What is natural about fear and delusion?

I didn't mention these, but "fear" is naturally a "survival mechanism" (re adrenalin/flight or fight).

"Delusion" involves psychological investment in a mythical "objective reality" beyond that which we all use for everyday transactions. Such "objectivity" is based on "persistances" with respect to our life spans but these "persistances" are naturally but erroneously extrapolated to non-relative (dualistic) scenarios in which "things" are considered to exist independently of the observers who do the "thinging". (Those naive realists who advocate the "existence" of "unobserved trees falling in forests" are forgetting that they themselves are still doing the observing "in their mind's eye").