In the modoc myth, what do the grizzly bears do that angers the chief of the sky spirits?

The Modoc myths were created by the Modoc, an American Indian tribe to explain the creation of the surrounding region. It was said that grizzlies could once walk on two feet and had the ability to speak. The grizzly bears disobeyed the Sky Spirit by marrying one of hiss daughters and having children that were not of his creation and so they were cursed to walk on four feet and they also lost the ability to speak.