Elephants as an animal model for self-domestication.

Humans are unique in their sophisticated culture and societal structures, their complex languages, and their extensive tool use. According to the human self-domestication hypothesis, this unique set of traits may be the result of an evolutionary process of self-induced domestication, in which humans evolved to be less aggressive and more cooperative. However, the only other species that has been argued to be self-domesticated besides humans so far is bonobos, resulting in a narrow scope for investigating this theory limited to the primate order. Here, we propose an animal model for studying self-domestication: the elephant. First, we support our hypothesis with an extensive cross-species comparison, which suggests that elephants indeed exhibit many of the features associated with self-domestication (e.g., reduced aggression, increased prosociality, extended juvenile period, increased playfulness, socially regulated cortisol levels, and complex vocal behavior). Next, we present genetic evidence to reinforce our proposal, showing that genes positively selected in elephants are enriched in pathways associated with domestication traits and include several candidate genes previously associated with domestication. We also discuss several explanations for what may have triggered a self-domestication process in the elephant lineage. Our findings support the idea that elephants, like humans and bonobos, may be self-domesticated. Since the most recent common ancestor of humans and elephants is likely the most recent common ancestor of all placental mammals, our findings have important implications for convergent evolution beyond the primate taxa, and constitute an important advance toward understanding how and why self-domestication shaped humans' unique cultural niche.

Human Prosocial Preferences Are Related to Slow-Wave Activity in Sleep.

Prosocial behavior is crucial for the smooth functioning of the society. Yet, individuals differ vastly in the propensity to behave prosocially. Here, we try to explain these individual differences under normal sleep conditions without any experimental modulation of sleep. Using a portable high-density EEG, we measured the sleep data in 54 healthy adults (28 females) during a normal night's sleep at the participants' homes. To capture prosocial preferences, participants played an incentivized public goods game in which they faced real monetary consequences. The whole-brain analyses showed that a higher relative slow-wave activity (SWA, an indicator of sleep depth) in a cluster of electrodes over the right temporoparietal junction (TPJ) was associated with increased prosocial preferences. Source localization and current source density analyses further support these findings. Recent sleep deprivation studies imply that sleeping enough makes us more prosocial; the present findings suggest that it is not only sleep duration, but particularly sufficient sleep depth in the TPJ that is positively related to prosociality. Because the TPJ plays a central role in social cognitive functions, we speculate that sleep depth in the TPJ, as reflected by relative SWA, might serve as a dispositional indicator of social cognition ability, which is reflected in prosocial preferences. These findings contribute to the emerging framework explaining the link between sleep and prosocial behavior by shedding light on the underlying mechanisms.

Childhood behavior problems and adverse economic outcomes: a 30-year population-based study of intergenerational income mobility.

BACKGROUND: The objectives of this study were to (a) assess the associations between early behavioral problems and intergenerational income mobility (i.e., the degree to which income status is transmitted from one generation to the next), (b) verify whether these associations are moderated by child sex, and (c) explore indirect effects of early behavioral problems on income mobility via high school graduation. METHODS: Data were drawn from the Quebec Longitudinal Study of Kindergarten Children (n = 3,020; 49.17% girls). Participants were followed from age 6 to 37 years. Measures included parents' and teachers' ratings of behavioral problems at age 6 years as well as participants' (ages 30-35 years) and their parents' (when participants were aged 10-19 years) income data obtained from tax return records. Regression models were used to predict upward and downward mobility (i.e., increased or decreased income status from one generation to the next) from attention-deficit/hyperactivity problems, conduct/opposition problems, depression/anxiety problems, prosociality, and the quality of children's relationship with their caregiver. Two-way interaction effects between behavioral problems and child sex were examined and indirect effect models including high school graduation as a mediator of these associations were conducted. RESULTS: Despite their higher educational attainment, females had lower incomes and experienced lower upward (but higher downward) income mobility than males. For both females and males, higher levels of attention-deficit/hyperactivity and conduct/opposition problems were associated with decreased odds of upward mobility, whereas higher levels of attention-deficit/hyperactivity were associated with increased odds of downward mobility. Attention-deficit/hyperactivity problems, conduct/opposition problems as well as low prosociality were associated with lower educational attainment (no high school diploma), which in turn was associated with increased odds of downward mobility. CONCLUSIONS: Results highlight the importance of providing intensive support to children with early behavioral problems as a means of improving educational attainment and intergenerational income mobility.

