Abstract
This article provides an overview of the debate within social psychology concerning the possible existence of altruistic motivation. After presenting the social-psychological background, we describe selective investment theory, an evolutionary theory of altruistic motivation, and discuss the underlying neurobiology. We describe evidence of the theory’s generativity within health psychology and consider its implications for solving social problems in the areas of economics, overpopulation, peace negotiations, and environmental protection.
With few exceptions (Zahn-Waxler et al., 1984), psychology in the 20th century has considered self-interest to be the linchpin for understanding prosocial emotions, motives, and behavior. Consider the case of a mother’s love for her children, as conceptualized by Bowlby (1958). In highly regarded expositions on attachment and caregiving, Bowlby reconfigured what appears selfless into the selfish. He writes: “It is fortunate for their survival that babies are so designed by Nature that they beguile and enslave mothers” (p. 19). A child’s affectional tie to a parent was considered a proximity-seeking device to avoid predation rather than care and concern for the mother, and until relatively recently, parents’ motivation to care for their young was left unexplored. Archer (1997) adopted a similar view of love for pets, writing that humans are tricked into caring for them. Within this self-centered paradigm, even the most charitable and sacrificial acts—such as spending a lifetime in military service—can be presumed to arise from self-interested motivation, carefully sculpted over time through the process of natural selection (which is, in reality, agnostic with respect to human intention; Dawkins, 1976; see also Kropotkin, 1902, for compelling arguments that natural selection favors other-regarding motivation).
Empirical studies of selfless motivation within the academic field of social psychology were either missing or disregarded until Daniel Batson demonstrated, with his pioneering work in prosocial behavior (Batson & Shaw, 1991), that empathic concern (tenderness, compassion, soft-heartedness, warmth, and empathy) can cause individuals to willingly subject themselves to physical shocks intended for another, even when it is easy to escape the situation (Batson et al., 1981). Following this demonstration, the possibility that empathic concern could lead to altruism became an exciting subject for research and an enticing topic for lively debate (Cialdini et al., 1997).
While earlier research within social psychology had discovered several findings consistent with the possible existence of psychological altruism (Dovidio & Penner, 2001), they discouraged its study because of the difficulty with operationally defining altruistic motivation (Penner, 2008, personal communication). Moreover, enthusiasm for the empathy-altruism hypothesis was tempered by several egoistic alternative explanations for apparent altruism, including the motivation to relieve personal distress and guilt, as well as a sense of shared identity, in which helping the other was reclassified as helping the part of the self that resides within the other (Cialdini et al., 1997). After controlling for these egoistic alternatives, researchers found that only superficial, low-cost instances of helping behavior could be explained by empathic concern (Neuberg et al., 1997). These data were interpreted to mean that helping the other is always helping the self (so it cannot be selfless) and that empathy accounts for so little of the variance in helping that its study seemed a moot point. Even Daniel Batson once characterized (psychological) altruism as a “fragile flower” that is crushed under the weight of self-interest (Batson et al., 1983, p. 18).
Despite its lower position on the ladder of scientific respect, the idea of selfless motivation was resurrected with increasing public awareness of existential threats to mankind, such as climate change, weapons proliferation, income inequality, and ethnic conflict. The scientific enterprise responded by ignoring esoteric debate and starting to prioritize and encourage the study of what makes us care about one another and the planet.
Evolutionary Theories of Selfless Motivation
Despite psychology’s near-universal buy-in to self-interest as the prime mover of prosocial (and other) behaviors, there are well-conceived arguments and growing evidence to suggest that humans are also other-directed—that is, deeply interested in the welfare of others. As Marsh (2018, p. 2) wrote, “Humans are notable for the scope and variety of their prosocial behavior, which find no equal among any other species (Silk & House, 2011).” Understanding how and under which circumstances humans can be motivated to help others was the goal of selective investment theory (S. L. Brown, 1998, 1999; S. L. Brown & Brown, 2006), which sought to determine how the motivation for helping behavior can be favored by natural selection. Although kin-selection theory and reciprocal-altruism theory had been advanced to explain how it can be adaptive to help relatives (Hamilton, 1964) and those who reciprocate (R. L. Trivers, 1971), empirical treatments of the underlying motivation had been nonexistent, and widespread helping “across party lines,” so to speak (i.e., strangers, non-kin, and nonreciprocators), begged for a theoretical explanation.
