somehow I doubt that someone with depression/bipolar disorder would be the best candidate to be a warrior
If they've even lived long enough, no absolutely not. Unless you think someone who is routinely depressed is 'vigilant'.
[Hypo]mania is not the primary state of a bipolar patient. Can't speak to schizophrenia, but for those I've seen with that illness, functioning isn't their primary state, either.
Thinking mania can be controlled like an on-off switch.
Why even bother posting?
And someone who experiences mania indicates an uncontrolled illness. Depression and mania prevent normal functioning. You seem to believe an unmedicated bipolar individual is a functional individual with some inkling of rational thought that could 'go into battle with no fear'.
If you don't know, don't post. And you don't know.
I don't know where you are getting the notion that I am saying that mania is rational or controllable. I was speculating based on personal experience around high stress situations. I do not understand why you are choosing to attack the notion that there could be evolutionarily advantageous benefits conferred upon the group.
Edit: we agree that I am speculating. I disagree with you that I have no right to speculate