Around Chaco Canyon, New Mexico, NASA’s Thermal Infrared Multispectral Scanner (TIMS) detected over 200 miles of a prehistoric roadway system (shown in red, fanning out from lower right). Compare these prehistoric roads with the current day roads, in yellow, which follow the topography and path of least resistance in construction. Why were the Chacoan roads designed with exacting linearity, surmounting any topographic obstruction, built to a width of 20 feet or more, and constructed by people who did not even employ beast of burden in their lives? (Image courtesy of NASA.)