At some point in our lives, we've all cried "It's not fair!" In fact, it's human nature for us to dislike unequal situations, and we often try to avoid or remedy them. Now, scientists have identified the first evidence of this behavior's neurological underpinnings in the human brain.

The results show that the brain's reward center responds to unequal situations involving money in a way that indicates people prefer a level playing field, and may suggest why we care about the circumstances of others in the first place.

"Our study shows that the brain doesn't just reflect self-interested goals, but instead, these basic reward processing regions of the brain seem to be affected by social information," said study author Elizabeth Tricomi, a professor of psychology at Rutgers University in New Jersey. "That might explain why what happens to other people seems to matter so much to us, even when it might not actually directly affect our own situation."