[2] Research has suggested that parochial altruism may have evolved in humans to promote high levels of in-group cooperation, which is advantageous for group survival.
[5][6] While Darwin first described the general concept of parochial altruism, the term was first coined in 2007 by economists Jung-Kyoo Choi and Samuel Bowles.
[4] Following Darwin's initial theories, modern researchers in fields such as evolutionary biology and social psychology began investigating the evolution of group dynamics and altruism.
The complexity of human motivation makes the distinction between altruism and self-interest difficult to identify, and this is an ongoing debate within psychology and philosophy alike.
[13][14][15] Kin selection is a theory in evolutionary biology that may offer a foundational framework to help explain the mechanisms underlying parochial altruism.
The rule posits that evolutionary processes may favor altruistic behaviors when they benefit close genetic relatives, thereby indirectly promoting the transmission of shared genes.
In essence, kin selection suggests that individuals are more likely to perform altruistic acts if the cost to themselves is outweighed by the benefit to their relatives.
[20] Reciprocal altruism extends beyond kin selection, as it benefits individuals based on their previous actions, not just genetic relatedness.
Reciprocity has been observed in a wide range of species, indicating its evolutionary advantage in fostering cooperation among non-kin group members.
[19] In the context of parochial altruism, the expectation of reciprocity fosters social connection and a sense of mutual obligation that is preferential to the in-group.
The idea of war and altruism being intricately interconnected may also help explain the high frequency of intergroup conflicts observed in ancient human societies.
The study illustrated that participants who were determining punishment for out-group members who have transgressed show greater activity and connectivity in a network of brain regions that modulate sanction-related decisions, while participants who were determining punishment for in-group members who have transgressed show greater activity and connectivity in brain regions that modulate mentalizing.
Joseph Henrich and colleagues conducted a large-scale research study examining cross-cultural variations in economic and dictator games in 15 small-scale societies.
For example, they found that societies with a higher level of market integration and adherence to religion showed more fairness in economic games.
Societies with strong clan or tribal affiliations, and particularly those with more frequent conflict, tend to exhibit more pronounced parochial altruism, reinforcing cooperation and unity within the social group.
In regions with a history of intergroup conflict or scare resources that must be fought over, groups may exhibit stronger in-group loyalty and out-group aggression as an adaptive response to the environment.
This is achieved through the in-group favoritism that is characteristic of parochial altruism, whereby individuals selectively behave altruistically towards members of their own group.
[citation needed] The study of parochial altruism extends beyond human societies, with various animal models providing insight into the evolutionary origins and mechanisms of this behavior.
Researchers conducted studies before, during, and after riots in Northern Ireland, investigating how the conflict influenced real-world measures of cooperation, such as charity and school donations.
[17] Emerging research seeks to investigate the neural basis of parochial altruism, using modern technologies such as neuroimaging and neurobiological approaches.
[46][47][48][49] Studies utilizing functional magnetic resonance imaging (fMRI) have identified specific brain regions that are activated during in-group versus out-group interactions, indicating a potential neural basis for parochial decision-making.
A study by De Dreu et al. demonstrated that intranasal administration of oxytocin increased in-group trust and cooperation, as well as aggression toward perceived out-group threats.