic literature search, 128 texts were extracted. However, only three eligible texts were included in this review, and these were divided on the basis of the analysis target as follows: medical and human community support systems and digital systems. It is important to develop medical and social care systems and to construct and advance social personal identification systems, including medical and human community support systems and digital systems, for persons with dementia. However, this systematic review clarified that there have only been a few reports about the development and construction of social systems for missing and unidentified persons with dementia. People who interact with persons with dementia should consider this problem, which is increasing each year, and strive to build a social system that can be applied to personal identification as soon as possible.

The Effects of Body Mass on Immune Cell Concentrations of Mammals.

Theory predicts that body mass should affect the way organisms evolve and use immune defenses. We investigated the relationship between body mass and blood neutrophil and lymphocyte concentrations among more than 250 terrestrial mammalian species. We tested whether existing theories (e.g., protecton theory, immune system complexity, and rate of metabolism) accurately predicted the scaling of immune cell concentrations. We also evaluated the predictive power of body mass for these leukocyte concentrations compared to sociality, diet, life history, and phylogenetic relatedness. Phylogeny explained >70% of variation in both lymphocytes and neutrophils, and body mass appeared more informative than other interspecific trait variation. In the best-fit mass-only model, neutrophils scaled hypermetrically (b=0.11) with body mass, whereas lymphocytes scaled just shallow of isometrically. Extrapolating to total cell numbers, this exponent means that an African elephant circulates 13.3 million times the neutrophils of a house mouse, whereas their masses differ by only 250,000-fold. We hypothesize that such high neutrophil numbers might offset the (i) higher overall parasite exposure that large animals face and/or (ii) the higher relative replication capacities of pathogens to host cells.

Tolerant and intolerant macaques show different levels of structural complexity in their vocal communication.

We tested the social complexity hypothesis which posits that animals living in complex social environments should use complex communication systems. We focused on two components of vocal complexity: diversity (number of categories of calls) and flexibility (degree of gradation between categories of calls). We compared the acoustic structure of vocal signals in groups of macaques belonging to four species with varying levels of uncertainty (i.e. complexity) in social tolerance (the higher the degree of tolerance, the higher the degree of uncertainty): two intolerant species, Japanese and rhesus macaques, and two tolerant species, Tonkean and crested macaques. We recorded the vocalizations emitted by adult females in affiliative, agonistic and neutral contexts. We analysed several acoustic variables: call duration, entropy, time and frequency energy quantiles. The results showed that tolerant macaques displayed higher levels of vocal diversity and flexibility than intolerant macaques in situations with a greater number of options and consequences, i.e. in agonistic and affiliative contexts. We found no significant differences between tolerant and intolerant macaques in the neutral context where individuals are not directly involved in social interaction. This shows that species experiencing more uncertain social interactions displayed greater vocal diversity and flexibility, which supports the social complexity hypothesis.

Understanding Data-Driven Cyber-Physical-Social System (D-CPSS) Using a 7C Framework in Social Manufacturing Context.

The trend towards socialization, personalization and servitization in smart manufacturing has attracted the attention of researchers, practitioners and governments. Social manufacturing is a novel manufacturing paradigm responding to this trend. However, the current cyber-physical system (CPS) merges only cyber and physical space; social space is missing. A cyber-physical-social system (CPSS)-based smart manufacturing is in demand, which incorporates cyber space, physical space and social space. With the development of the Internet of Things and social networks, a large volume of data is generated. A data-driven view is necessary to link tri-space. However, there is a lack of systematical investigation on the integration of CPSS and the data-driven view in the context of social manufacturing. This article proposes a seven-layered framework for a data-driven CPSS (D-CPSS) along the data-information-knowledge-wisdom (DIKW) pyramid under a social manufacturing environment. The evolution, components, general model and framework of D-CPSS are illustrated. An illustrative example is provided to explain the proposed framework. Detailed discussion and future perspectives on implementation are also presented.

Comparing Cognitive Behavioral Therapy and Systemic Therapy for Social Anxiety Disorder: Randomized Controlled Pilot Trial (SOPHO-CBT/ST).

