The prospect of longer life is generally viewed as a positive trend and a substantial societal achievement. Global mortality has improved over time, though most of the reduction has been attained over the last 125 – 150 years. This unprecedented decline in mortality rates has caused life expectancies at birth to grow by nearly 30 years, up to 80 – 85 years in developed countries.
Life expectancy over time
For most of human history, up until 10,000 BC, life expectancy at birth has been estimated at about 25 years, and little progress was made through the Roman Empire. By the 1700s the life expectancy at birth reached 37 years in England1, rising to about 41 by circa 1820. Life expectancy remained stable during the period of the Industrial Revolution (1820 to 1870). Later, mortality fell further, with life expectancy reaching around 50 by the dawn of the 20th Century.
In the first half of the 20th Century, mortality continued to improve for children and young adults. These improvements were mostly due to the focus of governments on population-wide living, housing and health care initiatives.
Historical determinants of mortality improvements
Complex and intermingled factors (such as nutrition, breakthroughs in public health and medical treatments, urbanization, education, behavioral and lifestyle) contributed to these past mortality improvements. They appeared in sequence, building on the improvement provided by each previous determinant.
In the 18th Century, agricultural quality and yields increased substantially with the mechanization of the farming industry. British physician and demographer Thomas McKeown2 argued that better nutrition improved the population’s health. Robert Fogel3 later evidenced this in a series of publications between 1977 and 2004. Opponents to the nutrition theory argue that the disease burden changed mostly as a result of strong public health intervention.
Public health, vaccination and medical treatments
Samuel Preston4 made the case that the reduction in mortality occurred because of the improved overall public health in the context of increases in income. Major macroeconomic projects had taken place over several decades: filtering and chlorination of water, building sanitation systems, swamp drainage, milk pasteurization and mass vaccinations. Microeconomic efforts also contributed: better food conservation and protection from insects, promotion of better hygiene, ventilation of homes and rooms and preventative medicine programs.
Developments of new therapeutics to treat people with diseases (such as antibiotics, which were first developed in the 1930-40s) also contributed to the early steep mortality improvements. By 1970, water- and foodborne-diseases were almost eliminated from North America. It is estimated that about 50% of the mortality gains happened early in the 20th Century, mostly due to better water sanitation. Interestingly, the advances in medicine regarding cardiovascular mortality are a fairly recent development and only arrived after the 1960s.
Initially, large-scale urbanization had a negative effect on health and overall mortality due to the effects of unsanitary living conditions, consequently facilitating the spread of diseases in more crowded cities. Gradually, the situation improved as urban sanitation (running water, sewage, garbage clean-up), housing and access to health care centers improved.
Socio-economic changes (education, income, wealth)
Growing evidence indicates that reducing economic and social inequality (education, income, wealth, social status) has a positive effect on a population’s health. In many countries, addressing these inequalities has become a major focus of public health policies. Even in some countries that have relatively high income inequality, overall mortality improves, as the less fortunate of today are much more prosperous than their peers a century ago. In effect, while income inequality may actually increase, prosperity (and hence mortality) still improves as the entire scale moves up.
Behavioral and lifestyle factors
Smoking is a major risk factor for lung cancer and cardiovascular diseases. Additionally, research tends to indicate that non-smokers have made greater mortality improvement than smokers, though they do seem to have more room to do so! Smoking is generally associated with other adverse lifestyle habits. Conversely, people who engage in a “healthy habit,” such as regular dentist check-ups, may be more likely to engage in other positive habits (wearing seat-belts, regular physician check-ups, etc.) and consequently are statistically more inclined to exhibit better mortality than those who don’t.
Other behavioral risk factors, such as moderate drinking, regular physical activity, healthy eating choices and the use of preventative care (mammograms, prostate examination, colonoscopies, etc.) have all a positive correlation to improving long-term mortality.
There is no consensus today about how the interplay of all these factors affects mortality improvement. The link between behavioral, lifestyle and social status (education, income, wealth) on one side, and health on the other side remains complex and not yet fully understood. The fact is that, over the last 100 – 125 years, better nutrition, sanitation, housing and living kick-started the mortality improvements. More recently, the numerous medical breakthroughs in pharmaceuticals and medical procedures built upon previous mortality reduction.
