Evolutionary foundations of human prosocial sentiments

Directionality theory and mortality patterns across the primate lineage

Empirical studies of aging in primates show that local selective forces rather than phylogenetic history determine the exceptional nature of human longevity (Bronikowski et al., Science 331:1325-1328, 2011). This article proposes an evolutionary rationale for this pattern of primate mortality by invoking the parameter, Life-Table Entropy, a measure of the uncertainty in the life span of a randomly chosen newborn. Life-table entropy is positively correlated with maximal life span, that is, the mean life span of a species living under favourable conditions.The logic which underlies the exceptional nature of human longevity derives from the terrestrial life-history of humans - a singularity within the primate lineage; and the concomitant ecological constraints-the hunter-gatherer, agricultural, and industrial modes of subsistence, that have defined human evolutionary history. The effect of these ecological constraints on the evolution of life span is encoded in the Entropic Principle of Longevity: life-table entropy increases in equilibrium species, populations evolving in environments with stable, renewable resources; and decreases in opportunistic species, populations subject to fluctuating resource endowments.The Entropic Principle of Longevity is a derivative of Directionality Theory, an analytic study of the evolutionary process of variation and selection based on Evolutionary Entropy, a statistical measure of the uncertainty in the age of the mother of a randomly chosen newborn. Evolutionary entropy is the organizing concept of The Entropic Principle of Evolution: Evolutionary Entropy increases in equilibrium species and decreases in opportunistic species.

Wanting to matter and learning to care: A neurodevelopmental window of opportunity for (Pro) social learning?

Wanting to matter-to feel socially recognized, appreciated, and capable of actions that benefit others-represents a fundamental motivation in human development. The motivational salience of mattering appears to increase in adolescence. Evidence suggests this is related to pubertal increases in the incentive salience for gaining social value and personal agency. This can provide a useful heuristic for understanding motivational proclivities (i.e. wanting to matter) that influence action-outcome learning as young adolescents are exploring and learning how to navigate increasingly complex social and relational environments. Adolescence also brings new capacities, motives, and opportunities for learning to care about and contribute to the benefit of others. Together, these create a window of opportunity: a sensitive period for learning to gain salient feelings of mattering through caring prosocial actions and valued societal contributions. Successfully discovering ways of mattering by doing things that matter to others may contribute to formative socio-emotional learning about self/other. Advances in understanding these social and relational learning processes and their neurodevelopmental underpinnings can inform strategies to improve developmental trajectories of social competence and wellbeing among adolescents growing up in a rapidly changing and increasingly techno-centric world.

Brain Evolution in the Times of the Pandemic and Multimedia

BACKGROUND

In this paper, we argue that recent unprecedented social changes arising from social media and the internet represent powerful behavioral and environmental forces that are driving human evolutionary adaptive responses in a way that might reshape our brain and the way it perceives reality and interacts with it. These forces include decreases in physical activity, decreases in exposure to light, and face-to-face social interactions, as well as diminished predictability in biological rhythms (i.e., the sleep cycle is no longer dictated by natural light exposure and season).

SUMMARY

We discuss the roles of stress and of creativity and adaptability in Homo sapiens evolution and propose mechanisms for human adaptation to the new forces including epigenetic mechanisms, gene-culture coevolution, and novel mechanisms of evolution of the nervous system.

KEY MESSAGES

We present the provocative idea that evolution under the strong selective pressures of today's society could ultimately enable H. sapiens to thrive despite social, physical, circadian, and cultural deprivation and possible neurological disease, and thus withstand the loss of factors that contribute to H. sapiens survival of today. The new H. sapiens would flourish under a lifestyle in which the current form would feel undervalued and replaceable.

Emotional contagion and prosocial behaviour in fish: An evolutionary and mechanistic approach

In this review, we consider the definitions and experimental approaches to emotional contagion and prosocial behaviour in mammals and explore their evolutionary conceptualisation for studying their occurrence in the evolutionarily divergent vertebrate group of ray-finned fish. We present evidence for a diverse set of fish phenotypes that meet definitional criteria for prosocial behaviour and emotional contagion and discuss conserved mechanisms that may account for some preserved social capacities in fish. Finally, we provide some considerations on how to address the question of interdependency between emotional contagion and prosocial response, highlighting the importance of recognition processes, decision-making systems, and ecological context for providing evolutionary explanations.

Theoretical and Empirical Foundations for a Unified Pyramid of Human Motivation

Revisions are proposed to the taxonomic model of human motivation of Forbes (Review of General Psychology, 15(2), 85-98, 2011) in order to incorporate a heretofore missing fourth life domain, the spiritual. The growing literature on spiritual motives is systematically reviewed in accordance with literature review standards for theory development (Templier & Paré, 2018) focusing on the objective of identifying comprehensive theoretical systems that explicitly incorporate the spiritual domain as one of a limited set of human life domains. The structure of the Forbes model is contrasted with thirteen theoretical systems that explicitly incorporate the spiritual as a fourth life domain. Consistent with the Forbes model, the spiritual domain is proposed to consist of three modes of existence (Being, Doing, Having) represented as justice motivation, moral motivation, and transcendental motivation, respectively, as well as both promotion and prevention goals within each of the three motives. Empirical evidence is reviewed in support of a revised heuristic device wherein the Spiritual domain is closely linked with the Intrapsychic and Interpersonal domains, but not the Instrumental domain, resulting in a pyramidal structure and corresponding set of testable hypotheses.

