Journal of GEOLOGY, Series B, No 34, 11-12/2009, p

I. INTRODUCTION

In living habit of human and animals as well, we usually meet a strange phenome-non: some persons (or animals) like to eat … earth to the level of becoming addict. In science, this phenomenon is called as geophagy or geophagical custom.

Due to the anormal character of geophagical custom, many persons consider this as montrosity. At the end of 2004 – beginning of 2005, on popular means of information animatedly occurred interesting news on geophagy of inhabitants of the Lập Thạch area (Vĩnh Phú Province) with series of articles published in World Security (An ninh thế giới), People’s Security (Công an nhân dân), Sciences and Life (Khoa học và đời sống), Labour (Lao động), Vietnamnet, etc.. Especially, the Program “Strange talks in Việt Nam” of the Television of Việt Nam in the midday session of 14 May 2005 related the investigation trip on the geophagical custom in Lập Thạch area of the correspondent group accompanied by very lively illustrating images about the digging work, processing of “eaten tile” together with pretty show phases on earth eating of some local inhabitants, making audiences surprised and enjoyed. After that (26/08/2005), a Scientific Symposium on Geophagy organized by the Centre of Prehistory of SE Asia in Hà Nội with the topic “Geophagical custom in Việt Nam, current status and scientific views”, aiming to contribute a voice with the press in the explanation from different viewpoints of a custom known previously by scientists over a century in our country. In the Symposium, participants heard scientific reports, idea exchange on the current status of geophagical custom in Việt Nam as well as on the world, analysis of the origin of this custom from the historic, archaeologic, ethnologic, ethologic, dietetic, geologic, ... aspects, from this, one can suggest the orientation of further studies on the geophagical custom in our country.

Report of geologists in the Symposium setting forth some scientific opinions on the geophagical custom from the angle of medical geology received the sympathy of the audience, and proposals brought up in the report on the tasks, methods of study on the geophagical custom of the Geological branch have been considered as an important content in this study in the coming time [15]. In the occasion of publication of this special issue of the Journal of Geology, the authors present the content of the above report with some supplements and updates with new informations with the hope of contributing in the clarification of an old interesting custom of some Vietnamese nations.

II. BRIEF OUTLINES ON THE GEOPHA-GICAL CUSTOM IN SOME COUNTRIES OF THE WORLD

Geophagy is considered as a strange talk, exciting the attention of curious persons. In fact, for scientific set this phenomenon has been known long ago and is not rare in our country and on the world as well. Many literatures let see that this custom has been found in all continents and many nations, but most widespread in Africa and South America.

In Africa, this custom is most found in near-equatorial countries, from the Cote d’Ivoire, Ghana, Nigeria, Cameroon, Trung Phi, Gabon, Congo – in the west, to Uganda, Kenya, Tanzania – in the east. Besides, there still are scatteredly in other countries, such as: Maroc, Algerie, Tunisie, Sudan, Egypte, South Africa (Fig. 1). We can cite some some examples: according to investigation data from 285 school children in Kenya, there are 73% of them practice geophegy, as for in women this ratio is 154/275 (56%). In this country, each child everyday can eat from 8 to 108 g of earth in accordance to the age [2]. Apart from normal earth (clay, kaolin, bentonite, …); soil of termite mounds is also liked by many persons.

The geophagical custom in Africa is being paid special attention by scientific world. In many international and regional symposiums on medical grology, such as “First Symposium of Medical Geology in East and South Africa” organized in Nairobi (Kenya, 1999), and the Second – in Lusaka (Namibia, 2004), or “Symposium on Health and geochemical Environment” organized in Upsala (Sweden, 2000), the theme of geophagy is always present in the agenda.

In America, the geophagical custom existed in some tribes before this land was discovered by C. Colombo. Untill African slaves were brought to this land by Europeans, this custom was more widespread by the diffusion of immigrant slaves. At present, the geophagy still exists in South United States, Caribbean area, Venezuela, Peru and many other areas of South America.

