More people die from suicide than from murder and war combined, throughout the world, every year. In the United States, suicide recently surpassed automobile accidents as the leading cause of violence-related death, according to a recent study appearing in the American Journal of Public Health.

The majority of individuals who commit suicide suffer from depression or another mood disorder. Depression is a devastating illness characterized by persistent sadness and myriad well-known symptoms. Increasingly, researchers are identifying how genes contribute to depression. As we learn more about the human genome, scientists are finding evidence that while depression seems incredibly maladaptive, it was actually adaptive (helpful) to our ancestors.

Recently Drs. Miller and Raison, physicians at Emory University and the University of Arizona respectively, authored a paper "The evolutionary significance of depression in pathogen host defense" in which they proposed that some of the alleles (forms of genes) that increase one's risk for depression also enhance immune responses to infections.

Read more at The Atlantic.