A new study on the human brain suggests that we are hardwired to feel empathy for those close to us.

Researchers from the University of Virginia conducted functional magnetic resonance imaging (fMRI) brain scans on 22 young adults who in a series of experiments were presented with the threat of an electric shock. Seeing heightened activity in the regions of the brain associated with threat response -- the anterior insula, putamen and supramarginal gyrus -- was, of course, no surprise when an individual was threatened with being shocked themselves.

Also as expected, the researchers found that when a threat of shock was presented to a stranger, the brain activity in the fMRI patients' threat response regions displayed little activity.

But when the patients' friends were threatened with electric shock, the brain activity of the test subjects became essentially identical to the activity displayed under threat to the self.

"With familiarity, other people become part of ourselves," said James Coan, a psychology professor in U.Va.'s College of Arts & Sciences. "Our self comes to include the people we feel close to."

Coan said the correlation between self and friend was "remarkably similar."

"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."

As an explanation for the test results, Coan suggests that humans need to have friends and allies who they can side with and think of the same as themselves. Another way of thinking about it, he said, is that one hand needs another to clap.

"It's essentially a breakdown of self and other; our self comes to include the people we become close to," Coan said. "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."

Coan continues: "A threat to ourselves is a threat to our resources," he said. "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 and his colleagues research is published in the journal Social Cognitive and Affective Neuroscience.