Over-Population? Under-Population

Last week Raúl Grijalva (D-AZ), chair of the House Natural Resources Committee, introduced the Extinction Prevention Act, which will provide resources to protect some of the most imperiled wildlife species in our country. Grijalva wrote that "More than one million plant and animal species are at risk of extinction-- and species of all kinds are already disappearing at an alarming rate due to human activity. Among the species at the highest risk are those considered less 'charismatic' because support for the protection of these species has been underfunded for decades." His bill will give little thought-about species like North American butterflies, various Pacific Island plants, freshwater mussels and Southwest desert fish a fighting chance to survive the extinction crisis.

When I was in high school, we were taught about a theory of disastrous population growth-- Malthusianism-- named for Thomas Malthus, a paragon of conservatism, an English cleric and economist born in 1766. The general idea was that technology would increase food production which would in turn increase population growth until the population would again begin suffering from want and, ultimately, mass starvation. Sustained progress was impossible because population growth would wipe out progress. He wrote that "The power of population is indefinitely greater than the power in the earth to produce subsistence for man." Charles Dickens' character Ebenezer Scrooge, who felt fine about refusing to donate to the poor, represented the ideas of Malthusianism in A Christmas Carol. Today, modern day Malthusianists believe that unchecked population growth will eventually outstrip resources and that population growth must be curbed.

Over the weekend, NY Times writers Damien Cave, Emma Bubble and Choe Sang-Hun reported that the world population will soon be declining-- with fewer babies' cries, more abandoned homes and changes on the horizon "that are hard to fathom... All over the world," they wrote, "countries are confronting population stagnation and a fertility bust, a dizzying reversal unmatched in recorded history that will make first-birthday parties a rarer sight than funerals, and empty homes a common eyesore. Maternity wards are already shutting down in Italy. Ghost cities are appearing in northeastern China. Universities in South Korea can’t find enough students, and in Germany, hundreds of thousands of properties have been razed, with the land turned into parks. Like an avalanche, the demographic forces-- pushing toward more deaths than births-- seem to be expanding and accelerating. Though some countries continue to see their populations grow, especially in Africa, fertility rates are falling nearly everywhere else. Demographers now predict that by the latter half of the century or possibly earlier, the global population will enter a sustained decline for the first time. A planet with fewer people could ease pressure on resources, slow the destructive impact of climate change and reduce household burdens for women. But the census announcements this month from China and the United States, which showed the slowest rates of population growth in decades for both countries, also point to hard-to-fathom adjustments." Anti-Malthusianism? China's population is expected to fall from 1.41 billion now to about 730 million in 2100. In Japan adult diapers now outsell ones for babies.

The strain of longer lives and low fertility, leading to fewer workers and more retirees, threatens to upend how societies are organized-- around the notion that a surplus of young people will drive economies and help pay for the old. It may also require a reconceptualization of family and nation. Imagine entire regions where everyone is 70 or older. Imagine governments laying out huge bonuses for immigrants and mothers with lots of children. Imagine a gig economy filled with grandparents and Super Bowl ads promoting procreation.

...The 20th century presented a very different challenge. The global population saw its greatest increase in known history, from 1.6 billion in 1900 to 6 billion in 2000, as life spans lengthened and infant mortality declined. In some countries-- representing about a third of the world’s people-- those growth dynamics are still in play. By the end of the century, Nigeria could surpass China in population; across sub-Saharan Africa, [economically-insecure] families are still having four or five children.

But nearly everywhere else, the era of high fertility is ending. As women have gained more access to education and contraception, and as the anxieties associated with having children continue to intensify, more parents are delaying pregnancy and fewer babies are being born. Even in countries long associated with rapid growth, such as India and Mexico, birthrates are falling toward, or are already below, the replacement rate of 2.1 children per family.

At the end of last month, Steven Johnson author of Extra Life: A Short History of Living Longer and host of a PBS/BBC mini-series airing this month with the same title, penned a cover story for the NY Times Magazine, How Humanity Gave Itself An Extra Life, explaining how the average human lifespan doubled between 1920 and 2020. He wrote that "The period from 1916 to 1920 marked the last point in which a major reversal in global life expectancy would be recorded. (During World War II, life expectancy did briefly decline, but with nowhere near the severity of the collapse during the Great Influenza.) The descendants of English and Welsh babies born in 1918, who on average lived just 41 years, today enjoy life expectancies in the 80s. And while Western nations surged far ahead in average life span during the first half of the last century, other nations have caught up in recent decades, with China and India having recorded what almost certainly rank as the fastest gains of any society in history. A hundred years ago, an impoverished resident of Bombay or Delhi would beat the odds simply by surviving into his or her late 20s. Today average life expectancy in India is roughly 70 years. In effect, during the century since the end of the Great Influenza outbreak, the average human life span has doubled. There are few measures of human progress more astonishing than this. If you were to publish a newspaper that came out just once a century, the banner headline surely would-- or should-- be the declaration of this incredible feat. But of course, the story of our extra life span almost never appears on the front page of our actual daily newspapers, because the drama and heroism that have given us those additional years are far more evident in hindsight than they are in the moment. That is, the story of our extra life is a story of progress in its usual form: brilliant ideas and collaborations unfolding far from the spotlight of public attention, setting in motion incremental improvements that take decades to display their true magnitude."

