A new book reveals our lives continue to stretch ever longer. And, as Shane Gilchrist discovers, the end is not in sight yet.
For the past century, life expectancy in New Zealand has risen between two and two and a-half years per decade. If that rate of increase continues, life expectancy by 2100 will be 100 or more.
According to the authors of a new book, The Healthy Country?: A History of Life & Death in New Zealand, we are not even close to reaching the biological limits on longevity.''
There must be a limit. We just don't know where,'' says Tony Blakely who, with co-author Alistair Woodward, combines biological explanations for ageing with a statistical analysis of how changes in lifestyles and living conditions may affect population health.
"At the risk of making the same mistake that every other expert group has made in the last 60 or 70 years, I'd say it has to stop somewhere.
"If we just look at the simple fact that cells in your body keep dividing, at some point there will be a mutation. Sometimes these lead to cancer. Thinking it through logically, there must be a basal level of cancer that could kill us one day,'' Blakely says.
"The other thing is human beings are risk-takers so there will always be some level of accidental death.''
Statistics New Zealand figures (as of 2011) show non-Maori females (83.7 years) have the highest average life expectancy, followed by non-Maori males (80.2); in comparison, Maori females' lifespan was 76.5 and Maori males' 72.8.
Reading only non-Maori male figures over the decades provides a single, yet clear, sign of a pulse that has been growing stronger: in 1876, average life expectancy was 51.99; figures every second decade since read: 1886 (54.0), 1906 (58.8), 1926 (63.7), 1946 (66.7), 1966 (68.67), 1986 (71.38), 2006 (79.00)
''Between 1900 and 1960 there wasn't too much difference in how long people lived, but now it is going up steadily,'' Blakely says.
"People are living much longer beyond the age of 65. One obvious question that arises is: what does that mean in regards the age of entitlement to superannuation?''
In 2010, in 41 countries, a woman who reached the age of 40 was still short of half the national life expectancy. Worldwide, the long-term improvement in life expectancy at birth shows no sign of slowing down.
As Blakely and Woodward note, that's not true everywhere: in Russia male life expectancy has stumbled downhill since 1965; in South Africa HIV/Aids reduced life expectancy by 10 years in two decades.
Yet these are exceptions rather than the general rule, Blakely describing the rate of change in life expectancy as ''one of the greatest achievements of the 20th century''.
Blakely, professor of public health at the University of Otago (Wellington), says collating and dissecting the myriad data that underpins The Healthy Country? has been something of a voyage of discovery.
"We are epidemiologists, public health people and we often asked ourselves what would be interesting to include in the book. In the end it was as simple as including everything that interested us. Coming from public health, we are particularly interested in the big-picture view, in what is happening to whole populations.''
The idea for The Healthy Country? stemmed from a brief meeting, when Woodward showed Blakely a graph on life expectancy over the past 150 to 200 years; on it were overlaid reports from expert working groups at various times, all of whom pronounced life expectancy must stop increasing.
''They were all wrong. It just keeps going up and it shows no sign of slowing down.''
The Healthy Country? asks some big questions: does good health result from economic progress, or is it a cause? Are populations with a relatively even distribution of resources healthier than those with greater inequalities in living standards? And, what is the relative importance of factors such as medical treatments, education, public health services and ''good genes''?
The implications of our life expectancy increasing are also examined in detail. If, as The Healthy Country? shows, it is clear humans have the capacity to influence their own lifespans through technological and scientific advances, social policy, welfare and medical care, should we strive to further increase our time on Earth?
It's an important question, because long life does require trade-offs.
Those living in the 20th century benefited from the products of the Industrial Revolution: life expectancy doubled, globally, in a hundred years, in parallel with increases in consumption of natural resources and production of material goods (although The Healthy Country? notes that very high levels of consumption are not absolutely necessary for low mortality).
The point is: can open-ended consumption be sustained? And if not, what are the consequences for future generations?
''Climate change is the big existential threat here,'' Blakely says.
''For example, the effect on food systems of significant increases in temperature will have an effect on life expectancy.''
