MINORS WITH MAJORS

Precocious teenagers like Joe Kiani are a rare sight on college campuses—and getting rarer. Fewer than 1% of university students in the U.S. are younger than 18. Sixty years ago, that number was six times higher, with “academic redshirting”—parents delaying a child’s entrance into kindergarten to give them a later advantage—not yet in fashion. Back then, “everything was ‘the smarter you are, the faster you should go,’ ” says Harvard economic historian Claudia Goldin. “Now, it’s the opposite.”