Short answers, pulled from the story.
Walking is one of the main gaits of terrestrial locomotion among legged animals, defined as an inverted pendulum gait in which the body vaults over the stiff limb or limbs with each step. It applies to animals with any number of limbs, including arthropods with six, eight, or more legs.
In walking, only one foot leaves the ground at a time and there is a period of double-support, while running begins when both feet leave the ground during each step. The most effective test measures the center of mass at mid-stance: it reaches a maximum height during walking and a minimum during running.
The average human walking speed at crosswalks is about 5.0 kilometres per hour, roughly 1.4 meters per second or about 3.1 miles per hour. A brisk walk reaches around 6.5 km/h, and champion racewalkers can average more than 14 km/h over 20 km.
Footprints found on a former shore in Kenya suggest that ancestors of modern humans may have walked in ways similar to today as long as 3 million years ago. Among hominin ancestors, bipedal walking was one of the first defining characteristics to emerge.
Bipedal walking is believed to have been selectively advantageous in hominin ancestors during the Miocene because of metabolic energy efficiency. A 2007 study found that moving the human body costs approximately 75 percent less than that of chimpanzees.
Recreational and competitive walking includes scrambling, snowshoeing, beach walking, Nordic walking, walking meditation, and the Afghan walk, along with pedestrianism, power walking, and racewalking. Power walking runs at 7 to 9 km/h, and Olympic racewalking events include the 20 km and 50 km race walks.
A 2023 study found that walking at least 2,337 steps a day was associated with reduced risk of dying from cardiovascular diseases, and 3,867 steps a day reduced the risk of dying from any cause. Reviews indicate that 2.5 hours of brisk walking per week may reduce the risk of depression by about 25 percent.
A horse's walk is a four-beat gait averaging about 4 mph, following the sequence left hind, left front, right hind, right front. Elephants cannot trot, jump, or gallop, using only the walk and a faster running-like gait, and can reach a top speed of 18 km/h.