By Ian Morris
Fifty years ago, the British poet Philip Larkin saw that the world was shifting under his feet. As he described it in his 1967 composition Annus Mirabilis,
Sexual intercourse began
In nineteen sixty-three
(which was rather late for me)—
Between the end of the Chatterley ban
And the Beatles' first LP.
Larkin's poem was largely about his own bad luck in having been born too soon to be able to make the most of this tectonic shift, but its artistry lay in the way he connected his personal woes to upheavals that spanned the globe. The issue, he explained in the second verse, was that,
Up to then there'd only been
A sort of bargaining,
A wrangle for the ring,
A shame that started at sixteen
And spread to everything.
For 100,000 years, ever since modern humans evolved, sex had been part of a larger tradition of wrangling between male and female, young and old, about babies, property and responsibility. But in the blink of an eye, the coming of chemical contraception changed everything. For the '60s generation, Larkin enviously observed, sex would be all about fun: "All at once the quarrel sank … And every life became / A brilliant breaking of the bank, / A quite unlosable game."
Gender relations across the past 50 years have been a little more complicated than that, but Larkin was quite right to see that women's rising control over their own conception was one of the greatest upheavals in history. The way it transformed relationships within countries was made painfully clear in the United States' most recent presidential race. But it also transformed relationships between countries, and not surprisingly, it regularly features in discussions of geostrategy. But it's hard to shake the feeling that we still have a long way to go in working out exactly how biology, economics and politics fit together, let alone in envisioning just how our brave, new low-fertility world will develop in the decades to come.
Against the Laws of Survival
For most of our time on Earth, we humans have been high-fertility, high-mortality animals. Until 10,000 years ago, everyone lived by hunting wild animals and gathering plants, and the total fertility rate (TFR) — that is, the average number of live births each woman had — was probably around 5.0. This was well above the 2.0 needed to replace the living population, but high infant and child mortality meant that most women needed to have at least four babies to produce two adults who lived to reproductive age.
What is Global Affairs?
The TFR rose still higher after agriculture began because farmers' diets were typically poorer than foragers' and the crowding of village life made it easier for infectious diseases to spread. The average farmwife needed to bear six or seven babies to ensure mankind's survival. Given that she would normally become fertile in her late teens and would be dead by 40, almost every fertile woman spent most of her adult life pregnant and/or caring for small children.
TFRs began to drop sharply only after about 1750, and even then only in northwest Europe and its North American colonies. Improvements in public health, personal hygiene and food supply all played a part in lowering mortality rates. In the 1850s, about a quarter of all babies born in the United States still died before their first birthdays, but by 1970 this figure had fallen to 1 in 50. For a few generations, fertility rates remained high even though mortality rates had fallen, which meant that European and Euro-American populations grew rapidly. Well before 1900, though, couples were reducing the number of babies they conceived and raised. It is no coincidence that the first person to theorize the relationships between population growth and food supply, Thomas Malthus, did so in England in 1798.
Demographers call this drawn-out shift from high-mortality, high-fertility regimes to ones with low mortality and fertility "the demographic transition." Most rich countries had completed it by 1900 and maintained TFRs between 2.0 and 2.2 through much of the 20th century (in the United States, the TFR sank to replacement level in 1979). This not only allowed parents to invest more in the education of each child but also freed mothers to work outside the home, earning even more to invest in their fortunate offspring. Between 1940 and 1990, the proportion of American women working outside the home more than doubled, from 26 to 56 percent, and as early as 1950, fully half of American workingwomen were married.
Clearly, sex was about fun as much as babies long before 1963 (the rubber condom, after all, was invented in 1920), but Larkin was nevertheless right that the early 1960s were a turning point for the rich world. Birth rates now plummeted well below replacement levels. By 2014, the average woman in the European Union had just 1.58 babies, while the average Japanese woman managed only 1.40. So extraordinary is this "birth dearth" that Dutch demographers Ron Lesthaeghe and Dirk van de Kaa like to say the rich world has gone through a "second demographic transition" that began — exactly as Larkin said — in 1963.
If we take a global perspective, Larkin also appears to have been right, even if he jumped the gun a little. In 1968 the worldwide TFR was still 4.9, barely down at all from the early 20th century. But at that point Asians, Africans and Latin Americans began following the European and Euro-American lead, separating sexual intercourse from reproduction. By 2013, the global TFR was down to 2.3. Only a handful of countries, mostly in Africa, still have TFRs above 5.0.
This is a peculiar story. Through the whole of history prior to the demographic transition, high TFRs and population growth had been preconditions of national greatness, while low TFRs had been strategic suicide. This was already obvious to the Greek historian Polybius in the third century B.C., and Rome's first emperor took it so seriously that in A.D. 9 he passed laws trying to force aristocrats to have more babies. In the 21st century, by contrast, the inverse relationship between fertility rates and national success seems so firmly established that in 2009 the authors of a paper in the leading scientific journal Nature called it "one of the most solidly established and generally accepted empirical regularities in the social sciences."
