The monkey brain contains a special class of cells, called mirror neurons, that, surprisingly, fire when the animal sees or hears an action and when the animal carries out the same action on its own.

The discovery is shaking up numerous scientific disciplines, shifting the understanding of culture, empathy, philosophy, language, imitation, autism and psychotherapy.

Everyday experiences are also being viewed in a new light. Mirror neurons reveal how children learn, why people respond to certain types of sports, dance, music and art, why watching media violence may be harmful and why many men like pornography.