The Death of the Fittest

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Why do humans have children? According to one, very distinguished and influential line of thought, the answer is simply instinct.

“There is no exception to the rule that every organic being naturally increases at so high a rate that if not destroyed the earth would soon be covered by the progeny of a single pair,” Darwin asserted in The Origins of Species. “Even slow-breeding man has doubled in twenty-five years, and at this rate, in a few thousand years, there would literally not be standing room for his progeny.”

Deeply influenced by Thomas Malthus’ theories of over-population, Darwin believed (and many high school biology textbooks still teach) that all organisms will breed up to the limits of their available resources if given a chance. From this premise follows Darwin’s concept of “the struggle of existence” — or as it was later popularized, “the survival of the fittest.” Whether talking about micro-organisms or man, the competition and death brought on by population pressure means only the fittest stand much chance of producing surviving offspring, which is supposed to be the prime mechanism by which evolution occurs.

Yet here is a curious fact we do not dwell upon enough. In today’s world, the best-fed, most prosperous, and seemingly “adapted” people are the least likely to have descendants. This is true even though the comparatively few children of the affluent are generally more likely to survive to adulthood and to be materially advantaged.

As with individuals, so with nations. Indeed, among many of the world’s richest, most industrialized countries, such as Japan and Germany, birthrates have fallen to well below the levels necessarily to prevent ongoing population decline. In the United States, meanwhile, close to one out of five Baby Boomers never had children, and another 17 percent only had one, despite experiencing a higher material standard of living and better health status than any generation in history.

What is going on? It’s strange that Darwin assumed that humans have a natural tendency to overpopulate unless checked by hunger, war, or disease. After all, what today’s demographers call “sub-replacement fertility” is hardly just a phenomenon of modern times. Indeed, it has always been strongly associated with luxury and abundance.

Both ancient Greece and Rome, for example, eventually found that their elites had lost interest in the often dreary chores of family life. “In our time all Greece was visited by a dearth of children and a general decay of population,” lamented the Greek historian Polybius around 140 B.C., just as Greece was giving in to Roman domination. “This evil grew upon us rapidly, and without attracting attention, by our men becoming perverted to a passion for show and money and the pleasures of an idle life.” A century and half later, Caesar Augustus was so alarmed by the reluctance of Roman aristocrats to marry and start families that he imposed stiff "bachelor taxes.”

Birthrates were declining around the globe in Darwin’s time, too, and particularly among the so-called “well bred.” Women who graduated from Wellesley between 1879 and 1888, gave birth to an average .86 children, according to an alarmed study done in 1915. The phenomenon sparked fears of what Theodore Roosevelt, Margaret Sanger, and many other progressive figures of the early 20^thcentury called “race suicide” as they watched America’s old-line, New England Puritan stock dwindle away. With the brief exception of the post-World War II period, birthrates have been falling more or less continuously around the world for as long as we have clear records, particular among the elites of rich nations. That global population has nonetheless continued to grow is explained by reduced mortality, especially these days among infants and children in the developing world.

So it’s clear that humans are not hardwired, as perhaps fruit flies are, to reproduce to the point of overpopulation. Instead, in general, the more resources humans command, the less likely they are to have enough children to replace themselves. Why is this, and what does it suggest about our future?

If we were to make a “just so” story out of it, we could well say it’s all because humans have bigger heads than other animals. The oversized heads of human beings means that giving birth to one is an uncommonly painful and dangerous ordeal. This is the uniquely human mutation known to Bible readers as the “Curse of Eve.” In the Genesis account, Eve partakes of the Tree of Knowledge and God retaliates by threatening: “I will greatly multiply thy sorrow and thy conception; in sorrow thou shalt bring forth children.”

Whether or not one accepts the Biblical account, the large human head (and the related prolonged gestation of human beings) has historically made childbearing among the leading causes of death among women, and one that still caries considerable risk. According to a recent report by Amnesty International, more than a third of all women who give birth in the USA — 1.7 million women each year — experience some type of related complication that adversely affects their health. Recently the trend has been getting worse. The maternal mortality rate has doubled in the United States over the last 20 years, to 13.3 deaths per 100,000 births. This is higher than the risk of dying in auto crash in the United States, making childbirth statistically among the most dangerous things most mothers will ever do.

