Thanks for the great response!

Yes, that was the point I was trying to convey; we are living in a modern world with somewhat primitive brains, designed to navigate environments that are quite distinct from the cities and societies we live in.

Its hard to completely tease these things apart, but it does seem clear that our ancestors never experienced the stress-inducing stimuli that many of us face everyday. I am usually one to be sympathetic to the "a little bit of both" argument. With all of these novel stimuli comes novel adaptation and psychological conceptualization!

Be sure to check out the posts that this one builds on if your interested in delving further into this line of thought!
Is Your Brain Too Excited?! Neurodegeneration By Over-Stimulation
Manipulating Memories: Instantly Eliminate a Fear