Selective investment theory (S. L. Brown & Brown, 2006) and stakeholder theory (Roberts, 2005) are two attempts to address this theoretical lacuna. According to both theories, the motivation to help strangers and non-kin without reciprocation can be favored by natural selection if the helper and recipient share common fate related to their survival and reproduction (Hamilton, 1964). When this happens, they are said to share fitness interdependence (S. L. Brown, 1998, 1999).
Fitness interdependence certainly includes reciprocal altruists and relatives, but it also includes a variety of others who share fitness-related fate, such as spouses raising children together (who may or may not reciprocate), or (in ancestral times) cooperative hunting partners or migrating bands. Even modern-day fraternities and sororities might be considered interdependent in evolutionary terms. In such groups, one person can theoretically influence the reputation, power, mating success, or survival of all, even if separated by location or generation. The same could be said for sports teams, musical groups, and members of universities, religions, political ideologies, or nations, depending upon, of course, the context and whether cues for fitness interdependence are present and positively (as opposed to negatively) correlated. These cues would have included those for kinship (i.e., similarity, familiarity, and proximity), and reciprocity, but they would also have included sexual behavior (as a means of raising a common offspring) as well as shared goals and challenges, shared threats, and shared positive experiences (S. L. Brown et al., 2024; Cohn & Fredrickson, 2006).
From an evolutionary perspective, both the magnitude of fitness interdependence and its symmetry impact the safety and reproductive benefits of interpersonal relationships (see also R. Trivers, 1985). Common fate is effectively a protective mechanism, buffering altruists from threats to their survival and reproduction (S. L. Brown, 1999; S. L. Brown & Brown, 2006). The key insight in reconciling natural selection’s ability to favor helping non-kin, nonreciprocators, and even strangers is that another’s dependence upon oneself (vulnerability of the recipient) eliminates the power of natural selection to favor exploitation. So, the only requirement for evolution to favor altruistic motivation is to posit the existence of hard-wired neural mechanisms that are sensitive to context. These mechanisms need to recognize recipients who are vulnerable, who share fitness interdependence with the helper, and respond with altruistic motivation (and avoid doing so when fitness interdependence cues are absent; Rand & Nowak, 2013, make similar arguments regarding the role of context-dependent algorithms in shaping cooperation).
As S. L. Brown (1998) describes, the centrality of fitness interdependence to psychological altruism (and evolutionary theories of helping behavior) is clear: “If states of fitness interdependence discourage exploitation as well as provide fitness benefits, then these states constitute a logically appealing pre-requisite for [altruistic motivation]” (p. 19). Importantly, game theoretic modeling (Roberts, 2005) has confirmed this proposition.
Social Bonds as Altruistic Motivation
Fitness interdependence certainly describes contexts that can safely permit the evolution of altruistic motivation, but it is by no means synonymous with psychological altruism. On the contrary, it is a genetically selfish set of circumstances that happens to assure that psychological altruism (i.e., altruistic motivation) will lead more often than not to reproductive benefits (as opposed to reproductive costs). To illustrate the point, neural mechanisms that create parental motivation may be selected for because they increase the chance that children will survive and reproduce successfully. However, that same neural architecture can create parental motivation to invest in adoptive children without compromising its integrity. As we describe below, our argument is that parental neural architecture, honed by biological or genetic selfishness, nevertheless produces altruistic motivation that accounts for widespread helping in humans (Preston, 2013).
