Parasites aplenty riddled humans and their dogs at a swampy site in Bronze Age England. From left: Microscopic eggs of a fish tapeworm, giant kidney worm and Echinostoma worm found in ancient feces from the Must Farm site. (Black scale bar represents 20 micrometers.) (Credit: M. Ledger, Department of Archaeology, Cambridge University)

Around 3,000 years ago, people were going about their
business in a marshy corner of eastern England known as The Fens.

These Fenland folk had just built