Friendship network position and salivary cortisol levels

Height and integration in proximity networks among Tanzanian Hadza men

In recent years there has been much interest in investigating the extent to which social status or prestige are related to an individual's degree of integration in social networks. It has been shown that, among hunter-gatherers, social characteristics of an individual based on social status or prestige, such foraging reputation, friendship popularity, and pro-social reputation, can influence the extent to which an individual is embedded in a social network. However, little is known regarding the extent to which height, a physical trait that in Western societies is often associated with social status, is associated in integration in social networks among small-scale hunter gatherers. Here, we investigated the relationship between height and a position an individual occupies in proximity networks among Hadza men (n = 30), hunter-gatherers living in Northern Tanzania. The results of our study show that height is not related to the position an individual maintains in proximity networks. We argue that, in a relatively egalitarian small-scale hunter-gatherer societies such as the Hadza, social interactions driving proximity networks might be influenced by social traits, such as popularity and hunting reputation, rather than physical traits, such as height.

Cortisol dynamics in undergraduate nursing students during clinical practice: protocol for an exploratory cross-sectional study

INTRODUCTION

This paper presents a protocol for the Investigation of Cortisol Dynamics in Undergraduate Nursing Students, a funded project aiming to understand the fluctuations in anxiety and salivary cortisol levels due to clinical setting changes and the anxiety associated with clinical practice.

METHODS AND ANALYSIS

This study is an exploratory, cross-sectional, observational study that will be conducted at a health and science school in Portugal. Data collection will involve phycological assessment instruments for personality, anxiety, stress, depression and saliva cortisol levels. The target population consists of undergraduate nursing students enrolled in our institution for the academic year of 2022/2023 (N=272), of whom we aim to recruit 35% (N=96) to the study.

ETHICS AND DISSEMINATION

The project obtained approval from the Institutional Review Board of the Egas Moniz-Cooperativa de Ensino Superior, CRL, on 5 July 2022 (ID: 116/21.22) and ethical approval from the Egas Moniz Ethics Committee on 28 July 2022 (ID:1110.22). Informed consent will be obtained from those who wish to participate, ensuring students' voluntary participation in the project. The results of this study will be disseminated through open-access peer-reviewed publications and presented at scientific events.

Pathways from peers to mental health: Adolescent networks, role attainment, and adult depressive symptoms

Both adolescent peer networks and adult role attainment affect mental health in adulthood. However, whether adult roles mediate associations between adolescent networks and adult mental health is unclear. Using path analysis with survey data from the National Longitudinal Study of Adolescent to Adult Health (N = 8543) in the United States, we examine the direct impact of adolescent (grades 7-12) popularity (received ties) and sociality (sent ties) among school peers on adult (ages 33-43) depressive symptoms, and we assess mediation pathways through four key adult roles: marriage, employment, education, and residential independence. We then examine whether pathways differ across men and women. Results indicate that adolescent popularity, or how others view an adolescent's position in the peer network, benefits adult mental health through the attainment of marriage, employment, and education. Residential independence is a significant mediator for popularity in models for men. Sociality, or how an adolescent views their own position in the peer network, relates to adult depressive symptoms through the attainment of a college degree for women and marriage for men. Sociality also directly predicts lower depressive levels, independent of adult role attainment, in models for women. Overall, results indicate gendered pathways for how adolescent networks relate to mental health decades later through adult roles.

Embedded Distress: Social Integration, Gender, and Adolescent Depression

In adolescence, teens manage close friendships while simultaneously evaluating their social position in the larger peer context. Conceptualizing distinct local and global network structures clarifies how social integration relates to mental wellbeing. Examining local cohesion and global embeddedness in the context of key factors related to mental health, such as gender and friends' depression, can further distinguish when the structure and content of social integration relate to higher and lower depressive levels. Analyses using survey data from PROSPER (n = 27,091, grades 9-12) indicate global embeddedness is generally protective, but for girls, greater global embeddedness when friends are more depressive is associated with increased depressive symptoms. For girls, greater local cohesion reduces associations between more depressive friends and increased depressive levels, while for boys, both local cohesion and friends' depression are largely irrelevant. Results indicate the importance of considering both local and global network integration in tandem with gender and friends' depression to understand how social integration relates to mental health.