So, how do we go from having evolutionary “permission” to behave altruistically (i.e., fitness interdependence) to the psychology of finding the well-being of another person to be as compelling, or even more compelling, than our own? Few evolutionary theories of helping behavior incorporate motivation into their treatise; however, Darwin (1872) cited maternal love as a likely candidate mechanism for motivating maternal investment, and R. L. Trivers (1971) suggested that the social emotions, such as sympathy and compassion, are likely to increase the shared benefits of reciprocal altruism (i.e., reciprocal helping behavior). Tooby and Cosmides (1996) highlight the role of friendship in mediating between the evolved circumstances that favor altruistic decision-making and the motivational machinery designed by evolution to deliver benefits to others. From the vantage point of selective investment theory, these types of emotional, cognitive, and motivational mechanisms are required given the motivational conflict inherent in navigating decisions about whether to help, who to help, and how much help to provide (S. L. Brown & Brown, 2006). A long evolutionary history that selects for self-centered motivational systems would have predated mammalian parental investment and interfered with helping others. A specialized motivational system, such as the attachment bond (Bowlby, 1958), might be sufficient to overcome (and overwhelm) ancient self-centered impulses.
According to selective investment theory, the social bond Bowlby and Ainsworth referred to as attachment organizes the motivation to give to, or help, specific others. It emerges from fitness interdependence within any type of relationship (including friendship) and minimizes motivational conflict in favor of the well-being of another person. Characterized as a dynamic memory complex with cognitive and affective features (e.g., unconditional love), social bonds rely on ancient neural circuitry, described below, especially dopamine and the hormone and neurotransmitter oxytocin. These hormones down-regulate self-interest motivation and motivate caring for others using the same neural circuitry that motivates caring for helpless offspring (Numan, 2006)—which, following Preston (2013), we hypothesize to be the evolutionary progenitor of altruistic motivation.
Altruistic Neurobiology
Examples of non-human cooperation and apparent other-focused motivation occur throughout mammalian species (S. L. Brown & Brown, 2006; Sun et al., 2025). There are detailed animal (neurobiological) models of parental-investment behavior that describe the interweaving of neurotransmitters, hormones, and neural regions that coordinate parental investment (Marsh, 2018; Preston, 2013). It is important to note that, for the purposes of assessing other-focused motivation, parental-care neural circuitry relies on mechanisms for suppressing self-interest, mechanisms that uniquely recruit reward-inhibition and fear-inhibition networks (Numan, 2006; see Fig. 1). Together, these neural systems, which are coordinated by the medial preoptic area of the hypothalamus and surrounding ventral bed nucleus of the stria terminalis (vBST), initiate motor programs necessary for providing active help in rodents, including nest-building and retrieving pups. Further, they respond selectively to cues for distress or vulnerability, and to cues for fitness interdependence and social bonds, such as familiarity. Most importantly, lesions of the medial preoptic area interfere with parental behavior but do not affect other behaviors that are also under control of the hypothalamus, such as body-temperature regulation or locomotion. This suggests that the medial preoptic area may have evolved specifically to facilitate parental caregiving behavior. Attempts to generalize the role of the medial preoptic area of the hypothalamus have confirmed its role in motivating helping behavior among juveniles, males, and virgin animals across species (see also Preston, 2013).
Schematic representation of the neurobiology underlying social bonds
Neurotransmitters mediating the selective activation of these neural circuits include the release of oxytocin within the hypothalamus, and dopamine, which binds to inhibitory (D1) dopamine receptors in the nucleus accumbens (Numan et al., 2005), a reward center that mediates wanting, needing, learning, and addiction. (In reward motivation, activation of the nucleus accumbens typically relies on excitatory D2 receptors.) The role of oxytocin in establishing fitness interdependence and social bonds has been well established, and it is causally related to parental investment and other forms of helping behavior (S. L. Brown & Brown, 2006). Numan (2006) has hypothesized that oxytocin binds to receptors in the medial preoptic area of the hypothalamus, in addition to other regions in parental-care neural circuitry, such as the amygdala and the nucleus accumbens. Because the medial preoptic area of the hypothalamus relies on dopamine to inhibit the nucleus accumbens (in the context of providing active help), neural circuits that restrict dopamine release, associated with learned helplessness and hopelessness, are expected to interfere with activation of parental neural circuitry (S. L. Brown & Brown, 2015) as much as they interfere with reward-seeking drives. In other words, a lack of autonomy or free will may disrupt the mammalian caregiving motivational system as much as it disrupts psychological well-being.
