Three millennia ago, King Solomon wrote that “folly is bound up in the heart of a child.” Seven centuries later, Aristotle characterized youth as “hot-tempered, carried away by impulse, unable to control their passion.” Comparatively recently, the erstwhile optimist and American prophet of a new Enlightened age, Thomas Jefferson, lamented in his retirement that “the useless [self-]sacrifice of the generation of ’76 to acquire self-government and happiness to their country is to be thrown away by the unwise and unworthy passions of their sons.”

It has ever been and will ever be thus. The rueful old lament about the apparent decadence of the young. In her new book Generations, social scientist Jean Twenge suggests an obvious explanation for this ageless trend: “It might be because they [are] always right. With technology making life progressively less physically taxing, each generation is softer.”

Twenge rejects the cyclical theory popularized in the 1990s by William Strauss and Neil Howe, whose model emphasized the defining influence of major events on generational identity. They identified four recurring generational “mood era” types, mirroring a loosely cyclical pattern in Anglo-American history. This historical pattern culminates in “High” eras of strong institutions and collective consensus, then followed by “Awakening” eras of greater personal autonomy in which institutions may be critiqued. This produces an era of “Unravelling,” characterized by strident individualism that eventually produces an era of “Crisis” defined by institutional collapse. The subsequent impulse to rebuild then resets the cycles. Strauss and Howe’s corresponding generation types were the “Prophets,” the complacent children of post-Crisis abundance, who critique institutions they take for granted; “Nomads,” born during periods of Awakening and shaped primarily by social chaos; pragmatic “Hero” types, born in times of Unravelling and inclined to energetic leadership by an abundance of personal freedom; and “Artists,” compelled by the post-unraveling crisis to imaginative social and institutional regeneration.

In these terms, the Great Depression and Second World War formed the dual crisis in which a collectively-minded generation formed the strong institutions of America’s mid-century consensus. These were the “civic joiners” from whose participatory spirit Robert Putnam traces the subsequent decline in Bowling Alone. The well-fed children of post-war abundance, then, became the “Prophetic” anti-establishment Hippies of the ’60s, and so on. If such a theory strikes readers as overly neat and comprehensive, Twenge agrees. Indeed, many of Strauss and Howe’s predictions have already failed. The generation coming of age at the end of the ’90s, for example, did not revert to the interwar generation’s civic-mindedness, but continued now-sustained trends of ever-greater social fragmentation and isolation.

Twenge admits that her own “technology model” “is not completely comprehensive—there are certainly some causes of generational change not included here.” But this strengthens rather than weakens her work. Strauss and Howe may have constructed a model too fragile in its encompassing breadth. Twenge seeks only to trace underlying causes of consistently discernible trends. She acknowledges that “technology does not always cause generational change directly,” but posits that if we trace seemingly endless chains of causes downward, “for generational changes, [the underlying] cause is technology.” Thus, though never the only important causal impulse, technology causes social change both directly and indirectly, and is the most persistent driver of such change over time.

The broad groups into which Twenge sorts social trends illustrate this twofold operation of technology as both a direct and indirect driver of change. The most lasting and determinative social trends of the past century, Twenge labels either “individualism” (i.e., shifts to greater personal autonomy and diminished sense of obligation) or a “slow-life model” (i.e., taking longer to reach milestones of maturity such as marriage and/or full-time employment). For young adults in recent generations, social norms and personal expectations differ from their grandparents at the same age. Why? Perhaps because they weren’t required to work as teenagers in order to contribute to the family budget (a “slow-life” model). Perhaps that time was used instead to build their resume for college applications (a form of “individualism”). Yet, such formative social trends are often indirectly technological. A prolonged childhood free of economically productive labor requires material abundance. Smaller families in which parents invest more social and financial resources in each child reflect new birth-control technology. “Individualism,” Twenge writes, “can’t exist without modern technology. Every individualistic country in the world is an industrialized nation.”

Other changes are more obviously direct (though, like the technological innovations driving them, are seldom easy to predict). Writing at the dawn of the twenty-first century, Putnam expressed tentative optimism that the “Worldwide Web” might revive participatory civil discourse in a new public forum of illimitable possibility. Lolz, nope! Two decades later, we’re all inside watching Netflix. Wisely, then, Twenge devotes far more space tracing past change than predicting future trends. Generations is painstakingly researched, presenting more than 400 original charts and graphs. These depict sophisticated cross-correlated analyses of twenty-one major national datasets from federal bureaus, research universities, and the like. The datasets are regular (often annual) surveys reaching back as far as the 1940s and encompassing 40 million individuals.

Twenge endeavors to make this feat of scholarship acceptable to the largest possible audience with a tone of political neutrality. She isn’t always successful, occasionally betraying the left-of-center sensibilities typical to her field: Americans in 2020 failed to “come together collectively to face the challenge of the [Covid] pandemic [with a] strong sense of patriotic duty and rule-following.” Declining levels of trust in public institutions and news sources largely “explain the state of the country, … why misinformation spread so widely, [and] the results of the 2020 election were questioned.” Pronoun sharing isn’t going anywhere because “it’s practical!” But such instances are relatively few, and Twenge also makes some politically heterodox observations that may rankle progressive readers. She notes, for example, that declining religious participation leaves a basic human need increasingly unfilled. For many, the void is filled by their “belief in equality across race, gender, sexual orientation.” Though not observed unapprovingly, the implicit categorization of “Rainbow Coalition” dogma as a substitute cult is not an admission found in the Left’s authorized catechism.