This randomized controlled trial (RCT) aimed to pilot the newly developed manualized and monitored systemic therapy (ST) for social anxiety disorder (SAD), as compared to manualized and monitored cognitive behavioral therapy (CBT). We conducted a prospective multicenter, assessor-blind pilot RCT on 38 outpatients (ICD F40.1; Structured Clinical Interview for DSM (SCID); Liebowitz Social Anxiety Scale, LSAS-SR >30). The primary outcome was level of social anxiety (LSAS-SR) at the end of treatment. A total of 252 persons were screened, and 38 patients were randomized and started therapy (CBT: 20 patients; ST: 18 patients; age: M = 36 years, SD = 14). Within-group, simple-effect intent-to-treat analyses (ITT) showed significant reduction in LSAS-SR (CBT:d = 1.04; ST:d = 1.67), while ITT mixed-design ANOVA demonstrated the advantage of ST (d = 0.81). Per-protocol analyses supported these results. Remission based on reliable change indices also demonstrated significant difference (LSAS-SR: 15% in CBT; 39% in ST;h: 0.550), supported by blind diagnosticians' ratings of those who completed therapy (SCID; 45% in CBT, 78% in ST,p = .083). No adverse events were reported. CBT and ST both reduced social anxiety, supporting patient improvement with the newly developed ST for SAD; this has yet to be verified in a subsequent confirmatory RCT.

Este ensayo controlado aleatorizado tuvo como finalidad probar la terapia sistémica (TS) estandarizada y monitoreada recientemente desarrollada para el trastorno de ansiedad social en comparación con la terapia cognitivo-conductual (TCC) estandarizada y monitoreada. Realizamos un ensayo controlado aleatorizado prospectivo, multicentro y con enmascaramiento para el evaluador en 38 pacientes ambulatorios (CIE F40.1; Entrevista Clínica Estructurada para los trastornos del DSM (SCID); Escala de Ansiedad Social de Liebowitz, LSAS-SR > 30). El resultado principal fue el nivel de ansiedad social (LSAS-SR) al final del tratamiento. Se evaluó a un total de 252 personas, 38 pacientes fueron aleatorizados y comenzaron la terapia (TCC: 20 pacientes; TS: 18 pacientes; edad: promedio= 36 años, desviación estándar = 14). Los análisis intragrupales, de efecto simple, con intención de tratar demostraron una reducción significativa del LSAS-SR (TCC: d = 1.04; TS: d = 1.67), mientras que el análisis de varianza de diseño mixto con intención de tratar demostró la ventaja de la TS (d = 0.81). Los análisis por protocolo respaldaron estos resultados. La remisión basada en los índices de cambio fiable también demostró una diferencia significativa (LSAS-SR: 15% en la TCC; 39% en la TS; h: 0.550), respaldada por diferencias casi significativas en las valoraciones con enmascaramiento para los evaluadores de aquellos que completaron la terapia (SCID; 45% en la TCC, 78% en la TS, p = 0.083). No se informaron efectos adversos. Tanto la TCC como la TS reducen la ansiedad social y respaldan la mejora de los pacientes con la terapia sistémica recientemente desarrollada para los trastornos de ansiedad social; esto aun debe verificarse en un ensayo controlado aleatorizado confirmatorio posterior.

Adaptive Capacity of Households to Degradation of Ecosystem Services: A Case Study in the Colombian Andes.

The adaptive capacity (AC) of social systems to degradation of ecosystem services is defined as the response capacity of the system to a threat, such as changes in supply and delivery of ecosystem services (ES). In this paper, we propose an adaptive capacity composite indicator vis-a-vis the loss or degradation of ecosystem services that can be evaluated at household level in rural areas. For the estimation of the AC composite indicator, we evaluated 16 variables grouped into six categories that were previously validated with a group of experts in the area. The variables were evaluated in ten types of household profiles identified in relation with the services of water provision and erosion control in the Riogrande Basin in Colombia. The composite indicator is built both through experts' focus groups to find weights of the variables and categories and principal component analysis. In both methods, variables such as institutional efficiency, distribution and availability of information, technology and innovation, as well as local ecological knowledge were the main determinants of AC of the households.

