Thinking About the World’s Population

Posted: 20th October 2023 Key

I have been interested in the world’s population since 1960 when, at the age of nine, I won a cigarette card on the subject in a game of ‘fag cards’ in the school playground. The picture on the front of the card was of a mass of people in exotic clothes. The text on the back described the rapid growth in the world’s population, but concluded reassuringly that the entire world’s population could fit, standing up, onto the Isle of Wight. I asked my mother that evening whether she thought there was anything to worry about, and she told me that there wasn’t. All the same, my generation grew up uneasy about the inexorable rise in the number of people on planet Earth. That was perhaps our main anxiety about the future, though that particular worry has since been overtaken by other concerns, including climate change, pollution, global geopolitics and the pandemic.

In the last couple of decades, though population is still rising, the dynamics of change have altered drastically. Today’s statisticians predict that the world’s population will continue to grow to around ten billion by 2065 and fall slowly thereafter, but in the last few years these forecasts have been continually revised downwards. In this article I will look at some of the underlying factors behind the changes and hazard some guesses about how these factors might affect our lives.

This article doesn’t have a particular axe to grind. What I’m really trying to do is to lay out the facts in front of you and leave you to draw your own conclusions.

In writing about people, I am acutely conscious of the contrast between the reality of human experience on the one hand, and the detached objective neatness of statistics on the other. No one cares about figures on the battlefield or in the life-support ward. Using figures at all to summarise the tragedies of the pandemic or the Ukraine invasion can appear insensitive and glib. I feel uncomfortable writing in this way. I am fond of numbers while also realising that they are a language which can be used to explain certain aspects of our experience while completely failing to capture others.

It’s also true to say that all the statistics quoted here are probably inaccurate, and some of them possibly wildly inaccurate. However, I should also add that the data used here is generally available online and from what I would consider to be reputable sources.

The subject is made harder by the sheer size of the numbers. There are slightly more than eight billion people on earth. It’s nearly impossible to understand what eight billion people actually means. Today, around 367,000 people will be born and around 166,000 will die. In other words, by tonight there will be around 200,000 more humans on Earth than there were at the same time yesterday. Putting this into context, the most reliable statistics I can find tell us that around 200,000 soldiers have been killed in the Ukraine war up to this point (120,000 Russians and 80,000 Ukrainians). The indescribable bloodshed and miseries of this prolonged war have halted the growth in world population by just one day. Official statistics put the death toll for the Covid pandemic at seven million. This means that approximately one person out of every eleven hundred (1,100) of the human population died of Covid. Putting it the other way round, one thousand and ninety-nine out of every eleven hundred of us didn’t die of Covid. Covid set the growth of the human population back by slightly over a month – a relatively insignificant number. Yet for most of us the experience of Covid was massively significant – unprecedented, unpredictable and on many levels terrifying. All of which may explain something of why we find these huge numbers so hard to understand.

In considering the numbers, it’s worth bearing in mind that human tragedies are always newsworthy, while the quiet daily gain of 200,000 human lives is not.

World Population Growth 

 I’m not sure how anyone knows that there were a billion humans on earth in 1804 (was anyone around then to count the Kalahari bushmen or the eskimos?) but we are told that it was so. World population grew rapidly from that point, to two billion in 1927, three billion in 1960, four in 1974, five in 1987, six in 1998, seven in 2010 and eight at the end of last year. The intervals between each new billion souls being added grew shorter – from a hundred and twenty three years to thirty-three, and then fourteen, thirteen, eleven and twelve, but the trend is changing fast. The world has already passed ‘peak child’ – the number of children aged under five peaked at 690 million in 2017 and has already fallen by 5% to 557 million today and will continue to fall, according to the statisticians, from now till the end of the century and beyond.

What’s really changed is the fertility rate – the number of children born to every woman. In very poor societies, life expectancy is low, child mortality is high, and contraception is neither available nor understood. Families need to produce as many children as possible in order to have a chance that there will be at least some to carry on the parents’ trade and support them in old age – should they be lucky enough to survive that long. With growing prosperity, child mortality falls and population growth is rapid. Eventually behaviour changes, the fertility rate drops and populations stabilise.