Status does not predict stress among Hadza hunter-gatherer men

In recent years there has been much research regarding the extent to which social status is related to long-term indices of health. The majority of studies looking at the interplay between social status and health have been conducted in industrialized societies. However, it has been argued that most of human evolution took place in small, mobile and egalitarian hunter-gatherer groups where individuals exhibited very little variation in terms of material wealth or possessions. In this study, we looked at the extent to which two domains of social status, hunting reputation (being perceived as a good hunter) and popularity (being perceived as a friend), are related to physiological stress levels among Hadza men, hunter-gatherers living in Northern Tanzania. The results of our study show that neither hunting reputation nor popularity is associated with stress levels. Overall, our data suggest that, in at least some traditional small-scale societies exhibiting an egalitarian social model, such as the Hadza, the variation in social status measures based on both popularity and hunting reputation does not translate into one of the commonly used indices of wellbeing.

Hair cortisol reduction and social integration enhancement after a mindfulness-based intervention in children

BACKGROUND

Over recent decades, chronic stress at an early age has become a worrying health problem in children. We seek to evaluate an intervention involving mindfulness-based practices and prosocial activities in 7- to 8-year-old children.

METHODS

Stress levels were determined using hair cortisol concentration (HCC), and social integration was measured by means of a sociogram. The program had previously proven to be effective in decreasing salivary cortisol levels and in favouring social integration in children. A total of 35 children participated in the study: 18 constituted the intervention group and 17 the wait-list group. In both groups, HCC and social integration were evaluated before and after the intervention conducted throughout an entire school year.

RESULTS

The experimental group showed a significant reduction in HCC, as well as significant enhancement of social integration levels, whereas no changes were observed in the wait-list group.

CONCLUSIONS

This is the first research to show that HCC, a reliable neuroendocrine indicator, decreased as a result of a mindfulness-based program. This successful outcome adds new evidence to previous findings regarding the reduction of chronic stress in children following participation in this program.

Relationship between proximity and physiological stress levels in hunter-gatherers: The Hadza

In recent years there has been a great deal of documentation on how social relationships are related to various aspects of human wellbeing. However, until recently most studies investigating the effects of social relationships on wellbeing have applied social network measures to reported social contacts. Recent advances in the application of bio-loggers in biological studies have now made it possible to quantify social relationships based on in-person, rather than self-reported, social interactions. We used GPS-derived in-camp and out-of-camp proximity data to analyse how in-person proximity is related to Hair Cortisol Concentration (HCC) among Hadza hunter-gatherers. Time spent in close proximity to other camp members was associated with higher HCC, especially in women. In contrast, individuals who spent more time in close out-of-camp proximity to their best friend experienced lower HCC. Our study suggests that physiological costs related to group living might be mitigated by in-person interactions with close friends. We also find that the location (i.e., in-camp vs out-of-camp) of proximity to others and self-perceived friends is associated with HCC among the Hadza.

Who Does Cohesion Benefit? Race, Gender, and Peer Networks Associated with Adolescent Depressive Symptoms

Adolescence is a developmental period when peer network structure is associated with mental health. However, how networks relate to distress for youth at different intersecting racial/ethnic and gender identities is unclear. Using National Longitudinal Study of Adolescent to Adult Health survey data, cross-sectional models examine peer network cohesion predicting adolescent depressive levels for racial/ethnic and gender groups. The analytic sample is N = 13,055, average age 15.3 years, 50.2% female, 68.8 % White, 17.2% Black, 9.7% Hispanic, and 4.2% Asian. The results indicate that average cohesion, depressive levels, and cohesion associated with depressive levels differ by race/ethnicity and gender, with the greatest benefits for White and Black girls. This work clarifies patterns of adolescent networks and mental health by race/ethnicity and gender.