Gestural repertoire size is associated with social proximity measures in wild chimpanzees.

Studying the communication systems of primates can provide insights into the evolutionary origins of human language. Some theories propose that language evolved to help meet the demands of managing complex social relationships. Examining the associations between sociality and communication in the great apes can help to identify the specific selection pressures that may have been important for language evolution. In particular, gestural communication is believed to be important because it is a relatively recent trait seen only in primates and particularly in the great apes. However, the extent to which more complex gestural communication plays a role in managing social relationships, as compared to less complex gestural communication, is not well understood. Using social network analysis, we examined the association between complex gesturing (indexed as repertoire size) and complexity of social relationships indexed as proximity (the duration of time spent within 10 m, per hour spent in same party) in wild chimpanzees (Pan troglodytes schweinfurthii). Repertoire size (the total number of gesture types a focal subject produced toward other individuals) and dyadic repertoire size (the number of gesture types produced toward the dyad partner, per hour spent within 10 meters) were positively associated with proximity at the level of the group (centrality in the proximity network) and the dyad (proximity duration between dyads), respectively. Further, the repertoire size of visual and auditory short-range gestures was positively associated with proximity, while the repertoire size of tactile gesture was negatively associated with proximity. Overall these results suggest that gestural repertoire size has important implications for maintaining social relationships in wild chimpanzees and more broadly that gestural communication may have played an important role in language evolution.

Spatiotemporal distribution of individuals as an indicator for the social system of Lepilemur sahamalaza.

Primate social systems are highly diverse, complicating the classification of particularly elusive species that are difficult to observe. The spatial distribution of individuals over time is a critica lindicator for the social organization and long-term studies are important to establish patterns of social interactions. In recent years, species of the cryptic, nocturnal sportive lemurs of the genus Lepilemur were found to live in pairs in which a single male and a single female share and defend a mutual home range. The present study aimed to forward research into this underrepresented genus by determining the social organization and structure of the Sahamalaza sportive lemur, L. sahamalaza. We collected 773.15 hr of behavioral and GPS data during a period of 10 months (between 2015 and 2016) on 14 individuals: eight females and six males. There was no evidence of pair-specific home range use as intra- and intersexual home range overlap was high. No pattern of social interactions between focal individuals could be distinguished despite high range overlap. Individuals met and interacted infrequently, resulting in an interaction rate of 0.32 interactions/hr. Sleeping associations between adult individuals were never observed. While both sexes had access to multiple potential mating partners, range sizes or ranging distances did not increase in mating periods. Overall, the social system of Sahamalaza sportive lemurs exhibits aspects of a solitary social organization and structure with potential for the polygamous mating system. These findings underline the importance of detailed social ecology studies that can provide the basis for understanding potential environmental influences on social system variability of closely related species.

Where There Is Fire There Is SMOKE: A Scalable Edge Computing Framework for Early Fire Detection.

A Cyber-Physical Social System (CPSS) tightly integrates computer systems with the physical world and human activities. In this article, a three-level CPSS for early fire detection is presented to assist public authorities to promptly identify and act on emergency situations. At the bottom level, the system's architecture involves IoT nodes enabled with sensing and forest monitoring capabilities. Additionally, in this level, the crowd sensing paradigm is exploited to aggregate environmental information collected by end user devices present in the area of interest. Since the IoT nodes suffer from limited computational energy resources, an Edge Computing Infrastructure, at the middle level, facilitates the offloaded data processing regarding possible fire incidents. At the top level, a decision-making service deployed on Cloud nodes integrates data from various sources, including users' information on social media, and evaluates the situation criticality. In our work, a dynamic resource scaling mechanism for the Edge Computing Infrastructure is designed to address the demanding Quality of Service (QoS) requirements of this IoT-enabled time and mission critical application. The experimental results indicate that the vertical and horizontal scaling on the Edge Computing layer is beneficial for both the performance and the energy consumption of the IoT nodes.