Activation of the medial preoptic area also interrupts and inhibits transmission of threat signals from the amygdala that otherwise would signal the periaqueductal gray to mobilize sympathetic resources for the fight-or-flight response. The reliance of parental motivation on inhibitory processes within the brain’s reward-and-avoidance (stress response) neural circuits offers perhaps the most compelling evidence that the motivation for parental caregiving behavior cannot be reduced to reward-seeking or punishment-avoiding drives.
Evidence
There is much data from studies of anthropology and comparative animal behavior to show a mediating role of social bonds in the relationship between fitness interdependence and costly long-term investment in others (S. L. Brown, 1998, 1999; S. L. Brown & Brown, 2006). And, interactions between (a) the cortical structures that are responsible for recognizing social bonds and need in others and (b) the subcortical regions responsible for responding to need have led several researchers to argue in favor of the existence of altruistic motivation (e.g., Eisler & Levine, 2002; Marsh, 2018). Finally, the utility of making a distinction between self- and other-interested motivation has been particularly generative within health psychology.
One of the more prominent findings demonstrates that people in close relationships with others live longer than those who are socially isolated (House, Landis, & Umberson, 1988). Attempts to understand the mechanism for this effect have relied on the presumption that receiving social support from relationship partners would be beneficial for health and longevity. However, tests of the receiving social-support hypothesis have produced conflicting results, indicating that receiving support is sometimes beneficial, sometimes harmful, and sometimes shows no association (S. L. Brown et al., 2003). By recasting the functional significance of social bonds as creating altruistic, as opposed to self-interested, motivational states, the possibility that some of the longevity benefits of being in a close relationship would be due to giving as opposed to, or in addition to, receiving support became a new direction for empirical research. This research demonstrated a robust association between helping behavior and improved health of the helper, including lower mortality risk (S. L. Brown et al., 2003), lower morbidity (W. M. Brown et al., 2005), and fewer depressive symptoms following bereavement (S. L. Brown et al., 2008). More recent findings replicate and extend the positive effects of helping to other scenarios—even to spousal caregivers (S. L. Brown et al., 2009). The spousal-caregiver reassessment was particularly interesting because traditionally this kind of caregiving situation had been considered toxic to the caregiver—that is, researchers had typically inferred that the stresses of spousal caregiving produced harmful psychological and physical consequences for the caregiver, including increased mortality. However, these studies did not measure the actual amount of time spent helping a partner. In more recent studies, when spousal caregiving hours were measured directly, time spent actively helping the partner was typically associated with reduced mortality risk for the caregiver (R. M. Brown & Brown, 2014; Roth et al., 2013).
Implications
An argument can be made that, as a society, some of our most vexing problems arise from runaway self-interest, in which the rate of consumption of shared resources outpaces the renewal of those resources (because people presume that everyone will act selfishly). This is often referred to as the tragedy of the commons, and describes a scenario that underlies threats to the economy (e.g., hoarding) and to the environment (e.g., climate change). The possibility that people can also be motivated to care for and prioritize others in well-specified situations changes our perspective on these types of problems and their solutions. Below, we discuss the implications of selective investment theory (and other-focused motivation) for economic behavior, overpopulation, peace negotiations, and environmental protection. We conclude by considering how different our legal system might look through the lens of selective investment theory.
Economic behavior
The U.S. economic system is predicated on the assumption that people will always act in their own self-interest. The failure of this assumption to predict economic behavior has been used as an explanation for the financial crisis of 2008: de Waal (2012) suggested that the economic collapse was due to “bad biology,” that is, the superimposition of the rule of self-interest onto a more complex human motivational system that includes regard (and love) for others. By taking our other-regarding nature into consideration, it may be possible to leverage natural tendencies to share with one another (Smith et al., 2012), improving conservation efforts and reducing hoarding, which takes resources out of the economy (Preston et al., 2009).
