All the people: what happens if humanity’s ranks start to shrink?

The battle to feed humanity has been lost, Paul Ehrlich warned in his influential 1968 treatise, The Population Bomb. The world’s population was growing faster than the Earth could sustain, he predicted, and catastrophe loomed. “In the 1970s and 1980s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now.”

That doomsday message turned the entomologist into a celebrity and galvanised population control and environmental movements for years after. But another social wave gathering at the time would help prove his forecasts wildly wrong.

A University of Washington study published in the Lancet medical journal this month argued that the world’s population would peak at 9.7bn in 2064, then begin to decline. The UN’s demographics agency last year forecast the population peak may come later, around the end of the century. For their important differences, both agree: the ranks of humanity are going to start shrinking within a century, and not for reasons of disease or disaster.

A key driver are the feminist movements that were gathering steam as The Population Bomb was hitting bookshops. Their victories included new space for people to pursue careers, delay or eschew marriage, and have fewer children or none at all. Given such opportunities, women take them up in numbers so vast that the trajectory of our species is altered, says Christopher Murray, the director of the University of Washington’s Institute for Health Metrics and Evaluation, and the lead author of the Lancet study.

“We’ve realised there’s something different about our species, namely that women can control their fertility,” he says. “And as they get more educated and have access to jobs and careers they choose to have fewer children than replacement requires.”

As educational opportunities for women have grown and contraceptives have improved in quality and become more easily available, the same trend has been observed from the suburbs of America to the cities of Iran and villages of India. “I have always believed education is the best contraceptive pill,” says Poonam Muttreja, the executive director of the Delhi-based Population Foundation of India. “It is the magic contraceptive pill for fertility rates going down.”

The world in the year 2100 depicted in the Washington University study differs dramatically from ours: the populations of Japan, Thailand, Spain and 19 other countries will have declined by 50% or more; there will be nearly half as many Chinese citizens as the present day; if size is still linked to geopolitical influence, Nigeria (projected population: 791 million) will have taken its place as a global power.

It will be a significantly older world, the study says, the implications of which would touch everything from economic productivity, to the kind of culture produced, to the way buildings are designed and beyond. Working-age populations will have declined by several hundred million in India and China. Australia, Canada and the US would keep the size of their workforces steady only by keeping anti-migrant politics in check. Many of those new arrivals would come from Sub-Saharan Africa, whose population will have tripled in size.

Far from a future of governments scrambling to feed their populations, as some feared, such projections are driving many to find ways to persuade their citizens to procreate. Hungary’s prime minister, Viktor Orbán, promised last year that women who had four or more children would never pay income tax again. Iran’s state hospitals and clinics are no longer performing vasectomies or handing out contraceptives.

Stubbornly low birthrates may not just be a matter of empowered people exercising choice. Surveys in Europe and other highly developed economies show women generally want larger families than they end up having. Feminist activism gave people greater opportunity to work and have fewer children if they wished. The erosion of the welfare state and stagnating middle-class wages in many countries, however, have closed off the choice to spend more time at home and raise a large family. The expected deep recessions caused by the coronavirus lockdown may lead to even fewer children born in the years ahead.

Sweden is one of the few countries that found a formula to give its birthrate a jolt, says Murray, using a package of policies including childcare, flexible working conditions and generous maternity and paternity leave packages. But the increase to the fertility rate was marginal – just 0.2 children per woman, he says – and the same policy suite failed to nudge birthrates upwards when applied in countries such as Singapore, Japan and Taiwan. UN research says affordable, widespread and high-quality childcare programmes definitely make a difference, but the benefits of other pro-family policies such as cash payments or subsidised access to IVF appear to be less emphatic.

In India, whose population could peak at 1.6 billion in less than two decades according to the University of Washington study, slowing birthrates are enthusiastically welcomed. Muttreja sees the human benefits behind the statistics.

“If you look at the body language of young people in the villages, and especially girls who have gone to school, they look more confident; when you talk to them they have more determination, and many of them are convincing their families not to get them married early, to allow them to study,” Muttreja says.

Too much Indian birth control happens through sterilisation or unsafe abortions, she says, and the termination of female foetuses is still a scourge. But people are also absorbing messages to use contraception, space out pregnancies and delay marriage until adulthood.

“There are still young girls who have no control over their lives: they get married early, go through violence,” she adds. “But I am looking at girls who are stepping out. And also young boys who relate more to the values of their peers and not necessarily the family values of tradition and patriarchy.”

If the predictions come to pass, the reality of an older, shrinking population is likely to exert a heavier weight on public debates about forces such as capitalism and racism in the decades ahead – or at least it should, Murray says. “It really has a profound effect and people haven’t been thinking about it for a long time.”

“Having a society where the population pyramid is inverted, where there’s fewer people in the age group behind you and more people in the age group ahead of you – which is where we’re rapidly heading – just has incredibly profound effects on every aspect of how our society is organised,” he says.

“Who pays taxes? How do we afford health insurance and social security? Who’s respected in society? When there’s tons of people over 80 and very few under 30, everything gets totally scrambled and I think nobody’s really coming to grips just how different societies will be within an inverted age structure.”

As well as relieving the strain on the environment, “peak human” might force a reckoning with economic models that link prosperity to endless growth, says Derek Hoff, an associate professor of University of Utah’s David Eccles School of Business, who has written a book on the US population debate.

“The argument is that if you don’t have steadily rising populations you can’t have economic growth, and there there is this crisis for social support systems of too many old people and not enough young people to pay for them,” he says.

That growth orthodoxy is coming under increasing scrutiny, especially in developed economies. Hoff does not deny that ageing population throws up challenges, “but I don’t think it’s as big a crisis as is being suggested”, he says. “Look at Japan. Everyone say it’s in a demographic downward spiral. But it’s a very rich society and continues to get richer.”

As that debate takes place, the pushback against falling birthrates is likely to intensify. And if people cannot be persuaded to have more children, Murray says some governments might turn to more punitive methods.

“When societies really start to have geopolitical issues, what’s going to happen?” he says. “I think we will see a lot of energy going into trying to solve this problem. Some of that will be constructive – giving women more support to have careers and children. Some may be a real threat to women’s right to choose.”