Seven thousand Hopi Indians live on three desolate mesas in northwest Arizona where their ancestors settled at least nine centuries ago. They represent probably the oldest culture in the continental United States. In 1680 the Hopi revolted against Spanish missionaries who tried to convert them, and now, in commemoration, the California Academy of Sciences has mounted an exhibit in San Francisco’s Golden Gate Park. Inspired by architect Nathaniel Owings, a longtime admirer of the Hopi, the exhibit features a striking 10×20-foot model of an annual Kachina ceremony. It includes 86 figures representing friendly spirits—animals, plants, other Indian tribes—that the Hopi believe control the harvest. (In real life, Hopi don costumes to portray the spirits.) Hopi art is on display, too—including extraordinary 400-year-old paintings stripped from the walls of underground rooms 40 years ago by Harvard’s Peabody Museum, using special adhesives. The Hopi don’t allow photographs of their rituals or even everyday life. They are not totally untouched by modern commerce, however. They are fighting a bitter legal dispute over territorial rights with the Navajo, who occupy the land surrounding their mesas. And despite their reclusiveness, the tribe sells Kachina dolls in Arizona (price range: $100 to $500). The exhibit moves in October to Pittsburgh’s Carnegie Museum, then continues to Manhattan next February and later to Chicago and Washington, D.C.