The impact of sufferers' wealth status on pain perceptions: Its development and relation to allocation of healthcare resources.

Wealth-based disparities in health care wherein the poor receive undertreatment in painful conditions are a prominent issue that requires immediate attention. Research with adults suggests that these disparities are partly rooted in stereotypes associating poor individuals with pain insensitivity. However, whether and how children consider a sufferer's wealth status in their pain perceptions remains unknown. The present work addressed this question by testing 4- to 9-year-olds from the US and China. In Study 1 (N = 108, 56 girls, 79% White), US participants saw rich and poor White children experiencing identical injuries and indicated who they thought felt more pain. Although 4- to 6-year-olds responded at chance, children aged seven and above attributed more pain to the poor than to the rich. Study 2 with a new sample of US children (N = 111, 56 girls, 69% White) extended this effect to judgments of White adults' pain. Pain judgments also informed children's prosocial behaviors, leading them to provide medical resources to the poor. Studies 3 (N = 118, 59 girls, 100% Asian) and 4 (N = 80, 40 girls, 100% Asian) found that, when evaluating White and Asian people's suffering, Chinese children began to attribute more pain to the poor than to the rich earlier than US children. Thus, unlike US adults, US children and Chinese children recognize the poor's pain from early on. These findings add to our knowledge of group-based beliefs about pain sensitivity and have broad implications on ways to promote equitable health care. RESEARCH HIGHLIGHTS: Four studies examined whether 4- to 9-year-old children's pain perceptions were influenced by sufferers' wealth status. US children attributed more pain to White individuals of low wealth status than those of high wealth status by age seven. Chinese children demonstrated an earlier tendency to attribute more pain to the poor (versus the rich) compared to US children. Children's wealth-based pain judgments underlied their tendency to provide healthcare resources to people of low wealth status.

Schadenfreude or empathy? Children's emotional responses to the physical pain and pleasure of prosocial and antisocial others.

Adults' emotional reactions to the pain and pleasure of others are influenced by the moral character of those individuals. However, it remains unclear whether children's emotional responses also show such selectivity. To investigate this, we compared 4- to 8-year-old children's emotional responses to the physical pain and pleasure of prosocial versus antisocial puppets. In Study 1, children reported unhappiness after witnessing the pain of the prosocial and antisocial puppets but reported less unhappiness after witnessing the pain of the antisocial puppet. In Study 2, children reported happiness after witnessing the pleasure of both puppets but reported being less happy for the antisocial puppet. These results suggest that children are less likely to empathize with antisocial individuals. Meanwhile, children did not display Schadenfreude (pleasure at others' pain) or Gluckschmerz (displeasure at others' pleasure) toward antisocial individuals in our studies. Moreover, the selectivity of children's emotional responses disappeared after we manipulated the physical competence rather than the moral character of the puppets in Study 3. Our findings help to reveal the moral selectivity of emotional responses to others' pleasure and pain during early childhood.

What do children value more in a collaborator-Problem-solving capacity or fair sharing?

Collaboration requires individuals to find partners who are adept at problem-solving and act fairly when sharing the spoils of joint labor. Given that individuals might vary along both dimensions, it can create a dilemma with the challenging decision of whether to prioritize a potential partner's capacity to perform a task or the partner's level of fairness in sharing obtained resources. Here we tested whether young children can solve this dilemma when two potential partners have opposing qualities: One partner is high in the capacity to solve a problem but less likely to share fairly, whereas the other partner is lower in capacity but fair. In two studies with a total of N = 188 children aged 4 to 6 years, we found that children adjust their decisions based on the social context and the perceived difficulty of the collaborative task: Children show an overall preference for fair partners when collaborating in an easy task, but they choose partners high in problem-solving capacity and low in fairness when collaborating in a more difficult task. These results show that already young children can evaluate others along two dimensions and make trade-offs between capacity and fairness when deciding what is more relevant for a given situation.

Winning isn't everything: Guilt proneness and competitive vs. non-competitive motivation.