The rate of live births per woman needed to maintain a stable population is 2.1. Globally the fertility rate is still slightly above this level, at 2.42 in 2023, but the decline in this number is one of the most consistent factors in world demographics. World fertility peaked at 5.3 in 1963 and has been falling ever since. You can predict a stable world population in 2065 by assuming that the fertility rate continues to fall at a steady 2.0% a year, but looking at other trends it’s possible to speculate that the actual rate of decline will be much faster. And, as we’ll see, the fertility rate in some countries is already well below the replacement level.

Population Growth by Country

The fastest-growing countries, in terms of extra people per year, are not rich ones. They are all either middle-income or poor countries, and they’re all in Asia and Africa. They are –

Country                   Continent                    Current Annual Population Growth (million)

India                              Asia                                         11.6

Nigeria                         Africa                                        5.4

Pakistan                       Asia                                           4.8

DRC                              Africa                                        3.2

Ethiopia                       Africa                                        3.0

Tanzania                      Africa                                        3.0

Uganda                        Africa                                         2.8

Indonesia                    Asia                                            2.1

Kenya                           Africa                                         2.0

Philippines                  Asia                                            1.8


Different Countries Have Different Fertility Rates

When we look at fertility rates by country, the predominance of Africa becomes even clearer. The ten countries with the highest fertility rates (Niger, Chad, DRC, Central African Republic, Mali, Angola, Nigeria, Burundi, Benin), varying from 4.8 to 6.5, and the next four after them, are all in Africa, while none of the ten countries with the world’s lowest fertility rates is to be found there. Excluding the two Chinese territories of Hong Kong and Macau, the world’s lowest fertility rates are in South Korea, Singapore, San Merino, Malta, China, Ukraine, Thailand, Spain, Japan, Jamaica and Italy, with fertility rates varying from 0.9 to 1.3).

Exactly half of the world’s 204 countries now have fertility rates below the replacement rate of 2.1.

Africa’s population is 1.4 billion, which means that roughly one in every six people lives on that continent. It seems likely that this proportion will increase, as populations there seem bound to increase at the same time as those in other areas peak and decline.

Not only are growth rates falling, but populations in some countries are already in decline. Among larger countries (excluding places like St Vincent & the Grenadines and the Northern Mariana Islands) the following are experiencing falling populations, varying from an annual 1.0% to 0.1% (biggest decliners first) – Romania, Bulgaria, Ukraine, Croatia, Japan, Greece, Hungary, Poland, Russia, Portugal, Germany, Slovakia. Apart from Japan, all of the countries on this list are in Europe, or partly in Europe. Though roughly two-thirds of Russian land is in Asia, roughly two-thirds of its people are in Europe.

In some countries population decline is already an established trend. Japan, still one of the world’s most populous countries, is perhaps the best-known example, and is sometimes referred to as a ‘super-ageing society’. Japan’s population peaked at 128.1m in 2010 and has since fallen by nearly 4% to 123.3m. With an average age of 49 and a fertility rate of 1.37, there is no chance of the decline being halted any time soon. Government initiatives (free childcare, six months’ maternity leave, improved child benefits) to encourage people to have more babies have met with little success to date. Japan’s population is predicted to halve by the end of the century. Japan, with its ageing, declining population might seem to be a perfect home for migrants, but this hasn’t happened. At 2.5%, the proportion of foreign nationals in Japan is one of the lowest in the developed world.

Russia’s population has been in decline for even longer than Japan’s, having peaked at 147.4 million in 1989. Deaths have exceeded births every year since 2016, with the population decline being somewhat offset by immigration. In 2019, someone was born in Russia every 22 seconds and someone died there every 13 seconds. The net result was a loss of one person every 30 seconds, only partially offset by one net immigrant every four minutes. Russia was one of the heaviest sufferers from Covid, with the true death toll probably significantly higher than the four hundred thousand official total. Russia’s invasion of Ukraine has caused a further reduction of around two million people, combining war casualties and the brain drain of younger educated people escaping conscription and much higher levels of repression – though these emigrants will of course appear as increases to the populations of other countries.

