How STEM Built the Incan Empire

In size and sophistication, the most impressive empire in the Americas was the Incas. Established in Peru in the twelfth century, the Incan empire united millions of people and dozens of distinct cultures under a single governing system. The Incas lacked what many assume are essential to empire-building: writing, the wheel, a favorable climate. Still, the Incas overcame these challenges with incre...