Understanding altruistic behavior: The joint role of prefrontal damage and OXTR genotype

Altruism is a type of prosocial behavior that is carried out in the absence of personal benefit or even at an expense to self. Trait altruism varies greatly across individuals, and the reasons for this variability are still not fully understood. Growing evidence suggests that altruism may be partly determined by the oxytocin receptor (OXTR) gene, which regulates the emotions underlying altruistic attitudes, such as empathy and trust. Neuroimaging and lesion studies have also implied several higher-order brain regions, including the prefrontal cortex, in altruistic behaviors. Yet the existing reports are contradictory and suggest that the top-down control exercised by the prefrontal cortex may promote both altruistic and self-interested behaviors and, thus, could obscure one's natural proclivity towards altruism encoded by OXTR. Here, we hypothesized that extensive prefrontal damage would result in an increased influence of the OXTR genotype on one's altruistic attitudes and actions. To test this hypothesis, we recruited 115 male combat veterans with penetrating traumatic brain injury to the prefrontal cortex and other brain regions, as well as 35 demographically matched control subjects without brain injury. Participants completed a self-report altruism questionnaire and were genotyped for four OXTR single nucleotide polymorphisms implicated in prosocial behavior, including rs53576, rs1042778, rs2254298 and rs7632287. Consistent with the previous studies, we found that individuals homozygotic for the G allele of rs53576 and rs7632287 were significantly more altruistic than carriers of at least one "vulnerable" A allele. Remarkably, in patients with prefrontal cortex damage, greater lesion extent was associated with significantly lower altruism scores in carriers of the A allele of rs7632287, but not in G-homozygotes, suggesting that significant disruption of the prefrontal cortex increased the influence of genetic polymorphisms on prosocial behavior. This study presents the first account of an interaction effect between the OXTR genotype and the location and extent of brain damage.

What We Do When We Define Morality (And Why We Need to Do It)

All psychological research on morality relies on definitions of morality. Yet the various definitions often go unstated. When unstated definitions diverge, theoretical disagreements become intractable, as theories that purport to explain "morality" actually talk about very different things. This article argues for the importance of defining morality and considers four common ways of doing so: The linguistic, the functionalist, the evaluating, and the normative. Each has encountered difficulties. To surmount those difficulties, I propose a technical, psychological, empirical, and distinctive definition of morality: obligatory concerns with others' welfare, rights, fairness, and justice, as well as the reasoning, judgment, emotions, and actions that spring from those concerns. By articulating workable definitions of morality, psychologists can communicate more clearly across paradigms, separate definitional from empirical disagreements, and jointly advance the field of moral psychology.

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.

Primate Sex and Its Role in Pleasure, Dominance and Communication

Sexual intercourse in the animal kingdom functions to enable reproduction. However, we now know that several species of non-human primates regularly engage in sex outside of the times when conception is possible. In addition, homosexual and immature sex are not as uncommon as were once believed. This suggests that sex also has important functions outside of reproduction, yet these are rarely discussed in sex-related teaching and research activities concerning primate behaviour. Is the human sexual experience, which includes pleasure, dominance, and communication (among others) unique, or do other primates also share these experiences to any extent? If so, is there any way to measure them, or are they beyond the rigour of scientific objectivity? What would be the evolutionary implications if human-like sexual experiences were found amongst other animals too? We comment on the evidence provided by our close relatives, non-human primates, discuss the affective and social functions of sex, and suggest potential methods for measuring some of these experiences empirically. We hope that this piece may foster the discussion among academics and change the way we think about, teach and research primate sex.

Neural basis of prosocial behavior

The ability to behave in ways that benefit other individuals' well-being is among the most celebrated human characteristics crucial for social cohesiveness. Across mammalian species, animals display various forms of prosocial behaviors - comforting, helping, and resource sharing - to support others' emotions, goals, and/or material needs. In this review, we provide a cross-species view of the behavioral manifestations, proximate and ultimate drives, and neural mechanisms of prosocial behaviors. We summarize key findings from recent studies in humans and rodents that have shed light on the neural mechanisms underlying different processes essential for prosocial interactions, from perception and empathic sharing of others' states to prosocial decisions and actions.

Cognitive effort for self, strangers, and charities

Effort is aversive and often avoided, even when earning benefits for oneself. Yet, people sometimes work hard for others. How do people decide who is worth their effort? Prior work shows people avoid physical effort for strangers relative to themselves, but invest more physical effort for charity. Here, we find that people avoid cognitive effort for others relative to themselves, even when the cause is a personally meaningful charity. In two studies, participants repeatedly decided whether to invest cognitive effort to gain financial rewards for themselves and others. In Study 1, participants (N = 51; 150 choices) were less willing to invest cognitive effort for a charity than themselves. In Study 2, participants (N = 47; 225 choices) were more willing to work cognitively for a charity than an intragroup stranger, but again preferred cognitive exertion that benefited themselves. Computational modeling suggests that, unlike prior physical effort findings, cognitive effort discounted the subjective value of rewards linearly. Exploratory machine learning analyses suggest that people who represented others more similarly to themselves were more willing to invest effort on their behalf, opening up new avenues for future research.

Call combinations in chimpanzees: a social tool?

A growing body of evidence suggests the capacity for animals to combine calls into larger communicative structures is more common than previously assumed. Despite its cross-taxa prevalence, little is known regarding the evolutionary pressures driving such combinatorial abilities. One dominant hypothesis posits that social complexity and vocal complexity are linked, with changes in social structuring (e.g., group size) driving the emergence of ever-more complex vocal abilities, such as call sequencing. In this paper, we tested this hypothesis through investigating combinatoriality in the vocal system of the highly social chimpanzee. Specifically, we predicted combinatoriality to be more common in socially-driven contexts and in females and lower-ranked males (socially challenging contexts and socially challenged individuals respectively). Firstly, through applying methods from computational linguistics (i.e., collocation analyses), we built an objective repertoire of combinatorial structures in this species. Second, we investigated what potential factors influenced call combination production. We show that combinatoriality is predominant in 1) social contexts vs. non-social contexts, 2) females vs. males, and 3) negatively correlates with male rank. Together, these results suggest one function of combinatoriality in chimpanzees may be to help individuals navigate their dynamic social world. More generally, we argue these findings provide support for the hypothesized link between social and vocal complexity and can provide insight into the evolution of our own highly combinatorial communication system, language.

