What killed humankind isn’t something that can be touched or heard or seen, but it has to be imagined. It’s hard to recall the days when the buildings weren’t crumbling to dust, and the containment vessels held back their evil. The path to the earth’s demise should have been clear to its residences, but greed has a way of blinding eyes. All the advancements in science couldn’t save them, and it would be difficult to save the people from something they wanted so much. They became accustomed to consuming the cheapest from of energy put in front of them, even though better ways had already been discovered. The civilized proceeded in a way that was unsustainable.