You've got an extra 20 or 30 years coming, the money's got to come from somewhere.

Some people believe we are on the brink of being able to extend human lifespan significantly, because we've got most of the technologies we need to do it. People are going to do things they didn't get round to in their working lives. Current institutions are really not equipped at the moment to deal with such long lives.

I have no problem thinking the 60-year-old today should be like the 50-year-old and even a 40-year-old.

We've come up with a scenario: Starting around 2010, we could see lifespan increase dramatically.

Countries like Sweden and Italy have been having this huge debate for many years over population decline. A lot of the debate is about immigration: People have been telling them they need to increase immigration in order to keep the economy going.