The Native American or Indian peoples of North America do not share a single, unified body of mythology. The many different tribal groups each developed their own stories about the creation of the world, the appearance of the first people, the place of humans in the universe, and the lives and deeds of deities and heroes. Yet despite the immense variety of Native American mythologies, certain mythic themes, characters, and stories can be found in many of the cultures. Underlying all the myths is the idea that spiritual forces can be sensed through the natural world—including clouds, winds, plants, and animals—that they shape and sustain. Many stories explain how the actions of gods, heroes, and ancestors gave the earth its present form.