At what point in human evolution was depression seen as a useful trait that it still exists?

Well, I’m pretty sure depression was never really meant to be a “useful” trait – it’s more like a glitch in the system, like when your phone autocorrects “I’m fine” to “I’m dorky” for no apparent reason. But who knows, maybe there was some evolutionary advantage to feeling like a sad sack all the time – like maybe it made our ancestors more likely to stay in their caves and binge-watch Netflix instead of, you know, getting eaten by a saber-toothed tiger. Either way, I think we can all agree that depression is about as useful as a screen door on a submarine.

TLDR: Depression: a glitch in the system, about as useful as a screen door on a submarine.