Book excerpt: For more than half a century, grizzly bears roamed free in the national parks without causing a human fatality. Then in 1967, on a single August night, two campers were fatally mauled by enraged bears -- thus signaling the beginning of the end for America's greatest remaining land carnivore. Night of the Grizzlies, Olsen's brilliant account of another sad chapter in America's vanishing frontier, traces the causes of that tragic night: the rangers' careless disregard of established safety precautions and persistent warnings by seasoned campers that some of the bears were acting "funny"; the comforting belief that the great bears were not really dangerous -- would attack only when provoked. The popular sport that summer was to lure the bears with spotlights and leftover scraps -- in hopes of providing the tourists with a show, a close look at the great "teddy bears." Everyone came, some of the younger campers even making bold enough to sleep right in the path of the grizzlies' known route of arrival. This modern "bearbaiting" could have but one tragic result…