Short answers, pulled from the story.
Walking among tetrapods originated as early as 420 million years ago with air-breathing fish that could walk on the ocean floor. Little skates propel themselves by pushing off the seabed with pelvic fins before vertebrates set foot on land.
Human walking functions as an inverted pendulum gait that saves approximately 65 percent of energy used through gravity converting potential energy into kinetic motion. Motion capture studies show the center of mass reaches maximum height at mid-stance while dropping to minimum when legs spread apart.
The Centers for Disease Control and Prevention reported that those with diabetes who walked two or more hours weekly lowered mortality rates by 39 percent. A 2023 study in the European Journal of Preventive Cardiology found walking at least 2,337 steps reduced cardiovascular disease death risk.
The first purpose-built pedestrian street in Europe opened as the Lijnbaan in Rotterdam in 1953. Stevenage became home to UK's first pedestrianized shopping center in 1959 and Central Copenhagen converted from car traffic to pedestrian zone in 1962.
Racewalkers at the World Cup Trials in 1987 demonstrated competitive speeds exceeding 15 kilometers per hour over distances up to 50 kilometers. The absolute limit on individual walking speed occurs when upward acceleration exceeds gravitational force causing airborne vaulting.