Exploring and Expanding Supererogatory Acts: Beyond Duty for a Sustainable Future

Supererogation has gained attention as a means of explaining the voluntary behaviours of individuals and organizations that are done for the benefit of others and which go above what is required of legislation and what may be expected by society. Whilst the emerging literature has made some significant headway in exploring supererogation as an ethical lens for the study of business there remain several important issues that require attention. These comprise, the lack of primary evidence upon which such examinations have been made, attention has been given to only singular pro-social acts of organizations, and the focus has been upon the actions of large organizations. Furthermore, Heyd's (Supererogation, Cambridge University Press, 1982) original taxonomy of six supererogatory acts, comprising Moral Heroism, Beneficence, Volunteering, Favour, Forgiveness and Forbearance, has been considered to be complete and other forms of supererogatory acts have not yet been explored. In order to address these gaps this study poses the research questions: First, it studies how a single, contemporary SME performs multiple supererogatory acts in its attempts to address its social and environmental goals that go beyond CSR. Second, it seeks to gain a deeper theoretical understanding of Heyd's (Supererogation, Cambridge University Press, 1982) taxonomy of six forms of supererogation through the capture of primary data. This research makes a three-year case study examination of a single SME that has been formally recognized for its work in addressing social and environmental issues at local, national and global levels. Primary data are acquired of the supererogatory acts that it performs through a three-year participant observation case study, utilizing 61 interviews and 3 focus groups with internal and external stakeholders. In doing so, it addresses the empirical limitations of the extant research, substantiates each of the forms that supererogatory acts may take, and makes a contribution to the theory of supererogation by identifying a further class of act that is 'Sharing'.

Motivating children's cooperation to conserve forests

Forests are essential common-pool resources. Understanding children's and adolescents' motivations for conservation is critical to improving conservation education. In 2 experiments, we investigated 1086 school-aged children and adolescents (6-16 years old) from China, the Democratic Republic of Congo, and the United States. testING participants in groups, we assessed their motivation for conservation based on collective-risk common-pool goods games in which they are threatened with losing their endowment unless the group donation exceeds a threshold needed to maintain the forest.eExtrinsic motivations, rather than intrinsic , tended to lead to successful cooperation to maintain a forest. Certainty of losing individual payoffs significantly boosted successful cooperative conservation efforts across cultures (success rates were 90.63 % and 74.19% in the 2 risk-extrinsic conditions and 43.75% in the control condition). In U.S. participants, 2 extrinsic incentives, priming discussions of the value of forests and delay of payoffs as punishment , also increased success of cooperative conservation (success rates were 97.22% and 76.92% in the 2 extrinsic-incentive conditions and 29.19% and 30.77% in the 2 control conditions). Conservation simulations, like those we used, may allow educators to encourage forest protection by leading groups to experience successful cooperation and the extrinsic incentives needed to motivate forest conservation. This article is protected by copyright. All rights reserved.

Altered Processing of Social Emotions in Individuals With Autistic Traits

Social impairment is a defining phenotypic feature of autism. The present study investigated whether individuals with autistic traits exhibit altered perceptions of social emotions. Two groups of participants (High-AQ and Low-AQ) were recruited based on their scores on the autism-spectrum quotient (AQ). Their behavioral responses and event-related potentials (ERPs) elicited by social and non-social stimuli with positive, negative, and neutral emotional valence were compared in two experiments. In Experiment 1, participants were instructed to view social-emotional and non-social emotional pictures. In Experiment 2, participants were instructed to listen to social-emotional and non-social emotional audio recordings. More negative emotional reactions and smaller amplitudes of late ERP components (the late positive potential in Experiment 1 and the late negative component in Experiment 2) were found in the High-AQ group than in the Low-AQ group in response to the social-negative stimuli. In addition, amplitudes of these late ERP components in both experiments elicited in response to social-negative stimuli were correlated with the AQ scores of the High-AQ group. These results suggest that individuals with autistic traits have altered emotional processing of social-negative emotions.

Oxytocin and the Neurobiology of Prosocial Behavior

Humans are an unusually prosocial species, who engage in social behaviors that include altruism-whereby an individual engages in costly or risky acts to improve the welfare of another person-care, and cooperation. Current perspectives on the neurobiology of human prosociality suggest that it is deeply rooted in the neuroendocrine architecture of the social brain and emphasize the modulatory role of the neuropeptide hormone oxytocin. In this review, we provide a conceptual overview of the neurobiology of prosocial behavior with a focus on oxytocin's modulatory role in human prosociality. Specifically, we aim to encourage a better understanding of the peptide's susceptibility to diverse factors that produce heterogeneity in outcomes and the resulting methodological implications for measuring the behavioral effects of oxytocin in humans. After providing an overview of the state-of-the-art research on oxytocin's exogenous use, we elaborate on the peptide's modulatory role in the context of care-based altruism, cooperation, and conflict and discuss its potential for therapeutic interventions in psychiatric disorders characterized by social dysfunction.

