Neural responses underlying extraordinary altruists' generosity for socially distant others.

Most people are much less generous toward strangers than close others, a bias termed social discounting. But people who engage in extraordinary real-world altruism, like altruistic kidney donors, show dramatically reduced social discounting. Why they do so is unclear.

The adaptiveness of fear (and other emotions) considered more broadly: Missed literature on the nature of emotions and its functions.

We agree with Grossmann that fear often builds cooperative relationships. Yet he neglects much extant literature. Prior researchers have discussed how fear (and other emotions) build cooperative relationships, have questioned whether fear per se evolved to serve this purpose, and have emphasized that human cooperation takes many forms.

Unselfish traits and social decision-making patterns characterize six populations of real-world extraordinary altruists.

Acts of extraordinary, costly altruism, in which significant risks or costs are assumed to benefit strangers, have long represented a motivational puzzle. But the features that consistently distinguish individuals who engage in such acts have not been identified. We assess six groups of real-world extraordinary altruists who had performed costly or risky and normatively rare (<0.