Authors: Unknown
Questions about the cause and the nature of this syndrome still remain,
though, and they underscore the lack of solid information that accompanies
almost every instance of human geophagy. In the South, as in most places
where dirt-eating has been observed, the usual reaction has been to repress,
not study, the habit. From the earliest writings on the subject of geophagy, a
term used by Aristotle in the fourth century B.C., medical practitioners have
regarded the practice with a skepticism bordering on contempt. Many recognized the usefulness of clay in treating cases of poisoning. But as to the daily
consumption of dirt, one physician who lived in A.D. iooo wrote of the necessity of controlling it, "in boys by use of the whip, in older patients by restraints,
prison and medical exhibits, while incorrigible ones are abandoned to the
grave." Clay-eating until recently has been synonymous with pica, a perversion of appetite that causes one to ingest strange and unsuitable substances.
Perhaps part of this negative attitude toward geophagy has been due to the
misconception that dirt-eaters eat surface dirt, a truly inappropriate food
loaded with bacteria, parasites, and other potentially harmful substances. In
truth, most edible clays are taken from the band of clay-enriched soil ten to
thirty inches below the surface, and the fact that they are usually dried or
baked further reduces the possibility of contamination. Perhaps part of the attitude comes from a population that has always had enough meat and dairy in
their diet to make geophagy less vital and necessary. Whatever the cause, the
effect has been to cover up an aspect of human gastronomy that has been extremely important to the survival of the human omnivore-and extremely long-lived. Edible clays have been found at archaeological sites once occupied
by early man, and the fact that chimpanzees regularly ingest clays suggests
that this practice predates our evolution as a species.
Attitudes toward geophagy have been changing, though, largely as the result of the work of two scientists, Donald Vermeer and Timothy Johns, who
both "stumbled across" the practice of dirt-eating in the course of other research. Vermeer, a geographer with Louisiana State University and George
Washington University before he retired in 1996, was the first researcher to
recognize the great similarity between edible clays sold all over West Africa
and the commercial pharmaceutical Kaopectate. Johns is a plant biologist at
McGill University in Canada, best known for his work on the role that plant
toxins have played in shaping human diet and medicine.
In i96o, when Vermeer was preparing for his first trip to Africa, he came
across occasional references to the practice of geophagy in the scientific and
medical literature and assumed that dirt-eating must play a persistent but
fairly insignificant role in the dietary habits of the people of West Africa. When
he actually got to Nigeria, though, he found evidence of the habit everywhere:
in pestles full of clay pieces outside almost every home, in the pouches of edible clays that women wore around their waists, in the marketplaces where clay
was sold and sometimes consumed in public. He once watched a woman eat
about 150 grams of clay in five minutes. But the usual amount, he learned, was
a small handful of clay (30 to 50 grams), consumed over the course of a day.
Vermeer began to wonder if geophagy might in fact be almost universal in
West Africa, at least among pregnant women, and he decided to investigate
the mining, processing, and marketing of geophagical clays. He found that
four hundred to five hundred tons of eko, a clay from the village of Uzalla, in
Nigeria, were being produced each year and sold in markets as far away as
Liberia, Ghana, and Togo. Irregular blocks of these clays were sun-dried, then
smoked and hardened for two to three days over a smoldering fire. In the process, they were transformed from their original, gray-shale color into the rich
chocolate color and sheen of eko, the final product.
Vermeer also reported on how West Africans use this clay medicinally, and
he was the first, as I've said, to demonstrate the striking similarity between eko
and Kaopectate, widely used in the United States to counteract gastric upset
and diarrhea. Kaopectate is made of pectin and kaolin, a type of clay that
forms a protective coating on the mucous membranes of the digestive tract
and is capable of absorbing bacterial and plant toxins. Both eko and Kaopectate have X-ray diffraction patterns that reveal an almost identical quantity
and size of kaolin particles; not surprisingly, eleven of the nineteen prepara tions that village medicine men make out of eko are intended for stomach and
intestinal problems, including diarrhea. The other eight are for problems associated with pregnancy.
