The idea that clinical depression was evolutionarily selected for is why many real evolutionary biologists laugh at something like this as a classical "Just So Story."
It's caveated, has little real explanatory power, doesn't allow for alternative explanations, doesn't well explain away counterexamples and is generally weak.
Beyond that, Andy Thomson and Paul Andrews undercut their own theory, and at a grade-school level.
In response to criticism, they admit that, in essence, "We don't know what depression is."
Well, if you don't know what a trait is, how can you even claim it's selected for, in the first place? You've just said you don't know what it is, so you don't know what is being selected for.
And, of course, given the present (but growing) state of cognitive science and neuroscience, this is the case about ev psych, or rather, Pop Ev Psych, claims about just about any mental or emotional state.
Also, the end-of-story study said people focused only when **DISTRACTED** from their depressive thinking. Doesn't that hugely undercut the adaptationist idea?
Meanwhile, on his blog, Jonah Lerner, the author of the NYT Mag story, actually defends the general line of thinking of Thomson/Andrews, though in the story, he was good enough to marshal plenty of opponents of their claims.
More thoughts for Jonah:
Few more comments:
1. Jonah, when you caveat your own lede with "may," shouldn't you be a bit less bold in your claims?
2. Related to that, I had expected you to be less credulous here than in the "balanced" story, and not more so. Pop Ev Psych of the Thomson/Andrews nature doesn't even look at epigenetics on mental states issues, it would seem. We know that with things such as anxiety, the brain can literally be "reset," in a sense. Ditto, it would seem, with depression. And, with no adaptationist benefit, it would seem.
3. Self-loathing does not necessarily induce depression. Nor is it necessarily part of depression. I know one can self-loathe without being depressed, and think that to some degree the opposite is true, too. Kind of a false Zen diagram.
4. Lerner, as well as Thomson/Andrews, also has another "whiff," or semi-whiff, at least. Rumination, or a certain level of rumination, to the best of my knowledge, has never been causally correlated with depression. It seems like a pretty facile assumption was made here.