If I can bicycle, I bicycle.

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.

An understanding of the natural world and what's in it is a source of not only a great curiosity but great fulfillment...

The correct scientific response to something that is not understood must always be to look harder for the explanation, not give up and assume a supernatural cause.

Very few species have survived unchanged. There's one called lingula, which is a little shellfish, a little brachiopod about the size of my fingernail, that has survived for 500 million years, but it's survived by being unobtrusive and doing nothing, and you can't accuse human beings of that.

Fundamentally not to waste energy. If we were all to reduce our demands for energy, it would make an enormous amount of difference.

Before the BBC, I joined the Navy in order to travel.