101 Facts About Ageing #1: The World’s Human Population Is Growing Older On Average

As Daniel Patrick Moynihan, an American sociologist, politician, and diplomat once said: “Everyone is entitled to his own opinion, but not his own facts”. And we wholeheartedly agree. A shared set of facts is the first step to building a better world with longevity for all. In that spirit, we are creating a series that covers 101 indisputable facts about ageing, health and longevity.

The world’s population is getting older. In 1970, the global median age was 21.5 (meaning that half of the world’s population was older than 21.5, and half were younger). In 2019, this number had risen to over 30. In Japan, the median age is 48.4, while in Niger, it is only 14.9. Lower fertility rates are a major contributor to population ageing, and so countries with faster-growing populations tend to have a lower median age.

In many ways, population ageing is a symptom of successful modern society. Life expectancy has soared over the last 100 years, while fertility rates have plummeted. The latter is the result of factors such as more women in education and employment, better healthcare and education overall, and lower infant mortality – all great success stories. However, they leaves us with a mounting problem called the age-dependency ratio.

A stable working population is necessary to support a country’s economy. Demography often considers those between the ages of 15 and 65 as the working age population, while those outside of this group can be seen as at least partially dependant on the working age group. The ratio of the ‘dependant’ groups to the working group is called the age dependency ratio. If this ratio is high, there is a negative economic impact as a larger proportion of the working population is required to financially support and/or care for the dependant population.

In developed countries, age dependency ratios are rising due to population ageing: 67% in Japan, 58% in Italy, and 52% in the United States. However, the countries with the highest age-dependency ratios are developing countries in sub-Saharan Africa, and this is due to the size of the younger dependant group, not population ageing. As mentioned earlier, half of Niger’s population is under 15 years old – that country has an age dependency ratio of over 110%, meaning its working population is smaller than its dependant population.