Posts Tagged ‘geophagy’

Megafauna Geophagy

September 24, 2014

Sometimes animals eat dirt.  The official scientific word for dirt-eating is geophagy.  Animals eat dirt for 2 reasons: to obtain minerals otherwise lacking in their diet and to prevent toxins from being absorbed into their bloodstream.  Over 200 species of animals including deer, bison, elephants, bats, primates, and birds are known to eat dirt.  Minerals aren’t evenly distributed in the soil, and plants are often deficient in certain nutrients because of  poor soil, as gardeners well know.  Animals living in these environments actively seek out soils rich in sodium, calcium, or iron.  These locations are known as mineral licks because ungulates literally “lick” the soil.

Elephants enter caves to access salt.  They grind the salt off the walls with their tusks.

Animals eat clay for a different reason.  The negatively charged clay particles bind with positively charged toxins ingested from plants high in alkaloids, preventing absorption into the blood stream.  In 1 experiment James Gilardi fed parrots quinidin, a toxin.  He made clay available to some of the parrots but not to others.  The parrots given the opportunity to eat clay had 60% less quinidine in their blood than the other parrots.  Pregnant fruit bats also eat considerable quantities of clay because they eat twice as much fruit as they normally do, and therefore ingest greater quantities of toxins.

Chimpanzee licking dirt off his (her?) fingers.  The dirt is eaten before or after the ape consumes plants containing anti-malarial compounds.  It counteracts the toxins.  This is amazing.  It’s like the chimp is creating its own pharmaceutical.

Macaws & other Parrots Eat Clay

Macaws at a clay lick.

The Diagnostics and Statistics Manual used by psychiatrists lists geophagy in humans as a mental disorder.  Psychiatrists are wrong.  Humans eat dirt for the same reasons animals do.  Eating dirt is common among women in Africa who suffer from diets low in calcium.  Eating clay reduces toxins hazardous to the fetus, and it may alleviate morning sickness.  The clay they use is often harvested from termite mounds.  The termites bring up clay from deep underground where it is free from harmful micro-organisms and parasites.  Kaopectate and Pepto-Bismol, 2 popular over the counter medications, formerly contained kaolin clay.   Kaolin clay has been replaced with synthetic ingredients that mimic the same properties.

Pepto-Bismol formerly included kaolin clay as an ingredient but it has been replaced with a synthetic substance.

Georgia is rich in clay soils, especially along the kaolin clay belt just south of the fall line.  During the Pleistocene there were probably many clay licks that attracted mastodons, ground sloths, bison, horses, tapirs, etc.  The Great Buffalo Lick in Oglethorpe County (See:  was the last known location in Georgia where megafauna herds were known to lick the soil.  The areas around the licks were quite altered.  The animals licked these spots into gullies, and the general vicinity was composed of bare soil and a few sun-loving trees.  White clay-colored fecal matter littered the general area.  These licks are just another lost natural community once common but no longer extant in the region.


Starks, Phil; and Brittany Slabach

“Would you like some dirt with that?”

Scientific American 306 (6) 2012