Neurobiologist Calvin (The Ascent of Mind, 1990; The Throwing Madonna: Essays on the Brain, 1983) tackles an unlikely subject--archaeoastronomy--and brings to it his scientific training, a lively curiosity, and the ability to describe objects and phenomena clearly. Archaeoastronomy is Calvin's hobby, and he pursues it in Anasazi ruins in the American Southwest and in the remains of Stonehenge on England's Salisbury Plain. Describing a dozen simple methods to predict lunar eclipses that could have been used by ancient peoples, plus a couple of ways to detect an impending solar eclipse, Calvin argues the likelihood that the ability to forecast such celestial events preceded civilization. In doing so, he shows us a scientific mind at work, asking questions, collecting data, revising theories, seeking new evidence. His descriptions of camping out in Arizona's Canyon de Chelly and New Mexico's Chaco Canyon to test and refine his theories are fascinating. He is less successful, however, at explaining what it all means. In what ways did early forecasters--shamans, prophets, or protoscientists--signal the beginnings of religion and/or science, what powers did they wield, and what roles did they play in shaping their societies? Calvin conjectures freely on these and other questions, tossing out notions and then inexplicably abandoning them, leaving ideas unresolved and the reader up in the air. Perhaps that's his intent, but it's ultimately unsatisfying. One wishes he had spent as much time exploring the significance of archaeoastronomers as he does in persuading us of their probable existence. Still, lively and literate science for the nonscientist.