The evolution of morality and the role of commitment

A considerable share of the literature on the evolution of human cooperation considers the question why we have not evolved to play the Nash equilibrium in prisoners' dilemmas or public goods games. In order to understand human morality and pro-social behaviour, we suggest that it would actually be more informative to investigate why we have not evolved to play the subgame perfect Nash equilibrium in sequential games, such as the ultimatum game and the trust game. The 'rationally irrational' behaviour that can evolve in such games gives a much better match with actual human behaviour, including elements of morality such as honesty, responsibility and sincerity, as well as the more hostile aspects of human nature, such as anger and vengefulness. The mechanism at work here is commitment, which does not need population structure, nor does it need interactions to be repeated. We argue that this shift in focus can not only help explain why humans have evolved to know wrong from right, but also why other animals, with similar population structures and similar rates of repetition, have not evolved similar moral sentiments. The suggestion that the evolutionary function of morality is to help us commit to otherwise irrational behaviour stems from the work of Robert Frank (American Economic Review, 77(4), 593-604, 1987; Passions within reason: The strategic role of the emotions, WW Norton, 1988), which has played a surprisingly modest role in the scientific debate to date.

Individual Goffin´s cockatoos (Cacatua goffiniana) show flexible targeted helping in a tool transfer task

Flexible targeted helping is considered an advanced form of prosocial behavior in hominoids, as it requires the actor to assess different situations that a conspecific may be in, and to subsequently flexibly satisfy different needs of that partner depending on the nature of those situations. So far, apart from humans such behaviour has only been experimentally shown in chimpanzees and in Eurasian jays. Recent studies highlight the prosocial tendencies of several bird species, yet flexible targeted helping remained untested, largely due to methodological issues as such tasks are generally designed around tool-use, and very few bird species are capable of tool-use. Here, we tested Goffin's cockatoos, which proved to be skilled tool innovators in captivity, in a tool transfer task in which an actor had access to four different objects/tools and a partner to one of two different apparatuses that each required one of these tools to retrieve a reward. As expected from this species, we recorded playful object transfers across all conditions. Yet, importantly and similar to apes, three out of eight birds transferred the correct tool more often in the test condition than in a condition that also featured an apparatus but no partner. Furthermore, one of these birds transferred that correct tool first more often before transferring any other object in the test condition than in the no-partner condition, while the other two cockatoos were marginally non-significantly more likely to do so. Additionally, there was no difference in the likelihood of the correct tool being transferred first for either of the two apparatuses, suggesting that these birds flexibly adjusted what to transfer based on their partner´s need. Future studies should focus on explanations for the intra-specific variation of this behaviour, and should test other parrots and other large-brained birds to see how this can be generalized across the class and to investigate the evolutionary history of this trait.

On experimental tests for studying altruism in capuchin monkeys

Altruism is often considered as the ultimate form of prosociality and is defined as any act that benefits others without direct benefit to the actor. Many nonhuman species have been reported to express different forms of altruism, although their expression in experimental studies is highly dependent on the paradigm used. Tufted capuchin monkeys are one of the most studied species; however, the evidence for altruism in this species remains inconclusive. This study aimed to investigate whether two paradigms, adapted from those in which great apes have shown altruism, could be useful for revealing signs of altruistic capabilities in capuchins. Pairs of monkeys were tested in two experiments involving a similar mechanism but with different costs to acting altruistically. The first used a more costly operant sharing task in which an operator could unlock a door to allow a recipient to enter the room and share his food. The second consisted of a less costly helping task, in which the operator's food was secured but he could help the recipient to get other food that was in a locked container. The results suggest that capuchins, although apparently unwilling to share their food in a costly operant situation, might altruistically help selected recipients, in response to requesting by the latter. While our small sample size along with procedural limitations preclude firm conclusions, we discuss how further ameliorations of our tasks could further contribute to the study of altruistic capacities in primates.

Prosociality and reciprocity in capybaras (Hydrochoerus hydrochaeris) in a non-reproductive context

Prosocial behaviours (providing benefits to a recipient with or without cost for the donor) have been found to be highly influenced by sex and by hierarchy. Rodents, in particular, are good model for studying prosocial responses, as they were found to exhibit intentional prosocial behaviours to reward a conspecific, and are very sensitive to reciprocity. In our study, we conducted a Prosocial Choice Test (PCT) in which four capybaras (Hydrochoerus hydrochaeris) living in a social group could choose between three tokens: choosing the prosocial token rewarded simultaneously the subject and a recipient, while choosing the selfish token only rewarded the subject; and choosing the null token provided no reward to anyone. Dominance within each dyad was also studied, both before and during the PCT experiment. Our results showed an influence of hierarchy: subjects were more prosocial towards the recipient when it was a subordinate than when it was a dominant individual. These results could be interpreted as a desire of strengthening a hierarchical rank regarding the subordinate, of punishing aggressive conspecifics (usually the subject's direct dominant), and of weakening dominant individuals in order to modify the pre-existing hierarchy. Additionally, our results highlighted a direct reciprocity phenomenon, a subject being more likely to be prosocial towards a prosocial recipient. All these findings suggest that prosociality could be well developed in other taxa than Primates and that, in long enough PCT experiments, subtle rules could influence individual prosocial strategies.

Prosociality and reciprocity in bottlenose dolphins (Tursiops truncatus)

Some moral behaviours, often regarded as reflecting high cognitive abilities (such as empathy, cooperation, targeted helping) are known to only be present in very few species, like great apes, elephants and cetaceans. Prosocial behaviours (producing a benefit for the recipient without necessarily involving a cost for the actor) have been mostly found in primates and, more recently, in elephants. Despite dolphins' reputation for helping their conspecifics, experimental studies about their prosocial and empathic abilities are rare. We conducted Prosocial Choice Tests in six bottlenose dolphins. The subjects had to choose between three objects: choosing the prosocial object induced the simultaneous rewarding of both the subject and a recipient individual; choosing the selfish object induced a reward only for the subject; choosing the null one did not reward anyone. We found prosociality and direct reciprocity in our subjects, and our results suggested that bottlenose dolphins might be able to modulate their prosocial and reciprocal tendencies according to partner-specific information. Subjects seemed to be more prosocial towards the other sex and more reciprocal towards same-sex recipients. This reciprocity might be underpinned by the same features that rule their behaviours in the wild (cooperating with same sex conspecifics). Moreover, an audience effect was reported, as the presence of the subject's young increased subjects' likelihood of prosocial response. Our findings highlighted that prosociality could appear in taxa other than primates, suggesting a convergent evolutionary phenomenon.

