Scientific models warning us about unchecked population growth have been around for hundreds of years, most notably from the reverend Thomas Malthus in the late 18th century who concluded that “the power of population is indefinitely greater than the power in the earth to produce subsistence for man.”
More recently, a work that sparked ethical questions over whether couples ought to have children came in 1968 from Stanford professor Paul Ehrlich. His book, The Population Bomb, sounded an alarm that there would not be enough food to support humanity over coming decades. He predicted famines in the 1970s would kill hundreds of millions of people and only stringent birth control measures could be the solution. When The Population Bomb became a bestseller, overpopulation was dubbed the leading environmental crisis of our time and couples at home and abroad began to reconsider whether they would have children at all.
These dire predictions didn’t come to pass. Five decades after The Population Bomb’s publication, average calories consumed per person have risen in populous countries such as India and China. The Green Revolution made it possible to grow more food so that where and when famines do occur today, they are largely the result of distributional shortcomings rather than an inadequate food supply.
Since the 1960s, global fertility rates—the number of live births per woman—have decreased dramatically, with no stringent birth control measures required. Scientists now predict that the human population will peak within this century, somewhere around 10 billion, before declining for the first time in modern history.
I’m not going to suggest that the errors in previous population models were entirely due to being created by men, but we now know that those responsible (mostly) men didn’t anticipate the way women would opt to have fewer children when their circumstances changed.
During the last half-century, in both developed and developing nations, more women were educated, joined the labor force, and had access to birth control, making better family planning possible. Meanwhile, scientific innovations like antibiotics and vaccinations kept families healthier. As a result, women all over the world chose to have fewer children. The global fertility rate has fallen from close to five live births per woman in the 1960s to about 2.5 births today and will continue to decrease in the future. It remains high in places like sub-Saharan Africa and Southeast Asia where child mortality is high and health conditions are poor.
Still, Ehrlich and his predecessors were not entirely wrong. We do face many real challenges, but not every person has the same impact on Earth. The real danger isn’t in sheer number of humans, but how specific individuals and societies use resources.
Consider global energy consumption, which is directly related to food, water, and climate change: On a per capita basis, the average Texan consumes about twice as much energy as the average American, four times as much energy as the average person in the United Kingdom, and eight times as much energy as the average person in China.