A big tree seemed even more beautiful to me when I imagined thousands of tiny photosynthesis machines inside every leaf. So I went to MIT and worked on bacteria because that's where people knew the most about these switches, how to control the genetics.

It was like stepping on to an escalator I could do anything. I was just made for science.

Generally, older people in their fifties, sixties, and seventies are running most countries and are CEOs of corporations. Which isn't to say there aren't entrepreneurs, but if the young were better in every respect, there'd be no reason for the old. Our life span reflects our particular life strategy.

Life's too short to not be around nice people.

I eat some fruit every day, but not too much and almost no processed food. I stay away from sweets, except 80 per cent chocolate.

Carbohydrates, and especially refined ones like sugar, make you produce lots of extra insulin. I've been keeping my intake really low ever since I discovered this. I've cut out all starch such as potatoes, noodles, rice, bread and pasta.

Ageing is very exciting. But if I didn't work on ageing, I'd want to work on the brain. There are really cool techniques you can use now. And bioinformatics. The methods you can use for comparing large data sets - that's so powerful.

The idea that ageing was subject to control was completely unexpected.

If the aging process is controlled in a similar way in worms and humans, then we can use what we learn about worms to speed our study of higher organisms.

I have always gotten a thrill, a kick, from learning new things.

You could have two completely different careers if you could stay healthy to 90. How fascinating that would be.