The same technology promising to make us smarter is preventing the one thing our brains need to actually think. For most of the 20th century, humanity got demonstrably smarter. In a phenomenon known as the “Flynn Effect,” average IQ scores climbed three to five points a decade across dozens of countries, progress fueled by better nutrition, healthcare, and education. Then, starting with people born after the mid-1970s, it shifted. By the late 1990s, decades of rising IQ scores began to level ...