Social status does not predict in-camp integration among egalitarian hunter-gatherer men

In the last few decades, there has been much research regarding the importance of social prestige in shaping the social structure of small-scale societies. While recent studies show that social prestige may have important health consequences, little is known about the extent to which prestige translates into actual in-person interactions and proximity, even though the level of integration into such real-life social networks has been shown to have important health consequences. Here, we determine the extent to which two different domains of social prestige, popularity (being perceived as a friend by others), and hunting reputation (being perceived as a good hunter), translate into GPS-derived in- and out-of-camp proximity networks in a group of egalitarian hunter-gatherer men, the Hadza. We show that popularity and hunting reputation differ in the extent to which they are translated into time spent physically close to each other. Moreover, our findings suggest that in-camp proximity networks, which are commonly applied in studies of small-scale societies, do not show the full picture of Hadza men’s social preferences. While men are in camp, neither popularity nor hunting reputation is associated with being central in the proximity network; however, when out of camp, Hadza men who are popular are more integrated in the proximity networks while men with better hunting reputations are less integrated. Overall, our findings suggest that, to fully understand social preferences among hunter-gatherers, both in-camp and out-of-camp proximity networks should be considered.

Early-life social experience affects offspring DNA methylation and later life stress phenotype

Studies in rodents and captive primates suggest that the early-life social environment affects future phenotype, potentially through alterations to DNA methylation. Little is known of these associations in wild animals. In a wild population of spotted hyenas, we test the hypothesis that maternal care during the first year of life and social connectedness during two periods of early development leads to differences in DNA methylation and fecal glucocorticoid metabolites (fGCMs) later in life. Here we report that although maternal care and social connectedness during the den-dependent life stage are not associated with fGCMs, greater social connectedness during the subadult den-independent life stage is associated with lower adult fGCMs. Additionally, more maternal care and social connectedness after den independence correspond with higher global (%CCGG) DNA methylation. We also note differential DNA methylation near 5 genes involved in inflammation, immune response, and aging that may link maternal care with stress phenotype.

A School Intervention Helps Decrease Daily Stress While Enhancing Social Integration in Children

Stress coping is highly relevant during childhood. This study analyses how the participation in a behavioral intervention involving mindfulness-based practices and empathic collaboration activities impact on diurnal cortisol rhythm and social integration in children. In both experimental and waitlist groups, we evaluated before and after the intervention: daily stress, by sampling salivary cortisol at three measurement time-points, and social integration, assessed by a social preference index. Daily average cortisol (DAC) and the area under the curve (AUC) differed when comparing pre-post intervention values in both groups: in the experimental group these measures decreased while in the waitlist group DAC and AUC increased. At the end of the intervention, the experimental group showed an enhancement in the social preference index whereas this parameter diminished in the waitlist group. This kind of behavioral intervention seems to be effective at reducing daily stress and improving social integration in Primary School children.

Social network dynamics predict hormone levels and behavior in a highly social cichlid fish

Group living confers many benefits while simultaneously exposing group members to intense competition. An individual's rise to prominence within a group may conflict with the overall functioning of the group. There is therefore a complex and dynamic relationship between the behavioral displays that directly benefit an individual, the consequences of these actions for the community, and how they feed back on individual-level fitness. We used a network analysis approach to study the link between behavior, social stability, and steroid hormone levels in replicate communities of the cichlid fish, Astatotilapia burtoni, which live in social groups with a dominance hierarchy. We demonstrate that individual behavior can have direct and indirect effects on the behavior of others while also affecting group characteristics. Our results show that A. burtoni males form stable social networks, where dominant individuals act as hubs for social interactions. However, there was variation in the temporal stability in these networks, and this variation in stability impacted hormone levels. Dominant males had higher testosterone levels, however, the differences in testosterone levels between dominant and subordinate males were greatest in stable communities. In sum, our analyses provide novel insights into the processes by which individual and community properties interact.