Let’s take a quick look at the world’s two most populous countries, China and India. With around 1.4 billion nationals apiece, these two countries exceed by more than fourfold the next most populous country (the US with 330m). If Africa was a country, it would have the same population as these two giants. Over half the world’s population lives in either India, China or Africa.


China’s unique demographic journey dates back to the time of Chairman Mao, who successfully encouraged families to have as many children as possible. In the fifteen years before his death in 1975, China’s population grew by 40% to 915 million, with a very low average age. Mao’s successor Deng Xiaoping, anticipating an uncontrolled increase in mouths which China was unable to feed, introduced the one-child-per-family policy in 1979. The policy was so successful that it was relaxed though not entirely abandoned in 2015 by the government of Xi Jinping, but to everyone’s surprise the anticipated leap in the birthrate failed to ensue. People had moved to cities and adopted an urban lifestyle. Large families were no longer a status symbol or felt to be needed for support in old age – couples now relied more on their savings for that. They had grown to like their pampered only children, known as the ‘little emperors’.

Interestingly, this cohort of children was known as the ‘little emperors’, not ‘little empresses’. An unlooked-for by-product of the one-child policy was the lopsided preponderance of boys over girls. If families could only have one child, they would prefer a boy, who would not require a dowry, and who (for some reason) would be expected to be a more reliable carer for his parents in old age. A friend of mine who travelled extensively in rural China heard many tales of infanticide of baby girls, and of abortion of female foetuses. The consequences can be seen today in China’s population, which is the world’s most unequal, with 716m males to 684m females.

In 2023, China’s population is expected to fall slightly for the first time, after flatlining in 2022. With a median age of 39, and a fertility rate of 1.7, this gradual decline is likely to become a trend. The fertility rate has been creeping up recently, but at its current growth rate will not reach 2.1 for decades. China’s working population has been in decline for several years.


In the 1970’s India’s population pyramid looked similar to China’s, with a large cohort of young people at its base and relatively few old people at its peak. Without a one-child policy India has remained the fastest growing of the world’s most populous countries and has overtaken China within the last year as the worlds’ most populous. But its demographics are maturing rapidly. Its fertility rate has been in steady decline, and at 2.14 this year, is only just above the 2.1 replacement level. A percentage fall in 2024 of a similar order to this year’s would take India below its stable level. Without net migration, a decline would follow in due course – something unimaginable two decades ago.


Religious beliefs can be reflected in decisions on family size. Catholics have often traditionally had large families, and yet the world’s 1.3 billion Catholics appear to have shared in the rest of the world’s tendency towards smaller families. Many of the countries with the largest Catholic populations now have fertility rates below the 2.1 stable level – for example Brazil (1.6) Mexico (1.8) France (1.85) Spain (1.4) and Italy (1.25). In Italy, home to the Vatican, last year’s birth total, four hundred thousand, was the lowest on record. That year deaths exceeded births by a factor of twelve to seven, and overall Italy’s population declined by 179,000 despite net migration of 129,000. This isn’t a recent phenomenon either – Italy’s fertility rate hasn’t been above 1.5 for over forty years.

Life Expectancy 

Life expectancy is a major factor in predictions of future population sizes.

We know that life expectancy is around thirty years in primitive societies and that industrialisation increases life expectancy, which has been growing steadily in the west since the early nineteenth century and is predicted to continue growing till at least the end of this century. But will it? The United Nations certainly thinks so. A look at recent history alongside the UN’s predictions makes interesting reading. For this purpose, I have chosen the UK and the US as examples.

The figure usually quoted is ‘life expectancy at birth’, a figure which tells you how long a newborn child, given average luck, can expect to live. The number is different between the sexes – women live longer always and everywhere – but the figures I’m quoting here are aggregates.


