LAUSR

Research using social network analyses has been booming since the start of the 2000s, with studies not only in humans but also many nonhuman species. Primates are no exception, with the number of retrievable items using the keywords “social networks primates” increasing tenfold from 2000 to 2017 (Fig. 1a). Studies are in various domains including psychology, behavioral sciences, and sociology, as well as neurosciences and infectious diseases (Fig. 1b). To our knowledge, several special issues and books have focused on animals (Croft et al. 2008; Whitehead 2008; Krause et al. 2009; Sheldon 2015; Sueur and Mery 2017) but with only one special issue devoted to primates (Sueur et al. 2011). In the last decade studies have evolved from describing structures (Manno 2008; Carter et al. 2013; Bret et al. 2013) and topologies of social networks or centrality of group members according to their sociodemographic characteristics (Lusseau and Newman 2004; Kanngiesser et al. 2011), to a more holistic approach where the function and evolution of networks are linked to ecological factors, behavioral mechanisms, network topologies, and vice versa (Brent et al. 2013; Fisher et al. 2016; Balasubramaniam et al. 2018). In this new special issue, our aim is to present this integrative and multilevel approach along with state-of-the-art methodologies and theoretical approaches for the study of primate social networks. Statistical techniques applied to social network analysis have greatly evolved in the last 10 years (Hoppitt and Laland 2013; Farine 2017; Finn et al. 2017; Sosa 2018). Papers in this issue show that whilst it is commonly accepted now to use permutation tests to avoid interdependence of social data (Koyama and Aureli 2018; Kawazoe and Sosa 2018, Rodrigues and Boeving 2018), new tools have emerged to study the social positions of individuals inside their network (i.e., egocentric network; Grampp et al. 2019), the multidimensional nature of networks (i.e., multiplex networks; Smith-Aguilar et al. 2018) and their dynamics (e.g., through ERGMs, exponential random graphs models; Lutz et al. 2019). Researchers are also increasingly using modeling to simulate social transmission of diseases or of information (based on network-based diffusion analysis, Wild and Hoppitt 2018) or to simulate network resilience through targeted deletion (Puga-Gonzalez et al. 2018). These new tools allow a better understanding of the complexity of a network. Social relationships reflect the interplay of many types of interactions (e.g., grooming, aggression, proximity, genetic relatedness), and multiplex networks can give accurate information about the social position of group members, as shown by Smith-Aguilar et al. (2018) on wild spider monkey (Ateles geoffroyi). The tools developed over the past decade also bring new possibilities for comparing species despite differences in group size or composition, as shown in the study by Lutz et al. (2019) on play network organization in three species (brown capuchins, Sapajus apella; hamadryas baboons, Papio hamadryas; diademed sifakas, Propithecus diadema). Network dynamics, referring to changes across time, seasons, or group composition, is also a vibrant topic given the availability of tools that can now tackle this problem. Papers in this issue include Xia et al.’s (2019) study of seasonal dynamics, especially the impact of reproductive season, on grooming networks in Tibetan macaques (Macaca thibetana), and Kawazoe and Sosa’s (2018) analysis of how social Social networks analysis in primates, a multilevel perspective