The Effect of Emotion on Prosocial Tendency: The Moderating Effect of Epidemic Severity Under the Outbreak of COVID-19

During the outbreak of COVID-19, information on the epidemic inundated people's lives and led to negative emotions (e.g., tension, anxiety, and fear) in many people. This study aims to explore the effect of various emotions on prosocial tendencies during the COVID-19 outbreak and the moderating effect of the severity of the epidemic. We explore these effects by conducting a text analysis of the content of posts by 387,730 Weibo users. The results show that the severity of the epidemic promotes prosocial tendencies; anger motivates prosocial tendencies significantly; and the severity of the epidemic moderates the effects of three emotions-anger, sadness, and surprise-on prosocial tendencies. These findings provide a reference for exploring the positive significance of major disasters.

Exploitative leaders incite intergroup warfare in a social mammal

A classic explanation for the prevalence of complex warfare in human societies is leadership by exploitative individuals who reap the benefits of conflict while avoiding the costs. Here, we extend the classic hawk−dove model to show that leadership of this kind can also explain the evolution of severe collective violence in certain animal societies. We test our model using long-term data from wild banded mongooses, and show that female leaders incite fights with rival groups to gain genetic benefits, while males bear the costs of fighting. The result is unusually severe levels of intergroup violence. Our findings suggest that the decoupling of leaders from the costs that they incite amplifies the destructive nature of intergroup conflict.

Collective conflicts among humans are widespread, although often highly destructive. A classic explanation for the prevalence of such warfare in some human societies is leadership by self-serving individuals that reap the benefits of conflict while other members of society pay the costs. Here, we show that leadership of this kind can also explain the evolution of collective violence in certain animal societies. We first extend the classic hawk−dove model of the evolution of animal aggression to consider cases in which a subset of individuals within each group may initiate fights in which all group members become involved. We show that leadership of this kind, when combined with inequalities in the payoffs of fighting, can lead to the evolution of severe intergroup aggression, with negative consequences for population mean fitness. We test our model using long-term data from wild banded mongooses, a species characterized by frequent intergroup conflicts that have very different fitness consequences for male and female group members. The data show that aggressive encounters between groups are initiated by females, who gain fitness benefits from mating with extragroup males in the midst of battle, whereas the costs of fighting are borne chiefly by males. In line with the model predictions, the result is unusually severe levels of intergroup violence. Our findings suggest that the decoupling of leaders from the costs that they incite amplifies the destructive nature of intergroup conflict.

Beyond the Household: Caribbean Families and Biocultural Models of Alloparenting

Alloparental or extramaternal care is an integral aspect of human childrearing. This behavior has been explored both as an extension of the primary mother–infant dyad that evolved to meet the demands of altricial offspring and as an economic exchange of energy and resources. Much of this research centers on foraging or small-scale communities and positions the household as the central unit through which to explore negotiations of care. In this review, I use evidence from Black Caribbean communities living in industrialized countries to challenge the broad applicability of the analytical model of the bounded household and to question whether our current articulations of theory and empirical assessments of extramaternal care are well suited to investigations of these behaviors in the vast majority of contemporary human populations. Alloparental practices in the Caribbean reflect dynamic responses to maternal migration and the local influence of global labor markets. The children who remain at home experience variability in the care received from their surrogate parents. The dynamic aspect of the care practices enacted by these transnational families reveals the behavioral flexibility that has been integral to human survival.

Sex-specific effects of cooperative breeding and colonial nesting on prosociality in corvids

The investigation of prosocial behavior is of particular interest from an evolutionary perspective. Comparisons of prosociality across non-human animal species have, however, so far largely focused on primates, and their interpretation is hampered by the diversity of paradigms and procedures used. Here, we present the first systematic comparison of prosocial behavior across multiple species in a taxonomic group outside the primate order, namely the bird family Corvidae. We measured prosociality in eight corvid species, which vary in the expression of cooperative breeding and colonial nesting. We show that cooperative breeding is positively associated with prosocial behavior across species. Also, colonial nesting is associated with a stronger propensity for prosocial behavior, but only in males. The combined results of our study strongly suggest that both cooperative breeding and colonial nesting, which may both rely on heightened social tolerance at the nest, are likely evolutionary pathways to prosocial behavior in corvids.

Intergenerational resource sharing and mortality in a global perspective

Resource sharing has always been a central component of human sociality. Children require heavy investments in human capital; during working years, help is needed due to illness, disability, or bad luck. While hunter-gatherer elders assisted their descendants, more recently, elderly withdraw from work and require assistance as well. Willingness to share has been critically important for our past evolutionary success and our present daily lives. Here, we document a strong linear relationship between the public and private sharing generosity of a society and the average length of life of its members. Our findings from 34 countries on six continents suggest that survival is higher in societies that provide more support and care for one another. We suggest that this support reduces mortality by meeting urgent material needs, but also that sharing generosity may reflect the strength of social connectedness, which itself benefits human health and wellbeing and indirectly raises survival.

Autism does not Dictate Children's Lack of Sharing in a Prosocial Choice Test

Studies have examined the association between theory of mind (ToM) and prosocial behavior in children with mixed results. A handful of studies have examined prosocial sharing behavior in children with autism, who typically exhibit ToM deficits. Studies using resource allocation tasks have generally failed to find significant differences between the sharing behavior of children with autism and neurotypical children. We presented 18 neurotypical children and 33 children with autism with the Dictator Game. Children had the opportunity to allocate toys in recipient present and absent conditions. Both groups donated more items in the recipient present versus absent condition and chose the prosocial option at above chance levels. Children with autism behave as prosocially as neurotypical children do in this paradigm.

