"Until the popularization of the family car, horses and humans lived, worked, and played side by side. With the invention of the wheel, saddle, bit, and bridle; horses pulled far-flung lands closer together at the speed of a gallop. Trade, agriculture, exploration, and war-none of these would have been possible in the same way without horses. In dazzling spreads packed with maps, sidebars, and other hidden gems, Jennifer Thermes tackles the history of the horse. Horse Power explores horses' evolution. It tracks their migration as they find homes on six continents, and it shows readers what kinds of jobs they've had. And, ultimately, it explores the shift from "horse power" to "horsepower"-when humans traded manure in the street for pollution in the air. An encyclopedic look this amazing animal, Horse Power offers a unique view of world history from atop a horse's back"-- Provided by publisher.