Altruism in social networks: Evidence for a ‘kinship premium’

Why and under what conditions are individuals altruistic to family and friends in their social networks? Evolutionary psychology suggests that such behaviour is primarily the product of adaptations for kin‐ and reciprocal altruism, dependent on the degree of genetic relatedness and exchange of benefits, respectively. For this reason, individuals are expected to be more altruistic to family members than to friends: whereas family members can be the recipients of kin and reciprocal altruism, friends can be the recipients of reciprocal altruism only. However, there is a question about how the effect of kinship is implemented at the proximate psychological level. One possibility is that kinship contributes to some general measure of relationship quality (such as ‘emotional closeness’), which in turn explains altruism. Another possibility is that the effect of kinship is independent of relationship quality. The present study tests between these two possibilities. Participants (N= 111) completed a self‐report questionnaire about their willingness to be altruistic, and their emotional closeness, to 12 family members and friends at different positions in their extended social networks. As expected, altruism was greater for family than friends, and greater for more central layers of the network. Crucially, the results showed that kinship made a significant unique contribution to altruism, even when controlling for the effects of emotional closeness. Thus, participants were more altruistic towards kin than would be expected if altruism was dependent on emotional closeness alone – a phenomenon we label a ‘kinship premium’. These results have implications for the ongoing debate about the extent to which kin relations and friendships are distinct kinds of social relationships, and how to measure the ‘strength of ties’ in social networks.     

The sibling uncertainty hypothesis: Facial resemblance as a sibling recognition cue

For the same reason that fathers could not have been certain their mates’ offspring were their genetic progeny during human evolutionary history, full siblings could not have been certain that they shared paternal genes. Previous kin recognition research suggests facial resemblance is a cue men use to help solve the adaptive problem of paternity uncertainty and identify their biological offspring. Facial resemblance may also be a cue individuals use to identify siblings who share paternal genes. In the current study, facial resemblance between siblings was hypothesized to be positively associated with their emotional closeness and altruism, and inversely related with their frequency of conflict. Within families, individuals reported greater closeness and altruism toward siblings who more closely resembled them. In contrast with previous offspring recognition research, the effects of resemblance were not sex-differentiated, suggesting that facial resemblance is a cue both sexes use in sibling recognition.     

My Mother: My Best Friend? Adults’ Relationships with Significant Others Across the Lifespan

In order to investigate the significance of adults’ relationship to their parents, this relationship is compared to relationships with siblings, friends, partners, and children. German adults (N = 902) between the ages of 20 and 86 completed the Network of Relationships Inventory (Furman and Buhrmester 1992). Participants felt most supported by their partners, followed by their children, mothers, friends, fathers, and siblings. Conflicts were more frequently found within the family (especially with the partner, followed by children, mothers, fathers, and siblings) than with friends. Except for partner relationships, both conflict and support decreased with age. Concerning relative power within their relationships, partners, mothers, and siblings are seen as equals, friends and especially fathers are perceived as more powerful, and children as less, yet increasingly powerful. Regarding all relationship types and relationship qualities, the differences between women and men were small.     

Exposure to maternal vs. paternal partner violence,PTSD, and aggression in adolescent girls and boys

Adolescents who witness interparental violence (IPV) are at increased risk for perpetrating aggressive acts. They are also at risk for post‐traumatic stress disorder (PTSD). In this study, we examined the relation between exposure to maternal vs. paternal physical IPV and adolescent girls' and boys' aggressive behavior toward mothers, fathers, friends, and romantic partners. We also assessed the influence of PTSD (as assessed by the Diagnostic Interview for Children and Adolescents‐IV (DICA‐IV)) on the relation between exposure to IPV and aggressive behavior. Participants were 63 girls and 49 boys, ages 13–18, consecutively admitted to a youth correctional facility or assessment facility designated to serve aggressive and delinquent youth. Structural equation modeling was used to estimate unique relations between exposure to maternal vs. paternal IPV and youth aggression in relationships. Girls who observed their mothers' aggressive behavior toward partners were significantly more aggressive toward friends. Similarly, boys who witnessed their fathers' aggression were significantly more aggressive toward friends. Adolescent girls and boys who observed aggression by mothers toward partners reported significantly higher levels of aggression toward their romantic partners. Approximately one third of our sample met PTSD criteria; the relation between exposure to parental IPV and aggression was stronger for individuals who met criteria for PTSD. The implications of understanding the relations between parents' and their daughters' and sons' use of aggression are discussed within the context of providing support for families in breaking intergenerational patterns of violence and aggression. Aggr. Behav. 32:385–395, 2006. © 2006 Wiley‐Liss, Inc.     

