It's a moral question about whether we have the right to exterminate species.

The notion of ever more old people needing ever more young people, who will in turn grow old and need even more young people, and so on ad infinitum, is an obvious ecological Ponzi scheme.

In the West, that's what's happening. The birth rate has been dropping steadily and still is. But there is still a vast amount of the world where that's not the case. And that is where the big population growth is taking place.

It is that range of biodiversity that we must care for - the whole thing - rather than just one or two stars.

I just wish the world was twice as big and half of it was still unexplored.

Apart from anything else, I am designed by evolution, like we all are: if we see a little thing like that, big eyes, tiny nose, we go 'aaah'. That's what evolution does. We are programmed to do that. So to find babies the most amazing, isn't surprising, I don't think.

I suppose happiness is something one enjoys, but I suspect that happiness is not a state but rather a transition.