In Europe, geophagy has been found in Germany, United Kingdom, and Italy. In the United Kingdom, according to investigation data there are about 3000 women confess that they have been eating brick and earth by craving during the gestation period. Annually, European countries have to import hundreds tons of earth for processing, answering the demand of geophagical addicts.

Figure 1. Schema of distribution of localities having geophagical custom in Africa (Lagercrantz, 1958).

In Asia, there are China, Japan, India, Russia (Siberia), Việt Nam, … where geophagical custom is rather widespread. In Siberia (Russia), local inhabitants in some areas have the habit of taking with oneself an earth pack of the native country in each long trip for eating a bit when occurs the nostalgie.

Geophagical custom occurs also in some animals. In Ruwanda the gibbon genus Gorilla is fond of eating a clay type similar to kaolin. As for the chimpanzee genus, it likes to eat the earth of termite mound. In the Elgon Mt situated on the Kenya-Uganda border, there is a mine of calcite-zeolite, which is the mineral fond by many animals, especially the African elephants [3].

The mineral analysis of earth samples from this area lets see the abundant presence of following minerals: calcite (CaCO₃), halite (NaCl), gypsum (CaSO₄.2H₂O), anhydrite (CaSO₄), natron (Na₂CO₃), magnesite (MgCO₃), mirabilite (Na₂SO₄.10H₂O)…

Some wild beasts usually come to drink water and lick the soil in the springs of mineral water of high salt content. Therefore, professional hunters usually come to exposures of mineral water for hunting.

Among birds, the love bird of South America and Australia are fond of earth eating. Sometimes, there are many flocks of these birds hang on rock cliffs for pecking and extracting nutritious mineral matters from the rock surface.

The above argues let see that the geophagical custom is a rather widespread phenomenon on the world, and exists not only in human, but also in some animals. So, in Việt Nam what it is manifestated, what is the cause, it has been studied at what level, and what needs to be realized in coming time?

III. GEOPHAGICAL CUSTOM IN VIỆT NAM

In Việt Nam, the geophagical custom is rather widespread. Maybe, the first information on this custom has been found in the article “Geophagical persons in the Tonkin” by T. Hamy published in 1899. Then, in 1908, on the journal Revue Indochinoise issued in 15/9 occurred a work of ethnologic study by the French Vietnamese scholar G. Dumoutier under the title “Essais sur les Tonkinois” (Essay on Tonkinese), in which he tells on his field survey in the Sơn Tây, Hà Đông, Nam Định, and Thái Bình areas for making a study on geophagy of aborigines[1]. He collected samples and sent to Paris for analysis; results let see that “earth” eaten by inhabitants of above areas consists of clay containing Fe, Ca, P, and N. Two Vietnamese scholars Nguyễn Kính Chi and Nguyễn Đổng Chi talked also about geophagy of Bahnar people in their monograph “Kon Tum barbarians” (1937): “After a flood there is a bed of thin mud deposited on the earth surface. When it is dried, they peel this mud for eating, and call it as “porktub”. They tell that this mud is sweet-smelling and very delicious”.

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[1] This reference we write in accordance to the quotation of Prof. Lê Nhâm Tuyết [8] but, still not getting in touch with the original. Authors.

The Vietnamese scientist having contribution in the study on geophagy from the ethnologic and ethologic angle is Prof. Lê Nhâm Tuyết. Against the historic current to the initial time of Vietnamese nation, Prof. Lê Nhâm Tuyết basing on a simple note in the book “History of Lĩnh Nam” (Lĩnh Nam chích quái) talking on marriage custom in the Hùng Vương time: “In the marriage the earth packet is considered as most important”, has been believing that this is a rite manifesting the cultural procedure originating from geophagic custom, not only existing in the ancient Vietnamese community, but also in some other nations belonging to the Môn-Khmer language family, having many close features with Vietnamese nation, such as Xá, Kháng, Bahnar, etc.. For deeply understanding the geophagy, in 3/1969 she carried out a field investigation in the Lập Thạch District (Vĩnh Phúc Province) and found in this locality many persons being addict this “dish” with following description: “The most part of “addict” persons, apart from old persons of 60-70 years, comprise men of 40-50 age, women of 30-40 age (not only pregnant ones). These earth-pregnant persons usually tell that earth is “very delicious, sweet-smelling, nutty as pig liver, can be eaten a basket for a while” [8].