Behavior expectations in cross‐sex friendships,same‐sex friendships,and romantic relationships

Abstract In 2 studies, university students from the United States rated the importance of 43 behavior expectations about their cross‐sex friends, same‐sex friends and romantic partners. In Study 1, all 399 participants had a current romantic partner, whereas in Study 2, romantic partner status varied across the 165 participants. Participants always rated their expectations for romantic partners higher than for either type of friend, and expectations for behaviors promoting emotional closeness were always rated higher than expectations about behaviors promoting social companionship or relationship positivity. In Study 2, expectations for cross‐sex friends were rated lower and more similar to same‐sex friends when participants had a current romantic partner than when they did not.     

Possible olfaction-based mechanisms in human kin recognition and inbreeding avoidance

Three studies explored kin recognition through olfaction. In Study I, adults (N=22) were tested for ability to identify the odors of themselves; their mother; their father; a sister; a brother; a familiar, unrelated individual; and a stranger. Acquaintances were identified as accurately as biological kin, implicating an association mechanism. However, biological kin were often confused, implicating phenotypic matching. Same-sex kin were confused more than opposite-sex kin, but mainly when same-sex kin had odors of similar intensity. Study II implicated phenotypic matching. Mothers (N=18) could identify their biological children but not their stepchildren. The preadolescent children (N=37) identified their full siblings but not half-siblings or stepsiblings. Thus, olfactory cues may help mediate favoritism of blood relatives. In Study III, mutual olfactory aversion occurred only in the father-daughter and brother-sister nuclear family relationships. Recognition occurred between opposite-sex siblings but not same-sex siblings. Thus, olfaction may help mediate the development of incest avoidance during childhood (the Westermarck effect).     

Relationship work among young adult couples: Romantic,social, and physiological considerations

We examined romantic, social, and physiological variables associated with partners discussing romantic challenges together and with friends, a process known as relationship work (RW). Actor‐partner interdependence models examining 71 heterosexual, young adult couples and their friends suggested social network approval, friendship quality, and partners' perspective taking were each associated with partners' RW patterns. Skin conductance activity readings revealed males universally experienced greater physiological arousal when discussing romantic problems than females. Unexpectedly, both males and females experienced greater skin conductance activity when discussing romantic challenges with friends than with partners. Males were more likely to discuss romantic challenges with friends when their female partners experienced greater baseline skin conductance activity. Findings inform researchers regarding links between romantic, social, and physiological functioning.     

Partner preferences across sexual orientations and biological sex

This study examined how partner preferences differ across interpersonal contexts (romantic attachment and relationship expectations) based on sexuality and biological sex. Participants completed measures of attachment and behavioral expectations for their romantic partners, cross‐sex friends, and same‐sex friends. The attachment anxiety results revealed an effect of sexuality: Single heterosexuals scored higher for their cross‐sex friends than same‐sex friends, single lesbian/gay individuals scored higher for same‐sex friends than cross‐sex friends, and bisexuals' attachment anxiety was equal regardless of friends' biological sex. The behavioral expectation results revealed an effect of biological sex indicating that, regardless of sexuality, women are preferred over men for emotional/social needs. Finally, an interaction revealed that lesbians have higher expectations for their girlfriends/wives than straight men have for theirs.     