What are friends for? The impact of friendship on communicative efficiency and cortisol response during collaborative problem solving among younger and older women

Conversation is a skilled activity that depends on cognitive and social processes, both of which develop through adulthood. We examined the effects of age and partner familiarity on communicative efficiency and cortisol reactivity. Younger and older women interacted with familiar or unfamiliar partners in a dyadic collaborative conversation task (N = 8 in each group). Regardless of age, referential expressions among familiar and unfamiliar partners became more efficient over time, and cortisol concentrations were lower for speakers interacting with familiar partners. These findings suggest that communicative effectiveness is largely preserved with age, as is the stress-buffering effect of a familiar partner.

Social networks, group exercise, and anxiety among college students

This study aimed to evaluate the relationship between group exercise membership, social network characteristics, and general state anxiety in a sample of college students. Participants: 490 undergraduates from a private university in the southern US participated in the study. Methods: An egocentric network analysis was conducted to test whether demographic variables, leisure-time physical activity, group exercise membership, flourishing scores, and network variables were related to anxiety. Results: Regression analyses (R² = .174, F = 7.650, p < .0001) suggest group exercise membership (β = -.105, p = .034) and flourishing scores (β = -.342, p < .0001) were related to lower anxiety scores, while being a racial/ethnic minority (β = .094, p = .036), and having personal networks composed of more people who exercise often (β = .100, p = .025), were related to higher anxiety scores in this sample. Conclusions: Findings suggest a connection between group exercise membership, activity habits of peers, and anxiety. Encouraging group exercise participation could be an effective way of combating anxiety for college students.

Agency, communion, and pubertal status: Separating between- and within-person associations to examine social goals development

OBJECTIVES

Agentic (status/independence) and communal (acceptance/connectedness) social goals are thought to shape how adolescents transact with their social environments. Despite their theoretical importance, little work has focused on the development of these higher order personality dimensions. Informed by developmental neuroscience and evolutionary psychology theoretical frameworks, the current study examined associations between pubertal status, a person's level of pubertal development at a single point in time, and agentic and communal social goals across early to middle adolescence.

METHODS

This longitudinal study consisted of 387 (55% female) adolescents (Wave 1 M age = 12.1) who were assessed annually across three waves. Hierarchical linear modeling was used to examine growth in pubertal status and agentic and communal goals and to distinguish between- and within-person associations between pubertal status and social goals.

RESULTS

Within-person pubertal status was concurrently associated with higher levels of agentic and communal goals. In the cross-sectional and longitudinal models, between-person pubertal status was associated with higher levels of agentic social goals. No support was found for social goals prospectively predicting pubertal status.

CONCLUSIONS

These findings provide support for the hypothesis that puberty, in part, may drive developmental shifts in the value adolescents place on close peer relationships and obtaining status and independence.

A social network approach to analyzing body dissatisfaction among sorority members using two network generators

Objective: This article uses social network analysis (SNA) to analyze how various measures of social connectedness relate to body dissatisfaction (BD) in sorority members.Participants: 208 sorority members participated in the study.Methods: Measures of social connectedness (network variables) were created based on two relational networks: persons members felt closest to and persons they spent the most time with. SNA tested whether demographic variables, body mass index (BMI), compulsive exercise, and network variables were related to BD in both networks.Results: Members reported BD was related to less social connectedness in the "close-to" and the "time-spent" networks, although specific network variables varied between the two. Compulsive exercise, BMI, and grade classification were related to BD in both networks.Conclusions: How a sorority member connects to others in her network could impact BD in this population. This study supports efforts facilitating increased social connection within a sorority as a means to decrease BD.

