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.

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.

For a long time, science has gone in the direction of sort of putting people in their place. We learned that the sun doesn't revolve around the Earth, the Earth revolves around the sun; we learned that we're just another species, evolved, like all other species, so we're just another animal, really.

Even very smart people can try to shoehorn new information that just doesn't fit into an existing paradigm.For a long time the story that we've been telling ourselves is that humans are just another animal. We evolved from other animals and our place in the universe isn't particularly special. What I'm trying to convey in my book [The Sixth Extinction] is that we are unusual.

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.

Though it might be nice to imagine there once was a time when man lived in harmony with nature, it’s not clear that he ever really did.

As best as can be determined, the world is now warmer than it has been at any point in the last two millennia, and, if current trends continue, by the end of the century it will likely be hotter than at any point in the last two million years.