I figure we were put here by some intergalactic space traveling superior species of Aliens for their return trip home. Much like we use livestock or bees, they left us here to gather resources into concentrated areas making it much easier to stock up on supplies.
Luckily, I live in a small town not worth the effort to "harvest" so we'll be left here as seed stock for future trips, unlike all you big city types who'll get "processed" along with all the metals and other supplies they might need.
I have as much 100% scientifically proven evidence to support my theory as the other guys do
Murray