Public: countries with the oldest and youngest populations (and how there’s a 40-year gap between the two ends of the scale)

It is undoubtedly best known as the residence of the Pope.

But Vatican City has another claim to fame: it has the oldest population in the world.

The inhabitants of the microstate surrounded by Rome have an average age of 57.7 years.

In comparison, Niger’s number is just 14.5, making it the youngest country in the world.

The global average for 2021 was 30, according to statistics collected by the Oxford University-backed Our World in Data platform and published as an interactive map you can use here.

Meanwhile, the UK and US ranked 53rd and 73rd respectively.

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The average age serves as an indicator of the age distribution of a population.

In its simplest form, it is calculated by counting everyone’s ages and then noting how old the person in the middle is.

In contrast, the average will be found by adding the ages of everyone and dividing by the number of people living there.

A higher average score usually indicates that a country is wealthier, while a lower age usually indicates countries with population growth.

At the Vatican, nearly all of the 800 residents are priests and nuns who have been granted citizenship by the pope or papal authority because they were influential or important to Catholicism, leaving the population aging.

The Vatican is followed by Monaco (54.5 years), the island of St. Helena in the Atlantic Ocean (50.9), Japan (48.4) and Italy (46.8).

Portugal (45), Germany (44.9) and Greece (44.7) are all in the top 20 oldest populations.

But Britain does not fall into this category. With an average age of 39.6 years, the country ranks 53rd.

The US now has a younger population of 37.7, which ranks 73rd in the world.

The younger population may be due to the fact that the UK and US have higher birth rates than countries such as Japan, Italy and Greece, which lowers the average age.

The UK had a birth rate of 10.1 per 1,000 people in 2021 and the US had 11.1 births. In comparison, it was just 6.9 in Italy and 6.6 in Japan, data show.

At the other end of the scale, after Niger, the Central African Republic (14.7), Chad (15) and Mali (15.1) have the youngest populations.

These figures are due to the fact that, according to the United Nations, Africa is the fastest growing continent in the world. It assumes that by 2050 more than half of global population growth will occur in Africa.

Niger, which has the youngest population in the world, has the highest birth rate in the world, with the average woman giving birth to 7.2 children, according to the Population Reference Bureau.

The statistics office attributes this to the fact that women marry young – which extends their childbearing years – and that only one in ten women use contraception.

But it is not because of wealth that the average age is higher in some countries because birth rates have fallen there.

For example, Japan has an average age of 48.4 years, making it the fourth oldest country in the world. But in 2022, the population dropped by 800,000 people.

Researchers say countries with lower average ages tend to have higher population growth rates, as shown here by the correlation between average age and birth rate

Niger (pictured) has the youngest population in the world and the highest birth rate in the world, with the average woman giving birth to 7.2 children, according to the Population Reference Bureau’s 2018 World Population Fact Sheet

This trend – described by officials as a crisis – is attributed to people marrying later and preferring to have fewer children for financial reasons.

There are fears that other countries will follow the same pattern.

Birth rates in developed countries have been falling for years, with the average woman giving birth to two and a half children in 2020, compared to five fifty years ago.

The reasons for these alarming trends are higher levels of education and contraceptives as well as increasing numbers of women entering the workforce.

Experts fear that society will have “more grandparents than grandchildren” and face “major” challenges, such as too few young people working, paying taxes and caring for the elderly.

Researchers at Our World in Data found that in 2018, for the first time, there were more people Worldwide, there are more people over 64 than children under 5.

“As the global population of those over 64 continues to grow, it is clear that we are moving towards an aging world,” it added.