Poets have long waxed lyrical about the pain of a broken heart. Now, as Panksepp explains in his Perspective, this metaphor may reflect real events in the mammalian brain. A new brain neuroimaging study (Eisenberger et al.) reveals that the brain areas that are activated during the distress caused by social exclusion are also those activated during physical pain. Thus, we now have an explanation for the feeling of physical pain that accompanies emotional loss-whether that be the loss of a loved one, rejection by one's social group, or the distress of separation experienced by young animals.