Last week the United Nations Population Fund released a report heralding the birth of the world’s 7 billionth person. The milestone is important, the United Nations explains, because their calculations now project that global population is likely to hit 9.3 billion by 2050 and could go as high as 15.8 billion by the end of the century. As you might imagine, these dire warnings were greeted with eager and solicitous concern by the alarmist media.
“Population Growth Taxing Planet’s Resources,” announced one Washington Post story. CNN tried to contextualize the number 7 billion by helpfully informing readers, “Seven billion ants, at an average size of 3 milligrams each, would weigh at least 23 tons (46,297 pounds).” Why a pretend pile of insects? “Population experts are hoping that more people begin to grasp the 7 billion concept soon, because the number has skyrocketed in recent years and the situation is becoming more urgent.” The New York Times carried a debate on overpopulation in which the Population Institute’s William Ryerson argued that societies with fertility rates below the replacement level—which is to say every industrialized nation in the world—must not try to increase their fertility because to do so will cause “serious environmental and social problems.”
The nub of these arguments is that the world is overcrowded, and there is not enough water, food, energy, or land to sustain an asymptotically increasing population. Happy to go the full Malthus, MSNBC wheeled out a buffet of essays on the subject. The package featured Paul Ehrlich, who testified that “seven billion people is already facing us with horrendous problems, including almost 1 billion people hungry and contributing greatly to the chances of catastrophic climate disruption.” He warned that “a global civilization is in peril” and argued that all governments should adopt the slogan “patriotic citizens stop at two children” while imposing penalties on “over-reproducers and those unethical elements in society that are pro-natalist.”
Following Ehrlich was a piece by actress Alexandra Paul, who argued that Ehrlich’s “only have two” plan—which would merely hold population constant—was madness. She insisted that “we must work to lower the world population to 2 billion.” Meaning that of every ten people alive today, she wants seven scrubbed from the face of the earth.
Ehrlich’s intellectual authority stems from a book he wrote in 1968 which claimed that overpopulation would kill “hundreds of millions” of people in a matter of months. Paul’s derives from the fact she once played a lifeguard with skin cancer on a Very Special Episode of Baywatch. It is difficult to say which is the bigger fool.
Then again, foolishness envelops nearly every popular discussion of demographics these days.
To understand what 7 billion people means, it’s useful to have a sense of population history. It took nearly 500,000 years for the world’s population to hit 5 million, which it did some time around 8,000 b.c. Human life was plenty nasty and brutish back then, but it was the shortness that mattered most. The reason it took so long to get to 5 million was that it was devilishly hard to keep 5 million people alive all at once. But the advent of agriculture improved access to food, which produced gains in health and longevity, which led to a pickup in the rate of population growth: From 8,000 b.c. to the age of Julius Caesar (45 b.c., give or take) the world’s population grew to somewhere in the neighborhood of 300 million.
That growth rate continued more or less from Caesar, through the Middle Ages, until about 1750—bringing the total number of people on our little blue ball of mud to 800 million. But with the 18th century, the pace began to pick up again. This time by a lot. We crossed the threshold of 1 billion around 1825. And while it took thousands of years to get a billion people alive at the same time, it only took another 100 years to get to 2 billion, which is where we stood in 1925. The third billion was added even faster: We hit that milestone in 1960 and have been off to the races ever since.
But the post-1750 population explosion was not caused by more babies being born. It was the result of declining mortality. As nutrition, sanitation, and medicine improved, people began living longer. In ancient Rome, life expectancy was about 25 years. In 19th-century England it was 40 years—an increase of barely 60 percent over the course of 2,000 years. Since then, the average life expectancy in the first world has just about doubled in less than two centuries. As demographers Nathan Keyfitz and Wilhelm Flieger once sardonically noted, the explosion in population after 1750 was “due to death control’s exceeding birth control.” Or, as Nicholas Eberstadt put it, people didn’t suddenly start breeding like rabbits; they stopped dying like flies.