>>> Cynicism is fundamentally about self-defense from future pain.

I agree with this. In my experience, the highest proportion of cynics was among medics. These people deal with life-or-death situations on everyday basis, and their cynicism seems to be a way of anaesthetising their own mirror neurons, which otherwise would cause them too much pain.

As for the relationship of evolutionary psychology and cynicism, my own experience was quite interesting. The moment I understood evolution at the gut level, the moment I saw life as a purely physical phenomenon, my cynicism towards humanity just disappeared completely. How can one be cynical about rain, wind or gravity?

(It's been a while since that moment, and now cynicism started to surface again, from time to time. Maintaining the True Sight does require effort.)