Depression and mania as its counterpart are states of the psyche out of emotional balance. Those are emotional struggles which need to be overcome by their bear

Depression and mania as its counterpart are states of the psyche out of emotional balance. Those are emotional struggles which need to be overcome by their bearers. Clinical depression based on endocrine imbalances does count as well, as it has the same impact as temporal depression. Sometimes the struggles are so hard that at times it may seem easier just to give up. If you just let those states continue to persist without any countermeasures you'll never learn how to deal with them as they continue to wreak havoc to your perceptive and reflective cognitive abilities, which work best in emotional equilibrium by the way. So, basically saying that depression in itself might have some evolutionary purpose seems a bit far fetched.