From The Scientist: Mummies’ parasites.

Enterobius vermicularis, or pinworm, is an itchy but harmless intestinal parasite that has been with humans since before they were human. Pinworm eggs have been recovered from a communal latrine near the ancient Dead Sea settlement of Qumran, from fossilized feces in Dust Devil Cave in southern Utah, and from the intestinal contents of an Argentinean mummy. Since pinworms require a human host for their entire life cycle, their genes could be used to answer the controversial question of how humans arrived in South America in the first place.

"During the movement from North to South America, this parasite had to have been with humans in order to get here," says Vicente. "Did the pinworms that are here now, come with these ancient human migrations across the Bering land bridge?" The alternative theory – transpacific migration – posits that a second influx of humans took place by sea on South America’s west coast. If that’s the case, then human pinworms from North and South America will have different evolutionary histories. [continue]