Hello @saho :)

Thank you for writing about this topic!

I was particularly interested in the part you highlighted the evolutionary significance of depression, which, I would prefer to word it as the evolutionary significance of low-mood.

Of course, while it is quite obvious for one to understand how fear has helped us to survive as a species (fight or flight response), the benefits of having low-moods such as sadness are not that clear. Still, it has been suggested that they yield adaptive functions. For instance, they often cause people to reconsider failed plans and even problems.

I was also glad to see you talking about posture and expressions, as a result of low-mood. From an evolutionary perspective this has been seen to be useful in non-human animals - rhesus macaques - whose submissive posture is thought to be an evolved adaptive strategy to being defeated :)

I find it truly interesting. But, I am not going to take any more of your time. I will stop here :D

All the best @saho!