I am really not following. Some study, or I guess a whole book, about how frequently pregnant women in different cultures eat dirt.
It's from Columbia University, so I'm going to assume it's real. Apparently, the practice is called pica, which is apparently not short for People Inexplicably Chewing A-- see? too short.
Craving Earth: Understanding Pica--the Urge to Eat Clay, Starch, Ice, and Chalk [columbia.edu via boingboing]
Pica is one of the first things they usually talk to you about when you go in to verify your pregnancy. They also tell you to report it if you start to crave laundry detergent, dirt, anything that's not an actually /food/. I guess for a man it would be crazy to hear, but women are used to being warned about Pica. *shrug*
Be happy you are from a dairy rich culture. The body has strange ways of dealing with a calcium deficiency.