Neural, cognitive, and evolutionary foundations of human altruism

Abstract

This article considers three forms of altruism from both a psychological and a neural perspective, with an emphasis on homologies that can be observed across species and potentially illuminate altruism's evolutionary origins. Kin-based altruism benefits biological relatives and, according to the theory of inclusive fitness, is ultimately beneficial to the altruist from a genetic standpoint. Kin selection adequately explains some altruistic behavior, but it is not applicable to much human altruism. Little is known about the neural processes that support it, but they may include cortical regions involved in processing autobiographical memory and the identities of familiar others. Reciprocity-based altruism is performed in expectation of future rewards and is supported by dopaminergic cortico-striatal networks that guide behavior according to anticipated rewards. Care-based altruism is aimed at improving the well-being of distressed and vulnerable individuals and is closely linked to empathic concern. This form of altruism is thought to rely on the subcortical neural systems that support parental care, particularly structures densely populated with receptors for the hormones oxytocin and vasopressin, including the amygdala, stria terminalis, and striatum. The amygdala may be a particularly important convergence point for care-based altruism because of its dual role in responding both to cues that signal infantile vulnerability and those that signal distress. Research on altruism continues to converge across disciplines, but more research linking molecular-level neural processes to altruistic behavior in humans and other species is needed, as is research on how various forms of altruism intersect. For further resources related to this article, please visit the WIREs website.

Amygdala–midbrain connectivity indicates a role for the mammalian parental care system in human altruism

“…In interviews, many altruistic donors report that the urge to donate a kidney followed hearing a story featuring a stranger suffering from kidney failure. Our findings are consistent with the possibility that these sympathetic urges in response to depictions of distressed and vulnerable others correspond to the structure and function of a network of regions, including the amygdala and PAG, that serve essential roles in motivating offspring care across mammalian species [4,7,13,14]. Together, these results support the possibility that costly altruism toward strangers, rather than being a wholly inexplicable outcome, may represent an exaptation of the mammalian parental-care system.…”

“…Risky, life-saving acts on behalf of strangers represent extraordinary manifestations of altruism, broadly defined as a voluntary, costly behaviour aimed at improving the welfare of another individual [1,2]. Altruism can assume several distinct forms, each reflecting distinguishable underlying neurocognitive processes [2][3][4][5]. Costly altruism toward strangers, while rare, has been documented across multiple social species, including humans, chimpanzees and dolphins [2,6,7] and is thought to reflect the exploitation of deep and evolutionarily conserved proximal neural mechanisms that evolved to support parental care for distressed or vulnerable young [4,[7][8][9].…”

“…For example, one scenario describes a young girl who is teased about her appearance in the school cafeteria. Half of the scenarios were preceded by distress cues, specifically preattentively (27 ms) presented backward-masked fearful expressions, which signal vulnerability and distress [4]; the other half were preceded by neutral expressions (electronic supplementary material, figure S1). After reading each scenario, participants reported how much sympathy they felt for the protagonist via button press.…”

Altruism in behavioural, motivational and evolutionary sense

“…Thus, improving the well-being of distressed and vulnerable individuals is often prompted by empathic concern (Batson 2011;Kolm 2006;Marsh 2016;Oliner and Oliner 1988;Schokkaert 2006;Sen 1977). This is shown in experiments (Batson 2011), but also in natural settings (Oliner and Oliner 1988).…”

“…However, these psychological benefits may just be unintended consequences of altruistic behaviour and not the main motivational factor. The fact that a psychological benefit can be foreseen does not mean that achieving it was the goal of the action (Marsh 2016).…”