Marked by Time

I open the book with two children from our long-term study, Darnell and Andre, who at first glance seemed destined to lead similar lives. They grew up in the same city, at the same poverty level, with similar family and neighborhood backgrounds. Yet they held very different tickets in the birth lottery of history. Andre was born in the early 1980s; Darnell in the mid-1990s. Though alike in background, they came of age in different social worlds.

Andre’s cohort grew up amid the rise of drug-related violence. They became teenagers during the murder epidemic of the early 1990s and lived through rising incarceration and aggressive drug policing. By contrast, violence had plummeted when children born in the mid-1990s entered adolescence, and drug arrests fell by roughly 90 percent between 1995 and 2020. Darnell’s cohort was fortunate in other ways as well. Lead exposure, which is known to impair child development, declined sharply. By the time they turned 25, incarceration had dropped to its lowest point in more than a quarter century.

These two individuals capture the story of their birth cohorts. By age 20, youth born in the mid-1990s were arrested at about half the rate of youth born just a decade earlier, in the early to mid-1980s. The younger cohorts were also less likely to witness gun violence or to use guns as adults. 

These cohort inequalities were not explained by race, family structure, poverty, self-control, or a host of other factors. Large-scale social change, not the usual suspects, distinguished the life trajectories of Andre’s and Darnell’s cohorts. 

Another surprising finding is that the decline in arrest rates between cohorts was strongest for the most disadvantaged young people, particularly poor Black youth. Even among the poorest children, things got much better. That runs against the familiar narrative of unbroken societal decline.

My hope is that readers will come to see social change—and the unfolding of our lives—in a new and more constructive way. Rather than fixating on predicting individual criminality or a supposed criminal character, we should focus on building the institutions and environments that prevent crime and help us meet the unexpected challenges that the future will bring. Backed by long-term data, Marked by Time presents a vision for what it might mean to build such a future.

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