Strategies for Sharing Limited Resources among Children and Adolescents in Three Traditional Societies of East Africa: Sociocultural and Genetic Factors

Egalitarianism, pursuit for equality, and altruism are the most important evolutionarily stable strategies in the human society. This study presents data on the results of economic games for sharing with a potential friend or unfamiliar peer in three ethnic groups of East Africa (Hadza, Iraqw, and Meru). The total sample was 583 children and adolescents; mean age, 13.5 ± 3.1 years. In addition, DNA analysis was carried out and the OXTR gene rs53576 single nucleotide polymorphism was genotyped for 162 Meru individuals. The pronounced individual variability in making decisions on sharing with a potential partner was established. Children and adolescents behaved altruistically towards friends significantly more frequently as compared with strangers. Carriers of the OXTR rs53576 GG variant displayed altruism significantly more frequently both to friends (U = 3376.500, p = 0.047; OR = 3.075, p = 0.032) and to strangers (U = 3478.000, p = 0.025; OR = 3.133, p = 0.007). Significant intergroup differences in egalitarianism, egoism, and altruism were also demonstrated. Data obtained suggest a positive group selection towards altruists.

Children are sensitive to reputation when giving to both ingroup and outgroup members

Previous studies establish that reputation concerns play an important role in outgroup giving. However, it is unclear whether the same is true for ingroup giving, which by some accounts tends to be motivated by empathic concerns. To explore this question, we tested the extent to which 5 to 9-year-old children (Study 1: N = 164) and adults (Study 2: N = 80) shared resources with ingroup and outgroup members, either when being watched by an observer (where we expected reputation concerns to be salient) or in private (where we expected no effect of reputation concerns). We also assessed whether children and adults differ in their beliefs about which form of sharing (ingroup or outgroup giving) is nicer. Although we found that both children and adults exhibited an ingroup bias when sharing, there was no evidence in either group that reputation concerns were greater for outgroup members than for ingroup members. We also found that, in contrast to adults, children shared more resources when observed than in private. Additionally, children evaluated ingroup giving as nicer across different sharing scenarios, whereas adults identified outgroup giving as nicer when the two forms of giving were contrasted. These results are the first to suggest that reputational concerns influence children's sharing both with ingroup and outgroup members, and that children differ from adults in their reasoning about which form of group sharing is nicer.

Not by the same token: A female orangutan (Pongo pygmaeus) is selectively prosocial

Studies of prosocial behavior in nonhumans have focused on group-living social animals. Despite being highly social and closely related to humans, chimpanzees have rarely exhibited prosocial preferences in experimental tasks. Fewer studies have provided their non group-living relatives-orangutans-with the opportunity to express prosocial preferences. Here, we allowed a single female orangutan to provide rewards for herself and for her mother, sister, or both, across various phases, using a token economy task. The orangutan was more likely to choose prosocially when she could provide rewards to her sister and herself compared to when she could provide rewards to her mother and herself. However, when presented with the simultaneous options of providing rewards for self, self and mother, or self and sister, she chose prosocially equally often to her mother and sister. She made the largest number of prosocial choices in a phase when she could provide rewards to all participants (herself, her sister, and her mother) rather than providing rewards only to herself or only to herself and one other participant. Despite the obvious limitations of a single case study, the study adds to the limited information on prosocial preferences in less social primate species, particularly when given the chance to share food items with different kin.

Assessing African grey parrots' prosocial tendencies in a token choice paradigm

Prosociality is defined as a voluntary, typically low-cost behaviour that benefits another individual. Social tolerance has been proposed as a potential driver for its evolution, both on the proximate and on the ultimate level. Parrots are an interesting species to study such other-regarding behaviours, given that they are highly social and stand out in terms of relative brain size and cognitive capacity. We tested eight African grey parrots in a dyadic prosocial choice test. They faced a choice between two different tokens, a prosocial (actor and partner rewarded) and a selfish (only actor rewarded) one. We found that the birds did not behave prosocially when one subject remained in the actor role; however, when roles were alternated, the birds' prosocial choices increased. The birds also seemed to reciprocate their partner's choices, given that a contingency between choices was observed. If the food provisioned to the partner was of higher quality than that the actor obtained, actors increased their willingness to provide food to their partner. Nonetheless, the control conditions suggest that the parrots did not fully understand the task's contingencies. In sum, African grey parrots show the potential for prosociality and reciprocity; however, considering their lack of understanding of the contingencies of the particular tasks used in this study, the underlying motivation for the observed behaviour remains to be addressed by future studies, in order to elucidate the phylogenetic distribution of prosociality further.

Agents' pivotality and reward fairness modulate sense of agency in cooperative joint action

The sense of agency (SoA) experienced in joint action is an essential subjective dimension of human cooperativeness, but we still know little about the specific factors that contribute to its emergence or alteration. In the present study, dyads of participants were instructed to coordinate their key presses to move a cursor up to a specific target (i.e., to achieve a common goal). We applied random deviations on the cursor's trajectory to manipulate the motor fluency of the joint action, while the agents' motor roles were either balanced (i.e., equivalent) or unbalanced (i.e., one agent contributed more than the other), making the agents more or less pivotal to the joint action. Then, the final outcomes were shared equally, fairly (i.e., reflecting individual motor contributions) or arbitrarily in an all-or-none fashion, between the co-agents. Self and joint SoA were measured through self-reports about feeling of control, that is, using judgment of (felt) control (JoC), and electrodermal activity was recorded during the whole motor task. We observed that self and joint JoC were reduced in the case of low motor fluency, pointing out the importance of sensorimotor cues for both I- and we-modes. Moreover, while self JoC was reduced in the low pivotality condition (i.e., low motor role), joint JoC was significantly enhanced when agents' roles and rewards were symmetrical (i.e. equal). Skin conductance responses to rewards were impacted by the way outcomes were shared between partners (i.e., fairly, equally or arbitrarily) but not by the individual gains, which demonstrates the sensitivity of low-level physiological reactions to external signs of fairness. Skin conductance level was also reduced in the fair context, where rewards were shared according to individual motor contributions, relative to the all-or-none context, which could mirror the feeling of effective responsibility and control over actions' outcomes.

