The Neuroscience of Altruism
While it has been argued that organisms are selfishly hardwired to promote their own genes, mammals frequently show altruistic acts of kindness and care towards unrelated others. Recent findings in neuroscience can help us explain the anatomical processes that relate to these behaviors and can inform perspectives to an age old question about altruism: Are people truly capable of altruism that is free of selfish intent?
Definition of Altruism
The neuroscience of altruism often focuses on “Altruistic Responding” which is defined as any form of helping where the giver is motivated to assist a specific target after perceiving their distress or need. [1] This definition is made to exclude passive or accidental acts that aid another. Altruistic responding has been observed in many mammals including rats, dogs, dolphins, elephants, apes, and humans. [2] [3] [4]
Evolution of Altruism
Generally speaking, mammals give live birth and require a greater care during prolonged development in youth. This ability to understand the needs of and care for one’s own offspring is thought to be the evolutionary root of altruism. [1] [5] [6] Given the ability to care for others, the adaptive value of strategic helping, sharing and cooperation in larger groups is likely to have selected for extending caring from offspring to others. These additional pressures are explained in “multi-level fitness” models that hold that altruism towards relatives, those likely to reciprocate, and other group members is adaptive as it provides future rewards in the form of access to limited resources such as food, mates, and coalition partners [7].
Anatomy of Altruism
Across many mammalian species, Altruistic Responding overlap anatomically with structures related to basic approach and avoidance related behaviors [1]. This includes an intimate relationship with the "Reward System”, which is comprised of the dopaminergic mesolimbic and mesocortical pathways. The mesolimbic pathway is widely believed to be the “Reward” pathway and runs from the ventral tegmental area (VTA) to the nucleus accumbens and to the rest of the limbic system. [8] The mesocortical pathway connects the ventral tegmentum to the cerebral cortex and is thought to be involved in motivation and emotional response [9].
Offspring Care System
Connections to the reward system are made that allow for mammals to take in sensory information in their environment and translate it to socially relevant information that may lead to altruism. Sensory information is processed and arrives at the amygdala and is passed to the medial preoptic area of the hypothalamus (MPOA), ventral bed of the stria terminalis (vBST), and ventrail striatum which may increase signaling to the VTA and inhibit signaling in the anterior hypothalamus(AHN) and periaqueductal gray (PAG). More evidence is needed to clarify the exact for of the MPOA in humans, but animal models show that activation in this area and the subsequent release of oxytocin increase approach motives and decrease avoidance to help offspring. [1] However, behavioral studies in humans have found that providing participants with oxytocin increases helping by increasing the motivation to approach others in need and decreasing fear and uncertainty present in the moment, suggesting a similar anatomical function of these regions. [10]
Extended Caregiving System
The extended caregiving system utilizes the offspring care system and adds connections to cortical areas responsible for domain-general processes that help interpret the context and the stimuli. This information is then passed to areas in the prefrontal cortex that relate to reward based decision processes which allow for developmental and behavioral flexibility. The result is a interaction of stimuli, context, and learned behavior that can result in the application of the offspring care system to unrelated others. [1] [6]
Within extended caregiving there can be significant differences between mammals depending on the avenues social signaling are likely to occur. For example, rodents’ olfactory inputs play a substantial role in deciphering when to utilize the offspring care system, while in humans the system is biased to react to auditory and visual cues of distress. [11] [12]
Implications for Altruism
In reviewing this material, it is necessary to distinguish between the evolutionary explanations for altruism and the motivational experiences that lead to altruistic acts [13] [14]. While altruism appears to hold evolutionarily adaptive advantages for those who exercise it strategically, it is clear that many organisms, such as dogs and rodents, are not capable of deliberating on the genetic advantages of a potential altruistic act. Similarly, many social signaling is also not found in some species that display acts of altruism. [1] In humans, studies have shown that people often report a general impulse to act altruistically, without much deliberation or accompanying thoughts. [15] Given the flexibility of the extended caregiving system, we can explain occurrences of altruistic behavior that have such a high potential cost to the self that they are likely to be mal adaptive and yet still acted on. [16] Overall, these findings suggests that altruistic acts may hold some personal benefit, but that benefit is unknown or not considered consciously to the actor when the altruistic act is done.
However, this does not necessarily mean that altruistic acts can be done soley for the benefit of the other. The anatomical overlap of the basic reward system, the offspring care system and the extended caregiving system behind altruism suggests that basic desires to approach beneficial things and avoid harmful things are the main drives in altruistic acts. This suggests that altruistic actors do not think “I will do this for some personal benefit” nor will they think “I will do this to solely benefit this person” but instead they are compelled by a more basic drive to simply “Do this.”
References
- Preston, S. D. (2013). The Origins of Altruism in Offspring Care. Psychological bulletin.
- Waal, F. de. (2010). The Age of Empathy: Nature’s Lessons for a Kinder Society. Random House Digital, Inc.
- Masson, J. M. (2009). When Elephants Weep: The Emotional Lives of Animals. Random House Digital, Inc.
- Warneken, F., Hare, B., Melis, A. P., Hanus, D., & Tomasello, M. (2007). Spontaneous Altruism by Chimpanzees and Young Children. PLoS Biol, 5(7), e184.
- De Waal, F. B. M. (2008). Putting the Altruism Back into Altruism: The Evolution of Empathy. Annual Review of Psychology, 59(1), 279–300.
- Churchland, P. S. (2011). Braintrust: What Neuroscience Tells Us about Morality. Princeton University Press.
- Boone, J. L. (1998). The evolution of magnanimity. Human Nature, 9(1), 1–21.
- Berridge, K. C. (2007). The debate over dopamine’s role in reward: the case for incentive salience. Psychopharmacology, 191(3), 391–431.
- Berridge, K. C., & Kringelbach, M. L. (2008). Affective neuroscience of pleasure: reward in humans and animals. Psychopharmacology, 199(3), 457–480.
- Feldman, R., Weller, A., Zagoory-Sharon, O., & Levine, A. (2007). Evidence for a neuroendocrinological foundation of human affiliation. Psychological Science, 18, 965–970.
- Broad, K. D., Curley, J. P., & Keverne, E. B. (2006). Mother–infant bonding and the evolution of mammalian social relationships. Philosophical Transactions of the Royal Society of London: Series B. Biological Sciences, 361, 2199–2214.
- Insel, T. R., & Young, L. J. (2001). The neurobiology of attachment. Nature Reviews Neuroscience, 2, 129–136.
- Batson, C. D. (2011). Altruism in humans. New York, NY: Oxford University Press.
- Preston, S. D., & de Waal, F. B. M. (2002b). Empathy: Its ultimate and proximate bases. Behavioral and Brain Sciences, 25, 1–20.
- Darley, J. M., & Latané, B. (1968). Bystander intervention in emergencies: Diffusion of responsibility. Journal of Personality and Social Psychology, 8, 377–383.
- Macaulay, J., & Berkowitz, L. (Eds.). (1970). Altruism and helping behavior: Social psychological studies of some antecedents and consequences. New York, NY: Academic Press.