The SDT began emerging in the West after World War II. As societies became richer and goods cheaper and more plentiful, people no longer had to rely on traditional families to afford basic needs like food and shelter. They could look up the Maslovian ladder toward “post-material” goods: self-fulfillment, exotic and erotic experiences, expressive work, education. Values changed to facilitate these goals. People in wealthy countries became more antiauthoritarian, more critical of traditional rules and roles, and more dedicated to individual expression and choice. With the help of the birth-control pill, “non-conventional household formation” (divorce, remarriage, cohabitation, and single parenthood) went from uncommon—for some, even shameful—to mundane. Lesthaeghe predicted that low fertility would also be part of the SDT package, as families grew less central. And low fertility, he suggested, would have thorny repercussions for nation-states: he was one of the first to guess that developed countries would turn to immigrants to restock their aging populations, as native-born young adults found more fulfilling things to do than clean up after babies or cook dinner for sullen adolescents.