Depression Reduces Capacity to Learn to Actively Avoid Aversive Events

Only the system as a whole must carry superior fitness, not each of its individual components. Given a sufficiently complex system, its rather expected that there will be negative, or even outright destructive functions that arise. You can certainly try to find a positive reason for why cancer, disease, death during conception, etc exist, but there is a much simpler explanation.

Depression in this view, isn't something outright that was adaptively constructed, but merely a side effect of how the mind works.

Patience, "biding our time", "hunkering down", etc. are actual emotional states we can experience and recognize, and depression doesn't feel even remotely like for most people as far as I'm aware.

Also, this explanation would only really work if the entire group entered a dormant depressed state together. Otherwise, the non-depressed ones would capitalize the tribe's resource and everyone would still end up screwed. But depression doesn't seem to have that sort contagious social component. On the contrary, when someone is depressed, the immediate response by people around them is generally try to "cheer them up" or encourage them to exit that depressed state. And while the depressed person is likely conveying a whole lot of negative sentiment, most aren't actively attempting to get the people around them to be depressed too. That's the last thing most depressed people want.

I remember from my days studying to be an actuary that the population that can best estimate mortality odds from the gut are actually the depressed. (Most of us tend to be way too optimistic about common risks and pessimistic about uncommon ones.)

This was also used to explain mammalian postpartum depression, when the mother has to make a wretching call as to whether to keep the offspring given its health, her health and the environmental context.

My understanding is the existence of selection does not necessarily mean every trait that exists right now has an evolutionary benefit. It is more coarse grained that anything that doesn’t prevent you from breeding is acceptable. Depressed people are not made infertile by their depression, so there will be a subset of depressed people (assuming depression even has a hereditary component). This doesn’t mean the trait of depression has an advantage in order to exist, it just isn’t so much of a disadvantage that it doesn’t exist.

ChatGPT, asked to translate to a high schooler: "Basically, this study found that young people with depression sometimes struggle to break automatic habits, especially when they’re trying to avoid something bad and there isn’t a prize or reward for doing it."

Example:

Case 1: Subject tries piano sight-reading exercises, if they get less than 80% accuracy a loud annoying horn will blare. Then subject goes again and try to improve the score.

Care 2. Subject tries piano sight-reading exercises, and if they get less than 80% accuracy they get notified that they didn't succeed at the test. Then they go again and try to improve their score.

The article strongly implies depression will make improvement more difficult in case 1 by the amount found in the study. But it doesn't necessarily imply that (or anything strongly) for case 2.

Your summary strongly implies that depression impedes progress in both cases at the same rate as the outcome of the study.

I'm not a domain expert but I'm going to guess "having bad outcomes" is as poor a paraphrase of "overriding prepotent responses" here as "having functions" would be to characterize functional programming languages.

Of course that mental state would hinder learning, you're missing all the brain signals and reward feedback to care about anything.

The ability to make any mental and physical effort is greatly reduced to "depressed" levels.

It is the subconscious version of a situation where you need to climb out of a pit, but the walls are perfectly flat and oiled. Even though you need to get out of the pit, instead of scrambling, you just sit down.

The situation may not really be like that, but some deep cognitive machinery has concluded that it is.

It isn't anything like sadness. Although sadness could be part or proximate cause of a particular depressive episode, it is neither a necessary or sufficient condition.

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I do believe depression has a real purpose. To turn off motivated but misdirected behavior, and force us to perform a reset of deeply held assumptions, expectations and motivations.

Pain effectively changes our expectations and behavior in the moment. Depression is like pain for complex situations. It forces major change, by disabling our current ineffective directives and giving us "time out" to slowly rewire. Until the subconscious believes we have found a new mental path, more aligned with reality, and lets motivation flow again.

But like battle surgery, it is a blunt instrument for doing something profound, and may inflict damage as well as repair it.

And when life circumstances don't let us take the pause and rest our brain is trying to enforce, it is a bit of living hell.

This is how SSRI has felt for me also, incidentally: an even deeper apathy, setting in from lack of any emotion at all.