Meanwhile, that same big head makes room for a big brain, which, to continue our “just so story,” has gradually allowed humans to organize knowledge-based societies of increasing complexity. That complexity, in turn, means that endowing human offspring with the skills and capital they need to navigate on their own has come to take longer and longer, often extending to more than two decades in modern times. The increasing complexity of human civilization also means that there are ever more ways to earn a living and secure support in old age without having to depend on the labor of one’s individual children.

Which brings us to the last, and most controversial, way the human head gets in the way of human reproduction: its brain is powerful enough to weigh the pros and cons of parenthood and to act decisively when they do not add up. Long before the Pill, human beings knew very well how to control their fertility. Baptismal records document collapsing birthrates among the bourgeoisie of Northern Europe starting in the 17^thcentury. There is ample literary evidence of widespread family planning before that — with strategies ranging from celibacy, non-coital sex, the rhythm and withdrawal methods, to the once widespread, fail-safe practice of abandonment and infanticide.

So if that’s the human condition, why do some people not only still have children, but desperately want them? The same Bible that speaks of the curse of Eve also speaks of the sorrows of Rachel, who wailed, “Give me children, or else I die.” My late wife, Robin, often used to speak of her identification with Rachel. As she and I tried unsuccessfully for seven years to have children, attempting ever more expensive, humiliating, and (for her) physically debilitating in vitro fertilization cycles, she sank into a depression that sometimes bordered on suicidal. With this life experience, I know perhaps better than most the pain that barrenness can bring to even the most thoroughly modern woman, and man.

Where does this pain come from? It does not, I submit, come from anything like human nature, or else it would be universal. Instead, it comes, if it comes at all, from cultural DNA. Given the high the cost of parenthood in personal health, money, and freedom, a human culture, if it is to endure, must strive to provide its members with reasons to think that they cannot be happy without children.

One way is to provide sacred texts that enjoin young adults to “go forth and multiply,” and that equate marriage and procreation with holiness. Another is to socialize parents to think that grandchildren will at last make them happy even if their own children did not, which contemporary social science says is the usual experience. As Harvard psychologist Daniel Gilbert has observed in his remarkable book, Stumbling on Happiness, the human race probably would have ended eons ago were it not for those mothers who bear false witness to their daughters (and perhaps to themselves as well) about the pains of childbearing and their own disappointments with family life.

Sustaining replacement-level fertility probably also requires that these pro-natal messages, whether they come from religion or members of one’s own family, be more or less monolithic. The big brain of the young human adult must not be allowed to encounter any reinforcement to the all too obvious thought that raising children in a long-term, monogamous relationship just might not maximize his or her happiness. In a society of small, isolated villages dominated by patriarchal clans adhering to pro-natal religious customs and family-based production, preventing such a line of thought from entering young people’s big heads was comparatively easy. In a world of urbanization, globalization, and ubiquitous television, not so much.

The very good news is that women no longer have to have four or five children just to be sure that at least two live long enough to have children of their own. The decline in infant and child mortality, in turn, has allowed for the slow dismantling of pro-natal norms that are at odds with the modern, secular idea of freedom, including segregated gender roles, prohibitions against birth control, and homosexuality.

But it now appears that in a truly secularized society in which traditional pro-natal norms eventually become vestigial (whether 3^rdcentury Rome or today’s Italy), the equilibrium point of human fertility is well below replacement rates — and all the more so when many individuals have abundant access to luxuries. This is not enough to overthrow Darwinism. But it is enough togive an important new twist to our understanding of how “survival of the fittest” actually works in civilized societies.

Yes, resource depletion has contributed to the ruin of many civilizations, as it may yet to ours. But the best available evidence suggests that it is not mindless human breeding that is responsible for overtaxing soils, forests, water supplies, and other natural resources. Advanced societies are by their nature slow-breeding.

Instead, it is more often expanded luxury that turns the cycle toward decline. This is both because the unsustainable forms and levels of production required to support sumptuary lifestyles (such as the slave-driven, soil-destroying plantation systems of the late Roman Empire) and because the well-to-do of all eras often fail to reproduce themselves.  

Remember this the next time someone tells you that you’re selfish for bringing children into the world.

Phillip Longman is a senior research fellow at the New America Foundation and Schwartz Senior Fellow at the Washington Monthly. His latest book, co-authored with Ray Boshara, is The Next Progressive Era: A Blueprint for Broad Prosperity.