It is regrettable that afterwards, there was not successor developing the study direction of Prof. Lê Nhâm Tuyết therefore, the work must be stopped, and 10 years after, it has been recommenced by Dr. Nguyễn Văn Việt, Director of the Centre of Prehistory of SE Asia. In archaeological excavations of the cave vestige in Trại Village (Lạc Sơn District, Hòa Bình, 1981) and Đú Sáng vestige (Kim Bôi District, Hòa Bình, 2004), he succeeded in finding strange rock pieces lying between gastropod shells (genus Melania) together with quadruped bones and nuts that were main food of ancient inhabitants of this area, forecasted as from 9,000 to 20,000 years before, belonging to the Hoà Bình Culture (Fig. 2). These rock pieces have the dimension of some fingers with the main petrographic composition of claystone, sandstone covered by a thin coating of ferrous or manganesian hydroxide of chocolate or yellow colour by weathering, bearing parallel scratches – sign of scraping of human. By nature they completely differ from in-situ rock (limestone), proving that they were carried from other places, maybe from beds of terrigenous sediments forming hills in surrounding areas [11, 12]. Researchers have been collecting 4 samples and sending for analysis. Results let see that the rock composition consists mainly of clay-kaolin minerals containing some nutritious micro-elements, such as Ca, Na, K, Mg, Fe, Mn, Zn, P (Table 1).

Comparing the composition of these rock samples with that of rock used by Mãng nation (Yên Bái Province) as food they are similar. Comparing these rock pieces with those collected from Đồng Vườn, Đa Bút, and Cồn Cỏ Ngựa vestiges belonging to the Đa Bút Culture, mainly distributed in North Thanh Hoá and Ninh Bình Provinces, having the age of 8000-5000 years, they have similar composition Basing on this, archaeologists have been estimating that, the strange rock pieces collected from above vestiges are just “eaten rock” of ancient human, proving that geophagical custom existed in ancient Việt nation, at least from the Hòa Bình Culture period and transmitted through the Hùng Vương period up to present time (could it be that this custom, at present, is conserved rather concentratedly in the Ancestral land and adjacent areas as a traditional cultural feature?).

Table 1. Chemical composition of rock pieces collected in the Đú Sáng cave and Trại Village (samples M4, M5, M7, M11) compared to eaten rock of present Mãng nation in Yên Bái Province (sample M8) [11, 12].

No	Sp.	SiO₂	Al₂O₃	Fe₂O₃	TiO₂	CaO	MgO	K₂O	Na₂O	MnO	P₂O₅	ZnO	N	C
1	M4	0.98	21.1	1.71	0.08	2.35	0.09	3.54	0.5	0	2.232	0.0099	0.38	0.08
2	M5	62.78	20.43	5.62	0.8	0.39	0.84	3.15	0.5	0	0.004	0.0099	0.21	0.07
3	M7	1.08	22.34	0.33	0.01	0.39	0.09	6.82	0.03	0	3.25	0.0082	0.27	0.06
4	M11	60.02	23.03	6.2	0	0.39	0.74	2.37	0.03	0	0.524	0.0029	0.17	0
5	M8	15.15	27.96	32.2	6.62	1.95	0.74	1.04	0.03	0.04	0.89	0.0178	0.25	0.1

