Crop circles, those beautiful and complex patterns that are visible from the air in fields around the world, have long fascinated the public, media, and scientific community. Vital Signs is a comprehensive guide for newcomers to these puzzling patterns and an essential history for those who are already intrigued. Illustrated with hundreds of full-color and black-and-white photos, this chronological and photographic history is an accessible discussion of the various crop circle theories, physical and statistical evidence, and the surprising effects these formations have had on observers and researchers.