[BizarroLand]

It might also be that Autistic traits would be a good solo or small tribe survival adaptation.

Highly logical, no breaking down in a fit of misery, less susceptible to loneliness, very useful for times when you're stuck in a survival situation.

[labster]

I doubt autism correlates that strongly with resilience and grit. But I have long thought that groups benefit from having a portion of the population having autism. Variance in thinking means more potential strategies for success. Too much variance probably hurts group cohesion.

[PeterisP]

IMHO the most effective adaptation for "solo or small tribe survival" that we and other primates have is all the factors that decrease one's chances of being put in the very disadvantageous solo or tiny tribe situation. (For example, various submissive behaviors and the quite interesting concept of crying seem to be adaptations towards that - continuing to live in a larger tribe instead of leaving) It's simpler and more effective to try and avoid or fix that problem in the first place, instead of trying to optimize for tolerating the problem.