Hence the question: Did humanity in 1963 (or perhaps 1750) break the iron law of biology that reproduction is the secret of success? Or — as Zhou Enlai is supposed to have said in 1972 when asked about the legacy of the French Revolution — is it still too soon to say?
Ahead of the Curve . . .
If the former, then for once I can claim to be at the cutting edge of a global transformation. I belong to what evolutionary scientist Peter Richerson and anthropologist Robert Boyd have called "one of the most bizarre traditions in the whole ethnographic record … a subculture of people who devote more time to, and are prouder of, the length of their publication list than the number of their children." Being childless-by-choice is a badge of honor among Western academics; by my count, the 17 professors in my department at Stanford University have between us produced just nine children. Our departmental TFR of 1.06 makes even Japan look fruitful.
To be sure, we Western academics are hardly the first subculture in history to have failed to reproduce ourselves biologically. In theory, at least, Catholic priests and monks had a TFR of zero and relied entirely on attracting new members from outside their ranks to perpetuate their profession as insiders died off. There is a telling difference, however, between the medieval Catholic hierarchy and modern academia. Until roughly the year 1000, priests and monks normally were not celibate. This requirement was imposed on them by zealots who seized the church's leadership in the 11th century. The main issue involved was the church's control of fabulous wealth, which allowed the holders of political office to accuse bishops and prelates of being nothing more than a parallel state that conned believers into giving them property that they then bequeathed, along with their offices, to their sons. Religious radicals struck back by shoring up their ideological credentials and cutting a deal: If kings and emperors kept their hands off church property and allowed popes and archbishops to go on appointing the men who controlled it, all church officials would forgo the right to breed their own heirs.
The anthropologist Ernest Gellner called this "gelding" — a mechanism for smoothing conflicts between rulers and vital but potentially threatening subordinates by stopping those subordinates from reproducing themselves. Sometimes the gelding was literal, as in the practice (common from Byzantium to China) of giving top positions in the state bureaucracy to eunuchs. Other times it was institutional, as with the Catholic Church. But either way, rulers imposed gelding on dangerous groups as a way to set them apart from the rest of the population, which generally bred as fast as it could.
Professors are worlds apart from the earlier gelded groups. University trustees do not require their faculty to desist from sex (except with their own students), nor does gelding set professors apart from the rest of the population. We professors are choosing not to reproduce for reasons of lifestyle and career, and the only thing that sets us apart is that we tend to make this choice a little more often than other people. ("A kid's a book," one of my academic friends likes to say, pointing out that every live birth has major consequences for careers, promotions and salary.)
If we professors are indeed the vanguards of the low-fertility revolution and others continue to follow our lead, we can expect the world's population to peak in the mid-21st century and then decline — which is, in fact, exactly what the United Nations predicts. Humanity will indeed have broken evolution's law of the survival of the (reproductively) fittest, and small, rich populations will win the evolutionary struggle against large, poor ones. Plenty of pessimists predict that computers and robots are on the verge of destroying most middle-class jobs; if they are right, then shrinking populations might turn out to be the only ones that are economically viable.
. . . Or Past Our Prime?
Another possibility, though, is that the low fertility-high income link will prove to be temporary. Some demographers are already arguing that the relationship between fertility and income is actually a J-curve rather than a steady decline. Although per capita income increases as TFRs fall, they suggest, once people hit a certain level of prosperity they start breeding again. Just as the population explosion of the 19th and 20th centuries was a temporary stage of adjustment, they argue, the demographic stabilization of the 21st century is also merely a phase, to be followed by renewed expansion.
If so, it might turn out that groups that sacrificed fertility for prosperity will eventually pay a terrible price. If history reverts to the long-term norm and large populations once again become the basis of power and prosperity, we can expect a geostrategic revolution. Africa's population currently stands at 1.1 billion people, or 15 percent of the world's total. The United Nations expects it to reach 2.5 billion, or 26 percent of the total, by 2050, and 4.4 billion, or 39 percent of the total, by 2100.
Rich countries are already struggling to come to terms with the aging populations and declining ratios of young workers to old consumers bequeathed to us by falling fertility. The obvious solution — encourage poor, young people to migrate from high-fertility countries in Africa, Latin America and the Middle East to Western Europe and North America — has generated political turmoil in the rich world and backlash against human mobility. There is a real possibility, though, that we ain't seen nothing yet, and that during the 21st century demography will overturn the international balance, as it has done so often before. And for the rich world, the last lines of Larkin's poem might turn out to be more prophetic than they seem:
So life was never better than
In nineteen sixty-three
(Though just too late for me)—
Between the end of the Chatterley ban
And the Beatles' first LP.