Relationship Between Parental Attachment and Stress Elevation and Synchrony in Pediatric Occupational Therapy Patient-Parent Dyads

IMPORTANCE

Populations already experiencing chronic stress, such as families with children who are neurologically atypical, are at particular risk for developing stress-related disease.

OBJECTIVE

To establish feasibility of collecting salivary samples from pediatric occupational therapy patients and their parents in a clinical setting and at home and to examine associations among parental attachment style, parent self-reported stress, and physiological stress (i.e., cortisol) in pediatric occupational therapy patients who were neurologically atypical and their parents (N = 10 dyads).

DESIGN

Cross-sectional pilot study to test feasibility.

SETTING

Sliding-scale university clinic.

PARTICIPANTS

Participants were 10 children undergoing occupational therapy treatment and their parent. Families were approached and told the study was voluntary and would not affect their treatment. Families provided informed consent.

OUTCOMES AND MEASURES

Parents completed measures to assess their own attachment style, general and parenting stress, and stress in their child. Children and parents provided saliva samples during an occupational therapy clinic visit and collected samples at home to measure cortisol level.

RESULTS

Parent attachment avoidance was related to increased parent cortisol levels in the clinic and increased child cortisol levels at home. Parent and child cortisol levels had a strong, positive relationship in the clinic but not at home. We did not observe a difference between cortisol levels in children or parents in the clinic or at home.

CONCLUSIONS AND RELEVANCE

We concluded that this protocol is feasible and provide suggestions for future research.

WHAT THIS ARTICLE ADDS

Stress physiology in pediatric occupational therapy clients should be considered within the context of the family system. Family-based interventions may be particularly helpful for reducing client stress in this population.

Status does not predict stress: Women in an egalitarian hunter-gatherer society

It is widely believed that there is strong association between physiological stress and an individual's social status in their social hierarchy. This has been claimed for all humans cross-culturally, as well as in non-human animals living in social groups. However, the relationship between stress and social status has not been explored in any egalitarian hunter-gatherer society; it is also under investigated in exclusively female social groups. Most of human evolutionary history was spent in small, mobile foraging bands of hunter-gatherers with little economic differentiation - egalitarian societies. We analysed women's hair cortisol concentration along with two domains of women's social status (foraging reputation and popularity) in an egalitarian hunter-gatherer society, the Hadza. We hypothesized that higher social status would be associated with lower physiological indicators of stress in these women. Surprisingly, we did not find any association between either foraging reputation or popularity and hair cortisol concentration. The results of our study suggest that social status is not a consistent or powerful predictor of physiological stress levels in women in an egalitarian social structure. This challenges the notion that social status has the same basic physiological implications across all demographics and in all human societies.

Loneliness and cortisol are associated with social network regulation

This study examines how loneliness and the body's stress response system interact to regulate social connections. We suggest that the drive to reconnect signaled by loneliness can be accompanied physiologically by the production of cortisol, which can offer supportive coping resources. Thus, we investigated how loneliness, cortisol levels, and their interaction predicted changes in network connections in a social organization. Participants (n = 193; 53% female) provided friendship network data at two times. At time 1, participants reported on loneliness and donated saliva (later assayed for cortisol). Results revealed that concurrently, lonely individuals reported fewer friendships, whereas over time, they named more friends. These results support the hypothesis that loneliness is a signal to develop connections. We also explored whom lonely individuals befriended over time. Results showed that cortisol significantly moderated the preference for friends with a similar level of loneliness. Specifically, lonely individuals with higher cortisol befriended those who were less lonely over those who were lonelier. Thus, cortisol levels may serve an adaptive function in mobilizing resources to develop connections that fulfill social belongingness needs. Results supported the theorized signaling function of loneliness and revealed that loneliness and the stress response system interact to shape social connections.

