The neurohormones oxytocin (OT) and arginine vasopressin (AVP) are involved in social behaviors and psychiatric conditions. However, more research on nonhuman primates with complex social behaviors is needed. We studied two closely-related primate species with divergent social and mating systems; hamadryas baboons (Papio hamadryas, n=38 individuals) and anubis baboons (Papio anubis, n=46). We measured OT in cerebrospinal fluid (CSF, n=75), plasma (n=81) and urine (n=77), and AVP in CSF (n=45), and we collected over 250hours of focal behavioral observations. Using Bayesian multivariate models, we found no clear species difference in hormone levels; the strongest support was for hamadryas having higher CSF OT levels than anubis (posterior probability [PP] for females = 0.75, males = 0.84). Looking at nine specific behaviors, OT was associated with affiliative behaviors (approach, proximity, grooming, PP ~ 0.85 - 1.00), albeit inconsistently across sources of measurement (CSF, plasma, and urine, which were uncorrelated with each other). Most behaviors had low repeatability (R ~ 0 - 0.2), i.e. they did not exhibit stable between-individual differences (or \"personality\"), and different behaviors did not neatly coalesce into higher-order factors (or \"behavioral syndromes\"), which cautions against the use of aggregate behavioral measures and highlights the need to establish stable behavioral profiles when testing associations with baseline hormone levels. In sum, we found some associations between peptides and social behavior, but also many null results, OT levels from different sources were uncorrelated, and our behavioral measures did not indicate clear individual differences in sociability.

Social deficits are frequently observed in patients suffering from neurodevelopmental disorders, but the molecular mechanisms regulating sociability are still poorly understood. We recently reported that the loss of the microRNA (miRNA) cluster miR-379-410 leads to hypersocial behavior and anxiety in mice. Here, we show that ablating miR-379-410 in excitatory neurons of the postnatal mouse hippocampus recapitulates hypersociability, but not anxiety. At the cellular level, miR-379-410 loss in excitatory neurons leads to larger dendritic spines, increased excitatory synaptic transmission, and upregulation of an actomyosin gene network. Re-expression of three cluster miRNAs, as well as pharmacological inhibition of the actomyosin activator ROCK, is sufficient to reinstate normal sociability in miR-379-410 knockout mice. Several actomyosin genes and miR-379-410 family members are reciprocally dysregulated in isogenic human induced pluripotent stem cell (iPSC)-derived neurons harboring a deletion present in patients with Williams-Beuren syndrome, characterized by hypersocial behavior. Together, our results show an miRNA-actomyosin pathway involved in social behavior regulation.

Vocal turn-taking has been described in a diversity of species. Yet, a model that is able to capture the various processes underlying this social behaviour across species has not been developed. To this end, here we recorded a large and diverse dataset of marmoset monkey vocal behaviour in social contexts comprising one, two and three callers and developed a model to determine the keystone factors that affect the dynamics of these natural communicative interactions. Notably, marmoset turn-taking did not abide by coupled-oscillator dynamics, but rather call timing was overwhelmingly stochastic in these exchanges. Our features-based model revealed four key factors that encapsulate the majority of patterns evident in the behaviour, ranging from internal processes, such as particular states of the individual driving increased calling, to social context-driven suppression of calling. These findings indicate that marmoset vocal turn-taking is affected by a broader suite of mechanisms than previously considered and that our model provides a predictive framework with which to further explicate this natural behaviour at both the behavioural and neurobiological levels, and for direct comparisons with the analogous behaviour in other species.

Whether avian migrants can adapt to their changing world depends on the relative importance of genetic and environmental variation for the timing and direction of migration. In the classic series of field experiments on avian migration, A. C. Perdeck discovered that translocated juveniles failed to reach goal areas, whereas translocated adults performed \'true-goal navigation\'. His translocations of > 14 000 common starlings (Sturnus vulgaris) suggested that genetic mechanisms guide juveniles into a population-specific direction, i.e. \'vector navigation\'. However, alternative explanations involving social learning after release in juveniles could not be excluded. By adding historical data from translocation sites, data that was unavailable in Perdeck\'s days, and by integrated analyses including the original data, we could not explain juvenile migrations from possible social information upon release. Despite their highly social behaviour, our findings are consistent with the idea that juvenile starlings follow inherited information and independently reach their winter quarters. Similar to more solitarily migrating songbirds, starlings would require genetic change to adjust the migration route in response to global change.

