Acceptance of spontaneous generation—that living things appear spontaneously from non-living material—goes back long before the start of civilization. A 17th century example cited is a recipe for creating mice: place sweaty underwear and husks of wheat into an open-mouthed jar; after 21 days, the wheat husks will have been changed into mice. Even in the scientific world, the last vestiges weren't wiped out until 1859, when Pasteur demonstrated that microorganisms followed the dictum that life comes only from life.
Well into the early 20th century, some farmers held that horse hairs,
falling into horse drinking troughs, would be transformed into horsehair worms. These
creatures, belonging to a group of animals without known close relatives, look very
much like long, coarse hairs, this undoubtedly giving rise to the superstition. The
animal lives in water and is widespread on most continents. Locally, it occasionally
has caused a stir when village water systems have drawn individuals into the
distribution pipes. People have been understandably disturbed at an active hair
suddenly appearing in water drawn from their faucet!
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
Illinois Natural History Survey