From fear recognition to kidney donation.

Valerie Maupin’s best friend had a loved one who needed a kidney. In an act of extraordinary altruism, Maupin offered one of hers, but she was not a match. Then she wondered: If I’m willing to do this for someone I know, why not for someone else whose need is just as great? With that thought, Maupin, a 24-yold nursing student and hair stylist living in San Diego, decided to do something even more extraordinary. She would donate one of her kidneys to a stranger. A few months later, her kidney was in Florida, filtering the blood of a grateful 50-y-old woman and fellow nurse named Christine Curti (1). What makes someone give up a part of her body for a complete stranger? What might we learn about human nature from studying such extraordinary individuals? In PNAS, Marsh et al. describe the cognitive and neural characteristics of 19 extraordinary altruists who, like Valerie Maupin, gave their kidneys to strangers in need (2). Marsh et al. find that these altruists, compared with a set of matched control subjects, have (on average) larger right amygdalae. (The amygdala is a structure within the temporal lobe known for its role in the evaluation of affectively salient stimuli.) (3) What’s more, their right amygdalae are selectively more responsive to facial fear expressions. Finally, these individuals are better at recognizing fear expressions, although they show no advantage at recognizing expressions of anger.