In his 1873 book titled Life Among the Modocs, Joaquin Miller related that the Shasta Indian creation myth told of how grizzly bears once walked on two legs, talked, fought with clubs, and possessed all the land from Mount Shasta to the sea.
A grizzly married the daughter of the Great Spirit who lived inside the mountain. Carried by the wind down the mountain as a child, she had been raised by the grizzlies. Her children were the first Indians.
Years later the Great Spirit learned where his daughter was and rushed down the mountain to fetch her. Miller wrote, “But when he saw the children and learned how the grizzlies that he had created had betrayed him into the creation of a new race, he was very wroth.” He ordered the bears to hold their tongues and get down on their hands and knees. Ever since, grizzlies have walked on all-fours, except when they have to fight for their lives, and the Great Spirit permits them to stand up and fight with their fists like men.
Miller said the myth explained why Indians around Mount Shasta avoided killing or interfering with grizzlies.
Source: Miller, Joaquin. Life Among the Modocs: Unwritten History. London: Richard Bentley and Son, 1873. 242-246.