(Fig. 3). There, earth is clean and of chocolate colour. One tell that “all women (especially those are being pregnant) in neighbouring villages come to this cave for taking earth to eat” [4]. Then, he organized a field trip of large scale in the Lập Thạch Townlet, Vĩnh Phúc Province. In this locality, he contacted with many local inhabitants for making a study on the geophagical custom existing there long ago. They all told: “This village all eat it, there is anything strange for writing on newspaper”. Many people told: “It is very soft and greasy”. Directly chatting with madam Nguyễn Thị Lạc (84 years) – a “connoisseur” in geophagy, at the same time, a “master” in the locality in the selection and processing of eatable tile, the journalist was told: “In the market, there are some tens shops selling eaten earth (she called as eaten “tile”), each time going to the market, I buy some pieces and put in the pocket; on the way home I walk and taste, to the house the pocket is just empty!”. She still enthusiastically led the journalist to climb on a hill to a deep pit that is the place where one excavates and takes earth home for processing into eaten tile. She also bored a hole in the soil bed, selected a “lean” piece and invited the journalist to taste it. She took an earth pack and at home she put on the cook, then took leaves of guava and myrtle for burning, the odour of smoke is very aromatic (Figs. 4, 5). She told that by this form of processing the “tile” will be more delicious. She let know that not only in Lập Thạch, but in almost all markets in Việt Trì, Vĩnh Tường, Phong Châu, … areas there are shops selling eating “tile” similar to confectioneries, always sold like hot cakes. One still told that in the neighbouring village, a hill was made even and villagers dug a hole of tens metres in depth for taking earth making “eaten tile”.

So, the geophagical custom really existed and is existing in Việt Nam, but its distribution degree still has not enough basis for assessing, therefore, in this article, basing on the synthesis of news published in popular informational means, and on oral rumours, we preliminarily established a schema of distribution of points having the geophagical custom in North Việt Nam (Fig. 6). It is sure that this schema is still not sufficient and exact, but we should think that it will have the guide significance to further researches.

From above expositions, we can draw some general remarks on characteristic manifestations of the geophagical custom as follows:

1. In general, earth-addict persons belong to all objects, but frequently met in women, children and poor people in rural and mountainous areas.

2. Eaten earth is not hazardously taken but carefully selected from pure, fine-grained, homogenous, of bright colour (white, brownish, greenish, yellow, etc.) soft, agreeable in odour raw materials called by people as “lean earth”. It usually is clay, kaolin, montmorillonite, bentonite, condensed mud in river bottom, loess, etc.. It can be used in natural form or through processing (baked, smoked out, mixed with perfume, sugar, and salt, cooked with aliments, pressed into pieces, etc..).

3. The places of taking eaten earth are usually concentrated in fixed localities, passed through long standing use, and through many generations, guaranteeing the health security and good biological effect. Therefore, for succeeding in taking “delicious” eaten earth, sometimes, one (and wild animals as well) must go very far, up to dangerous areas for finding.

4. Geophagy may be happened regularly, in long term, but sometimes occurs in fixed conditions (such as women in pregnant period or nursing baby, famine misfortune, state of illness, etc.).

5. Level of desire in eaten earth and quantity of eaten earth usually change by seasons: the requirement increases in autumn-winter (cold period), but decreases in summer (hot period).

6. The distribution of the geophagical custom usually has the community character, in the clan, village scale, however sometimes occurs only in single individuals.

III. ESSAY IN FINDING THE ORIGIN OF THE GEOPHAGICAL CUSTOM

The geophagical custom is a complicated phenomenon the origin of it still has different interpretations:

- Caused by the requirement of supplementing nutritious micro-elements to the body or medically treating;

- For detoxicating food or disinfecting after eating food containing toxins;

- For “deceiving” the stomach, creating the feeling “full” in the famine time;

- Due to the habit formed from the customs of the community, and the religious-spiritual factor;

- Due to the hereditariness caused by the gene hereditary from ancient ancestors – anthropoids;

- For releasing stresses in the nerve or psychology, etc..

We try to analyze some main interpretations from different angles.