BACKGROUND:  Social decision-making (SDM) is often studied through gaming paradigms, in which participants allocate resources among themselves and others based on predefined rules. In an adapted version of the ultimatum game (UG), SDM behavior was modulated in response to the degree of fairness of monetary offers and the social context of opponents, designed to generate either prosocial or punishing behaviors.
OBJECTIVE:  To investigate whether SDM evaluated by the UG is affected by age and schooling, as it is relevant to know whether sociodemographic variables may bias UG results.
METHODS:  A total of 131 healthy adults participated: 35 young university students and 96 participants in Universidade de São Paulo\'s USP 60+ program (formerly known as Universidade Aberta à Terceira Idade, a program for people aged ≥ 60 years to attend university). The sample was divided into 3 age groups (17-22, 60-69, and 70-79 years) and 3 schooling groups (4-8, 9-11, and ≥ 12 years of schooling).
RESULTS:  Age and schooling did not affect performance in fair monetary offers. Differences were observed in the unfair conditions. The oldest group (70-79 years) accepted less frequently the baseline unfair offers (without social context), when compared with the 17-22 and the 60-69 years groups (17-22 = 60-69 > 70-79). Regarding the prosocial unfair and punishing unfair conditions, older adults accepted such offers more frequently (17-22 < 60-69 = 70-79). Schooling effects were not observed.
CONCLUSIONS:  In the context of SDM, older adults may show prosocial behaviors more frequently than younger adults. The findings suggest performance in the UG is affected by age, but not by schooling.
BACKGROUND:  A tomada de decisão social (TDS) é frequentemente estudada por meio de paradigmas de jogo, em que os participantes alocam recursos entre si e outros com base em regras predefinidas. Em uma versão adaptada do jogo do ultimato (JU), o comportamento de TDS foi modulado em resposta ao grau de justiça das ofertas monetárias e ao contexto social dos oponentes, projetado para produzir comportamentos pró-sociais ou punitivos.
OBJECTIVE:  Investigar se a TDS avaliada pelo JU é afetada pela idade e escolaridade, pois é relevante saber se variáveis sociodemográficas podem influenciar os resultados do JU. MéTODOS:  Participaram 131 adultos saudáveis, sendo 35 jovens universitários e 96 participantes do programa USP 60+ (antigo Universidade Aberta à Terceira Idade). A amostra foi dividida em 3 faixas etárias (17–22, 60–69 e 70–79 anos) e 3 faixas de escolaridade (4–8, 9–11 e ≥ 12 anos).
RESULTS:  Idade e escolaridade não afetaram o desempenho em ofertas monetárias justas. Diferenças foram observadas nas condições injustas. O grupo mais velho (70–79 anos) aceitou menos as ofertas injustas de referência (sem contexto social), quando comparado com o grupo de 17–22 e o de 60–69 anos (17–22 = 60–69 > 70–79). Em relação às condições pró-sociais injustas e punitivas injustas, os idosos aceitaram com maior frequência tais ofertas (17–22 < 60–69 = 70–79). Efeitos da escolaridade não foram observados. CONCLUSãO:  No contexto da TDS, os idosos podem apresentar comportamentos pró-sociais com mais frequência do que os adultos mais jovens. Os resultados sugerem que o desempenho no JU é afetado pela idade, mas não pela escolaridade.

UNASSIGNED: Responding to social signals by expressing the correct behavior is not only challenged in autism, but also in diseases with high prevalence of autism, like Prader-Willi Syndrome (PWS). Clinical evidence suggests aberrant pro-social behavior in patients can be regulated by intranasal oxytocin (OXT) or vasopressin (AVP). However, what neuronal mechanisms underlie impaired behavioral responses in a socially-aversive context, and how can they be corrected, remains largely unknown.
UNASSIGNED: Using the Magel2 knocked-out (KO) mouse model of PWS (crossed with CRE-dependent transgenic lines), we devised optogenetic, physiological and pharmacological strategies in a social-fear-conditioning paradigm. Pathway specific roles of OXT and AVP signaling were investigated converging on the lateral septum (LS), a region which receives dense hypothalamic inputs.
UNASSIGNED: OXT and AVP signaling promoted inhibitory synaptic transmission in the LS, which failure in Magel2KO mice disinhibited somatostatin (SST) neurons and disrupted social-fear extinction. The source of OXT and AVP deficits mapped specifically in the supraoptic nucleus→LS pathway of Magel2KO mice disrupting social-fear extinction, which could be corrected by optogenetic or pharmacological inhibition of SST-neurons in the LS. Interestingly, LS SST-neurons also gated the expression of aggressive behavior, possibly as part of functional units operating beyond local septal circuits.
UNASSIGNED: SST cells in the LS play a crucial role in integration and expression of disrupted neuropeptide signals in autism, thereby altering the balance in expression of safety versus fear. Our results uncover novel mechanisms underlying dysfunction in a socially-aversive context, and provides a new framework for future treatments in autism-spectrum disorders.