The UK is in thirtieth place in the league table of life expectancy by country. A child born in 2003 could expect to live to be 78.4 years old, while their younger sibling, born in 2013, could expect to live another 2.5 years, or 3.2% longer. Something changed around 2013 that almost stopped the growth in life expectancy in its tracks, because a child born another ten years later in 2023 could only expect to live another 0.9 years, or 1.1% longer than in 2013. I have seen no convincing explanation for this sharp deceleration in the upwards trend. Covid isn’t the answer, because it affects older people, and would make little difference to the life expectancy of a newborn baby. Obesity is a more likely contributing factor. Studies show that an obese person is likely to live around three years less than they would have done otherwise, and in the more extreme cases the difference can be as much as ten years. There are many other factors which could possibly have a bearing on the global number. Perhaps there were fewer medical advances which prolonged life. The change in trend has affected life insurance companies, who have been making ‘mortality releases’ each year, to reflect the reality that their clients have been dying earlier than expected.

Looking to the future, the UN predicts that UK life expectancy will re-accelerate to 1.9% in the ten years to 2033, 1.6% in the ten years to 2043, and 1.3% in the ten years to 2053, continuing then in a ruler-straight upwards line to the end of the century. I cannot tell you that the UN’s predictions on life expectancy are wrong, but I am wondering whether they might be. Without an explanation of why life expectancy is growing so much more slowly than before, and what factors might cause it to rebound, it is hard to ignore the evidence of the last ten years.

To check if the UK is an exception, I looked at the equivalent figures for the US.

United States

The US is 47th in the league tables of countries’ life expectancies.

The equivalent figures are :-

2003 – 2013 Actual growth in life expectancy from 77.2 to 78.9 years – plus 1.7 years or plus 2.2%

2013 – 2023 ditto from 78.9 years to 79.1 years – plus 0.2 years or plus 0.2%

2023 – 2033 UN growth projection – from 79.1 years to 81.0 years – 1.9 years or 2.3%

2033 – 2043 ditto – from 81.0 years to 82.4 years – plus 1.4 years or plus 1.7%

2043 – 2053 – ditto – from 82.4 years 83.8 years – plus 1.4 years or plus 1.7%

These figures are a more extreme version of the pattern we saw in the UK – a sharp decline in the growth of life expectancy over the last ten years, which appears to be ignored in the projections.

In the US, obesity is an epidemic, with 100 million adults (40% of all adults) and 19 million children (20% of all children) registered as obese – numbers that have risen considerably since the start of the millennium. Other lethal factors particular to the US are the opioid epidemic and the prevalence of gun crime. How can the UN be sure that these killer factors will fade in the years ahead?


My generation grew up in fear of an exponential growth in the world population leading to disaster in the not-too-distant future. Tomorrow’s population crisis looks more like an excess of old people with insufficient young ones to support them. Populations are maturing and starting to roll over at amazing speed, everywhere except Africa and parts of Asia. Forecasts of future growth in life expectancy in the developed world look optimistic. In Africa things look grim. The recent coup in Niger follows the pattern in a continent drifting towards more repressive authoritarian regimes. It seems likely that the urge to emigrate from Africa will increase, perhaps exponentially.

Countries with maturing demographics will have to work out how to cope with a surge in migration. Everyone wants an orderly flow of civilised, qualified migrants, but is faced instead with a chaotic torrent of people fleeing from places where life has become unbearable, and tries to decide who should stay and who should go using outdated distinctions between who is an ‘economic migrant’ and who is a genuine refugee. The bureaucracy is excessive and is overwhelmed. Readily available statistics tell us that this situation is likely to intensify in the years ahead.

Tony Yarrow

October 2023

Sources – a lifetime’s interest in the subject backed up by a plethora of reputable websites. Most of the figures quoted here are readily available online.

Please note, these views represent the opinions of Tony Yarrow and do not constitute investment advice. This document is not intended as a recommendation to invest in any particular asset class, security or strategy. The information provided is for educational purposes only and should not be relied upon as a recommendation to buy or sell securities. The value of investments can go down as well as up and you may not get back the amount originally invested. Wise Investment is authorised and regulated by the Financial Conduct Authority, number 230553.
















Tony Yarrow