1. Earth eating for supplementing nutritious micro-elements to the body and medically treating

According to the medical geology pointview, the geophagical custom has been considered as manifestation of the shortage of nutritious micro-elements in the body, demanding to be supplemented with them for re-creating the nutritional balance, or medically treating illnesses caused by nutritional disorders. We know that, for existing and developing the human and animal body needs to be fully provided with nutrients, among them, apart from protid, lipid, glucid, and vitamine (organic nutrients) there still are mineral salts and micro-elements (inorganic nutrients), such as C, H, O, N, Ca, Na, K, Mg, Cl, S, Fe, Mn, Cu, Mo, Co, P, Se, I, Zn, etc.. The demand of body in mineral salts and micro-elements is very little, but they have an extremely important role for the life. Missing them, the body will be hypotrophic, easy to get disease or the death. For example: the deficiency in Fe leads to the anaemia; the deficiency in iodine – to the goitre and stupidity; the deficiency in fluorine – to the toothless, etc..

Mineral salts and nutritious micro-elements usually exist in earth and rocks with different content in accordance to thr geographic position. They are absorbed by vegetations and preserved in their trunk, leaves, flowers, fruits and rootstalks. In areas where earth and rocks contain many mineral salts and nutritious micro-elements vegetations growing there are also rich in these matters, and on the contrary. Inorganic nutrients go in human and animal body following food of floral origin (cereals, fruits, vegetables, etc.) and faunal origin (meat, fishes, eggs, milk, etc.). So, in the human and animal body in the nature is formed a continuous nutritious succession, if it is interrupted, for instance, stopped in the provision with some necessary elements due to the famine, at that time one feels to be strangely thirst for a certain food, sometimes, very “quaint”, such as leaves, tile, brick, chalk, mortar, etc., forced to seach for eating at any cost. Popular lamguage calls that as "pica", usually met in pregnant women. Or we have been heard that during the time of hard war of resistance, our soldiers operated in mountainous areas lacked salt to the state of the eyes growing dim, the limbs feeling weak; they were forced to burn thatch and eat these ashes. The salt content in ashes is very little, but it somewhat diminishes the salt hunger, and helps to recover the health.

The real connection with characteris-tics of the geochemical environment of the Lập Thạch area lets see that samples of eaten earth collected there by the Centre of Prehistory of SE Asia contain some nutritious elements possible to be useful to the body (Table 1). For checking up this, the mineralogist Kiều Quý Nam (Geological Institute, Việt Nam Institute of Natural Sciences and Technology) has been carrying out a field trip also in the Lập Thạch Townlet area. There, the topography has the relict hill form, originated from geological unit belonging to the Thác Bà Formation (PR₃-ε₁tb), with the main composition from quartz-sericite-chlorite schist and quartzite, covered by Neogene sediments of the Phan Lương Formation (N₁pl) (?) composed of conglomerate, sandstone, clay shale and coaly shale. The geological section at the survey point is situated in the centre of the townlet, about 200 m far from the police post of the district, including 4 beds (in ascending order) [7]:

1. White-grey, very fine-grained clay; thickness: 0.5 m; the bed bottom has not been observed (A1).

2. Yellow-grey clay shale and clayey siltstone; thickness: 1-2 m (A2).

3. Clay shale, clayey siltstone interbedded with some fine-grained sandstone; thickness: 0.5-1.5 m (A3).

4. Clay mixed with sand, containing some yellow-grey ferrous concretions; thickness: 0.5-5 m.

The earth sample taken from the A1 bed consists of white-grey, white, very fine clay not bearing traces of bedding. When touching it, it gives the smooth and fresh feeling. When tasting it, it has not odour, with the salt taste, quickly dissolved in the mouth by its very fine granularity. Just due to this characteristic, local inhabitants must dig deep holes for reaching this “lean” earth and taking it to make eaten tile.

