Letting things slide is always the easiest thing to do, in parenting no less than in banking, public education, and environmental protection. A lack of discipline is apparent these days in just about every aspect of American society. Why? This should be is a much larger question, one to ponder as we take out the garbage and tie our kids' shoes.

You've got to do everything, everything's got to be pointing in the same direction and you've got to really turn this whole economic engine from one that's based on fossil fuels to one that isn't.

I don't think there are too many places left that humans haven't pretty thoroughly explored.

[On the birther movement:] Here we are, quadrillions of bytes deep into the Information Age. And yet information, it seems, has never mattered less.

Some of these species that are now no longer with us were killed off by a fungal disease that was moved around the planet by people.

Humans will eventually become extinct. People treat that as a radical thing to say. But the fossil record shows us that everything eventually becomes extinct. It depends what "eventually" means. But the idea that were going to be around for the rest of global history...I don't think there's any scientist who would suggest that is true. It could be millions of years from now. We may leave descendants that are humanlike.

The Earth is big. There are huge natural forces that have worked over geological time. But it turns out, when you look carefully at the geological time, you can't find anything like us.