Future mortality improvements, specifically in North America
According to Jay Olshansky5, the future mortality improvement rate may be slowing down, since some of the reductions obtained in the 20th Century may not be reproducible for individuals under the age of 50. With mortality at younger ages already very low, it has become more difficult to raise life expectancies at birth. Therefore, according to Olshansky, the current and future focus is on improving the mortality for the middle and older ages, where the impact may be much less, hence his argument for an improvement-rate slowdown. Other notable experts, most notably James Vaupel, dispute this perspective.
Medical advances in diagnostics, treatment and other life-sustaining methods
When might the next major breakthroughs happen, pushing the average life expectancy from around 80 or 85 today to 100, considering that past breakthroughs just happened and were never planned? Today, numerous new medical technologies in the areas of cancer, heart and circulatory diseases may make it possible for individuals to survive the initial onset of diseases.
Olshansky mentioned further that even if we discovered an intervention that effectively eliminates a major mortality factor (cancer, cardio-vascular disease, etc.), nature may replace, to a certain degree, the newly created mortality improvement with another human killer. In fact, we may already be experiencing this (mortality improvement from smoking reduction is gradually being replaced by increased consumption of fast or processed foods, leading to increased incidence in obesity, diabetes and other metabolic diseases).
What could the next breakthrough in medical advancements be? Will it be genotype-specific therapies? What will come of the progress in the regenerative and rejuvenating of human tissues, in the replacement of malfunctioning genes, in genetic engineering, nano- or quantum technologies or yet unknown and waiting to be discovered?
Current biomedical research is generating much knowledge about the genetic basis for diseases. However, the translation into the population level of newly found genetic and aging discoveries into advances for medical treatments and interventions remains challenging – what works for one may not work for others. Presently, many people are living longer and better due to pacemakers, beta-blockers and statin drugs as well as devices like artificial hips or knees. Will future improvements be more subtle in the sense of “one person at a time” versus an entire segment of a population? Should the past and current public health philosophy of “the greatest good for the greatest number” be broken?
Behavioral and lifestyle changes
What is the impact of social inequalities and access to health care on mortality? Some research indicates a very high correlation of longevity between level of education, income and overall wealth, as well as early-life and childhood living conditions, social conditions in adulthood and, last but not least, family genealogy.
Other behavioral and lifestyle changes include
- Reduction in smoking (lung cancer)
- Continuous safer driving (alcohol, drug, speeding, graduated licensing programs, seat belts, air bags, etc.) and prevention of the emerging “distracted driving” (cell phone use or texting)
- Better nutrition and exercising (thus reducing hypertension, high cholesterol, obesity and other metabolic risk factors such as diabetes)
- Higher occupational safety standards and improved work conditions
- Better suicide/homicide prevention if possible
- Education about excessive drinking (liver diseases and accidents)
- Impact on fast food on educational scores6.
Forecasting is an inexact science, and behaviors are particularly very complex to predict. Will the increase in obesity in the US and Canada become so significant that it could wipe out the mortality improvements obtained:
- In less smoking (one-third reduction since the 1960s),
- Less excess drinking (20% decline since the 1980s)
- Overall improved risk factor control for cardiovascular diseases?
Evidence suggests that obesity is becoming pandemic. Mexico recently overtook the US as having the highest obesity rate in the world. Countries in Europe are also experiencing higher obesity rates though admittedly from a lower starting point.
Could further improvement at the population level be achieved by improving the patient’s education about preventative medicine and compliance to the recommended medication and dosage?
To survive, pathogens (infectious agents) need a reservoir. Animals and non-living sites (soil, water) are reservoirs for diseases infecting humans. Strong regulations may need to be implemented to successfully protect the public from infectious diseases, typically by eliminating the pathogen from its natural reservoir or interrupting its route of transmission. Measures like safe water supply, effective sewage treatment and disposal, education about food safety, animal control and mass vaccination and education programs have helped reduce and even eliminate some of the most dangerous and common infectious diseases.