The earth samples analyzed in laboratories of the Department of Geology and Mineral Resources of Việt Nam and the Geological Institute (Việt Nam Institute of NS&T) have the average composition as follows (%): SiO₂ = 59.5; TiO₂ = 0.62; Al₂O₃ = 23; Fe₂O₃ = 3.24; MgO = 1.17; CaO = 0.62; K₂O = 3.2; Na₂O = 0.01; Zn < 0.001; Pb < 0.001; MKN = 6.

On the petrography and mineral sides, samples of eaten earth have the main composition of smectite, hydromica (illite), halloysite and quartz. Compared with previously analyzed samples (Table 1) they are rather similar. During the time of “tile” processing by smoking out, earth pieces absorbe savour from leaves (myrtle, guava, etc. used as firing), creating an attractive aroma. Possibly, it is also a factor causing the “conditional reflex”, causing the “violent desire” when smelling this characteristic odour.

What a pity that the research work of Dr. Kiều Quý Nam has been aiming only to simple geology and mineralogy, lacking the synchronism with research on nutrition, bio-medicine, therefore, there are not enough real materials for interpreting convincingly the relation between geophagy and the local geochemical environment. In spite of that, basing on study results of foreign scientists and theoretical bases of ecological geochemistry and medical geology, we can believe that this relation is real.

In animals, the earth-addict habit is also the manifestation of requirement of supplementation with nutritious micro-elements. Regarding wild species living in the environment lacking needful minerals, they usually get diseases or develop slowly. For maintaining a normal life following the genetic habit, they know to move to localities having necessary nutritious factors. In national parks or nature preservation areas, for meeting the geophagical demand of wild beast, one usually place scatteredly on pasture or forest masses of “salt-lick” processed from clay, kaolin, etc. mixed with necessary minerals liked by them. In the cattlebreading branch, one usually applies the method of scattering salt-lick in the farm for preventing diseases and increasing the productivity of cattle.

However, while recognizing the relation between geophagical custom and the local environment, it should not simply understand the problem that in localities having the geological environment (accompanying this, food, drinking water) not guaranteeing the nutritious demand of human body, certainly there is geophagical custom! Because at present, when the economic exchange is widely opened, the relation between local geochemical background and content of nutritious micro-elements in the food is not tight as in the self-sufficiency economy. In the other side, the sufficiency or deficiency of nutritious elements in human body, apart from local Clarke content cause there still are other impacts, frequently very complicated, such as geochemical state (pH, Eh), geochemical barriers, presence in the environment “resonant” or “obstructive” matters, bioavailability of nutritious (or toxic) elements, etc..

Apart from above cited natural factors, there may still are socio-human agents, such as ethnologic characteristics, habits and customs including drinking and eating custom, living in group way of the community, etc. are also the root, sometimes, playing the deciding role of geophagical custom. This means that, in the work of searching the root of geophagical custom, if we incline to the factor of natural environment, sometimes, we can not evade from deadlock; therefore, it is necessary to pay allround attention to socio-human and religious factors as well.

2. Earth eating for detoxicating food and curing toxicosis

The geophagical custom sometimes starts from the experience of food detoxication. We know that in some foods of floral origin (vegetables, roots, fruits, grains, mushrooms, etc.) usually contain toxicant matters, even causing death if eaten. For guaranteeing the health, one must apply measures of excluding toxins, among them, according to popular experiences, there is a effective way: using clay. We can cite an exemple: some South American indigenous peoples have the habit of mixing clay into potato when preparing for excluding glycoalkaloid – a toxin existing in its sprout. Ainu people in Japan usually put clay into vegetable soup for detoxicating it. By their genetic gene, some faunal genera, such as chimpanzee, elephant, etc. know also to use clay in the prevention or cure of toxicosis by foods.

3. Earth eating for “deceiving” the stomach during the famine time

This is also a tragedy seen in poor people, especially in famine time caused by natural calamities and enemy ravages. At that time, one use earth as a “food” for provisionally mollifying the hunger. For example: the Otomac clan in Venezuela living along the Orinoco River knows only fish chase by bows in dry season for making food. But, during the flood season, usually prolonging 2-3 months, that prevents from fish chase, they only know to take earth and ball up for getting by on these earth pieces. In the recent world food-stuff crisis, in Haïti area (Caribbean), poor people takes clay to roll into balls, then dries them for making food and buying.