Existential threats notwithstanding, Blakely and Woodward are unafraid to suggest ''a fully fledged research assault'' on the biological process of ageing is needed and, significantly, translating such knowledge to ''population-level interventions''.''
Presumably some as yet undiscovered neurochemical modulator or inhibitor, or perhaps a cocktail of known compounds, could be administered en masse to the population to slow ageing,'' the authors write.
In short, a magic pill, an approximation of the fountain of youth?
''So expressed, it sounds fanciful,'' they concede.
''We believe such interventions probably are unrealistic, at least for the next few decades.''
Here's another question: if science has a means of providing someone with a longer (and, importantly, relatively good standard of) life, would it be unethical to deny that?
Blakely: ''Phew, that's a big one.''
''There are still going to have to be resources allocated for them to achieve that.
''Imagine there was a process by which a person could take drugs that slow the ageing process. You'd simply confront a drug-rationing problem, which is similar to issues now faced by agencies such as Pharmac.
''What we are trying to suggest is that it is probably time to sit back a bit and ponder the social goals we should have.''
The story of life expectancy in New Zealand is a fascinating one.
Over the course of our history, the major causes of improvement in lifespan have varied from one period to another.
Diet (adequate caloric intake), standard of living and family size had the greatest effects in the 19th century; organised public health programmes and regulations and improved socio-economic conditions contributed in the first half of the 20th century; and reductions in smoking, better diets and life-saving treatments (such as cardiovascular procedures) added to the gains in the latter half of the 20th century.
''Life expectancy has a huge number of potential determinants. But what determines an increase in life expectancy can vary with time,'' Blakely says.
''For example, New Zealand non-Maori had the highest recorded life expectancy in the world from about 1870 to 1940 - and that was, we believe, because of good protein consumption.
''We were living off the sheep's back, eating mutton, as well as dairy products. And that helped kids and adults be more resilient to infectious disease, which in those times had a major effect on life expectancy.
''But fast-forward to 1970 and a high-meat, high-fat diet was not good for increases in life expectancy because of heart disease.
''I've just raised that as one example. There are heaps of things that contribute to increases (or decreases) in life expectancy.''
Blakely says another interesting point is that up until World War 2 the contribution of healthcare services - essentially going to the doctor or hospital - probably made little difference to life expectancy.
''But that has changed, particularly since 1970. The classic example is a massive fall of 80% to 90% in cardiovascular mortality. About half of that is due to better treatment.''
Blakely points out while non-Maori had one of the highest life expectancies in the world, from 1870-1940, that came at the expense of Maori, largely because of a transfer of resources.
Lower living conditions and poorer food sources were key factors, as was disease, Old World infections such as measles, influenza and pertussis causing many deaths among Maori, whose mortality rates peaked in the late 1800s (in 1891, the average life expectancy for Maori males was 25.3 and females 22.5).
However, this was followed by a dramatic recovery. Life expectancy rose by 20-25 years in the first half of the 20th century, and the gap between Maori and non-Maori was almost halved. As non-Maori life expectancy increased by two years every decade in the last century, Maori life expectancy increased by three to four years every decade on average. As of 2011, it stood at 72.80 for Maori males and 76.50 for Maori females.
''If you scan back at the past 150 years, there is a steady closing of the life expectancy gap between Maori and non-Maori,'' Blakely says.''
It hasn't just happened by chance; there have been deliberate social policies that have helped. And it's conceivable there may be no differences between Maori and non-Maori by 2040, but that will only happen through ongoing policies such as tobacco eradication.''
For the past century, life expectancy in New Zealand has risen between two and two and a-half years per decade. If that rate of increase continues, life expectancy by 2100 will be 100 or more.
According to the authors of a new book, The Healthy Country?: A History of Life & Death in New Zealand, we are not even close to reaching the biological limits on longevity.''
There must be a limit. We just don't know where,'' says Tony Blakely who, with co-author Alistair Woodward, combines biological explanations for ageing with a statistical analysis of how changes in lifestyles and living conditions may affect population health.
"At the risk of making the same mistake that every other expert group has made in the last 60 or 70 years, I'd say it has to stop somewhere.