OBJECTIVE: Guilt proneness is associated with both high motivation to succeed and enhanced concern for others. However, in competition, achieving success requires harming others' interests, which demotivates guilt-prone individuals. Given the prevalence of competition in social and professional life, we examine the relation between guilt proneness, general motivation, and competitive motivation. METHOD: Two experiments and two laboratory studies (N = 1735) measured guilt proneness, general motivation, and competitive motivation, and their effects on competitive preferences and choices. Study settings included students' choice of playing a game individually vs. competitively (Study 1), physicians' likelihood to seek residency in medical fields characterized by high competitiveness (Study 2), amateur athletes' preferences between inclusive and win-oriented team strategies (Study 3), and online workers' evaluations of a hypothetical scenario (Study 4). RESULTS: Guilt proneness was related positively to general motivation, but negatively to competitive motivation. Guilt proneness, indirectly through lower competitive motivation, predicted a lower likelihood of pursuing competitive paths and preference for non-competitive strategies. Emphasizing prosocial aspects of competitiveness attenuated these effects. CONCLUSIONS: Guilt proneness is related to high general motivation but to a lower desire to win. Guilt-prone individuals strive for excellence, but through non-competitive paths, whereas people with lower guilt proneness prefer competing.

The Medusa effect reveals levels of mind perception in pictures.

Throughout our species history, humans have created pictures. The resulting picture record reveals an overwhelming preference for depicting things with minds. This preference suggests that pictures capture something of the mind that is significant to us, albeit at reduced potency. Here, we show that abstraction dims the perceived mind, even within the same picture. In a series of experiments, people were perceived as more real, and higher in both Agency (ability to do) and Experience (ability to feel), when they were presented as pictures than when they were presented as pictures of pictures. This pattern persisted across different tasks and even when comparators were matched for identity and image size. Viewers spontaneously discriminated between different levels of abstraction during eye tracking and were less willing to share money with a more abstracted person in a dictator game. Given that mind perception underpins moral judgement, our findings suggest that depicted persons will receive greater or lesser ethical consideration, depending on the level of abstraction.

COVID-19 within families amplifies the prosociality gap between adolescents of high and low socioeconomic status.

COVID-19 has had worse health, education, and labor market effects on groups with low socioeconomic status (SES) than on those with high SES. Little is known, however, about whether COVID-19 has also had differential effects on noncognitive skills that are important for life outcomes. Using panel data from before and during the pandemic, we show that COVID-19 affects one key noncognitive skill, that is, prosociality. While prosociality is already lower for low-SES students prior to the pandemic, we show that COVID-19 infections within families amplify the prosociality gap between French high school students of high and low SES by almost tripling its size in comparison to pre-COVID-19 levels.

Association of maternal pre-pregnancy body mass index with resilience and prosociality of the offspring aged 6-7 years old: a population-based cohort study in Japan.

The association between maternal pre-pregnancy obesity and child behavior problems has been widely researched, leaving a gap in understanding the positive aspects of children's mental health. The present study aimed to investigate the association between maternal pre-pregnancy body mass index (BMI) and resilience and prosociality among 6-7 year-old children in Japan. A retrospective cohort study was conducted using data from the Adachi Child Health Impact of Living Difficulty (A-CHILD) study, a population-based study in 2017 and 2019 including all first-grade students in public schools in Adachi, Tokyo, Japan (n = 7328, response rate = 84.7%). Resilience and prosociality were measured by the Children's Resilient Coping Scale and the Strength and Difficulties Questionnaire, respectively. Maternal pre-pregnancy weight and height were reported based on the Mother and Child Health Handbook, and BMI was categorized as underweight (BMI < 18.5), normal weight (BMI 18.5-24.9), overweight (BMI 25.0-29.9), and obesity (BMI ≥ 30). Linear regression models were employed to control for covariates. Maternal pre-pregnancy obesity was found to be negatively associated with child resilience (coefficient: - 3.29; 95% CI - 6.42--0.15), while maternal underweight was negatively associated with child prosociality (coefficient: - 0.12; 95% CI - 0.24--0.005) compared to mothers of pre-pregnancy normal BMI. Perinatal factors, such as gestational weight gain, gestational age, and birth weight, did not mediate the association. Our findings suggest that maternal pre-pregnancy obesity is linked to decreased resilience and maternal underweight is linked to decreased prosociality in children aged 6-7 years. Maintaining an appropriate BMI range before pregnancy may be crucial for enhancing resilience and prosociality of offspring.