Exploring the relationship between umbilical blood cord donation and the impact of social distance on altruism and trust

Allogeneic umbilical cord blood (UCB) donation is a pro-social behaviour directed to strangers that has a certain cost for the donor. Although the promotion of such behaviour is an important goal for many countries' health systems, little is known about the reasons that would lead to it. With this study, we explored how the impact of social closeness on altruism and trust could be related to UCB donation in a sample of new-mothers (N = 167). Participants played hypothetical Dictator and Trust games with socially close (e.g., parents) or distant (e.g., strangers) others. They donated more money to parents and siblings compared to cousins, friends and strangers and they trusted more parents, siblings and friends than cousins and strangers. Interestingly, the lower the impact of social closeness on altruism (i.e., generosity towards socially distant others), the higher the intention and the actual probability of UCB donation. A mediation analysis has shown that the relationship between social closeness on altruism and UCB donation was mediated by objective intention to donate (i.e., having followed all the procedures needed). These findings show that other-oriented motivations towards distant others might have important practical implications in identifying the targets of interventions for the promotion of UCB donation.     

Altruism predicts mating success in humans

In order for non‐kin altruism to evolve, altruists must receive fitness benefits for their actions that outweigh the costs. Several researchers have suggested that altruism is a costly signal of desirable qualities, such that it could have evolved by sexual selection. In two studies, we show that altruism is broadly linked with mating success. In Study 1, participants who scored higher on a self‐report altruism measure reported they were more desirable to the opposite sex, as well as reported having more sex partners, more casual sex partners, and having sex more often within relationships. Sex moderated some of these relationships, such that altruism mattered more for men's number of lifetime and casual sex partners. In Study 2, participants who were willing to donate potential monetary winnings (in a modified dictator dilemma) reported having more lifetime sex partners, more casual sex partners, and more sex partners over the past year. Men who were willing to donate also reported having more lifetime dating partners. Furthermore, these patterns persisted, even when controlling for narcissism, Big Five personality traits, and socially desirable responding. These results suggest that altruists have higher mating success than non‐altruists and support the hypothesis that altruism is a sexually selected costly signal of difficult‐to‐observe qualities.     

Kinship and altruism: A cross‐cultural experimental study

Humans are characterized by an unusual level of prosociality. Despite this, considerable indirect evidence suggests that biological kinship plays an important role in altruistic behaviour. All previous reports of the influence of kin selection on human altruism have, however, used correlational (rather than experimental) designs, or imposed only a hypothetical or negligible time cost on participants. Since these research designs fail either to control for confounding variables or to meet the criteria required as a test of Hamilton's rule for kin selection (that the altruist pays a true cost), they fail to establish unequivocally whether kin selection plays a role. We show that individuals from two different cultures behave in accordance with Hamilton's rule by acting more altruistically (imposing a higher physical cost upon themselves) towards more closely related individuals. Three possible sources of confound were ruled out: generational effects, sexual attraction and reciprocity. Performance on the task however did not exhibit a perfect linear relationship with relatedness, which might reflect either the intrusion of other variables (e.g. cultural differences in the way kinship is costed) or that our behavioural measure is insufficiently sensitive to fine‐tuned differences in the way individuals view their social world. These findings provide the first unequivocal experimental evidence that kinship plays a role in moderating altruistic behaviour. Kinship thus represents a baseline against which individuals pitch other criteria (including reciprocity, prosociality, obligation and a moral sense) when deciding how to behave towards others.     

Recovering from conflict in romantic relationships: a developmental perspective

This study adopted a developmental perspective on recovery from conflict in romantic relationships. Participants were 73 young adults (target participants), studied since birth, and their romantic partners. A novel observational coding scheme was used to evaluate each participant's degree of conflict recovery, operationalized as the extent to which the participant disengaged from conflict during a 4-min "cool-down" task immediately following a 10-min conflict discussion. Conflict recovery was systematically associated with developmental and dyadic processes. Targets who were rated as securely attached more times in infancy recovered from conflict better, as did their romantic partners. Concurrently, having a romantic partner who displayed better recovery predicted more positive relationship emotions and greater relationship satisfaction. Prospectively, target participants' early attachment security and their partners' degree of conflict recovery interacted to predict relationship stability 2 years later, such that having a partner who recovered from conflict better buffered targets with insecure histories.     

