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.

In the early '90s, we discovered mutations that could double the normal life span of worms.

I loved the idea that biology was logical.

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

Maybe one day we will be able to take a pill that keeps us young and healthy much longer. I believe in my heart that this will happen.

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

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.