"The extent to which the many different ethnic groups in West Africa are
aware of the antidiarrheal properties of eko is uncertain," Vermeer concludes
in a paper in the journal Science. "The fact that so many medicinal preparations in the village of Uzalla use eko, however, supports the notion that the
therapeutic qualities of the clay are recognized by those who supply it to the
West African market system and possibly by those who purchase it."
Why was he the first Westerner to document the uses and composition of
eko? I once put this question to Vermeer, a tall, unassuming, and very genial
geographer. We were having lunch one day when he was in New York to attend
the annual meeting of the Association of American Geographers, and I was
struck by the fact that so many tons of this clay are produced and sold every
year, yet only west Africans had been aware of its existence.
"I don't know," Vermeer answered in a soft, raspy voice he has acquired
from his ongoing treatments for throat cancer. "People must have had blinders on. They must have automatically condemned this practice."
"And why didn't you?" I pursued.
Then Vermeer told me about a childhood spent largely outdoors, in the
hills outside of Oakland, California, where he grew up, and in the deserts of
New Mexico, where he visited his missionary uncle and played and rode bareback with Navaho children. He has been looking at rocks and soils all his life,
he said, so he couldn't not see them in the markets of Africa. In order to better understand the practice of geophagy, Vermeer also began sampling clays in
Africa, and the good ones, he says, dissolve like a piece of chocolate in the
mouth. He has tried hundreds of different clays, and most taste like chalk. He
has yet to detect the pleasant "sour" taste that so many women say they enjoy
about eating clay.
Eko is not the only clay consumed in West Africa, and as Vermeer continued to investigate the practice of geophagy, he found numerous examples that
do not paint as neat a picture as eko and Kaopectate. There were coastal
groups in Ghana that regularly consumed sand, a totally inert substance-a
practice for which he has yet to come up with any kind of plausible explanation other than that it was a habit that formerly interior-living people took
with them to the coast. There were groups for which clay clearly seemed to
serve a nutritive purpose, such as the Tiv of Nigeria, where women eat clay
that is very high in calcium. But they live right next door, so to speak, to groups where the same explanation doesn't hold. The Igbo people live near
the Tiv, and theirs is also a nondairy culture. Igbo women have the same need
for calcium as Tiv women, yet the clay they routinely consume has very little
of this mineral.
The mystery of why people eat clay continued to expand with Vermeer's
work in the American South, where the habit was once so widespread that clay
removal caused considerable damage to roads, and some states posted signs
requesting that local inhabitants not dig into the banks. Since most of the
Southerners who eat clay are blacks, the usual explanation for the clay-eating
habit in America is that slaves brought it to this country from Africa. But clayeating has never been an exclusively black habit-in Africa or in the South. In
Africa, Europeans used to carry their stashes of edible clays in little silver
cases; David Livingstone once observed that both slaves and rich men were affected. In the South, the appellations "sand lickers," "sand lappers," and "sand
hillers" refer to the practice among poor whites. During the course of his research, Vermeer has also come across numerous examples of whites eating
clay, such as the nurse in Holmes County, Mississippi, with a Master of Science degree in public health. She pulled Vermeer aside one day to say, "I just
wanted you to know that I am also a practitioner."
Clay-eating in the South is more prevalent, though, in the black population, and in the 1970s, 50 percent of black women admitted to eating clay,
about four times the frequency among white women. The percentage of
blacks admitting to clay-eating has dropped since then, as clay-eaters have become increasingly aware of the stigma attached to their practice and have either broken their habit or switched to eating cornstarch or laundry starch (a
switch, by the way, that spares women from the humiliation of being known
as a dirt-eater, but adds only calories to their diets). Nevertheless, the practice
is still widespread.
As in Africa, the clays commonly eaten in the South are dug from clay deposits below the surface. And, as in Africa, clays are usually dried before they
are eaten, either in the oven or on top of the stove. Clay consumption averages
one to two ounces (thirty to fifty grams) daily, and clay-eating among blacks
often occurs under social conditions such as watching Tv; the habits of white
women, on the other hand, are much more private and covert.
