Back to Abbey:

"A world without huge regions of total wilderness would be a cage; a world without lions and tigers adn vultures and snakes and elk and bison would be -- will be -- a human zoo. A high-tech slum."

  What exactly does that mean? Well I think he is saying unless we have the chance to take our place back in the wilderness, we will place ourselves in the equivalent of a human zoo. A zoo is the antithesis of wilderness. It is a totally artificial visual representation of something that may once have been but has since been made functionless. Zoo animals cannot interact as they should.

  So in this human zoo, we too cannot interact as we should. We evolved in the "wilderness" and I think coded somewhere in our DNA (or possibly in our micochondrial RNA, never can be sure) is an immutable need to be part of that wilderness even in small ways. E.O. Wilson calls it "biophilia", but I think it goes a bit beyond that. We need to be scared. We need to have the shit scared out of us. We need sometimes to be in a place where we are what all animals are: sometimes predator, sometimes prey. It's the very real possibility that you could be some cougars's dinner that makes us alive. That's not to suggest we should dangerously risk our lives, that's to say we should experience those wild places and let ourselves be scared to remind us what to be human truly is.