Stress, cortisol, and social hierarchy

We review the literature on the relationships between cortisol, stress, and various forms of social status, concluding that cortisol (and stress) is typically elevated when one chronically lacks, or may soon lose, status. Moreover, cortisol is lower when status is higher, as long as that status is stable, enhances one's sense of control, and does not also substantially increase one's responsibilities. Because cortisol is both an output (stress indicator) and input (cause of behavioral inhibition), this low cortisol may be both a cause and consequence of stable status. Altogether, the cortisol-status relationship depends not just on one's status but on what that status means for the individual (e.g. How frequent and severe are stressors? Does one feel a sense of control? Does one need to be vigilant and deferential?).

From maternal tending to adolescent befriending: The adolescent transition of social support

Attachment theory holds that parental relationships have lifelong effects on offspring social lives. The tend-and-befriend hypothesis posits that female friendships among humans evolved as part of a primate-wide coping mechanism to mediate stress by relying on social support. Here we bridge developmental and evolutionary frameworks to examine adolescent girls' perception of their reliance on female friendship for social support, how perceptions of parental relationships affect peer relationships, and the extent to which parent and peer relationships buffer depressive symptoms. We predict perceived maternal relationship quality will be positively associated with close female friendships, and maternal relationships, paternal relationships, and female friendship will buffer depressive symptoms. Participants were adolescent girls from a summer science camp (N = 95). Participants filled out demographic information, social network surveys, the Parent-Adolescent Communication Scale, and the Center for Epidemiology Depression Scale. Data was analyzed with Pearson's correlations, t tests, and path analysis. Adolescent girls with few female friends, compared with girls who had more than two very close female friends, experienced more depressive symptoms (t = 3.382, p = .001, D = 0.784). Adolescent girls with few female friends experienced more depressive symptoms compared to girls with two or more very close female friends (t = 3.382, p = .001, D = 0.784). Stronger maternal and paternal relationships were associated with having more female friends (maternal: t = -3.213, p = .003, D = 0.837; paternal: t = -2.432; p = .017). In the path analysis model, only maternal relationship quality significantly predicted female friendship category (β = .33, CR = 2.770, p < .006). Furthermore, participants with two or more very close female friends and higher paternal relationship quality had significantly fewer depressive symptoms (friends; β = -.19, CR = -2.112, p = .035; paternal: β = -.33, CR = -3.220, p < .001), and older participants had more depressive symptoms (β = .17, CR = -1.931, p = .036). These results provide additional support for the tend-and-befriend hypothesis, suggesting that maternal tending sets the stage for close female friendships.

Social Ties Cut Both Ways: Self-Harm and Adolescent Peer Networks

Peers play an important role in adolescence, a time when self-harm arises as a major health risk, but little is known about the social networks of adolescents who cut. Peer network positions can affect mental distress related to cutting or provide direct social motivations for self-harm. This study uses PROSPER survey data from U.S. high school students (n = 11,160, 48% male, grades 11 and 12), finding that social networks predict self-cutting net of demographics and depressive symptoms. In final models, bridging peers predicts higher self-cutting, while claiming more friends predicts lower cutting for boys. The findings suggest that researchers and practitioners should consider peer networks both a beneficial resource and source of risk associated with cutting for teens and recognize the sociostructural contexts of self-harm for adolescents more broadly.

Social network analysis for assessing college-aged adults' health: A systematic review

OBJECTIVE

Social network analysis (SNA) is a useful, emerging method for studying health. College students are especially prone to social influence when it comes to health. This review aimed to identify network variables related to college student health and determine how SNA was used in the literature.

PARTICIPANTS

A systematic review of relevant literature was conducted in October 2015.

METHODS

Studies employing egocentric or whole network analysis to study college student health were included. We used Garrard's Matrix Method to extract data from reviewed articles (n = 15).

RESULTS

Drinking, smoking, aggression, homesickness, and stress were predicted by network variables in the reviewed literature. Methodological inconsistencies concerning boundary specification, data collection, nomination limits, and statistical analyses were revealed across studies.

CONCLUSIONS

Results show the consistent relationship between network variables and college health outcomes, justifying further use of SNA to research college health. Suggestions and considerations for future use of SNA are provided.