The challenge is how to facilitate fitness interdependence and social bonds without compromising an individual’s sense of freedom. To establish fitness interdependence, one must highlight the vulnerability of those in need of help (which protects helpers against exploitation), perhaps with perspective-taking exercises that involve creative expression as a means of cultivating vulnerability (Worthy et al., 1969). Less is known about how social bonds emerge from fitness interdependence; however, research efforts to study this question might include natural experiments with people who decide to live in larger groups and share the costs of living. Information from such studies can inform interventions that foster fitness interdependence without limiting autonomy or creating negative interdependence.
Overpopulation
Establishing natural limits on population growth might be an added benefit of interventions focused on increasing interdependence and strengthening social bonds. Selective investment theory assumes that interdependence and social bonds create the motivation to allocate valuable resources to others, including one’s own offspring (S. L. Brown & Brown, 2006). If so, then those offspring, themselves the beneficiaries of high-quality investment, are likely to “pay it forward” when they are parents, opting for quality investment in fewer children (Chisholm, 1993; MacDonald, 1988; Simpson & Gangestad, 1991).
Peace negotiations
What we know about fitness interdependence might also be used to prevent war. A common enemy, for example, is often invoked by politicians, the military, religious zealots, and cults to manipulate or bait others into violent action. In addition, a tradition of social-psychological research has documented the within-group cohesion that arises from (and creates) out-group hostility (Sherif et al., 1961), making war all the more appealing. However, an alternative strategy of creating positive fitness interdependence within groups (not necessarily involving a common enemy) has been advanced as a provocative new way to cultivate world peace. As Glowacki (2024) has stated, peace is always in the best interest of nations, and the decision to go to war is typically made by a single individual (or small group of individuals) who elevate their own need for revenge or status above the needs of the rest of the group (Glowacki, 2024). Thus, when followers of such an individual become a vessel for the leader within hierarchical structures (Flescher, 2013), the will of one person can lead an entire military, business corporation, or international intelligence operation astray. According to Glowacki, it is “positive-sum interdependent relationships” (p. 1; fitness interdependence) within groups that may shield countries against this. Indeed, perceived interdependence and egalitarianism facilitate cooperation and negotiation and reduce conflict (Harrel, 1997). Because of this, shared positive experiences among the disenfranchised or injured could diminish their motivation to lead nations astray (S. L. Brown et al., 2024).
Environmental protection
Fitness-interdependent issues that involve altruistic motivation might include human and animal rights, issues that cross party lines and might help everyone to feel better about their financial contributions. For example, protecting the rainforest is a fitness-interdependent issue because the rainforest supplies oxygen to all living things (https://apps.npr.org/lookatthis/posts/brazil/). The rainforest also offers a prototype for studying the environmental prophylactics that reverse desertlike conditions—conditions that destroy habitats, agriculture, and ecosystems. Another fitness-interdependent issue is the proliferation of the telecommunications industry, which, by relying on non-ionizing radiation, destroys habitats and compromises the health of everyone (Shinjyo & Shinjyo, 2014), presumably also its investors. If those with political aspirations were able to create fitness interdependence with their constituents by selecting platforms with fitness-interdependence issues and viewing their constituents as banking partners in joint ventures such as these, there is no telling what could be accomplished and how much better off everyone would be.
