This is why for pretty much the majority of human history, we had some form of religion to trick ourselves into ignoring this. Now that religion is on a decline...
Depression is not a rational response though, is it? It's an irrational response that persists even when there is no reason to be unhappy.
That's why I give little credence to ideas like those in your link. I don't consider the worldview of depressed people to be valuable to my own life experience.
Depressive realism might be. And there is no ethical way for me to argue for that.
My link is also not arguing for being depressed. Once you are here, by all means make the best of it. But to give you all a flashback to sex ed, do the right thing and use a condom.
Sure it is. "Depression" might just be our perception of the biological phenomenon where an individual decides to spare the group's resources and thereby increasing the chances of the group. First by becoming tired (saving resources, biding time), cutting off contacts, and finally disappearing if nothing changes in the environment.
Self-sacrifice occurs in animals too. From what I've seen, it isn't controversial.
> It's an irrational response that persists even when there is no reason to be unhappy.
What if there is?
Generally, we are not very good at judging what makes us happy. Happiness research points to things that many of us are indeed missing in life: physical activity, social connectedness, interacting with nature.
The reason for unhappiness might also be internal; bad diet, lack of exercise, etc. throws your body's hormones off-balance, making you feel like crap and causing, quite predictably, unhappiness.
Let's not conflate unhappiness with depression. Many a depressed person who has tried can tell you that exercise, social contact, and immaculate diet do not cure depression.
They can certainly help a bit sometimes, just like not punching yourself in the face every day while you have a broken leg helps with the pain and makes recovery go more smoothly. But it is not a solution to the underlying problems in many cases.
These things are important to everyone's wellbeing, but there are many, many people who eat like crap and don't exercise who are not clinically depressed. And there are plenty of people living with depression despite being disciplined in these important lifestyle choices.