Does Prosociality in Early-to Mid-Adolescence Protect Against Later Development of Antisocial Behaviours?

Connections between prosociality and antisocial behaviors have been recognized; however, little research has studied their developmental links longitudinally. This is important to illuminate during early adolescence as a sensitive period for social development in which prosociality could protect against the development of later antisocial behaviors. This study investigates the within-person developmental links between prosociality and antisocial behaviors, as well as a potential mediating role of peer relationships, across ages 11, 13, and 15 (N = 1526; 51% male) using random-intercept cross-lagged panel models. Results indicated that neither self-reported nor teacher-reported prosociality was associated with reduced aggressive behaviors but suggested a direct protective ('promotive') effect of teacher-reported prosociality on bullying perpetration. These findings suggest that promoting prosociality in early adolescence may help reduce some antisocial behaviors over early to mid-adolescent development. Improving prosociality could be explored as a target in intervention approaches such as school-based anti-bullying interventions.

Threat-induced anxiety and selfishness in resource sharing: Behavioral and neural evidence.

In real life, it is not unusual that we face potential threats (i.e., physical stimuli and environments that may cause harm or danger) with other individuals together, yet it remains largely unknown how threat-induced anxious feelings influence prosocial behaviors such as resource sharing. In this study, we investigated this question by combining functional magnetic resonance imaging and a novel paradigm. Together with an anonymous partner, each participant faced the possibility of receiving a 10-s noise administration, which had a low or high probability to be a threat (i.e., the intensity of noise can induce a high level of unpleasantness). Each participant first reported her/his immediate feeling of anxiety about the current situation (being threatened by the unpleasant noise), then decided how to split a number of resources (which could relieve the noise) between her/him and the partner. Behavioral results revealed that the participants showed a selfish bias in the threat conditions than in the safe conditions, and that self-reported anxiety feeling significantly predicted this bias. Functional magnetic resonance imaging results revealed that: (1) the activation level of the anterior insula was correlated with self-reported anxiety and (2) the connectivity between the anterior insula and the temporoparietal junction was sensitive to the modulating effect of anxiety on the selfish bias. These findings indicate the neural correlates of the association between threat-induced anxiety and prosocial tendencies in social interactions.

Apes reciprocate food positively and negatively.

Reciprocal food exchange is widespread in human societies but not among great apes, who may view food mainly as a target for competition. Understanding the similarities and differences between great apes' and humans' willingness to exchange food is important for our models regarding the origins of uniquely human forms of cooperation. Here, we demonstrate in-kind food exchanges in experimental settings with great apes for the first time. The initial sample consisted of 13 chimpanzees and 5 bonobos in the control phases, and the test phases included 10 chimpanzees and 2 bonobos, compared with a sample of 48 human children aged 4 years. First, we replicated prior findings showing no spontaneous food exchanges in great apes. Second, we discovered that when apes believe that conspecifics have 'intentionally' transferred food to them, positive reciprocal food exchanges (food-for-food) are not only possible but reach the same levels as in young children (approx. 75-80%). Third, we found that great apes engage in negative reciprocal food exchanges (no-food for no-food) but to a lower extent than children. This provides evidence for reciprocal food exchange in great apes in experimental settings and suggests that while a potential mechanism of fostering cooperation (via positive reciprocal exchanges) may be shared across species, a stabilizing mechanism (via negative reciprocity) is not.

Thinking About God Encourages Prosociality Toward Religious Outgroups: A Cross-Cultural Investigation.

Most humans believe in a god or gods, a belief that may promote prosociality toward coreligionists. A critical question is whether such enhanced prosociality is primarily parochial and confined to the religious ingroup or whether it extends to members of religious outgroups. To address this question, we conducted field and online experiments with Christian, Muslim, Hindu, and Jewish adults in the Middle East, Fiji, and the United States (N = 4,753). Participants were given the opportunity to share money with anonymous strangers from different ethno-religious groups. We manipulated whether they were asked to think about their god before making their choice. Thinking about God increased giving by 11% (4.17% of the total stake), an increase that was extended equally to ingroup and outgroup members. This suggests that belief in a god or gods may facilitate intergroup cooperation, particularly in economic transactions, even in contexts with heightened intergroup tension.

