As rapid advancements in technology render last year's inventions obsolete, it's reassuring to know that a 13,000-year-old innovation is still being used today: mud. This economical building material aids in the construction of everything from grand palaces and temples to simple shops and homes. Gus Van Beek, an anthropologist from the Smithsonian's National Museum of Natural History, and his wife, Ora, an independent scholar, have been researching methods of ancient and contemporary mud architecture in Southwest Asia, the Middle East, North Africa, Europe and the United States since 1971. One of their findings is that mud houses are best suited for desert climates, as they absorb and dissipate heat slowly, providing an ambient interior temperature. Concrete structures, by contrast, trap heat and act like ovens. Get more dirt on this building material in Glorious Mud!, a new reference book from Smithsonian Institution Scholarly Press. "Mud," says Ora, "is a magnificent property for humanity."