'Stick with your own kind, or hang with the locals?' Implications of shoaling strategy for tropical reef fish on a range-expansion frontline.

Range shifts of tropical marine species to temperate latitudes are predicted to increase as a consequence of climate change. To date, the research focus on climate-mediated range shifts has been predominately dealt with the physiological capacity of tropical species to cope with the thermal challenges imposed by temperate latitudes. Behavioural traits of individuals in the novel temperate environment have not previously been investigated, however, they are also likely to play a key role in determining the establishment success of individual species at the range-expansion forefront. The aim of this study was to investigate the effect of shoaling strategy on the performance of juvenile tropical reef fishes that recruit annually to temperate waters off the south east coast of Australia. Specifically, we compared body-size distributions and the seasonal decline in abundance through time of juvenile tropical fishes that shoaled with native temperate species ('mixed' shoals) to those that shoaled only with conspecifics (as would be the case in their tropical range). We found that shoaling with temperate native species benefitted juvenile tropical reef fishes, with individuals in 'mixed' shoals attaining larger body-sizes over the season than those in 'tropical-only' shoals. This benefit in terms of population body-size distributions was accompanied by greater social cohesion of 'mixed' shoals across the season. Our results highlight the impact that sociality and behavioural plasticity are likely to play in determining the impact on native fish communities of climate-induced range expansion of coral reef fishes.

Site fidelity facilitates pair formation in aggregations of coral reef cardinalfish.

Colonial animals often form stable pair bonds, returning to the same site to breed with the same partner every year. Familiarity with both partner and breeding site has the potential to enhance an individual's reproductive success. However, it is often unknown whether the mating system arises because of site fidelity, mate fidelity or both. Here, observational and experimental studies are used to identify causal links between site fidelity and pair formation in a group-living coral reef cardinalfish, Sphaeramia nematoptera. A long-term field tagging study was undertaken to quantify site and mate attachment. This was followed by both mate removal and mate transplant experiments to test whether the prolonged association with home sites was primarily because of mate or site fidelity. Adult S. nematoptera exhibited a prolonged association with home sites and partners, with some pairs lasting more than 4 months at the same site. A Bayesian mixed effect model showed that individuals in pairs were more likely to remain site attached, regardless of sex and maturity. Following mate removal, 78% of S. nematoptera found a new partner within 2 weeks on the same site, supporting the hypothesis that individuals primarily exhibit site fidelity. This was confirmed by the partner translocation experiment, with only 1 of 24 fish following their translocated partner to a new site. In these cardinalfish, strong site attachment facilitates long-lasting pair bonds, as well as new pair formation when necessary, suggesting that site rather than mate fidelity is the major driver of the reproductive system.

Intra-specific variation in social organization of Strepsirrhines.

Strepsirrhines, that is, lemurs, galagos, and lorises, are considered basal primates, making them important to understand the evolution of primate sociality. Apart from some lemurs, they are nocturnal and solitary living, though the view of their sociality nature has changed with field studies being completed. We conducted a review of the primary literature about the social organization (group composition) of strepsirrhines, with the aim to determine whether intra-specific variation in social organization (IVSO) occurs and to determine how many species are pair-living, group-living, or solitary living. We found data in 83 peer-reviewed studies for 43 of the 132 strepsirrhine species and compared our results using two databases on social systems of mammals published in 2011 and 2013. While it is often assumed that primates show relatively fixed social organizations, we found that 60.5% of species for which data exist have IVSO. We found only 7% of the species to be truly solitary living (with 34.9% additional species to be sometimes solitary living), which is in contrast to the other databases, which had reported 60.9% and 37.7% of species to be solitary. We further explored group compositions by designating "functional groups" (e.g., foraging, breeding, and infant care groups). While functional groups might explain IVSO within a single species, this was not consistent over species with IVSO, such that IVSO was poorly explained by functional groups. Our study supports the view that most strepsirrhines are social (58.1% of species with another 34.9% of species sometimes living in pairs or groups) and show complex and often variable social organizations; reinforcing the assumption that the ancestor of all primates was social and not solitary.