KEY POINTS:
Not a month goes by, it seems, without another wave of panic sweeping the world spreading gloom about the latest killer.
We are doomed - if obesity doesn't kill us soon, the latest strain of some hitherto unknown disease (remember bird flu?) will.
And yet, in spite of ourselves, we are living longer. Figures released by Statistics New Zealand this week show that, on average, a girl born between 2005 and 2007 will live 82.2 years - just over one year longer than a girl born between 2000 and 2002.
For boys, the news is even better. A boy born between 2005 and 2007 will live to 78, about 1.7 years longer than one born between 2000 and 2002. Why? We consulted the experts:
What factors are behind improving life expectancy? According to Dr Mark Jacobs, the Health Ministry's director of public health, the biggest gains have come from the reduction in deaths from cardiovascular diseases.
Thank better detection and treatment of high cholesterol and high blood pressure, but the single biggest impact is the reduction in smoking rates.
The less people smoke, the lower the death rate from strokes, heart attacks and respiratory diseases, let alone cancer. "We're also getting better and better at treating cancers, but it also comes back to the risk factors," said Dr Jacobs.
Health Information Service figures show the death rate from all cancers has fallen from 140 in 100,000 people in 1996 to about 120 in 100,000 in 2004.
Why have older men seen the biggest improvement? Over the past five years, the group which contributed most to the improvement in average life expectancy was men aged 60 to 79 years. Dr Jacobs says that was mainly thanks to the reduction in smoking rates.
Martin Connolly, the Freemasons' professor of geriatric medicine at Auckland University, said another factor was there was less "ageism" in healthcare.
"Twenty years ago if you were 66 and you had an MI [heart attack], you didn't get admitted to the coronary care unit," said Professor Connolly. "Nowadays, that is very, very much less true."
That change has come about from improvements in care and health resources, but also because people will demand treatment more often.
"Today's 75-year-old is much less likely to accept 'no, you can't go to a coronary care unit'."
Professor Connolly said the chances of surviving a heart attack were dramatically better.
"When I was a junior doctor, you admitted them to coronary care if they were lucky, gave them oxygen, pain-killers, and that was about it."
But it's not just older men doing better, is it? In our history, some of the greatest gains have come about because of improvements in neo-natal and obstetrics care.
"Changes early on make a bigger difference to average life expectancy than changes made later on," said Professor Connolly.
"If you save a baby's life and that baby lives to 30, you've gained 30 years. But if you save a 75-year-old's life and he lives to 85, you've gained 10 years."
A 2006 report by Statistics NZ examining historic trends points out that improvements in hygiene from the late 1800s led to less diarrhoea and enteritis, major causes of death among infants.
So there is a pattern of improvement? Professor Connolly said that between about 1600 and 1850, average life expectancy was about 40. From 1850, the trend began swinging upwards.
"From 1850 to now, for every 10 years of chronological time that has elapsed for the Western world, average life expectancy has increased by two years. For every 10 days you live, you get an extra weekend."
He credits this improvement as mankind's greatest achievement.
What about the obesity epidemic?
Obesity began climbing in the early 1990s, Dr Jacobs said. It is too soon to say we have turned the corner, but he believes there are signs the rate could be about to start declining.
Although the effects of obesity-related diseases are already being felt in the health system, he does not believe the impact will be big enough to counter the gains in other areas.
LIMIT COULD BE 130 YEARS
What is the limit of human life expectancy? It's a guess, but Professor Martin Connolly believes it could be 130. "More and more of us in a couple of hundred years are going to be getting to that," says the Auckland University gerontologist. "Ninety is going to be today's 70."
The next biggest advance contributing to improved life expectancy, he believes, could be in genetics - identifying and treating people with genetic pre-dispositions to certain diseases. "If we continue making advances in terms of genetic research, I'm reasonably confident we'll see inroads in 30 years."