Mostly, though, Twenge’s tone is quite neutral. Indeed, this may be both the strength and fatal weakness of her book. Generations is compendious but easily readable. The main point of each section is usually clear from the first paragraph and a glance at the numerous charts. Interested readers may explore the point in greater granularity or pass to the next section without losing whatever passes for a narrative arch in a work of social science data analysis. But, perhaps to avoid alienating potential readers in the increasingly fragmented society she describes, Twenge offers very few firm conclusions on the meaning of social trends, and no prescriptive dicta. Without a firm argument, Generations may fail to earn the longevity best produced by a compelling appeal to readers’ moral imagination. That would be a shame. If only as a detailed reference guide to the present, it deserves to be widely read.

Each substantive chapter describes general trends characterizing the six commonly demarcated generations currently living in the United States: the “Silents” (born 1925–45), Boomers (b. 1946–64), Gen X (b. 1965–79), Millennials (b. 1980–94), Gen Z (b. 1995–2012)—to which Twenge has tried without success to give the more aptly descriptive name “iGen”—and the youngest generation, whom she calls Polars (born since 2013). A concluding chapter tentatively predicts some future trends. What are some of the trends Twenge identifies in each of these generations? More to the point of her theoretical model, what major technologies have defined them?

Despite taking their name from a 1951 Time magazine pronouncement that “the [present] younger generation … does not issue manifestos, make speeches, or carry posters,” Twenge finds that Silents led most of the reform movements commonly associated in popular memory with Boomers. Silents dominated Earl Warren’s Supreme Court, Congress, and other institutions of government in the Civil Rights era. On average, they profess “more trust in other people” and are “less cynical than the generations that followed them.” Born in wartime, their habits of civic participation were lifelong. This is despite their younger average age, compared to all subsequent generations, of marriage and childrearing: domestic obligations are now commonly cited as limiting availability for public engagement.

In contrast, Boomers are the “me generation”—or, rather, the pioneers in a sequence of increasingly self-absorbed generations. Boomers started the trend of declining membership in religious institutions combined with increasing rates of self-reported “spirituality.” They wrote self-help books containing previously uncommon words such as “unique” and “identity,” and they attended self-enlightenment seminars in droves. They had premarital sex, divorced more frequently, and had fewer children in their ’20s but more in their ’30s. Most of the trends they started have grown more pronounced. Their youth was the golden age of the motor car: they got driver’s licenses as soon as they could and enjoyed cheap gas and uncongested roads.

Compared to Boomers, and more so to Silents, Gen Xers first had sex at younger ages, married later, and participated in civic life less. They recall childhoods defined by parental divorce and the absence of adult supervision, though Twenge suggests that collective memory may overstate the extent of both. One definitive technology was television, which produced “a more unified pop culture than has existed since.” Later, there were computers: “Every Gen Xer has a story of arguing with a Boomer over why something can be done on a computer rather than on paper.”

Boomer parents—perhaps full of self-help books and spiritual seminars—instilled in their Millennial children remarkably high rates of self-esteem, though often “without any particular basis.” Ironically (or predictably?), as these self-confident youths reached maturity, “depression … started to soar.” Notwithstanding, this collectively low mood and the popular narrative that the timing of economic trends has disfavored them, Millennials have consistently enjoyed higher average income than Gen X did before them. Technologically, they “came of age as the internet was blossoming.” Old enough to remember rotary phones, they are the bridge generation between their Boomer parents and “digital native” children. But if forums for online chat proliferated, Millennials are yet to fulfill Putnam’s hope for a new era of civic participation; that decline has continued.

Twenge’s previous research focused on Gen Z, and unsurprisingly, her insights feel most pointed and lucid here. Conservative-minded readers may be likelier to share my alarm and pessimism at the trends described in her final chapters. Though she remains almost exclusively descriptive, the undertones of warning absent from earlier chapters are strongly suggestive. Even in their teenage years, when Millennials professed heroic self-belief, Gen Z is lonelier, more depressed, and more suicidal. As teens, Gen Zers spend an hour less per day socializing with friends than Gen X did. This owes largely to the defining technology of their lives: screens. In 2021, Gen Zers spent 8.5 hours a day using screens in school and at home. Nearly half of 8th graders spend three hours a day on social media. Millennials had less sex as teenagers than Gen X, partly due to greater rates of adult supervision. Gen Z has continued this trend, despite their apparently great interest in the idea of sexuality—as young adults, 1-in-6 identify as something other than straight. Preferably as declining rates of teenage sex may be, underlying causes such as anxiety-ridden reclusiveness and the feeling that “porn … [is] a replacement for real-world sex” are not healthy trends.

What has happened to Gen Z is, in truth, happening to us all. It is only that the effects are most noticeable and devasting in the lives of the youngest. A great cultural Rubicon was passed with the advent of the smartphone. Echoing the work of fellow social scientist Jonathan Haidt’s Coddling of the American Mind, Twenge highlights abundant data showing that “something clearly went wrong in the lives of teens around 2012,” the year that smartphone ownership passed fifty percent. It is difficult to overstate how pervasively Gen Z and now Polars relate to one another through their phones. They share videos, memes, and such “content” as a form of social interaction even when physically present together. Their social life goes everywhere with them, even home; unlike their parents at the same age, they are never truly alone or in a quiet atmosphere. Twenge calls this rise of smartphone culture “the fastest adoption of any technology in human history.” Teens are more depressed because—thanks to their phones—they get less sleep, have fewer real friendships, bully one another, and obsess over unrealistic physical images.

Older readers may not be on TikTok, but chances are that we all use our phones in similarly deleterious ways. So as Jean Twenge eschews prescriptive advice, I will conclude with some of my own: Go and drop your kid’s smartphone in the nearest toilet. Then drop yours.