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Public Radio's Environmental News Magazine (follow us on Google News)

Eating Dirt

Air Date: Week of

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A woman on Pemba Island, Zanzibar, Tanzania, collects soil to eat.

The practice of eating dirt is known as geophagy and it’s much more common than you may think. Sera Young, a professor of nutritional sciences at Cornell University, reviewed nearly 500 papers about people all over the earth. .. who eat earth. Host Bruce Gellerman asks her about this abnormal appetite and bites the dust himself.


GELLERMAN: In the book "The Grapes of Wrath", one of John Steinbeck’s main characters is caught eating dirt. Dirt is also part of the diet for a character in Pearl Buck’s novel, "The Good Earth", and it’s on the menu in Don Quixote. Turns out, eating dirt isn’t just the stuff of fiction - in fact, scientists say in some places it’s fairly common, they even have a name for it - geophagy.
Sera Young is a nutritional anthropologist at Cornell University. She’s author of a new book about dining on dirt, and has paper in the latest edition of the Quarterly Review of Biology called
"Why on Earth?"
Professor, welcome to Living on Earth!

YOUNG: Thanks, nice to be here!

GELLERMAN: Professor, have I pronounced that correctly- geo-FAY-gee?

YOUNG: That’s correct, you could also say: GEOF-agy. I’ve heard it, tom-ay-to, tom-ah-to kind of thing.

GELLERMAN: Well, you wrote a paper about geophagy, eating dirt, it’s actually a study of a lot of other studies, right?

The cover of a dissertation from 1691: "Dissertatio medica de pica" by Didericus Christiani.

YOUNG: Well, there have been a lot of observations of eating dirt, so missionaries, anthropologists, plantation doctors have observed this and remarked on it on population levels. But no one has assimilated those findings to analyze or assess any hypotheses.

GELLERMAN: But it’s a long history - it goes back millennia.

YOUNG: It does. In fact, there is archaeological evidence that it’s even maybe two million years old. And then we have the first written example from 400 BC, thanks to Hippocrates, and Aristotle wrote about it, about 100 years after that.

GELLERMAN: So, why do people eat dirt?

YOUNG: That’s a very good question and it’s one I’ve been studying for the last decade or so. There are a number of explanations, and what we’ve found is that the best one, the one that fits the most of the observations that we’ve made is that it’s a protective behavior. So, clay is a big component of the earth that’s eaten. And clay is really good at binding, it almost acts as like a mud mask for your face, except it’s a mud mask for your gut in a way. It sucks up these pathogens like viruses and bacteria and harmful chemicals and lets them evacuate from your body without entering your bloodstream.

GELLERMAN: There’s something in the dirt that protects us?

YOUNG: Exactly. And what’s so, sort of, paradoxical about what we’ve found is that dirt can in fact be cleansing. People are really selective about the dirt that they eat. It’s not just any dirt, and the dirt that’s preferred is, well, often described as ‘clean dirt’. And it’s also very clay-rich, so what you find is very soft, malleable, it’s not like the sand you find at the beach, or the black humus-y kind of soil that you’d like to plant your tomatoes in.

GELLERMAN: I have a bag of dirt that we got from Sam’s General Store in White Plains, Georgia. It’s called ‘Grandma’s Georgia White Dirt’ and I just got it - it says: Not intended for human consumption, but I’m going to try it anyhow…


YOUNG: (Laughs).

GELLERMAN: It looks like chalk and it feels slippery…ooh it is… and it gets all over my hands …

Georgia White Dirt from Sam’s General Store is for the gourmet geophagist.


GELLERMAN: It crumbles….yeah, it tastes like chalk, clean chalk.


YOUNG: You’ll notice it’s sort of, kind of astringent and drying on your tongue.


YOUNG: And, so you can imagine that it’s absorbing the spit on your tongue, the same way that when you swallow it, it will probably bind with some of the food that you’ve eaten. But in fact, what we’re finding is, it is associated with micronutrient deficiencies, people who eat earth are frequently anemic. Such that people who are eating this stuff - it seems to be causing anemia if you eat enough of it.

GELLERMAN: Now when people have a craving for a non-traditional food item, that’s called pica? Did I pronounce that right?

YOUNG: Pica, that’s right. It can also be pronounced: peeka.

Host Bruce Gellerman has not developed a taste for the white clay that many pregnant women crave.

GELLERMAN: Well, the word pica comes from the word magpie, which is a bird.

YOUNG: Right. It's a bird that was thought to have an indiscriminate appetite because it builds its nest will all of these sort of found objects. And so, in the early, I think it was the early 1300s, this name was given to the phenomenon of women, of pregnant women typically, who were craving all of these non-food substances.

But, with the case of the bird, it was a misnomer, they weren’t eating these things - they were building their nests with them. And in the case of the pica phenomenon in humans, it’s also a misnomer because people are not indiscriminate at all - people have extremely, extremely specific cravings.

GELLERMAN: So what is it about pregnant women?

YOUNG: Pregnant women’s behavior is easily dismissed because pregnant women: they know not what they do. But in fact, they’re immuno-compromised. Which means that their immune system is tamped down to avoid rejecting the fetus or the embryo, and at the same time they really need to be shielding this very vulnerable thing growing in them from insults - including pathogens like viruses and bacteria and other harmful chemicals.

So, people with rapidly dividing cells such as pregnant women and also young children are at greatest risk, or in most need of protection. Geophagy is a protective behavior. It fits with our hypothesis because in fact it is pregnant women and young children who do this most frequently.

GELLERMAN: And there are some really weird things that people eat: paint chips, chalk, baby powder, newspaper, coffee grinds, burnt matches…

YOUNG: Right, and you’ll see that there’s something that all of those substances have in common and that’s that they’re a dry, powdery, absorptive. Another substance that is commonly craved is corn starch. Corn starch up until the 60s was sold in chunks that looked a lot like clay.

GELLERMAN: Professor, have you ever developed a taste for dirt?

YOUNG: Well, I’ve been tasting dirt right and left ever since I started doing this as an anthropologist - participant observation is a really important part of your work. But to really take the plunge, I thought - let me see if getting pregnant and having a baby would help me develop this taste because certainly your sense of smell and taste change - but that one backfired. I am left with a charming, lovely little baby girl, Stella, but I never did develop really strong uncontrollable cravings for non-food substances.

GELLERMAN: I have a secret craving.

YOUNG: Tell me.

GELLERMAN: You know the paper they cook cupcakes in?


GELLERMAN: I eat the cupcake and then I eat the paper, the paper is even better!

Sera Young tells the story of the strange compulsion that is “pica” in Craving Earth.

YOUNG: (Laughs.) Well, are you pregnant?

GELLERMAN: (Laughs.) Well, you know, we’re going to have a contest, Professor, we’re going to ask our listeners to tell us about their dirt-eating experience and we’ll post it on our Facebook page - PRI’s Living on Earth - and, if we dig it, we’ll send them some gourmet ground from White Dirt of Georgia. Sound good?

YOUNG: I love that. In fact, what we could do is Colombia University Press would be happy to send the most compelling entry a free copy of my book - “Craving Earth” - that just came out last month.

GELLERMAN: Well, Professor, it was really fun, thanks a lot.

YOUNG: My pleasure.

GELLERMAN: Professor Sera Young from Cornell University is the author of the new book: “Craving Earth.” And I’m going to take another bite. Now I’m all white. (Laughs).

YOUNG: (Laughs). The dangers of pica.

GELLERMAN: I know… tastes like chalk…



A map that plots worldwide distribution of cultural reports of geophagy.


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