Conclusions
Once upon a time, in Athens, Greece, the media, cultural arts, and stories were used to create a socially bonded and cohesive populous. As selfless as Greek citizens were when interacting with one another on the battlefield, these motives did little to disrupt genocidal impulses and practices directed toward out-group members who were deemed to be of inferior breeding (Kulberg & Singer, 2012). Knowledge of an innate tendency toward altruistic motivation is no guarantee that world peace will prevail, that human and animal rights will take center stage, or that the natural environment will be preserved. Like any tool, the effects of this knowledge will depend upon the motives and wisdom of the individuals using it. Corrupt ulterior motives will maintain the status quos. However, if a more altruistic population insists on a more altruistic legal system that prioritizes collective wellbeing above profit, it may be possible to create more ethical legal practices, negotiate solutions in good faith with other countries, expose heretofore hidden attempts to exploit or abuse others, and secure the funds needed to make helping others a reality. For example, to more ethically distinguish perpetrators from innocent victims, investigative efforts could ascertain whether laws were broken for other-focused versus self-focused reasons, and whether there were unavoidable circumstances. Possession or use of illegal drugs, for example, could indicate either a victim of or perpetrator of abuse depending on the context. Forged documents or illegal border crossings could be forgiven if they were judged to reflect a good faith effort to protect children, fight war crimes, or defend human rights. By exonerating those who lack intent to harm others, the overburdened legal system would be freed up to focus instead on prosecuting individuals who are a danger to others, perhaps in consultation with the victims and/or their families to reach more appropriate types of renumeration. Non-disclosure agreements could be declared unconstitutional if they can be shown to cover-up human rights violations or attempting to negotiate in bad faith. The information obtained could then be used to paint a more educated portrait of the sociopolitical environment, easily identify perpetrators, and reallocate monies recouped from illegal enterprises to more humane causes, such as protecting the rainforest or transforming unethical businesses into ethical ones, or addressing the needs of indigenous populations, whose poverty often incentivizes their desire to trade away their own natural resources. Importantly, these types of changes to the legal system could help to restore faith in the United States as a safe haven for the weary, tired, “huddled masses” in a race against time to heal one another and the planet. And perhaps this interdependent repositioning of the United States with respect to immigration would encourage a deeper bond to the United States among its immigrants, who might otherwise want to put loyalty to race or country of origin ahead of common sense legislation.
It was Admiral Stansfield Turner, former President of the Naval War College and director of the Central Intelligence Agency from 1977 to 1981, who may have described the problem best when he stated that it is only through discovering our shared humanity with those on the other side of the world that we have a chance to outpace the weapons revolution and the public’s perilous indifference (Turner, 2012). A belief that altruistic motivation can and does exist might facilitate this process.
Recommended Readings
Carter, C. S. (1998). Neuroendocrine perspectives on social attachment and love. Psychoneuroendocrinology, 23, 779–818. Describes some of the most important original work in the area of oxytocin research, including its relationship to shared threat.
Dovidio, J. F. & Penner, L. A. (2001). Helping and Altruism. (pp. 162–195). In G. J. O. Fletcher, & M. S. Clark (Eds). Blackwell Handbook of Social Psychology: Interpersonal Processes. Oxford, UK: Blackwell Publishing. A comprehensive description of the classic studies of helping behavior within social psychology including a review of the bystander intervention studies and the empathy-altruism literature.
Eisler, R., & Levine, D. S. (2002). Nurture, nature, and caring: We are not prisoners of our genes. Brain Mind, 3, 9–52. A comprehensive review of neuroscience and evolutionary biology that concludes with a specific model describing how caring motivation can be unlocked by contextual cues.
Hoffman, M. L. (1978). Psychological and biological perspectives on altruism, international. Journal of Behavioral Development, 1, 323–339. Advocates the integration of evolutionary theories of altruism with psychological motivational systems that are altruistic.
Oliner, P. M., & Oliner, S. P. (1992). Promoting extensive altruistic bonds: A conceptual elaboration and some pragmatic implications. In P. M. Oliner & S. P. Oliner (Eds.), Embracing the other: Philosophical, psychological, and historical perspectives on altruism (pp. 369–389). New York University Press. Describes some of the research on rescuers during Nazi Germany showing that social bonds distinguished helpers from nonhelpers and provides detailed explanations for considering how social bonds and altruism may be related to the self-concept.
Sherif, M., Harvey, O. J., White, B. J., Hood, W. R., & Sherif, C. W. (1961). (See References). Examines the process of creating fitness interdependence through sharing a common enemy, illustrating that old enemies can cooperate and work together.
Wilson, J. & Musick, M. (1999). The effects of volunteering on the volunteer. Law and Contemporary Problems, 62, 141. A review of the volunteerism literature and of the earliest findings showing mortality benefits for volunteers.
