The proof is often in the pudding, but sometimes it’s in the poop. That’s the case in western China, where scientists have found fossilized intestinal parasites in 2000-year-old human excrement: the first evidence of infectious diseases spreading along the Silk Road. Preserved by the arid climate and stone walls of the latrine in which they were found, the poo was deposited on “hygiene sticks,” bamboo sticks with strips of cloth used to wipe the nether regions. The sticks, excavated in 1992 from a latrine at a relay station where travelers most likely slept and ate, were kept in a museum and forgotten about until now. The sticks—and their trimmings—were transported to the University of Cambridge in the United Kingdom, where researchers examined the feces under microscopes. They discovered eggs from four different parasites, including the Chinese liver fluke—a flatworm endemic to marshy areas. People contract the parasite by eating infected fish. Because the sticks were found on the eastern edge of the Taklamakan desert—dry and arid even then—scientists concluded the parasite must have been picked up from the marshy lands of modern-day Guangdong province, about 2000 kilometers away. The findings, reported today in the Journal of Archaeological Science: Reports , suggests two things: that infectious diseases were carried and spread along the Silk Road, and that these early travelers toted a lot more than silk.