Geophagy is widespread amongst animals especially amongst birds. Grouse, pigeons, hornbills, corvids, cracids and cassowaries have all been known to indulge in geophagy.
Parrots in particular are well known for indulging in geophagy. Hundreds of parrots use the licks that overlook the Tambopata River in Peru. Grey parrots in the Congo basin forest and parrots in Papua New Guinea also indulge in geophagy.
Most of the soil consumed by birds show that they like soil with high clay content. Additionally tests also show that these soils contain minerals like sodium and calcium.
The prehistoric site at Kalambo falls in Zambia contains the prehistoric remains of Homo habilis, an ancestor of Homo sapiens. White clay, rich with calcium was found next to the remains, it is believed that this is the earliest evidence of geophagy practice in humans.
A lump of birch bark tar with tooth marks was discovered in North West Finland dating back to around 3000 BC. Birch-bark tar has antiseptic compounds. It is thought that Neolithic people who suffered from gum infections chewed birch bark tar to treat their condition.
Native Americans in California as well as indigenous Peruvians ate clay with acorn and potatoes. Clay reduced the tannic acid of the acorns thus making the acorns edible.
Slaves and some poor whites consumed white clay, it was one of the old home remedies that they used. It was a cultural practice that the slaves brought with them from Africa.
The short video below shows tribes of Ghana eating dirt. The clay is reported to contain magnesium, calcium, copper and potassium.
Susan Allport, who wrote "Women Who Eat Dirt" wrote "In the 1970s, fifty percent of Black women admitted to eating clay, about four times the frequency among white women," Susan notes that the percentage has since gone down.
The Vedda in Sri Lanka ate rotting wood with honey, closer examination reveals that the bacteria produced vitamin B.
Every year around one million people from Central America and Mexico make the pilgrimage to Esquipulas in eastern Guatemala.
They go to commune with the black Christ's shrine, clay tablets are sold by the vendors mostly to women who eat it, to induce or nurture pregnancy.
It is also still practiced on a large scale in villages and much of rural Africa, the pregnant women there eat clay from termite mounds. Clay consumption also takes place in villages in India and parts of the rural USA.
In western culture it is viewed as an eating disorder and a horrible practice. Even though in non western culture this is clearly not the case. Geophagy has obvious dangers and also benefits.
History shows that it was a widespread practice around the world, were they all merely suffering from an eating disorder back then or did they have a greater grasp of what nature has to offer? I suggest it's the latter.