In 2005 drought came to Niger. Then came locusts. Then came famine.
Even in times of plenty, Nigeriens must struggle for a sparse existence in the heart of the Sahel—the barren, southern fringe of the Sahara. Land-locked and impoverished, the country suffers the tragic distinction of ranking last of the 177 countries in the Human Development Index, a UN measure of health, education and living standards.
So when the drought sucked the land dry in 2005 (as it had in 1974), Niger had few reserves to draw on. The plague of locusts ravaged the stunted, surviving crops, food became scarce, and children began starving. Despite ample warning, wealthy countries mounted a feeble response until shamed by BBC television images of children with bellies distended by hunger.
No one knows how many died.
The drought is now gone, but another kind of catastrophe looms on the horizon. Today, there are 14.2 million Nigeriens. Tomorrow, there will be about 1,320 more. Next year there will be almost half a million more. By 2050, the Population Reference Bureau estimates there will be 53 million Nigeriens.
What no one can predict: Will there be enough food? Enough water? Enough shelter? Enough teachers? Enough medicines?
If ever the world brought forth the demographic nightmare envisioned by the political economist Thomas Robert Malthus, it is 21st century Niger. With an average of 7.1 births per woman, Niger has the highest fertility rate in the world. It offers a case study in unrestrained population growth in a drastically under-resourced environment. But Niger is hardly the only country whose population is racing down an unsustainable path. Consider Nigeria. Its infant mortality rate is 25 times that of western Europe and its life expectancy is 47 years. Already the largest country in Africa with 144 million people, Nigeria is expected to almost double its population by mid-century. Or Pakistan. Nearly one-third of its children under 5 are underweight. And that country's population is estimated to swell from about 169 million today to almost 300 million by 2050.
So, why is no one talking about population any more? And, why should they be?
In 1798, Malthus penned "An Essay on the Principle of Population," arguing that human populations tend to increase faster than their food supplies. The Malthusian vision is a brutal demographic system of checks and balances: A population incessantly outraces its capacity to sustain itself, suffering famine, misery and massive death. The idea that birth—the driving engine of population growth—could lead to massive famines and death fixed itself in the human imagination.
It's not difficult to envision cataclysm when you examine global population throughout human history. For centuries, the number of people in the world changed little. Population was limited by infectious disease and subsistence living. Then, in the 1600s or so, population began to arc upward. Essentially, it took all of human history until 1800 to reach 1 billion people. Then it took just 130 years to reach the second billion, 30 years to make the third... Since 1950, global population has more than doubled to its current 6.6 billion today.
The 20th century's spike in global population was undoubtedly aided by public health. Water treatment, vaccines, antibiotics and improved nutrition and hygiene saved countless lives and doubled life expectancy in many countries. But by the 1960s, people began worrying about a "population explosion" that would unleash a global Malthusian catastrophe. In The Population Bomb, the zeitgeist's central text first published in 1968, author Paul R. Ehrlich warned, "The birth rate must be brought into balance with the death rate or mankind will breed itself into oblivion." Even mainstream demographers in the 1970s predicted global population would reach 20 billion or so by the mid-21st century. (Current estimates forecast 9.2 billion people by then.) But a strange thing happened on the way to global disaster—birth rates began falling and the population story became more complex.
From today's perspective, Ehrlich and others' rants have a whiff of quaint hysteria—especially the predictions about developed countries. Ehrlich warned in The Population Bomb that Japan would double its 1965 population of 100 million in 63 years, but we now know Japan will never get close to 200 million people. In fact, its population will likely retreat from its current 127 million to 100 million by 2050. Russia's population is expected to drop by 23 percent by then to 109 million. Meanwhile in much of Europe, fertility rates have fallen below the replacement level, meaning the average number of children born per woman is below the 2.1 considered necessary for a constant population level.
And tumbling fertility rates were not exclusive to wealthy countries. Many other countries in Asia and Latin America have made what population experts call the "demographic transition," shifting from high birth and death rates to low birth and death rates. In Bangladesh, for example, the total fertility rate of 6.6 children per woman in 1970 has fallen to 3 (though it has stalled at about 3 for more than a decade). Iran's total fertility rate plummeted from 6.5 in 1980 to 2.0 today.
