Living longer better
Every year, the number of elderly people increases in both developed and developing countries, thanks to modern medicine's genius for pushing back the frontiers of death. But is longevity necessarily a good thing?
In California, fitness is taken to extremes. There are shops in image-obsessed Beverly Hills packed with pills and potions to extend life. In Santa Monica there are so many fitness boot camps and yoga sessions taking place in public parks that local officials are considering a clampdown.
"In California you see people exercising at 05:15 and it's either great for them or it is part of a really neurotic psychosis where they're desperately unhappy because they're getting older," says Ed Saxon, who produced the film Fast Food Nation in 2006.
"The 55-year-old imagining that they look like a 25-year-old and getting surgery or fanatically exercising to do so - it all strikes me as a bad idea.
"The obsession with looking younger than you are means you are denying reality and you are probably denying your own value in some way."
Alongside the craze for fitness goes the ever-changing advice on what to eat to stay young. Should I have blueberries, a kale smoothie, or gluten-free toast for breakfast? And is red wine good for me or not? And what about chocolate?
It can be bewildering, but the goal is clear - death must be delayed as long as possible.
"In the US it's almost taken for granted that longevity is a good thing," says Susan Jacoby, the author of Never Say Die.
"A lot of this irrational belief that there are things that you can do to buy insurance against getting older and diseased has to do with our real dislike, in America, of growing older."
Jacoby, who is 67, argues against the "lifestyle garbage" and "supplement garbage" that she says the age-management business is promoting.
"If you look beneath the people who are telling you that you can live to be a healthy 120, there's a guy or a woman who's selling something," she adds.
The fact is, most people who live into their 90s die after "an extended period of disability", Jacoby argues
"We're just accepting this myth that because we're healthier than ever at 67, it is going to be the case at 87 or 97. But what is true - thanks to some of the dubious advances of modern medicine, which keep people alive no matter what - is that there is going to have to be more thought about taking care of these people."
This challenge for policymakers has a corollary for every one of us. Do we want to live longer, if that means a longer period of age-related illness?
In 1980, James Fries, a professor of medicine at Stanford University outlined a vision in The New England Journal of Medicine of a society where chronic illness could be postponed and shortened. In this society, people would live a full healthy life and then die relatively quickly, decreasing the total amount of lifetime disability.
Fries called this "compressed morbidity" and his work has been credited with moulding the modern paradigm for healthy ageing.
The trouble is that it's easier to advise patients how to lengthen their healthy lives, than how to shorten any period of declining health.
Joseph and Anne Gias are a healthy couple in their 60s, but they worry about the ravages of old age.
"I don't want to live past 80," says Anne. "I think that between the ages of 80 and 85, people deteriorate a lot. I've seen a lot of mental deterioration in that age group and I don't want that for myself."
Despite Anne Gias's fears there are examples of very long healthy lives.
When Besse Cooper died last December, at 116, she was the world's oldest living person.
According to reports she was in "amazing" health and never complained of being in pain.
She lived an active life and refused to eat junk food.
On her last day, she had a large breakfast, had her hair set and enjoyed watching a Christmas video with friends.
She died peacefully in the early afternoon after suffering from breathing problems.
Ms Cooper is a rare but fine example of compressed morbidity - a long, healthy life and a good death.
You can find out more about What if the BBC's special series looking at aspects of the future, throughout February and March