"If we just look at the simple fact that cells in your body keep dividing, at some point there will be a mutation. Sometimes these lead to cancer. Thinking it through logically, there must be a basal level of cancer that could kill us one day,'' Blakely says.
"The other thing is human beings are risk-takers so there will always be some level of accidental death.''
Statistics New Zealand figures (as of 2011) show non-Maori females (83.7 years) have the highest average life expectancy, followed by non-Maori males (80.2); in comparison, Maori females' lifespan was 76.5 and Maori males' 72.8.
Reading only non-Maori male figures over the decades provides a single, yet clear, sign of a pulse that has been growing stronger: in 1876, average life expectancy was 51.99; figures every second decade since read: 1886 (54.0), 1906 (58.8), 1926 (63.7), 1946 (66.7), 1966 (68.67), 1986 (71.38), 2006 (79.00)
''Between 1900 and 1960 there wasn't too much difference in how long people lived, but now it is going up steadily,'' Blakely says.
"People are living much longer beyond the age of 65. One obvious question that arises is: what does that mean in regards the age of entitlement to superannuation?''
In 2010, in 41 countries, a woman who reached the age of 40 was still short of half the national life expectancy. Worldwide, the long-term improvement in life expectancy at birth shows no sign of slowing down.
As Blakely and Woodward note, that's not true everywhere: in Russia male life expectancy has stumbled downhill since 1965; in South Africa HIV/Aids reduced life expectancy by 10 years in two decades.
Yet these are exceptions rather than the general rule, Blakely describing the rate of change in life expectancy as ''one of the greatest achievements of the 20th century''.
Blakely, professor of public health at the University of Otago (Wellington), says collating and dissecting the myriad data that underpins The Healthy Country? has been something of a voyage of discovery.
"We are epidemiologists, public health people and we often asked ourselves what would be interesting to include in the book. In the end it was as simple as including everything that interested us. Coming from public health, we are particularly interested in the big-picture view, in what is happening to whole populations.''
The idea for The Healthy Country? stemmed from a brief meeting, when Woodward showed Blakely a graph on life expectancy over the past 150 to 200 years; on it were overlaid reports from expert working groups at various times, all of whom pronounced life expectancy must stop increasing.
''They were all wrong. It just keeps going up and it shows no sign of slowing down.''
The Healthy Country? asks some big questions: does good health result from economic progress, or is it a cause? Are populations with a relatively even distribution of resources healthier than those with greater inequalities in living standards? And, what is the relative importance of factors such as medical treatments, education, public health services and ''good genes''?
The implications of our life expectancy increasing are also examined in detail. If, as The Healthy Country? shows, it is clear humans have the capacity to influence their own lifespans through technological and scientific advances, social policy, welfare and medical care, should we strive to further increase our time on Earth?
It's an important question, because long life does require trade-offs.
Those living in the 20th century benefited from the products of the Industrial Revolution: life expectancy doubled, globally, in a hundred years, in parallel with increases in consumption of natural resources and production of material goods (although The Healthy Country? notes that very high levels of consumption are not absolutely necessary for low mortality).
The point is: can open-ended consumption be sustained? And if not, what are the consequences for future generations?
''Climate change is the big existential threat here,'' Blakely says.
''For example, the effect on food systems of significant increases in temperature will have an effect on life expectancy.''
Existential threats notwithstanding, Blakely and Woodward are unafraid to suggest ''a fully fledged research assault'' on the biological process of ageing is needed and, significantly, translating such knowledge to ''population-level interventions''.''
Presumably some as yet undiscovered neurochemical modulator or inhibitor, or perhaps a cocktail of known compounds, could be administered en masse to the population to slow ageing,'' the authors write.
In short, a magic pill, an approximation of the fountain of youth?
''So expressed, it sounds fanciful,'' they concede.
''We believe such interventions probably are unrealistic, at least for the next few decades.''
Here's another question: if science has a means of providing someone with a longer (and, importantly, relatively good standard of) life, would it be unethical to deny that?
Blakely: ''Phew, that's a big one.''
