This makes me think: is depression a human societal defense mechanism?
Having a diversity of perspectives along an optimism scale seems optimal when faced with an external threat to your tribe/group.
Having a diversity of perspectives along an optimism scale seems optimal when faced with an external threat to your tribe/group.
There are a number of good theories on what the function of depression is. The best I've seen is that it's the brain's deep problem-solving mode for when an organism needs to hunker down and deal with hard problems it doesn't know how to solve easily. The mind slips into rumination mode and turns a problem over again and again in hopes of discovering some new insight about it and cracking it.
"In summary, compared to nondepressed indi- viduals, depressives are “nay-sayers”. Depressives may be sadder but they are not wiser; rather, so- called “depressive realism” results from the bias of depressives to say “no”"
Cell division is obviously important for organisms to function, but it can run amok - that's cancer. Similarly, pessimism is sometimes a useful approach to solving a problem, but it becomes debilitating when it's out of control.
Depression is not a "problem solving mode" or anything like that; it's a disease. Depression (the medical condition, not just pessimism or being sad sometimes) is totally and completely draining. Someone who is depressed does not have the energy to solve the problem of "should I take a shower today," let alone "hunker down and deal with hard problems."
Sorry to pick on you, I just find the comment threads on articles like this so frustratingly ignorant sometimes.
Given the existence of depression in the animal kingdom, and it's persistence in humans despite its nonadaptive qualities, this accumulation of coincidences strongly suggests that it definitely had some adaptive purpose at some point.
I always have to remind myself that evolution doesn't optimise for happiness.
Having difficulty functioning in society is not.