They live in the world of "do"...they simply move about doing the next thing without a bit of thought about why they are doing it. Their behavior is almost completely habitual.
Of course, this doesn't apply to us Freepers.;-)
As an aside, I think almost all humans have fine brains...it's just that they don't use them.
I think of all the people who have said out loud : Buddy, I’m just trying to make it through the week to Friday (with no time to ponder beyond the immediate issue and moment).
Then I extrapolate to all the further people who don’t say these things out loud but are thinking and acting them nonetheless. Then I start to feel frightened for the coming of A.I. to “help” us live better.