Unraveling the role of oxytocin in the motivational structure of conflict

Current psychological perspectives emphasize “attack” and “defense” as the behavioral mechanisms underlying conflict. Here, we extend this view by highlighting the relevance of pathological altruism and the neuroendocrine pathways associated with hostile behaviors. Specifically, we elucidate the modulatory role of the neuropeptide hormone oxytocin in motivating extraordinary levels of in-group commitment that can promote extreme behaviors and endure conflict with out-groups.

Towards understanding atypical social affiliation in psychopathy

One distinctive feature of individuals with psychopathy is their reduced motivation and capacity to develop authentic social relationships, which are founded on an enjoyment of prosocial interactions or concern for others. Surprisingly, potential neurocognitive vulnerabilities contributing to atypical social affiliation, and lack of prosocial behaviours in psychopathy, have yet to be systematically investigated. Research efforts have largely focused on how individuals with psychopathy process negative emotions, and how this might affect their capacity to feel guilt or empathise with others' distress. Here, we propose a framework for understanding the development of atypical social affiliation and attachment in psychopathy, and outline several key processes and neural systems speculated to underpin them. We then describe present neurocognitive findings that suggest that these processes and neural systems are compromised in individuals with, or at risk of developing, psychopathy. Finally, we consider several research directions that would help with the understanding of the origin and development of social affiliation in individuals with psychopathy. This work has the potential to inform and enhance prevention and treatment strategies.

Wolves, but not dogs, are prosocial in a touch screen task

Prosociality is important for initiating cooperation. Interestingly, while wolves rely heavily on cooperation, dogs’ do so substantially less thus leading to the prediction that wolves are more prosocial than dogs. However, domestication hypotheses suggest dogs have been selected for higher cooperation, leading to the opposing prediction- increased prosocial tendencies in dogs. To tease apart these hypotheses we adapted a paradigm previously used with pet dogs to directly compare dogs and wolves. In a prosocial choice task, wolves acted prosocially to in-group partners; providing significantly more food to a pack-member compared to a control where the partner had no access to the food. Dogs did not. Additionally, wolves did not show a prosocial response to non-pack members, in line with previous research that social relationships are important for prosociality. In sum, when kept in the same conditions, wolves are more prosocial than their domestic counterpart, further supporting suggestions that reliance on cooperation is a driving force for prosocial attitudes.

The Caring Continuum: Evolved Hormonal and Proximal Mechanisms Explain Prosocial and Antisocial Extremes

Implicit in the long-standing disagreements about whether humans’ fundamental nature is predominantly caring or callous is an assumption of uniformity. This article reviews evidence that instead supports inherent variation in caring motivation and behavior. The continuum between prosocial and antisocial extremes reflects variation in the structure and function of neurohormonal systems originally adapted to motivate parental care and since repurposed to support generalized forms of care. Extreme social behaviors such as extraordinary acts of altruism and aggression can often be best understood as reflecting variation in the neural systems that support care. A review of comparative, developmental, and neurobiological research finds consistent evidence that variations in caring motivations and behavior reflect individual differences in sensitivity to cues that signal vulnerability and distress and in the tendency to generalize care outward from socially close to distant others. The often complex relationships between caring motivation and various forms of altruism and aggression are discussed.

Give one species the task to come up with a theory that spans them all: what good can come out of that?

Does the progress in understanding evolutionary theory depend on the species that is doing the investigation? This question is difficult to answer scientifically, as we are dealing with an n = 1 scenario: every individual who has ever written about evolution is a human being. I will discuss, first, whether we get the correct answer to questions if we begin with ourselves and expand outwards, and second, whether we might fail to ask all the interesting questions unless we combat our tendencies to favour taxa that are close to us. As a whole, the human tendency to understand general biological phenomena via 'putting oneself in another organism's shoes' has upsides and downsides. As an upside, our intuitive ability to rethink strategies if the situation changes can lead to ready generation of adaptive hypotheses. Downsides occur if we trust this intuition too much, and particular danger zones exist for traits where humans are an unusual species. I argue that the levels of selection debate might have proceeded differently if human cooperation patterns were not so unique, as this brings about unique challenges in biology teaching; and that theoretical insights regarding inbreeding avoidance versus tolerance could have spread faster if we were not extrapolating our emotional reactions to incest disproportionately depending on whether we study animals or plants. I also discuss patterns such as taxonomic chauvinism, i.e. less attention being paid to species that differ more from human-like life histories. Textbooks on evolution reinforce such biases insofar as they present, as a default case, systems that resemble ours in terms of life cycles and other features (e.g. gonochorism). Additionally, societal norms may have led to incorrect null hypotheses such as females not mating multiply.