Interactions of preschool and kindergarten friends and acquaintances

The interactions of 4-, 5-, and 6-year-old friends and acquaintances in a peer teaching and game-playing situation were examined. The sample consisted of 102 children who were divided into pairs of same-age, same-sex friends or acquaintances using sociometrics. One child in each pair was randomly chosen to be the teacher and the other the learner. The teachers taught a novel board game to the learners. The most common teaching method was a combination of explaining and demonstrating the rules before the game began; older children gave more comprehensive instructions than younger children. At all ages, teachers were more likely than learners to take the first turn, issue commands, and change the rules. Friends were rated more involved with their partners, more emotionally expressive, and more competitive than acquaintances. Teachers who taught friends were rated more domineering than teachers who taught acquaintances, and learners who were taught by friends were rated more playful and friendly than learners taught by acquaintances.     

Help Wanted and Help Received by Israeli Divorced Custodial Fathers

Comparing the help wanted and sought and the help received by 42 divorced custodial fathers with that wanted and sought and received by a matched group of 32 divorced custodial mothers, this paper investigates whether men who have assumed the traditionally female gender task of child care continue to adhere to the traditional male help-seeking and help-receiving patterns. Findings show that they do. Single custodial fathers both want and receive less help from own kin, friends, and ex-spouse's kin than do single custodial mothers, and are less prone to seek professional help. On the other hand, both groups seek and receive the most help from a new partner, followed by own kin, friends, and ex-spouse's kin.     

The child's social network: Sex differences from three to six years

The social networks of 85 young children as they make the transition from a home-centered to a more school-centered existence is examined using longitudinal data. When the children were three and six years of age, their mothers completed a questionnaire of network structure; at six years both the child and mother independently reported the friends that the child would invite to a birthday party. The effects of age and sex of child on the number and daily contact with peers, adults, kin, nonkin, males, and females were found. As expected, as children reached formal school age they had increased contact with peers and decreased contact with kin, while adult contact remained fairly consistent over the three- to six-year age period. Sex differences were also apparent. As predicted, children as early as 3 years, and to an even greater extent at six years, showed more same-sex compared to opposite-sex peer contact. At six years both children and mothers reported more same- as compared to opposite-sex friends who would be invited by the child to a birthday party. The findings suggest how children's social networks, as shaped by their parents and themselves, provide a framework within which experience and interaction is structured to fit cultural norms.     

Rejection sensitivity and male violence in romantic relationships

Rejection sensitivity is the disposition to anxiously expect, readily perceive, and intensely react to rejection by significant others. A model of the role of this disposition in male violence toward romantic partners is proposed. Specifically, it is proposed that rejection sensitivity is a vulnerability factor for two distinct maladaptive styles of coping with intimate relationships. Rejection‐sensitive men may attempt to prevent anticipated rejection by reducing their investment in intimate relationships. Alternatively, they may become highly invested in intimate relationships in search of an unconditionally supportive partner. Their low threshold for perceiving and overreacting to rejection, however, heightens their risk of responding aggressively to their partners’negative or ambiguous behavior. Cross‐sectional data from 217 male college students supported predictions derived from the model. Among college men who reported relatively high investment in romantic relationships, anxious expectations of rejection predicted dating violence. Among men who reported relatively low investment in romantic relationships, anxious expectations of rejection predicted reduced involvement in discretionary close relationships with friends and romantic partners and, more generally, increased distress in and avoidance of social situations.     

Longitudinal associations between parents' hostility and siblings' externalizing behavior in the context of marital discord.

This study examined longitudinal associations between parents' hostility and siblings' externalizing behavior in the context of interparental discord. The sample included 116 families (mothers, fathers, 2 siblings) assessed in middle childhood, when siblings were, on average, 8 and 10 years old, and in adolescence, at average ages of 14 and 16 years. Parents reported on their hostility toward each child and on each child's externalizing problems. Raters observed interparental hostility, and parents rated their marital quality. Results indicated both within-family and between-families effects. Specifically, the child who received more parental hostility than his or her sibling showed greater increases in externalizing problems than his or her sibling; this association was moderated by marital discord. In addition, the child who exhibited more behavioral problems than his or her sibling received greater increases in hostile mothering than did his or her sibling. Between-families effects were evident, in that children's externalizing problems were associated with increases in mothers' hostility toward both children in the family. Results support transactional models of development and family systems theory.