How did this great doubling of the human life span happen? When the history textbooks do touch on the subject of improving health, they often nod to three critical breakthroughs, all of them presented as triumphs of the scientific method: vaccines, germ theory and antibiotics. But the real story is far more complicated. Those breakthroughs might have been initiated by scientists, but it took the work of activists and public intellectuals and legal reformers to bring their benefits to everyday people. From this perspective, the doubling of human life span is an achievement that is closer to something like universal suffrage or the abolition of slavery: progress that required new social movements, new forms of persuasion and new kinds of public institutions to take root. And it required lifestyle changes that ran throughout all echelons of society: washing hands, quitting smoking, getting vaccinated, wearing masks during a pandemic.

...Paradoxically, the epic triumph of doubling life expectancy has created its own, equally epic set of problems for the planet. In 1918, there were fewer than two billion human beings alive in the world, and today there are nearly eight billion. Demagogues sometimes rant about irresponsible birthrates in developing-world countries, but the truth is the spike in global population has not been caused by some worldwide surge in fertility. In fact, people are having fewer babies per capita than ever. What changed over the past two centuries, first in the industrialized world, then globally, is that people stopped dying-- particularly young people. And because they didn’t die, most then lived long enough to have their own children, who repeated the cycle with their offspring. Increase the portion of the population that survives to childbearing years, and you’ll have more children, even if each individual has fewer offspring on average. Keep their parents and grandparents alive longer, and the existing population swells as the surviving generations stack up. Repeat that pattern all over the world for four or five generations, and global population can grow to eight billion from two billion, despite declining fertility rates.

All those brilliant solutions we engineered to reduce or eliminate threats like smallpox created a new, higher-level threat: ourselves. Many of the key problems we now face as a species are second-order effects of reduced mortality. For understandable reasons, climate change is usually understood as a byproduct of the Industrial Revolution, but had we somehow managed to adopt a lifestyle powered by fossil fuels without reducing mortality rates-- in other words, if we had invented steam engines and coal-powered electrical grids and automobiles but kept global population at 1800 levels-- climate change would be much less of an issue. There simply wouldn’t be enough humans to make a meaningful impact on carbon levels in the atmosphere.

Runaway population growth-- and the environmental crisis it has helped produce-- should remind us that continued advances in life expectancy are not inevitable. We know from our recent history during the industrial age that scientific and technological progress alone do not guarantee positive trends in human health. Perhaps our increasingly interconnected world-- and dependence on industrial livestock, particularly chickens-- may lead us into what some have called an age of pandemics, in which Covid-19 is only a preview of even more deadly avian-flu outbreaks. Perhaps some rogue technology-- nuclear weapons, bioterror attacks-- will kill enough people to reverse the great escape. Or perhaps it will be the environmental impact of 10 billion people living in industrial societies that will send us backward. Extending our lives helped give us the climate crisis. Perhaps the climate crisis will ultimately trigger a reversion to the mean.

No place on earth embodies that complicated reality more poignantly than Bhola Island, Bangladesh. Almost half a century ago, it was the site of one of our proudest moments as a species: the elimination of variola major, realizing the dream that Jenner and Jefferson had almost two centuries before. But in the years that followed smallpox eradication, the island was subjected to a series of devastating floods; almost half a million people have been displaced from the region since Rahima Banu contracted smallpox there. Today large stretches of Bhola Island have been permanently lost to the rising sea waters caused by climate change. The entire island may have disappeared from the map of the world by the time our children and grandchildren celebrate the centennial of smallpox eradication in 2079.

What will their life spans look like then? Will the forces that drove so much positive change over the past century continue to propel the great escape? Will smallpox turn out to be just the first in a long line of threats-- polio, malaria, influenza-- removed from Jefferson’s “catalog of evils”? Will the figurative rising tide of egalitarian public health continue to lift all the boats? Or will those momentous achievements-- all that unexpected life-- be washed away by an actual tide?