Jonathan Rottenberg

And once you have that capacity for low mood, you have the capacity for more serious, more severe, more long lasting low mood.

And so that is a very important adaptation.

Mood is what is integrating all of the inputs, both inside of your body and outside in your environment.

And mood is the thing that's asking the question, what should I do next?

Is this environment that I'm in good for action or is it bad for action?

And so low moods are unpleasant just as pain is unpleasant.

Anxiety is unpleasant, but I think it's easier for people to see that pain is an evolved mechanism that allows us to protect our body from physical damage, and anxiety is a mechanism that allows us to avoid pain.

threats, but what is the purpose of mood?

It's harder for people to see that mood itself could have a purpose, but it actually is sharing a great amount of similarity with anxiety, with pain, and with other mechanisms like fever that are protecting us.

It's telling us, should we proceed or should we stop?

So if you think at the most basic level of a little foraging animal where it's reached a patch of grass where there are no leaves of grass to eat, and everywhere it looks there's no leaves of grass to eat, should the organism keep moving or should the organism stop?

Writ large, imagine there's a famine and there's no food available.

Mood is a stop mechanism.

And when we come to humans, the situations that can prompt low mood become much more complicated than threats to your physical well-being.

They involve also your future prospects for survival and reproduction.

You experience low mood when there is a dilemma and it is uncertain whether or not you should proceed or whether you should stop.

And low mood forces you to think about the situation differently

maybe longer than you would like.

But without it, we would subject ourselves to harm and we would be moving forward rashly.

I mean, think about what happens after someone dies.