Have we identified the root of all evil?

Human cruelty, insensitivity to feelings, adolescent self-centredness, juvenile delinquency, narcissism and borderline personality states are linked by one thing, Professor Simon Baron-Cohen told the Bath Festival. It's a failure to empathise – to intuit or understand the feelings of another person.

He was exploring the grim topic of how humans can treat other people as objects and lose sight of their humanity. Among the less horrible examples cited were Nazi experiments on Jewish women whose hands were cut off and re-sewn back to front. "Using the concept of evil as an explanation, and saying evil is 'incomprehensible' is wholly unacceptable," he said.

His centre for autism studies in Cambridge uses a brain scanner to detect different levels of empathy in patients. He said empathy could be taught.

Professor Baron-Cohen has linked juvenile delinquency to neglect in childhood, when children have no parent to bond with. "What we give children through physical affection is the skill to empathise in later life." Children who are in trouble with the law often have bits of their brain "looking for an empathy circuit and finding nothing".