Geophagy, also termed as geophagia, came from the English word “geo” which means “earth” and the Greek word “phagein” which translates to “eat”. It is the habit of eating soil or similar earthy substances like chalk or clay. For instance, around 30% to 80% of individuals in Africa, particularly those who are pregnant and breast feeding eat between 100 and 400 grams of soil daily. This practice has been linked with pica, an eating disorder characterized by craving to eat nonnutritive substances such as soil, paper, glass, and brick. This disorder is not caused by poverty or lack of food as it is mainly caused by an abnormal craving.
The oldest proof of this kind of uncharacteristic diet was found at Kalambo Falls, situated on the border of Zambia and Tanzania. White clay which was rich with calcium was excavated alongside the remains of Homo habilis. There are also records of geophagy among early Greeks and Native Americans. In contemporary practices, clay-like rocks are being sold in some local markets in Africa and biscuits out of soil, salt, and oil are being sold in Haiti. Even in some parts of the U.S. it has been customary to gift pregnant/lactating women with "edible" dirt.