When you think about dirt, what comes to mind? Probably not eating it! We teach our children not to put dirt in their mouths from the moment they start crawling away from us in infancy, and we throw insults like "eat dirt" at people when we want to really stick it to them. Yet… humans have eaten earth, on purpose, for more than 2300 years. Humans also crave starch, ice, chalk, and a whole roster of unorthodox food items. Some even claim they become addicted and can't get by without these non-food food items… but why is that so?

My guest on the show this week is medical anthropologist Dr. Sera Young, an Associate Professor of Anthropology and Global Health at Northwestern university, who earned her PhD in International Nutrition from Cornell University. She draws on nutrition and medical anthropology training to take a biocultural approach in understanding the questions around eating and craving earth, a practice known as pica, and more broadly looks at how mothers cope to preserve their health and their family's health. She wrote an award-winning book called Craving Earth: Understanding Pica to explore the idea of phenomenon of eating dirt or earth.

Today we explore the evolutionary history of humans eating dirt and look at who in particular is most likely to eat it, and the potentially harmful and healthful effects they have. She reveals how pica is remarkably prevalent across every human culture, the substances that are most frequently consumed, and the many methods used to obtain them (even the Internet!).

Some of my favourite episodes are these ones, where we look to the food histories of the past to help understand current food-related behaviours, so I hope you enjoy this conversation as much as I did!

Learn More about Dr. Young's Work:

• Website
• Twitter: @ProfSeraYoung
• Craving Earth: Understanding Pica
• HWISE Water Security Research