Sera Young, a reproductive and infectious diseases researcher at UC Davis Medical Center, has investigated why people eat dirt, ice, chalk and other nonfood items to see if it was related in any way to health, medicine, pregnancy, religion or mental illness. While the research results of Young and others throughout history have been largely inconclusive, she found the age-old practice too fascinating to restrict to academia and turned it into a book for the masses. She writes about "pica," an abnormal desire to eat nonfood items, in accessible prose in "Craving Earth."
"People have been eating earth for a very long time," according to Young. She tells of people who sneak around to eat chalk and starch (both the laundry kind and the type you use to thicken gravy) so that their loved ones won't know, and about people who devote Facebook pages to this obsession; she also talks about a woman who buys an industrial-size ice machine to feed her ice-eating habit. Who knew?