Why humans once ate dirt and some still do today

One of the most common explanations for geophagy is deficiency. The body may crave minerals, especially iron or calcium, and respond in ways that seem unusual. Scientists have not fully settled the question, but there is a long-standing link between dirt-eating and anemia, pregnancy, and nutritional stress. In some cases, people who eat clay may also have low iron levels, though whether the craving causes the deficiency or the deficiency causes the craving is not always clear.

Pregnancy is especially important in this story. Across cultures, many pregnant women report cravings for non-food substances, including clay, chalk, ice, or starch. These cravings can be part of pica, a condition involving the desire to eat items with little or no nutritional value. For some women, clay may soothe nausea, settle the stomach, or simply offer a sensory comfort when ordinary food feels unbearable. That does not make the practice harmless, but it does make it understandable.

The body is not always elegant in the way it asks for help. Sometimes it sends signals that are messy, inconvenient, and difficult to decode. Dirt-eating may be one of those signals, a response to deficiency, distress, or a search for relief in a body under strain.