Bonobos respond prosocially toward members of other groups

Modern humans live in an "exploded" network with unusually large circles of trust that form due to prosociality toward unfamiliar people (i.e. xenophilia). In a set of experiments we demonstrate that semi-free ranging bonobos (Pan paniscus) - both juveniles and young adults - also show spontaneous responses consistent with xenophilia. Bonobos voluntarily aided an unfamiliar, non-group member in obtaining food even when he/she did not make overt requests for help. Bonobos also showed evidence for involuntary, contagious yawning in response to videos of yawning conspecifics who were complete strangers. These experiments reveal that xenophilia in bonobos can be unselfish, proactive and automatic. They support the first impression hypothesis that suggests xenophilia can evolve through individual selection in social species whenever the benefits of building new bonds outweigh the costs. Xenophilia likely evolved in bonobos as the risk of intergroup aggression dissipated and the benefits of bonding between immigrating members increased. Our findings also mean the human potential for xenophilia is either evolutionarily shared or convergent with bonobos and not unique to our species as previously proposed.

Reduced Laughter Contagion in Boys at Risk for Psychopathy

Humans are intrinsically social animals, forming enduring affiliative bonds [1]. However, a striking minority with psychopathic traits, who present with violent and antisocial behaviors, tend to value other people only insofar as they contribute to their own advancement [2, 3]. Extant research has addressed the neurocognitive processes associated with aggression in such individuals, but we know remarkably little about processes underlying their atypical social affiliation. This is surprising, given the importance of affiliation and bonding in promoting social order and reducing aggression [4, 5]. Human laughter engages brain areas that facilitate social reciprocity and emotional resonance, consistent with its established role in promoting affiliation and social cohesion [6, 7, 8]. We show that, compared with typically developing boys, those at risk for antisocial behavior in general (irrespective of their risk of psychopathy) display reduced neural response to laughter in the supplementary motor area, a premotor region thought to facilitate motor readiness to join in during social behavior [9, 10, 11]. Those at highest risk for developing psychopathy additionally show reduced neural responses to laughter in the anterior insula. This region is implicated in auditory-motor processing and in linking action tendencies with emotional experience and subjective feelings [10, 12, 13]. Furthermore, this same group reports reduced desire to join in with the laughter of others—a behavioral profile in part accounted for by the attenuated anterior insula response. These findings suggest that atypical processing of laughter could represent a novel mechanism that impoverishes social relationships and increases risk for psychopathy and antisocial behavior.

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Psychopathic traits are associated with a lack of enduring affiliative bonds

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Listening to human laughter engages brain areas that facilitate emotional resonance

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Boys at risk of psychopathy have reduced neural/behavioral responses to laughter

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This could reflect a mechanism underpinning reduced social connectedness

The difference between ice cream and Nazis: Moral externalization and the evolution of human cooperation

A range of empirical findings is first used to more precisely characterize our distinctive tendency to objectify or externalize moral demands and obligations, and it is then argued that this salient feature of our moral cognition represents a profound puzzle for evolutionary approaches to human moral psychology that existing proposals do not help resolve. It is then proposed that such externalization facilitated a broader shift to a vastly more cooperative form of social life by establishing and maintaining a connection between the extent to which an agent is herself motivated by a given moral norm and the extent to which she uses conformity to that same norm as a criterion in evaluating candidate partners in social interaction generally. This connection ensures the correlated interaction necessary to protect those prepared to adopt increasingly cooperative, altruistic, and other prosocial norms of interaction from exploitation, especially as such norms were applied in novel ways and/or to novel circumstances and as the rapid establishment of new norms allowed us to reap still greater rewards from hypercooperation. A wide range of empirical findings is then used to support this hypothesis, showing why the status we ascribe to moral demands and considerations exhibits the otherwise puzzling combination of objective and subjective elements that it does, as well as showing how the need to effectively advertise our externalization of particular moral commitments generates features of our social interaction so familiar that they rarely strike us as standing in need of any explanation in the first place.

A Social Reinforcement Learning Hypothesis of Mutual Reward Preferences in Rats

Although the use of neuroimaging techniques has revealed much about the neural correlates of social decision making (SDM) in humans, it remains poorly understood how social stimuli are represented, and how social decisions are implemented at the neural level in humans and in other species. To address this issue, the establishment of novel animal paradigms allowing a broad spectrum of neurobiological causal manipulations and neurophysiological recordings provides an exciting tool to investigate the neural implementation of social valuation in the brain. Here, we discuss the potential of a rodent model, Rattus norvegicus, for the understanding of SDM and its neural underpinnings. Particularly, we consider recent data collected in a rodent prosocial choice task within a social reinforcement framework and discuss factors that could drive SDM in rodents.

The Neural Mechanisms of Meditative Practices: Novel Approaches for Healthy Aging

Objectives

Meditation has been shown to have physical, cognitive, and psychological health benefits that can be used to promote healthy aging. However, the common and specific mechanisms of response remain elusive due to the diverse nature of mind–body practices.

Methods

In this review, we aim to compare the neural circuits implicated in focused-attention meditative practices that focus on present-moment awareness to those involved in active-type meditative practices (e.g., yoga) that combine movement, including chanting, with breath practices and meditation.

Recent Findings

Recent meta-analyses and individual studies demonstrated common brain effects for attention-based meditative practices and active-based meditations in areas involved in reward processing and learning, attention and memory, awareness and sensory integration, and self-referential processing and emotional control, while deactivation was seen in the amygdala, an area implicated in emotion processing. Unique effects for mindfulness practices were found in brain regions involved in body awareness, attention, and the integration of emotion and sensory processing. Effects specific to active-based meditations appeared in brain areas involved in self-control, social cognition, language, speech, tactile stimulation, sensorimotor integration, and motor function.

Summary

This review suggests that mind–body practices can target different brain systems that are involved in the regulation of attention, emotional control, mood, and executive cognition that can be used to treat or prevent mood and cognitive disorders of aging, such as depression and caregiver stress, or serve as “brain fitness” exercise. Benefits may include improving brain functional connectivity in brain systems that generally degenerate with Alzheimer’s disease, Parkinson’s disease, and other aging-related diseases.