This reference work describes the trial-and-error experiments, discoveries, and inventions of early humans who lived from before recorded history to the Middle Ages. Krebs travels through the ancient periods of Egypt, China, and Mesoamerica, to the classical Greek and Roman periods, and finally to the Christian era, providing students with the link between science and history, while revealing information about many cultures around the world. Each entry provides the who, when, and where of each discovery, invention, or experiment. Entries include calendars, gunpowder, anesthesia, contraception, spontaneous generation, the Arctic Circle, language, and tides. Part of the Groundbreaking Experiments, Inventions, and Discoveries through the Ages series, this book provides readers with a detailed look early humans' relation to world around them and the scientific advancements they made. It will be useful to high school and college students, teachers, and the general public interested in the history and science behind ancient civilizations.