The United States has long thought of itself as the land of infinite plenty, and historically we did have abundant resources. But now we are gradually exhausting our fisheries, our topsoil, our water. On top of that, we're coming to the end of world resources.

Much of human history has consisted of unequal conflicts between the haves and the have-nots.

Recent discoveries about apes suggest, however, that a gorilla or common chimp stands at least as good a chance being murdered as the average human.

No government is here forever. And there are other forces - the most potent force in our society, in fact, big business - doing good for the environment.

In much of the rest of the world, rich people live in gated communities and drink bottled water. That's increasingly the case in Los Angeles where I come from. So that wealthy people in much of the world are insulated from the consequences of their actions.

To dismiss the current extinction wave on the grounds that extinctions are normal events is like ignoring a genocidal massacre on the grounds that every human is bound to die at some time anyway.

The southward advance of native African farmers with Central African crops halted in Natal, beyond which Central African crops couldn't grow - with enormous consequences for the recent history of South Africa.