In our country, it is sure that many peoples have been reading the report “Making full” (or “Food in flood days") by writer Ngô Tất Tố, published for the first time in 5/1938 in the “Harvest” (Thời vụ) newspaper, telling on geophagy in the period before the August Revolution, 1945 in a poor rural area after a great flood causing failure of crops and famine. The article detailedly described the processing “food” of a poor peasant named as uncle Tụy that the author saw by its eyes, that was the way of making “rice pancake” by clay and “boiling earth” with small shrimps for replacing rice. These “special dishes” are indeed difficult to be bolted down, but children “vie with one another to break off and eat with great relish”. The scene is truly heart-rending, but uncle Tụy still plainly joked: “one says that we eat earth when died, but my family lives by earth, my dear!”, making readers burst out laughing, but it is a swimming with tears smile.

4. Geophagical custom – a cultural feature in the spiritual life of human society

Apart from above cited causes (or synchronourly with them), the geophagical custom may be formed from the customs of the community, or from religious-spiritual factors handed down from the primitive society up to present time. Possibly, this characterizes the geophagy in Lập Thạch area (and similar others), where this custom is no more the manifestation of poverty as in the old days. In the thought of prehistoric people, earth is a sacred symbol, “absolute lively source of agricultural inhabitants” [8]. Therefore, the entertainment of esteemed guests by a dish of “tile”, or “the marriage takes the earth pack as most important” are symbolic rites in the communication culture, originated from the cult of sacred earth, and from this the habit of earth eating is formed in the community as the inheritance of a traditional custom of ancestry, similar to the custom of betel chewing, teeth blackening, tatoo, etc..

Likewise, in some works of sociologic study on geophagical custom of South American negroes of African origin, scientists consider that the earth eating habit of this allochthonous inhabitant community is not simply caused by hunger or nutrient demand, but still is a religious manifestation with the sacred faith that when they swallow a piece of earth (maybe received from the native country) named as "Terra santa" (Holy earth) they keep in their body a little of material body of the dear mother land for after the death their soul will be lead by “Land Mother” to the native country Africa [2].

5. Geophagical custom – manifestation of the atavism

According to ethnologists and archaeologists the geophagical custom existed in prehistoric people and their ancient ancestors. This has been proved by excavation works in some residences of ancient persons. For example, in the excavation point of residence relic of the ape-man Homo habilis in Kalambo Falls (Tanzania), one found pieces of white clay lying between animal bones that were considered as eaten earth of ancient human. Such evidences have been discovered by Vietnamese archaeologists in Đú Sáng, Xóm Trại, and Đa Bút above cited vestiges. Possibly, through the evolution process, this habit gradually disappeared, but to present time in the contemporary human community in some places the status quo still is maintained or sometimes, some individuals suddenly reestablish the ancient habit. This phenomenon is named as atavism or throw-back. The phenomenon of custom atavism in mankind happens less than surgical atavism (such as grow hair, occurrence of tail, change of skin colour, etc.), however sometimes, it happens here and there, including the restoration of geophagical habit from the ape-man ancestor.

6. Earth eating as a habit or for releasing stresses

Apart from causes bearing the above said community character, geophagy can be met in particular cases, happening in some individuals, such as liking to eat earth due to habit: always liking to taste something for diminishing the hankering for food, such as betel chewing, smoking, gum chewing, or finger sucking in children, etc.. There are also persons eating earth only for releasing stresses in the nerve or in psychology, when there are grieves or anxieties by something.

