The nineteenth and twentieth centuries have been characterized by a massive decline in fertility, beginning in rich western countries and spreading all over the world. It is a transformation that is still underway in poor countries today.

Technological advances have, over the same period, radically decreased child mortality and increased life span. Modern parents need not have many children to ensure that one or two survive; almost all children survive to reproductive age. But Darwinian genetic interests cannot explain the modern decline in fertility (if Darwinian interests dominated, fertility should increase with increased survival, as observed in many historical elites). Rather, the fertility decline to present levels is mostly an economic response to the changing value of children, and to the changing economic relationship of parents and children. The economic transformation is not spontaneous, but the product of cultural transformation through education.

The economic value of children has decreased, but this is not the most important cause of the fertility decline. The transformation of countries from predominantly agricultural to predominantly urban reduced the value of children, especially where the industrial employment of children was restricted. Each child’s labor contributed positive value to a family farm or cottage industry, but in an urban setting, children began to have negative economic value. Indeed, the fertility decline correlates somewhat—though not perfectly—with the transformation from agrarian to city life.

But the fertility decline is not merely the product of a price effect of people having fewer children because children are more costly. Children are not normal goods (or even inferior goods, as might be surmised from low fertility among the highest income groups): they become not goods at all, but rather bundles of claims on their parents. This transformation is a culturally-controlled change in direction of the flow of resources. Before the fertility decline, resources flowed from children to parents (and even up to grandparents and kin); after the transformation, resources flowed from parents to children. In Mass education as a determinant of the timing of the fertility decline, John Caldwell argues that the vector of this cultural transformation has been mass education. He characterizes it as the replacement of “family morality,” in which children are expected to “work hard, demand little, and respect the authority of the old,” with “community morality,” in which children are dependent on their parents to become future productive citizens (perhaps even upwardly mobile) for the good of the country.

Caldwell identifies five mechanisms by which education reduces fertility by reshaping the economic relationship of parents and children. First, education reduces the ability of a child to work inside and outside the home – not just because school and studying take up time, but also because the child’s student status makes others reluctant to enforce traditional duties. Second, education increases the expense of raising a child, again not just because school is expensive, but because education increases a child’s demands on his parents for non-school expenses in a manner Caldwell describes as unprecedented. Third, education increases the dependency of children, reframing a formerly hard-working, productive child as primarily a future producer and citizen. Fourth, schooling speeds up cultural change and creates new cultures. Finally, fifth, in the developing world education specifically transmits the values of the Western middle class, which is contemptuous of traditional “family morality” as described above.

In each country, before the demographic transition, children were essentially the property of their parents. Their labor could be used for the parents’ good, and they were accustomed to strict and austere treatment. Parents had claims not only to their children’s labor in childhood, but even to their wealth in adulthood. To put it crudely, marrying a wife meant buying a slave factory, and children were valuable slaves.

After the transition, mediated by mass education, children were transubstantiated into persons. Their individual status increased, and parents no longer had a culturally recognized claim on their labor. Children’s culturally supported entitlements increased, including not only food and clothing, but also study and play time. Their relationship with their parents became more egalitarian and friendly, their treatment less strict.

But children do not exactly own themselves in the present situation: the government has claims on their future earnings, through taxation and other mandatory payments (and, increasingly, education loans). In essence, mass education is a communist transformation: individually-owned “goods” (children) are brought under national ownership, and returns from children flow to the country as a whole (through tax-based entitlement programs), rather than individually to their previous “owners.” When farms are communally owned, production suffers and famine results; when children are communally “owned,” fertility decline results. Social Security programs likely reflect this: the government provides (often poor quality) assistance to old people in place of their children, while undermining their direct claims on their children for assistance in old age.

There is another, related shift in the direction of resource flow during this time: resources (including labor) stop flowing from wives to husbands, and instead flow from husbands to wives, as a result of Western-style female liberation. This trend is also a result of education, and amplifies the trend toward low fertility. Since the emancipation of women frequently lags the child-parent economic transformation, it does not seem to be the first cause; Japan’s fertility decline occurred in the post-war 1940s, tracking the forced implementation of Western-style mass education, but women’s opportunities for education, professional employment, and political participation continue to be limited and were much more so in the 1940s, despite American-imposed female suffrage. Few would describe Japan in the 1940s as a hotbed of feminism and licentiousness, yet its fertility declined steeply and has not recovered since.

It does not seem that female emancipation was the primary cause of the fertility decline, although Caldwell details the many ways in which it amplifies the existing trend once established. It has long been noted by charitable organizations in poor countries that when resources are distributed directly to women, they are more likely to be spent on children’s needs, and when distributed to men, more likely to be spent on the men’s status and drug needs. Education and control of finances by women embrace and amplify the new flow of resources from parents to children, rather than children to parents. Educated children are expensive and demanding children, and an educated wife makes them more so. Higher education and labor force participation by women limits the time available for child bearing and rearing, especially during the more fertile periods of women’s lives.

Caldwell reports that the transition in Ghana was underway in the 1960s, and in many cases families had both children who had been to school and children who had not. Children who had been to school were treated drastically differently from their “illiterate siblings,” though they were often oblivious to this fact. That the transformation could be observed at this level—the treatment of children within the same family—suggests that changes in the status of children (expected to play, to devote time to studies, to be dependent on their parents) precede and underlie changes in gender roles.

Parental control of children’s sexuality and marriage does not last long once children have been transformed into persons, and with it goes the right to collect bride price, formerly a compensation for the burden of raising a female child. Even in dowry societies, dowry is increasingly supplemented or replaced with education, Caldwell notes, as a wealthy but uneducated woman is not seen as marriageable by Westernized elites. But this is only one aspect of the fertility transformation, rather than the prime driver; in a few countries, parental control over children’s marriage survived long after the fertility decline.

Industrialization negatively affected women’s productivity earlier than men’s productivity, usurping traditional female work from spinning and weaving to food production. The declining economic value of both women and children necessitated that they be granted symbolic value instead. The “cult of motherhood” beginning in the 1820s in England was a response to this – granting motherhood special status as a full-time occupation, and as a fulfilling life’s work. Similarly, as the economic value of children fell, their sacred value increased. Both of these value transformations are not spontaneously occurring, but culturally transmitted; and the vector for their transmission is mass Western-style education. Literature for the masses, from pamphlets of the 1820s to television, also plays a major role.

For many decades prior to the 1970s, the value of an adult (in terms of his productivity and real wages) rose; but the economic value of even an adult person has fallen in recent decades, as real wages attest. Fertility trends do not track the economic value of a human, as they might be expected to do if parents could realize a portion of the value of their offspring. Fertility trends can only respond to that share of the value of a person that a “producer of children” can recover – and the memetic transformation occasioned by mass education has essentially eliminated this share. Governments, meanwhile, claim an ever-larger share of their citizens’ resources. And accessing parental money by catering to (and creating, if necessary) the “needs” of children remains a profitable business plan. The producers of children have not benefitted from their children’s adult productivity in a long time, just as farm workers in China during the Great Leap Forward did not benefit from their labor.

So why did people used to have children? It’s hard for us even to imagine, but children used to be valuable—they used to be much more like slaves or farm animals, which are both very valuable. They were also treated much more like slaves, with patriarchs (at least) maintaining distance from children, as Caldwell notes. Consider the history of the study, compared to the lowly and shameful “man cave,” for a sense of the old style of family relations. A wife was not only a valuable RealDoll, but also a valuable slave factory. Making a new “person”—on which the state has claims, but you do not, and toward whom you have (class-dependent) obligations—is a much less economically attractive proposition than making a new slave.