Brain Sensitivity to Exclusion is Associated with Core Network Closure

Humans are driven to pursue and preserve social relationships, and these motivations are reinforced through biological systems. In particular, individual differences in the tuning of biological systems that respond to social threats may motivate individuals to seek out differently structured social environments. Drawing on a sample of adolescent males who underwent fMRI brain imaging (n = 74) and contributed Facebook data, we examined whether biological responses to a common scenario - being excluded from an activity with peers - was associated with their social network structure. We find that neural responses during social exclusion in a priori hypothesized "social pain" regions of the brain (dACC, AI, subACC) are associated with the density and transitivity of core friendship networks. These findings suggest that neural reactivity to exclusion may be one factor that underlies network "safety". More broadly, the study shows the potential of linking social cognitive tendencies to social structural properties.

The Role of Oxytocin in Social Buffering: What Do Primate Studies Add?

The ability to maintain close social bonds impacts on reproductive success, longevity, stress and health in social mammals, including humans (Silk et al., Curr Biol 20(15):1359-1361, 2010; Crockford et al., Horm Behav 53(1):254-265, 2008; Wittig et al., Horm Behav 54(1):170-177, 2008; Archie et al., Proc R Soc B 281(1793):20141261, 2014; Cameron et al., Proc Natl Acad Sci U S A 106:13850-13853, 2009; Schülke et al., Curr Biol 20:2207-2210, 2010; Silk et al., Science 302:1231-1234, 2003; Holt-Lunstad et al., PLoS Med 7(7):e1000316, 2010). Close social bonds provide an important social support system, at least in part by acting as a buffer against the deleterious effects of chronic exposure to stressors (Young et al., Proc Natl Acad Sci U S A 51:18195-18200, 2014; Heinrichs et al., Biol Psychiatry 54:1389-1398, 2003). There is accumulating evidence that individuals that provide predictable affiliation or support to others (bond partners) may moderate the perception of the stressor as well as of the physiological stress response. The neuropeptide, oxytocin, may mediate social buffering by down-regulating HPA activity and thus reducing the stress response. However, much within this process remains unclear, such as whether oxytocin is always released when exposed to a stressor, whether more oxytocin is released if there is social support, what aspect of stress or social support triggers oxytocin release and whether social support in the absence of a stressor also impacts oxytocin release and HPA activity, during everyday life. We review the literature that addresses each of these questions in an attempt to clarify where future research effort will be helpful. A better understanding of these dynamics is likely to have implications for enhancing social and health gains from human social relationships.

Social network centrality and hormones: The interaction of testosterone and cortisol

In this study we tested whether testosterone and cortisol interacted in predicting social network centrality within a male rugby team. Using social network analysis (SNA), three measures of centrality were investigated: popularity (i.e., the number of incoming ties a participant receives), gregariousness (i.e., the number of ties leaving from a participant and reaching out to others), and betweenness (i.e., the number of times a person lies between two other individuals). In line with the idea that testosterone and cortisol jointly regulate the emergence of social status, we found that individuals with high basal testosterone and low basal cortisol were more popular and more likely to act as connectors among other individuals (i.e., betweenness). The same hormonal profile was not predictive of gregariousness. However, in line with the small literature on the topic, we found that cortisol was inversely correlated with gregariousness. Despite the cross-sectional and correlational nature of our research design, these findings represent the first empirical evidence that testosterone and cortisol interact to predict complex measures of social hierarchy position derived from social network analyses.

