You might not guess it from all the wars that pockmark the planet, but neurobiologists Jean Decety and Perrine Ruby of Inserm, the French Institute of Health and Medical Research in Lyons, say humans have an empathy instinct hardwired into the brain.
Decety and Ruby asked 10 young male subjects to imagine everyday acts, such as peeling a banana, while lying in a PET scanner. Then the participants were told to think about somebody else performing the same task. In both cases, the area of the brain that directs voluntary muscle control lit up. But the latter test also excited the parietal cortex in the right hemisphere, the area that enables us to distinguish ourselves from others. The discovery suggests we understand another's behavior by imagining him or her carrying out an action and then mentally projecting ourselves into that situation. "Evolution has shaped our minds not only to express emotion but also to empathize with others," Decety says. "But aggression is also part of human nature. We have to find a balance between our instincts and the way we express them."