On the other hand, resistance to anti-microbial treatments – in particular to malaria and tuberculosis – is rising at an accelerating rate. New infectious diseases have appeared in the last decades such as AIDS, Legionnaire’s disease7, Hantaviruses8, Lyme disease9, and prions10. Most emerging infections appear to be caused by “sleeping” pathogens. They are “activated” when there is a change in the pathogen’s natural environment, such as ecological changes due to agriculture11, economic development or anomalies to the climate, human demographic changes and behavior, travel and commerce, microbial adaptation, resistance and mutation and, lastly, breakdown in public health measures12.
How mortality improvement will emerge in the future remains uncertain, but two main schools of thought have evolved:
- Mortality improvement will continue indefinitely and will follow a generally linear trend, with people living to age 150 and beyond (e.g., James Vaupel 13)
- Humans have, by design, a limited life span, and that future mortality gains will be smaller because of real and observable natural limitations (e.g., Jay Olshansky).
Reliable projections are complex and sophisticated due to a large number of possible determinants and drivers. According to the Office of the Chief Actuary (Canada), a life expectancy of 100 remains challenging given today’s mortality rates. If mortality rates improved at the same rate as in the last 15 years or so, then a life expectancy of 100 would be reached around 2090 to 2120 in Canada14.
Significant decreases in infant and childbirth mortality (in the late 1800s), improved schooling and education, major improvements in socio-economic conditions, public health and better access to medical care have been associated with past population mortality improvement. Currently, it appears that future gains in mortality may be measured in years rather than decades.
Some populations in North America may already be experiencing a slowdown in the rate of mortality improvement. The changes of disease patterns (such as obesity), economic and social disturbances (succession of recessions, downturns with fiscal restraints and austerity measures) or the (re)emergence of old and new infectious diseases may negatively influence future longevity gains, at least temporarily.
Does the prospect of ever-longer life remain the holy grail of societal achievement, and is an extra year of life expectancy worth the economic efforts required? These and other ethical questions will be the next area of debate, as isolated public health care providers begin to reassess their views and shift their focus on improving the quality of end-of-life years. How this trend will affect mortality improvement rates going forward from an actuarial standpoint will need to be determined.
1 Limited past credible mortality data exists, but England and Germany have historically the most robust (i.e. highest confidence).
6 K.J. Tobin (2013), "Fast-food consumption and educational test scores in the USA". Child: Care, Health and Development, 39: 118–124.
7 One of the main identified reason, is the wider availability of air conditioning systems.
8 Conversion of grassland to maize cultivation favoured a rodent that was a natural host for the virus.
9 It is estimated that the rising number of cases was largely due to reforestation, which increased the population of deer, and the deer tick as a carrier of the disease.
10 Prions are responsible for the Creutzfeldt–Jakob disease or CJD, the human variant of “mad cow disease”.
11 The avian flu pandemics appear to have their origin in the integrated pig-duck farming traditions in China, whereby waterfowls – like ducks – are major reservoirs of influenza and pigs serve as link for infecting humans.
12 For further details, please refer to Dr. Stephen Morse’s speech at SCOR’s 2014 pandemic conference in Paris
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D. M. Cutler, E. L. Glaeser, A. B. Rosen, 2009. "Is the U.S. Population Behaving Healthier?," NBER Chapters, in Social Security Policy in a Changing Environment National Bureau of Economic Research, Inc.
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R.J. Pokorsky, MD, MBA. “Pricing implications of trends in population mortality and underwriting effectiveness”, J Insur Med 2004;36:54-59.
M.C. Purushotham. “Mortality improvements”, The Actuary Magazine, August/September 2011 – Volume 8 Issue 4.
National Institutes of Health (US); Biological Sciences Curriculum Study. NIH Curriculum Supplement Series [Internet]. Bethesda (MD): National Institutes of Health (US); 2007-. Understanding Emerging and Re-emerging Infectious Diseases.
S.S. Morse. “Factors in the emergence of infectious diseases”.
J. Vaupel. "The advancing frontier of human survival”, presented at the Living to 100 symposium of the SOA – January 8-10, 2014