As Vermeer began to look into the reasons why Southern women consume
dirt, however, he could find no consistent mineral content in clays that could
explain the habit. Nor could he find any consistent medical or nutritional
problems, such as anemia, diarrhea, toxins in foods, parasite infection, etc., associated with eating clay. He concluded that eating dirt in the South does
not stem from either a physiological or nutritional need but is, rather, "a common custom arising from traditional values and attitudes."
"Millions around the world practice geophagy, and I hope I've encouraged
the medical establishment to approach geophagy with a more open mind,"
says Vermeer. Yet all that he can say with certainty about the practice is that it
is "neither good nor bad." It has the chance for being beneficial in some settings; in other settings, it seems to serve a purely psychological or cultural
purpose, transferred from one generation to the next, like smoking or dipping
snuff. And he warned me, as I began my research, that I will get as many answers about why people eat dirt as people I ask.
Timothy Johns, on the other hand, is much more convinced of the underlying nutritional and medical reason for most dirt-eating, a conviction that
stems in part from his knowledge of the ubiquitousness of plant toxins.
Like Vermeer, Johns saw his first edible clays in a market, but a market in
the mountains of Peru where the clays were being sold alongside potatoes.
Johns was in South America to study the domestication of the potato. So he
was, of course, curious. He knew that wild potatoes growing at high altitudes
are full of toxic, bitter-tasting chemicals called glycoalkaloids, which can cause
stomach pains, vomiting, and even death if consumed in sufficient quantity.
But he had always assumed that Indians living in the Andes ate a domesticated
and less toxic version of that wild and bitter food. So it was an eye-opening experience for him to learn that the clays were being sold alongside the potatoes
because the Indians ate the clays with their potatoes in order to take the bitterness out. They boil the potatoes, then dip them into a slurry of clay and
water before each bite.
"This sounds pretty awful," Johns said when we were discussing this novel
gastronomic technique over the phone, "but the clays are very fine, and their
texture isn't at all gritty. The taste is in fact quite pleasant, reminiscent of unsalted butter or margarine." Eating their potatoes in this way, the Indians consume several grams of clay at a meal, and that is enough, Johns has found
through extensive absorption studies, to take up most of the toxic glycoalkaloids in the potatoes. The clays that the Andean Indians choose to consume
with their potatoes are particularly fine, and they have cation-to-exchange
qualities that make them magnets for positively charged substances, particularly glycoalkaloids.
Johns's experience in the Andes gave him a new perspective on geophagy
and the role that geophagy probably played in human dietary history. "It's all
very well to say that humans have reduced the toxic load of their plants through domestication, but what did they eat before domestication?" he asks.
His findings suggest that clay-eating gave humans the flexibility to eat a
broader range of plants, and this flexibility was important not just in the
Andes, but all over the world. The use of clays in Africa had not before been
linked to the detoxification of plants. Vermeer, for instance, had not considered the role of detoxification, because he had never seen clays being eaten in
combination with specific foods. But when Johns tested edible clays from
West Africa, as well as from California and Sardinia, he found that they all
share this ability to absorb plant toxins.
According to Johns, then, clay-eating has allowed us to adapt to an everchanging array of foods. It is an important part of the behavioral repertoire of
experimental omnivores like us and is "a kind of buffer, or protective device,
for quelling gastrointestinal stress induced by barely tolerable wild plants or
pangs of hunger." It could also make a significant nutritional contribution
to the diet, in terms of calcium, iron, or zinc, but this role of clays is harder
to pin down because the mineral content of edible clays varies greatly from
one clay to the next. Until researchers invest the time and the money to examine geophagy very thoroughly-an unlikely occurrence in this day of cheap
mineral substitutes and many more pressing medical problems-we may
never know all the reasons why people eat dirt. Perhaps it is enough to know
that there are many good reasons, and that women, with the extra demands
of pregnancy and lactation, have the most reason of all. "Earth," says Johns,
"may not be to everyone's taste, but it is one of the oldest tastes known to
humankind."