IV. NEGATIVE IMPACT OF THE GEOPHA-GICAL CUSTOM

From above analyzed things, we see that geophagical custom has many causes and different actions, among them, the action of supplementing nutritious micro-elements to the body and detoxication of foods. However, scientists have been warning that geophagy creates also the danger of contaminating toxic elements, such as As, Hg, Pb, Cd, U, Ra, etc. together with worm eggs and microbes causing dangerous diseases. Even if when answering interview of the press or writing investigation notes of scientists on the health and disease state related to geophagical custom, the most part of “addict” persons has been telling that “there is not any happened event”, but these impulsive ideas are not able to argue in favour of the harmless character of this “food” type. Because the eaten earth can be taken with selection, in fixed places, through practical experiences handed down from many previous generations, guaranteeing the hygienic security, therefore, distinct calamity does not occur. But, at present, when the environment in every place is being seriously polluted by natural and man-made agents, making it, including areas having traditional “mines of eaten earth”, lost its primitive purity, nobody can guarantee to find a reliable place for taking eaten earth. In the other side, possibly “there is not any happened event”, because toxins existing in eaten earth belong to the type of cumulative toxins with low content, not enough for causing clear, acute toxic symtoms. But, through the long-term use, these toxins are accumulated in the body up to the moment they surpass the threshold, they will become the pathogenic agents. In this case, only special studies can discover. Therefore, one should not encourage the direct use of natural soil, but it should be processed for excluding harmful matters. In the medicine, medicaments have been prepared by white clay, montmorillonite, kaolin, bentonite, natron, etc. mixed with some nutrient minerals, vitamine, sugar, chocolate, aroma, etc., pressing into sticks, pills sold under trade marks: bicana (natrium bicarbonate), alusi (alumosilicate), cholacol II, naturclay (Fig. 7) for answering requirements of earth addict persons and treating for illness, mainly for disease of stomach (superfluous in gastric juice), of urination line, gall, liver, etc.. In fact, this is “ameliorated” geophagy.

V. CONCLUSIONS AND PROPOSALS

Geophagical custom is a complicated and sensitive problem. Although it is originated from the initial time of the humankind and is being widespread in many areas on the world, up to present time it still is considered as “strange story” and seen by the society with discriminated eyes. In fact, it is only a normal biological phenomenon, manifestating the deficiency in salt and nutrient micro-elements of the body, demanding to be supplemented for guaranteeing the physiological necessity of human and animals as well. At the same time, it can be also a hereditary habit, a cultural way in everyday life, or a religious-spiritual factor. So, geophagical custom is a study object of both social and natural sciences, and therefore, it needs to have a scientific, allround, and objective view, avoiding all prejudices and impositions. However, it should not encourage or to be indifferent, because the geophagical custom has also negative side, which is possible to cause the contamination of poison and infection to the body. For guaranteeing the two above requirements, it needs serious studies. Because of it, the opening of a program studying on geophagical custom in our country, realized independently or under a project lying in a larger program of medical geology, is very urgent. For reaching high effect, it needs a close combination between concerned sciences, such as geology, medicine, biology, history, ethnology, etc. and local authorities. On the aspect of medical geology, with their function, geologists can assume the responsability of study on problems of mineral geology, environmental geochemistry, ecological geology, medical geology related to geophagical custom by the realization of special tasks, such as:

- Field investigation for collecting and analyzing samples (rock, soil, water, vegetation, food, etc.), synthesis and processing of materials, establishment of maps of geo-ecology, environmental geochemistry, medical geology of localities having geophagical custom.

- Study on petrographic, chemical, mineralogic composition of eaten rock and earth existing at present or in archaeological vestiges.

- Collaboration with historians, ethnologists, medical scientists in the study on characteristics of addict persons in sex, age, nation, living standard, health state, disease, living habits, main provision and food, nutritive regime, etc. in comparison to persons not eating earth in the area.

- On the basis of study results, explain the relation between the geological-geochemical environment and health, diseases, and influence of geophagical custom to human and animal body. From this, determining exact scientific awareness on this custom for suggesting suitable directions to state organs in the management on the socio-cultural side and health of the community related to geophagical custom.

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