Who were the first humans to reach North America? When and how did they arrive? Noted author David L. Harrison explores the various theories of North America's first people: Some evidence suggests that they walked across the land bridge that once connected Siberia and Alaska. Elsewhere, a growing number of archaeologists believe that at least some, if not most, of our forefathers arrived by boat along North America's northwest coast, possibly from Southeast Asia or Japan. Other archeologists speculate that humans reached the continent by boat, crossing the frigid North Atlantic waters from Europe. With archeological field photographs and realistic illustrations by Richard Hilliard, the author demonstrates how scientists are like detectives, investigating mysteries that took place more than one hundred centuries ago. Includes maps, glossary, sources, index.