The gut microbiota and neurological development of neonatal mice are susceptible to environmental factors that may lead to altered behavior into adulthood. However, the role that changed gut microbiota and neurodevelopment early in life play in this needs to be clarified. In this study, by modeling early-life environmental changes by cross-fostering BALB/c mice, we revealed the effects of the environment during the critical period of postnatal development on adult social behavior and their relationship with the gut microbiota and the nervous system. The neural projections exist between the ascending colon and oxytocin neurons in the paraventricular nuclei (PVN), peripheral oxytocin levels and PVN neuron numbers decreased after cross-fostering, and sex-specific alteration in gut microbiota and its metabolites may be involved in social impairments and immune imbalances brought by cross-fostering via the gut-brain axis. Our findings also suggest that social cognitive impairment may result from a combination of PVN oxytocinergic neurons, gut microbiota, and metabolites.

Desert locust plagues threaten the food security of millions. Central to their formation is crowding-induced plasticity, with social phenotypes changing from cryptic (solitarious) to swarming (gregarious). Here, we elucidate the implications of this transition on foraging decisions and corresponding neural circuits. We use behavioral experiments and Bayesian modeling to decompose the multi-modal facets of foraging, revealing olfactory social cues as critical. To this end, we investigate how corresponding odors are encoded in the locust olfactory system using in-vivo calcium imaging. We discover crowding-dependent synergistic interactions between food-related and social odors distributed across stable combinatorial response maps. The observed synergy was specific to the gregarious phase and manifested in distinct odor response motifs. Our results suggest a crowding-induced modulation of the locust olfactory system that enhances food detection in swarms. Overall, we demonstrate how linking sensory adaptations to behaviorally relevant tasks can improve our understanding of social modulation in non-model organisms.

People often rely on social learning-learning by observing others\' actions and outcomes-to form preferences in advance of their own direct experiences. Although typically adaptive, we investigated whether social learning may also contribute to the formation and spread of prejudice. In six experiments (n = 1550), we demonstrate that by merely observing interactions between a prejudiced actor and social group members, observers acquired the prejudices of the actor. Moreover, observers were unaware of the actors\' bias, misattributing their acquired group preferences to the behavior of group members, despite identical behavior between groups. Computational modeling revealed that this effect was due to value shaping, whereby one\'s preferences are shaped by another\'s actions toward a target, in addition to the target\'s reward feedback. These findings identify social learning as a potent mechanism of prejudice formation that operates implicitly and supports the transmission of intergroup bias.

Social information is predicted to enhance the quality of animals\' migratory decisions in dynamic ecosystems, but the relative benefits of social information in the long-range movements of marine megafauna are unknown. In particular, whether and how migrants use nonlocal information gained through social communication at the large spatial scale of oceanic ecosystems remains unclear. Here we test hypotheses about the cues underlying timing of blue whales\' breeding migration in the Northeast Pacific via individual-based models parameterized by empirical behavioral data. Comparing emergent patterns from individual-based models to individual and population-level empirical metrics of migration timing, we find that individual whales likely rely on both personal and social sources of information about forage availability in deciding when to depart from their vast and dynamic foraging habitat and initiate breeding migration. Empirical patterns of migratory phenology can only be reproduced by models in which individuals use long-distance social information about conspecifics\' behavioral state, which is known to be encoded in the patterning of their widely propagating songs. Further, social communication improves pre-migration seasonal foraging performance by over 60% relative to asocial movement mechanisms. Our results suggest that long-range communication enhances the perceptual ranges of migrating whales beyond that of any individual, resulting in increased foraging performance and more collective migration timing. These findings indicate the value of nonlocal social information in an oceanic migrant and suggest the importance of long-distance acoustic communication in the collective migration of wide-ranging marine megafauna.