Lieberman suggests humans value short-term costs and benefits more than long-term consequences—a phenomenon called “hyperbolic discounting.” Consequences are often obscured by the cultural normalization of novel or harmful behaviors, and humans often confuse comfort and well-being. To exemplify, Lieberman discusses the consequences of shoes, reading, and sitting.

The oldest sandals that have been discovered were from 10,000 years ago, and developed societies have normalized wearing shoes and have made being barefoot in public taboo. Among running enthusiasts, two extreme views—one promoting barefoot running and one condemning it—have emerged. Lieberman takes a middle-ground approach, agreeing that humans evolved to travel barefoot but arguing that they have been using shoes for thousands of years without major consequences.

Shoes offer protection and support but cause side effects like preventing callus formation, interfering with sensory perception and stability, and weakening the arches of feet and causing flat feet and plantar fasciitis. Doctors often fail to treat the underlying causes of foot pain, instead treating symptoms by recommending patients wear shoes with stiff soles and arch supports, which may create a feedback loop that perpetuates foot pain. Mismatch issues also arise when people choose stylish, uncomfortable shoes like high-heels, which can cause hammertoes, bunions, abnormal posture, and injuries, and nonporous shoe materials that promote fungal and bacterial infections.