altruism and society

Study associates brain area with altruism,

"We went into this experiment with the idea that altruism was really a function of the brain's reward systems -- altruistic people would simply find it more rewarding," he said.

But instead, a whole other brain region, called the posterior superior temporal cortex (pSTC), kicked into high gear as altruism levels rose.

The pSTC is located near the back of the brain and is not focused on reward. Instead, it focuses on perceiving others' intentions and actions, Huettel said.

"The general function of this region is that it seems to be associated with perceiving, usually visually, stimuli that seems meaningful to us -- for example, something in the environment that might move an object from place to place," he explained.

This type of perception would have allowed humans' more primitive ancestors to quickly pick out a potential threat -- a crouching lion, for example -- from amid a mass of less important stimuli.