Cortisol and testosterone associations with social network dynamics

This study integrates behavioral endocrinology and network science to explore links between hormones and social network dynamics. Specifically, we examine how cortisol (C) and testosterone (T) are associated with creation of new friendships and maintenance of existing friendships. A collegiate marching band was used as a model system of a mixed-sex social organization. Participants (n=193; 53% female; M age=19.4years, 62.1% European-American) provided friendship nominations at time 1 and two months later at time 2. At time 1, participants donated saliva before and after rehearsal (later assayed for C and T). Stochastic actor-based models revealed that individuals with higher C levels were less likely to maintain their social relationships and more likely to create new friendships. In contrast, individuals with higher T levels were more likely to maintain friendships and less likely to create new relationships. Findings suggest that individual differences in C and T are associated with the initiation and maintenance of friendships and have several noteworthy theoretical implications.

The varying value of a friendly face: Experimentally induced stress is associated with higher preferences for friendship with people possessing feminine versus masculine face traits

Social support can provide a buffer to the negative consequences of stress. Previous research suggests that stress can promote affiliative and cooperative behaviours in those who are stressed. Here we examined how stress might influence who we choose to affiliate with. We measured preferences for friendships with friendly appearing feminized faces versus less friendly appearing masculinized faces after individuals undertook a stressful laboratory task. Stressed individuals had increased preferences for friendships with people with feminine faces. These data demonstrate that individuals prefer more friendly appearing feminine faced people as friends when stressed than when not stressed. This preference is likely adaptive in directing individuals towards others who are most likely to provide social support when it is needed and so reflect strategic friendship preferences.

Cortisol, salivary alpha-amylase and children's perceptions of their social networks

In recent years there has been a growing interest in the use of social network analysis in biobehavioral research. Despite the well-established importance of social relationships in influencing human behavior and health, little is known about how children's perception of their immediate social relationships correlates with biological parameters of stress. In this study we explore the association between two measures of children's personal social networks, perceived network size and perceived network density, with two biomarkers of stress, cortisol and salivary alpha-amylase. Forty children (mean age = 8.30, min age = 5, and max age = 12) were interviewed to collect information about their friendships and three samples of saliva were collected. Our results show that children characterized by a lower pre-interview cortisol concentration and a lower salivary alpha-amylase reactivity to the interview reported the highest density of friendships. We discuss this result in light of the multisystem approach to the study of children's behavioral outcomes, emphasizing that future work of this kind is needed in order to understand the cognitive and biological mechanisms underlying children's and adolescents' social perceptual biases.

Hormones, behavior, and social network analysis: exploring associations between cortisol, testosterone, and network structure

We used a new interdisciplinary paradigm of social network analysis (SNA) to investigate associations between hormones and social network structures. We examine these biobehavioral processes and test hypotheses about how hormones are associated with social network structures using exponential random graph modeling (ERGM) in a cohort of first-year students (n=74; 93% female; M age=27 years) from a highly competitive, accelerated nursing program. Participants completed friendship nominations and as a group simultaneously donated saliva (later assayed for cortisol and testosterone). ERGM analyses revealed that salivary cortisol levels were inversely associated with the number of outgoing ties (i.e., network activity). By contrast, testosterone was not related to friendship network structure. Integration of SNA and salivary bioscience creates a novel approach to understanding hormone-behavior relationships within the context of human social ecologies.

The effects of friendship network popularity on depressive symptoms during early adolescence: moderation by fear of negative evaluation and gender

We integrated a social network analysis and developmental perspectives to examine the effects of friendship network popularity on depressive symptoms during early adolescence. We explored whether the association between social status processes (i.e., friendship network popularity) and depressive symptoms was moderated by socio-cognitive aspects of peer relations (i.e., a fear of negative evaluation by peers) and gender. This longitudinal study was conducted with a sample of 367 adolescents (48.5 % female; M age = 11.9 years; 9 % European American, 19 % African American, 7 % Native American, 60 % Latino(a), 5 % other) attending sixth and seventh grades at Time 1. Results indicated that, for males with high levels of fear of negative evaluation, friendship network popularity was associated negatively with increases in depressive symptoms. Conversely, for females with high levels of fear of negative evaluation, friendship network popularity was associated positively with increases in depressive symptoms. Theoretical and clinical implications are discussed.