if we only want positive emotions why and how do people get depressed? for the same basic reason that people sometimes become overly angry or even violent the problem is that any emotions have the capacity to overwhelm us
the main reason for them being overwhelming is that once a path has been chosen which is not resulting in happiness the only response that the amygdala can generate to discourage that path is more negative emotion
unless we are able to interpret this signal correctly we are doomed to remain in a negative state until some new adequately positive input appears
since most of us do not know what negative emotions signify we are easily led into a state of continuing negative emotions
any one of the negative emotions can develop
this capacity probably springs from cave man days and because we have seldom improved our understanding of emotions over the millenia, emotions have retained the same power as ever
but now we seldom need this level of power in emotions we would be better off seeing negative emotions as warnings and taking considered action as a response but still this often doesn't happen
as long as we see emotions as ourselves as long as we take orders from emotions in the usual scenarios which are short term anger or long term depression then we only serve emotion not our own better interests
for a caveman gored by a wild boar who is in pain it might be that after his first agony he limps back to the cave and lies low and groaning at the back of the cave this low mood / affect, (which might be the earliest version of our modern day depression) might encourage clan members to bring him care, food, comfort and water.
but in our world when people withdraw and become quiet and less active the 'clan' response of helping the troubled ones may be less strong and so the low mood / affect persist. all emotions can escalate and in our society, with cues for feeling hard done by being so subtle and easily seen everywhere and the clan tendency being less tight in urban life then the possibility is for far more of this withdrawing, depressive behaviour. also our world encourages us to see ourselves as having some type of disease / affliction when depressed, (often treatable with drugs), and we are far less likely to see the problem as an old, poorly controlled neural circuit, getting out of control
to see it as an out of control primordial neural circuit,connected with survival only, gives us freedom to feel that we don't have to be dominated by it.
techniques that improve the separation of the cortex from the amygdala like meditation, can then be used to reduce that domination