For generations, we have seen depression as an illness, an unnecessary deviation from normal functioning. It’s an idea that makes sense because depression causes suffering and even death. But what if we’ve got it all wrong? What if depression is not an aberration at all, but an important part of our biological defense system? More and more researchers across specialties are questioning our current definitions of depression. Biological anthropologists have argued that depression is an adaptive response to adversity and not a mental disorder. In October, the British Psychological Society published a new report on depression, stating that “depression is best thought of as an experience, or set of experiences, rather than as a disease.” And neuroscientists are focusing on the role of the autonomic nervous system (ANS) in depression. According to the Polyvagal Theory of the ANS, depression is part of a biological defense strategy meant to help us survive.