Family first! Influence of parental investment in Guinea pigs (Cavia porcellus) prosocial choices.

Literature often assumed that prosocial behaviours (behaviours that benefit others with or without a cost for the actor) would have evolved many species to improve the effectiveness of parental care (Decety and Cowell 2014). While this hypothesis is rarely questioned at a phylogenetic scale, it was never tested at an individual scale to the best of our knowledge. Therefore, we chose to study the impact of effective parental care on prosociality by comparing the prosocial tendencies of Guinea pigs before mating, during mating and after parturition. We conducted Prosocial Choice Tests on three groups of Guinea pigs (males, multiparous females, and nulliparous females). Subjects had to choose between three options: a prosocial option (subject and recipient being rewarded), a selfish option (only subject was rewarded), and a null option (no reward). Our results showed high prosociality towards their mating partner and their young both in male and in female subjects. Males became selfish towards other males after parturition. Among other interesting results, we found a direct reciprocity phenomenon. We also highlighted an ability in our subjects to consider both the identity and relationship shared with the recipient, such as tolerance (enhancing prosociality), dominance rank (being tested with a dominant recipient increasing selfish responses), and its behaviour (begging calls eliciting prosociality, while threatening ones decreasing it), to choose an option. These findings suggested that prosociality could be modulated by many factors and that the constraints and stakes induced by breeding would highly influence prosocial strategies.

Evidence for a developmental shift in the motivation underlying helping in early childhood.

We investigated children's positive emotions as an indicator of their underlying prosocial motivation. In Study 1, 2-, and 5-year-old children (N = 64) could either help an individual or watch as another person provided help. Following the helping event and using depth sensor imaging, we measured children's positive emotions through changes in postural elevation. For 2-year-olds, helping the individual and watching another person help was equally rewarding; 5-year-olds showed greater postural elevation after actively helping. In Study 2, 5-year-olds' (N = 59) positive emotions following helping were greater when an audience was watching. Together, these results suggest that 2-year-old children have an intrinsic concern that individuals be helped whereas 5-year-old children have an additional, strategic motivation to improve their reputation by helping.

Predictors of changing patterns of adherence to containment measures during the early stage of COVID-19 pandemic: an international longitudinal study.

BACKGROUND: Identifying common factors that affect public adherence to COVID-19 containment measures can directly inform the development of official public health communication strategies. The present international longitudinal study aimed to examine whether prosociality, together with other theoretically derived motivating factors (self-efficacy, perceived susceptibility and severity of COVID-19, perceived social support) predict the change in adherence to COVID-19 containment strategies. METHOD: In wave 1 of data collection, adults from eight geographical regions completed online surveys beginning in April 2020, and wave 2 began in June and ended in September 2020. Hypothesized predictors included prosociality, self-efficacy in following COVID-19 containment measures, perceived susceptibility to COVID-19, perceived severity of COVID-19 and perceived social support. Baseline covariates included age, sex, history of COVID-19 infection and geographical regions. Participants who reported adhering to specific containment measures, including physical distancing, avoidance of non-essential travel and hand hygiene, were classified as adherence. The dependent variable was the category of adherence, which was constructed based on changes in adherence across the survey period and included four categories: non-adherence, less adherence, greater adherence and sustained adherence (which was designated as the reference category). RESULTS: In total, 2189 adult participants (82% female, 57.2% aged 31-59 years) from East Asia (217 [9.7%]), West Asia (246 [11.2%]), North and South America (131 [6.0%]), Northern Europe (600 [27.4%]), Western Europe (322 [14.7%]), Southern Europe (433 [19.8%]), Eastern Europe (148 [6.8%]) and other regions (96 [4.4%]) were analyzed. Adjusted multinomial logistic regression analyses showed that prosociality, self-efficacy, perceived susceptibility and severity of COVID-19 were significant factors affecting adherence. Participants with greater self-efficacy at wave 1 were less likely to become non-adherence at wave 2 by 26% (adjusted odds ratio [aOR], 0.74; 95% CI, 0.71 to 0.77; P < .001), while those with greater prosociality at wave 1 were less likely to become less adherence at wave 2 by 23% (aOR, 0.77; 95% CI, 0.75 to 0.79; P = .04). CONCLUSIONS: This study provides evidence that in addition to emphasizing the potential severity of COVID-19 and the potential susceptibility to contact with the virus, fostering self-efficacy in following containment strategies and prosociality appears to be a viable public health education or communication strategy to combat COVID-19.