There is no single reason for the falling fertility rates in so many different countries, but demographers point to changes in women's status and increased employment opportunities and education, older ages of marriage, more and better family planning choices, aggressive policies in countries like India and China, and so on.
As the fertility trends became manifest in the late 1970s through the 1980s, population issues slipped off the global health radar screen. (One indicator: Population is not mentioned among the UN's eight Millennium Development Goals, which seek to reduce poverty, improve maternal and child health and achieve other goals by 2015.) Yet global population overall continues to grow and populations of specific regions are experiencing sharp rates of increase. Even the lowest estimates predict that by 2050 there will be more than 8 billion people on earth. "You think, what is the world going to be like with roughly two more Indias on earth," says Duff Gillespie, a professor of Population, Family and Reproductive Health (PFRH) and formerly USAID's most-senior career professional in global health. "We are not at the catastrophic stage yet, but we potentially are approaching it unless we do something.
"The world is much more complex than the 'population bomb or no bomb,'" he says. "Static or declining population presents real problems for Japan, for Germany, et cetera, that have to be dealt with. That's obviously a markedly different problem than that faced in Nigeria, Pakistan or Ethiopia where you have the frightening prospect of very poor countries having twice as many people as they now have in your lifetime. In a place like Ethiopia, it's right on the cusp. In just about 28 years, they will go from 75 million people to 140 million, and you think, How is that going to work?"
As burgeoning populations in Ethiopia, Nigeria, Pakistan and elsewhere can attest, the population problem did not magically resolve itself. "The issue of rapid population growth is still important, it's just become more important for certain parts of world," says Amy Tsui, director of the Bill and Melinda Gates Institute for Population and Reproductive Health at the Bloomberg School. "Sub-Saharan Africa and parts of the Middle East are relatively impoverished and have low rates of female literacy. When you have poor gender equity, that also challenges solutions to managing reproduction. Those places are going to grow quickly. Our attention is now drawn to those regions."
At special risk are countries with a large percentage of young people yet to enter childbearing years—such as Kenya, Pakistan, Yemen and Laos. Demographers know that such states have "population momentum" that can launch a baby boom leading to sharp growth in population in subsequent decades. Even countries with a natural annual increase of 2 percent must prepare for dramatic changes in a short time. Laos' annual growth rate of 2.4 percent means that its population will double in just under 30 years. Niger's 3.4 percent rate will double its population in just over two decades.
Demographers take the long-term view. How many mouths will need to be fed in 50 years? Will there be adequate schools for the population? How do you secure a sustainable population mix of productive adults who can provide for a dependent population of the very young or the very old?
But population has immediate effects on the health of the society and the individual. "Anybody doing anything in international health has to be concerned about population. Patterns of fertility affect how well any of our interventions do," says Peter Winch, an associate professor of International Health. "In some ways if we ignore population issues, then all the work we do is being undone."
To reduce mortality of children under 5, for example, the standard public health tools include safe drinking water, good hygiene, better nutrition, adequate vaccinations and so on. But another key method: birth spacing. Increasing the time between births in a family not only reduces the number of children born to each woman, but it enhances a child's likelihood of survival. With finite resources, having fewer children means each child is likely to have more food, health care and school fees available for him or her. "Everything works better if you have birth spacing and a smaller family size," says Winch, MD, MPH '88.
The most immediate benefit of reducing fertility is that it saves women's lives. To communicate this idea to the developing country health professionals he trains, W. Henry Mosley asks them what is the number one cause of maternal mortality.
"They say eclampsia or hemorrhage. I say, 'It's pregnancy. You can't have maternal death unless a woman's pregnant,'" says Mosley, the former chair of the School's Department of Population Dynamics (a forerunner of what is now Population, Family and Reproductive Health). He notes that up to half of pregnancies in some countries are unintended. Robust family planning programs, he argues, would reduce maternal mortality. "We could save women's lives if they were not having so many children," he says. "If half of all pregnancies are unintended why are [countries] investing so much money in building maternity hospitals? It's like saying, 'Thousands of kids are dying of measles; we need more hospitals.' I say, why not just vaccinate them?"
