You're an animal that needs to move across the landscape, you can't anymore, and that's another way we're just changing the surface of the Earth in very dramatic ways.

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.

We can't say that when x happens we get a mass extinction. To the extent we understand mass extinction, one has been caused by glaciation event, one has been caused by a massive climate change, and one has been caused by an asteroid. These events turn out to have no precedent.

There's this idea of shifting baselines. It was coined by a guy named Jeremy Jackson. It's the idea that every generation takes what it sees, and says, "Okay, well, that's the norm."

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.

Well in the scientific there is virtually no debate over certain things. For example, that we are changing the world. Humans are changing the world very radically, very dramatically. Climate change, which I assume is one of the points you're alluding to, is at the heart of this.

Mitochondrial DNA, which is a sort of abridged version of DNA, is passed directly from mother to child, so it's something that can be looked at to trace matrilineal descent.