In less than two decades, older people are projected to outnumber children for the first time in U.S. history. America is not alone in that trajectory. With all First World countries below replacement levels and many Third World countries with even steeper rates of decline, demographers project that by 2065 the entire world will be in population decline. The implications of a childless and aging population for our economy, health care system and “every other system we hold dear” are both imminent and dramatic. New life provides the essential capital on which all modern economies are built.

But children do more than provide human capital. When renowned Harvard sociologist Carle Zimmerman published his sweeping analysis of the rise and fall of great civilizations, he made a striking conclusion: The defining feature of civilizations at their peak of creativity and progress was their orientation to children, specifically the bearing and nurturing of children within families.

As a culture we tend to focus on how much children depend on adults, and how challenging that “neediness” can be. We talk much less about how much we depend on children. Yet if Zimmerman’s extraordinary feat of research is right, we need children even more than they need us.

Consider how the presence of children orients societies to policies and practices that tend to benefit the whole of society — alcohol and drug laws, safety precautions, tax policies, broadcast ratings and standards. Even our cultural orientation to marriage results from the fact that helpless children come from sexual relations between adults. Society cares about marriage in order to give a baby the enduring bond and long-term care of its mother and father. The “ultimate beneficiary” is society itself, as marriage is strongly associated with an “incremental increase in happiness, health and productivity.”

Consider that men who marry and have children tend to “work harder, smarter and more successfully” than their unmarried peers. As they care for their children they experience biological changes associated with greater attentiveness to the needs of those they love, and less vulnerability to distractions. Mothers similarly experience biological changes from bearing children that appear to have lasting benefits. For both fathers and mothers, children mean greater religious involvement, and a return to faith.

Zimmerman’s remarkable colleague, Pitirim Sorokin, described this process as “the marriage-family school.” The task of loving and nurturing children “stimulate married persons to release and develop their best creative impulses. For surely the mission of molding their own … is as ennobling as the creation of a masterpiece.”

As he noted, this is not true just for the educated elite. The motivating influence of children is powerfully described in Kathryn Edin’s extensive research of single, low-income mothers, many of whom felt children had rescued them. In their words, “My kids have matured me a lot. If I hadn’t had them and gone to college, I probably would have gotten lost because of the drugs and stuff."

"I’d have no direction if I hadn’t had a child."

"There was no point to live for."

"Now I feel like I have a beautiful little girl!”

This is not to say that children always feel like a “rescuing” gift. Indeed, as Michael Novak aptly described, “The raising of children … brings each of us breathtaking vistas of our inadequacy.” As painful as that can be, it is also what makes children a critical gift. As Novak continues, “My bonds to them hold me back from many sorts of opportunities. And yet they are, I know, my liberation. They force me to be a different sort of human being in a way in which I want and need to be forced.”

Indeed, the morality of love, devotion and sacrifice that children invite from us is in Sorokin’s words, the very “fountainhead” of “interhuman solidarity.” After all, “charity or love does begin at home, at the cradle of the helpless baby. If there is no baby, no cradle, there can be no loving and caring parents, and no family-school to teach children the basic ABC’s of unselfish conduct toward their fellowmen and the world at large.”

In a touching passage of the New Testament, Jesus of Nazareth compares the joy of the promise of his Resurrection to the joy of a mother at childbirth — “she remembereth no more the anguish, for joy that a man is born into the world.” The joy of having children is the promise of new life — a symbol and evidence of the Easter story itself. Their presence breathes life into cultures, families and individuals.