Compliance or empathy-What links maternal sensitivity and toddlers' emotional helping?

Emotional helping-that is, helping based on others' emotional distress-has been suggested to be a central prosocial response to others in need. Developmental theorizing proposed that emotional helping has social origins. Whereas research indeed demonstrated a link between maternal sensitivity and children's emotional helping, developmental theories stress different mediating processes. Emotion-sharing theories claim empathic concern to be the crucial link for helping, whereas internalization theories base children's helping on children's compliance. To investigate these hypotheses, the current study explored empathy and compliance as two possible mediators for the relation between maternal sensitivity and children's emotional helping at 18 months of age. Overall, maternal sensitivity was positively related to children's empathy, children's compliance, and children's emotional helping. Interestingly, children's empathy-but not children's compliance-mediated the link between maternal sensitivity and children's emotional helping. These findings deepen our understanding of the psychological processes subserving emotional helping during infancy and support theories that stress the socioemotional origins of children's prosocial behavior.

Dispositional compassion shifts social preferences in systematic ways.

INTRODUCTION: How people attach value to the outcomes of self and other-social preferences-is central to social behavior. Recently, how dispositional and state emotion shape such social preferences has received researchers' attention. METHOD: The present investigation asked whether and to what extent dispositional and state compassion predict shifts in social preferences across 4 samples: two correlational samples (final ns 153 & 368, study 1a and 1b) and two experimental samples (final ns: 430 & 530, studies 2 and 3). RESULTS: In keeping with recent accounts of compassion, dispositional compassion predicted general preference for equality, expressed as dispreference for both monetary advantage over another (interaction ßs = -0.36, -0.33, -0.25, -0.22; all p < 0.001) and monetary disadvantage relative to others (ßs: 0.26, 0.27, 0.28, 0.17; all p < 0.01; positive coefficients imply dispreference). This dispositional effect persisted when controlling for prosociality, positivity, agreeableness, and respectfulness. Furthermore, these dispositional compassion effects were relatively unchanged by experimental emotion inductions in studies 3 and 4. The experimental inductions of state compassion and state pride showed little evidence of systematic effects on social preferences relative to each other or a neutral condition. DISCUSSION: Discussion focused on individual differences in emotion and social preferences.

Teaching varies with task complexity in wild chimpanzees.

Cumulative culture is a transformative force in human evolution, but the social underpinnings of this capacity are debated. Identifying social influences on how chimpanzees acquire tool tasks of differing complexity may help illuminate the evolutionary origins of technology in our own lineage. Humans routinely transfer tools to novices to scaffold their skill development. While tool transfers occur in wild chimpanzees and fulfill criteria for teaching, it is unknown whether this form of helping varies between populations and across tasks. Applying standardized methods, we compared tool transfers during termite gathering by chimpanzees in the Goualougo Triangle, Republic of Congo, and in Gombe, Tanzania. At Goualougo, chimpanzees use multiple, different tool types sequentially, choose specific raw materials, and perform modifications that improve tool efficiency, which could make it challenging for novices to manufacture suitable tools. Termite gathering at Gombe involves a single tool type, fishing probes, which can be manufactured from various materials. Multiple measures indicated population differences in tool-transfer behavior. The rate of transfers and probability of transfer upon request were significantly higher at Goualougo, while resistance to transfers was significantly higher at Gombe. Active transfers of tools in which possessors moved to facilitate possession change upon request occurred only at Goualougo, where they were the most common transfer type. At Gombe, tool requests were typically refused. We suggest that these population differences in tool-transfer behavior may relate to task complexity and that active helping plays an enhanced role in the cultural transmission of complex technology in wild apes.