Elephants and lions used to roam the Great Plains, and some scientists would like to put them back. But can we really hope to restore the world to its "original" state?
Our public lands have never been more crowded. As millions of us flock to the mountains and the deserts to revel in their wild beauty and restore our jaded spirits, perhaps it's time to ask: are we helping or hurting?
Even sober energy experts wonder if Alberta has gone mad as the province tears up a vast wilderness to get at the world's dirtiest, most expensive -- and perhaps last -- reserves of oil.