To protect Chinese emperor Qin Shihuang in the afterlife, thousands of clay soldiers joined him underground some 2200 years ago. The discovery of this Terracotta Army in the 1970s was a great gift to archaeologists — and fans of “ancient lost technology” stories. The trope, which has some basis in fact, suggests that our ancestors were privy to some knowledge or technology that would still be useful, but has since been lost to the ages.

When researchers discovered that this buried, ancien