"Please don’t call them 'severed feet.'" So says forensic scientist Gail Anderson of Simon Fraser University, whose research involving dead pigs plays a big role in getting to the bottom of a mystery that flummoxed Canadian locals and police near the Salish Sea off British Columbia's Vancouver Island for years: Why were sneaker-clad feet washing ashore? In an excerpt from Erika Engelhaupt's Gory Details: Adventures From the Dark Side of Science, National Geographic shares the fascinating science. The first foot washed up on August 20, 2007, and another—also a right foot in a men's size 12 sneaker—was found six days later. Over a 12-year period, 15 feet were found, leading to theories ranging from a serial killer to aliens. Science ultimately proved otherwise.
Engelhaupt recounts a 1977 Navy study that got to the first question: Does a dead body float or sink? The study determined that sinking to the bottom was likeliest, and a forensic anthropologist with the British Columbia Coroners Service explains that water pressure stops the expansion of gases that could otherwise bring the bodies back up. As for why the feet would have been come back up, in her work with dead pigs Anderson found underwater scavengers like shrimp and crabs gravitated toward softer tissues and ligaments, which is exactly what you'll find in our ankles. That makes it likely the feet naturally separated thanks to those scavengers. Credit today's sneakers for the rise, too: Most feature foam and gas-filled pockets in the soles that make them buoyant. But who do the feet belong to? Police now have an answer in nine of the cases, and all are thought to have died via accident or suicide. (Read the full story for much more on that.)