In 2009, a group of Tufts
University biology students took their curiosity to the next level—by eating dirt. As part of a class on Darwinian medicine, they tasted clay to explore geophagia, the ancient and widespread habit of consuming earth. From wild animals to expectant mothers, soil eating has been observed across species and cultures for centuries. Scientists from many fields have studied it, but the reasons behind this gritty craving still aren’t entirely clear.
Curious why so many creatures eat dirt? Dig into this gallery to uncover the surprising science behind geophagia.