WEDNESDAY, Aug. 28 (HealthDay News) -- Your brain is hardwired to feel empathy for those close to you, according to a new study.

Empathy is the ability to understand another person's feelings. "With familiarity, other people become part of ourselves," study author James Coan, a psychology professor at the University of Virginia, said in a university news release.

He and his colleagues used functional MRI to monitor the brain activity of 22 young adults while they, a friend or a stranger were under the threat of receiving a mild electrical shock. They saw that the same brain regions were activated when the participants were threatened with a shock or when a friend was under threat.

However, these brain regions showed little activity when a stranger was threatened with a shock, according to the study, published in the August issue of the journal Social Cognitive and Affective Neuroscience.

"The correlation between self and friend was remarkably similar," Coan said. "The finding shows the brain's remarkable capacity to model self to others; that people close to us become a part of ourselves, and that is not just metaphor or poetry, it's very real. Literally we are under threat when a friend is under threat. But not so when a stranger is under threat."

This reaction likely occurs because people need to have friends and allies they can side with and see as being the same as themselves, Coan said. And as people spend more time together, they become more similar.

"It's essentially a breakdown of self and other; our self comes to include the people we become close to," Coan explained. "If a friend is under threat, it becomes the same as if we ourselves are under threat. We can understand the pain or difficulty they may be going through in the same way we understand our own pain."

This is likely an evolutionary adaptation.

"A threat to ourselves is a threat to our resources. Threats can take things away from us. But when we develop friendships, people we can trust and rely on who in essence become we, then our resources are expanded, we gain. Your goal becomes my goal. It's a part of our survivability," Coan said.

More information

The Stanford Encyclopedia of Philosophy has more about empathy.