A new international study identifies a brain region that helps decide how generous we are toward friends versus strangers. Researchers from Germany and South Africa found that damage to the basolateral amygdala (BLA) reduces sharing with anyone outside one’s closest circle, while generosity toward close friends remains relatively intact. The study, recently published in the Proceedings of the National Academy of Sciences, sheds light on the biological roots of kindness and self-interest and could inform understanding of social disorders.
Generosity is deeply rooted in Thai culture, where nam jai (น้ำใจ) shapes temple offerings, acts of charitable giving, and neighborly help during floods. People naturally adjust resource sharing based on how well they know someone—a phenomenon scientists call social discounting. This research helps explain the brain mechanisms behind why we give freely to family or longtime friends but may hesitate with strangers or casual acquaintances.
The study followed five South African women with Urbach-Wiethe disease, a rare condition that destroys the BLA while largely sparing other mental functions. They were compared with culturally matched volunteers without the condition. Participants imagined sharing 200 South African Rand with eight people spanning social distance from a best friend to a total stranger. Healthy participants gradually tightened their giving as distance increased, while those with BLA damage became markedly selfish toward everyone except their innermost circle. For one participant, even close connections elicited little generosity.
This finding clarifies earlier mixed results about the amygdala’s role. Some studies suggested amygdala damage could increase altruism in abstract tasks or anonymous interactions. This study shows the BLA functions as a dynamic social calculator, adjusting generosity with emotional closeness rather than acting as a simple on/off switch.
“When BLA function is compromised, people revert toward self-interest—except for their closest friends,” the researchers explain. Evolutionary psychology supports this view: brains may have evolved to favor sharing with those most likely to reciprocate while protecting against exploitation by outsiders. In short, the brain’s generosity is adaptive, prioritizing bonds essential to survival and mutual support.
The research has practical relevance for Thai communities, where social networks extend beyond the immediate family. Conditions linked to amygdala dysfunction, such as certain aggressive behaviors or personality disorders, could eventually be better understood through the BLA’s role in social decisions. This knowledge might inform interventions that promote prosocial behavior and social harmony.
For Thai readers, these findings invite reflection on how cultural ideals of water-like generosity intersect with biology. Schools and community programs could help broaden empathy beyond tight circles, fostering cooperation across neighborhoods and villages.
Looking ahead, researchers will investigate whether interventions—such as mindfulness training shown to boost compassion in various contexts—can modulate BLA activity and influence generosity. Studies across age groups, genders, and cultures, including Thai populations, will further illuminate how social harmony and generosity are shaped by both mind and milieu.
For readers seeking to cultivate generosity, the science supports timeless Thai wisdom: while it’s natural to prioritize family, deliberate actions—volunteering, community involvement, or helping strangers—can expand one’s circle of care. Teachers and parents can encourage students to look beyond their ingroups through collaborative activities that promote empathy and understanding.
In short, next time you hesitate to help someone outside your inner circle, remember that your brain makes constant social calculations. Yet awareness and intention can override these impulses, contributing to a more generous and connected society.