''There are still going to have to be resources allocated for them to achieve that.
''Imagine there was a process by which a person could take drugs that slow the ageing process. You'd simply confront a drug-rationing problem, which is similar to issues now faced by agencies such as Pharmac.
''What we are trying to suggest is that it is probably time to sit back a bit and ponder the social goals we should have.''
The story of life expectancy in New Zealand is a fascinating one.
Over the course of our history, the major causes of improvement in lifespan have varied from one period to another.
Diet (adequate caloric intake), standard of living and family size had the greatest effects in the 19th century; organised public health programmes and regulations and improved socio-economic conditions contributed in the first half of the 20th century; and reductions in smoking, better diets and life-saving treatments (such as cardiovascular procedures) added to the gains in the latter half of the 20th century.
''Life expectancy has a huge number of potential determinants. But what determines an increase in life expectancy can vary with time,'' Blakely says.
''For example, New Zealand non-Maori had the highest recorded life expectancy in the world from about 1870 to 1940 - and that was, we believe, because of good protein consumption.
''We were living off the sheep's back, eating mutton, as well as dairy products. And that helped kids and adults be more resilient to infectious disease, which in those times had a major effect on life expectancy.
''But fast-forward to 1970 and a high-meat, high-fat diet was not good for increases in life expectancy because of heart disease.
''I've just raised that as one example. There are heaps of things that contribute to increases (or decreases) in life expectancy.''
Blakely says another interesting point is that up until World War 2 the contribution of healthcare services - essentially going to the doctor or hospital - probably made little difference to life expectancy.
''But that has changed, particularly since 1970. The classic example is a massive fall of 80% to 90% in cardiovascular mortality. About half of that is due to better treatment.''
Blakely points out while non-Maori had one of the highest life expectancies in the world, from 1870-1940, that came at the expense of Maori, largely because of a transfer of resources.
Lower living conditions and poorer food sources were key factors, as was disease, Old World infections such as measles, influenza and pertussis causing many deaths among Maori, whose mortality rates peaked in the late 1800s (in 1891, the average life expectancy for Maori males was 25.3 and females 22.5).
However, this was followed by a dramatic recovery. Life expectancy rose by 20-25 years in the first half of the 20th century, and the gap between Maori and non-Maori was almost halved. As non-Maori life expectancy increased by two years every decade in the last century, Maori life expectancy increased by three to four years every decade on average. As of 2011, it stood at 72.80 for Maori males and 76.50 for Maori females.
''If you scan back at the past 150 years, there is a steady closing of the life expectancy gap between Maori and non-Maori,'' Blakely says.''
It hasn't just happened by chance; there have been deliberate social policies that have helped. And it's conceivable there may be no differences between Maori and non-Maori by 2040, but that will only happen through ongoing policies such as tobacco eradication.''
Quantity and quality
Those with an interest in scanning palms might like to imagine parallel lines, one representing length of life, the other quality of life.
The importance of the latter should not be overlooked. Some call it ''compression of morbidity'' and associate it with a 1980 paper by academic James Fries, who envisaged a future in which people live longer, in good health, with frailty and disease compressed into a shorter period.
''As best we can tell - and it is hard to get good data on this from many countries over many years - the percentage of our lives spent in good health correlates with an increase in the length of life,'' Tony Blakely says.
''That's pretty good news. It'd be even better if morbidity was compressed to the point where we only spent a couple of months in poor health before we died, but that's not true.''
Blakely points to obesity as an example.
''It has a morbidity component: just being overweight lowers your quality of life. It also means you are more likely to get osteoarthritis and those types of health issues that don't kill you.
''Other issues such as diabetes can lead to death but that is also a chronic disease that lasts for a long time.''
The book: The Healthy Country?: A History of Life & Death in New Zealand, by Alistair Woodward and Tony Blakely, is published by Auckland University Press ($49.99)Tony Blakely is professor of public health at the University of Otago (Wellington). Alistair Woodward is professor of epidemiology and biostatistics at the School of Public Health, University of Auckland. The authors have published internationally on public health issues, from smoking to the connections between socio-economic status and health.
