People are now living longer worldwide while birth rates have declined well below replacement levels in the western world. This is widely interpreted in a negative light, and I have done so myself, but an article by Andrew Scott published by the World Economic Forum points out that when chronological age statistics (number of years one is alive) are converted to biological age (the health of your cells, or how old you really are) little or no increase in average "real age" can be discerned in most developed economies since the 1950s.
And another report by Mark Haas in The National Interest earlier this year claims ageing populations increase the likelihood of international peace. So, increased longevity offers unexpected dividends and public policy should be framed to harvest these dividends.
The UN estimates the share of population aged 60 years and over will increase in every country up to 2050. Life expectancy is growing fastest in emerging markets where the number of people aged 60 years and over is double that in the developed world. This ratio will increase to 4:1 by 2050.
Increased life expectancy and declining birth rates increase the average population age, eg in Japan median age rose from 26 years in 1952 to 46 years today. It is popularly argued that such ageing weakens economies because it increases the old-age dependency ratio (OADR), thereby slowing economic growth and putting pressure on public budgets. OADR is the proportion of the population over 64 years relative to the working age population (15 years to 64 years). The OADR concept assumes that older people are unproductive consumers of the government benefits generated by 15- to 64 year-olds.
As countries industrialise, birth rates decline, increasing the relative size of the elderly sector and one would expect average mortality to rise because mortality rates are higher for older people. However, while the average age in advanced economies has been increasing since 1950, average mortality rates have declined for all ages for several reasons – medical advances, falling smoking rates etc. Chronological ageing is offset by a longevity effect. The average citizen has become chronologically older but biologically younger.
The conventional demographic time-bomb picture described previously makes no distinction between ageing and longevity effects and predicts a very negative picture of the future. The picture is much brighter when the longevity effect is factored in and would become even brighter if birth rates were restored to replacement levels in the western world in the near term.
In advanced economies today 75-year-olds have the same mortality rates as 65-year-olds in 1950. Scott reports that when changed mortality rates are used to adjust for "age inflation" in order to determine "real" average age, little or no increase in real age is seen in recent decades in the UK, Sweden, France, Germany and the US. Japan is an exception with an increase of average real age from 31 years to 44 years. This is attributed to the dramatic collapse of birth rates in Japan since the end of the second World War.
Of course, as Scott points out, while the average person now lives a longer healthier life this does not apply to everybody and significant differences can be discerned based on income, lifestyle, education, environment and genetics. And, so, public policies must be devised both to help those who still age in the traditional sense and to harness the dividends offered by the many older-but-productive citizens, facilitating them in full employment or offering more flexible working arrangements.
Huge monies are now expended on anti-ageing research and it may be possible to significantly extend the span of healthy living further by developing medicines that slow down ageing while boosting the body’s defences against diseases. Some geneticists predict that people may live to 150 years by 2100.
Increased likelihood of world peace is a further dividend offered by our ageing societies. The big fear in this context is of war between the superpowers – US, Russia and China. Each power has a rapidly ageing population, particularly Russia and China. It is known that countries with a surplus of military-aged citizens (18-30 years) as a percentage of total population are more likely to engage in international hostilities than countries with older populations.
William Reville is an emeritus professor of biochemistry at UCC