Skip to main content

Clay Mineralogical and Related Characteristics of Geophagic Materials

Journal of Chemical Ecology volume 29, pages 1525–1547 (2003)Cite this article

Abstract

Geophagy is the deliberate consumption of soil and clay deposits by animals, including man. Various hypotheses have been advanced to explain geophagic behavior, the main ones being: detoxification of noxious or unpalatable compounds present in the diet, alleviation of gastrointestinal upsets such as diarrhea, supplementation of mineral nutrients, and as a means of dealing with excess acidity in the digestive tract. This review focuses on the mineralogical and chemical nature of the materials consumed, and considers whether this has been adequately characterized, particularly in the contexts of the above hypotheses. In many cases, the information provided is fragmentary and a number of inconsistencies and anomalies are identified. In particular, it is suggested that for these materials further information on their mineral constituents is required, particularly with respect to the kaolin minerals, interstratified kaolinite/smectite, the smectitic minerals and iron oxide and aluminous minerals. It is suggested that total chemical analyses of these materials are of little relevance unless supported by a physiologically based extraction test, this approach being essential in any study seeking to confirm the nutrient supplementation hypothesis.

This is a preview of subscription content, access via your institution.

Access options

Buy single article

Instant access to the full article PDF.

USD 39.95

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

References

  • Abrahams, P. W. 1997. Geophagy (soil consumption) and iron supplementation in Uganda. Trop. Med. Int. Health 2:617–623.

    Google Scholar 

  • Abrahams, P. 1999. The chemistry and mineralogy of three savanna lick soils. J. Chem. Ecol. 25:2215–2228.

    Google Scholar 

  • Abrahams, P. W. and Parsons, J. A. 1996. Geophagy in the tropics: A literature review. Geog. J. 162:63–72.

    Google Scholar 

  • Abrahams, P. W. and Parsons, J. A. 1997. Geophagy in the tropics: An appraisal of three geophagical materials. Environ. Geochem. Health 19:19–22.

    Google Scholar 

  • Anonymous. 1989. Recommended Dietary Allowances, 10th ed. NATIONAL RESEARCH COUNCIL. National Academy Press, Washington DC.

    Google Scholar 

  • Aufreiter, S., Hancock, R. G. V., Mahaney, W. C., Stambolic-robb, A., and Sanmugadas, K. 1997. Geochemistry and mineralogy of soils eaten by humans. Int. J. Food Sci. Nutrit. 48:293–305.

    Google Scholar 

  • Aufreiter, S., Mahaney, W. C., Milner, M. W., Huffman, M. A., Hancock, R. G. V., Wink, M. and Reich, M. 2001. Mineralogical and chemical interactions of soils eaten by chimpanzees of the Mahale Mountains and Gombe Stream National Parks, Tanzania. J. Chem. Ecol. 27:285–311.

    Google Scholar 

  • Bolton, K. A., Campbell, V. M., and Burton, F. D. 1998. Chemical analysis of soils of Kowloon (Hong Kong) eaten by hybrid macaques. J. Chem. Ecol. 24:195–205.

    Google Scholar 

  • Churchman, G. J., Whitton, J. D., Claridge, G. G. C., and Theng, B. K. G. 1984. Intercalation method using formamide for differentiating halloysite from kaolinite. Clays Clay Miner. 32:241–248.

    Google Scholar 

  • Delvaux, B., Herbillon, A. J., Dufey, J. E., and Vielvoye, L. 1990. Surface properties and clay mineralogy of hydrated halloysitic soil clays. I. Existence of interlayer K+ specific sites. Clay Miner. 25:129–139.

    Google Scholar 

  • Diamond, J., Bishop, K. D., and Gilardi, J. D. 1999. Geophagy in New Guinea birds. Ibis 141:181–193.

    Google Scholar 

  • Fossey, D. 1983. Gorillas in the Mist. Houghton Mifflin, Boston, Massachusetts.

    Google Scholar 

  • Geissler, P. W. 2000. The significance of earth-eating: Social and cultural aspects of geophagy among Luo children. Africa 70:653–682.

    Google Scholar 

  • Geissler, P. W., Mwaniki, D., Thiong'o, F., and Friis, H. 1997. Geophagy among primary school children in Western Kenya. Trop. Med. Int. Health 2:624–630.

    Google Scholar 

  • Geissler, P. W., Mwaniki, D., Thiong'o, F., and Friis, H. 1998a. Geophagy as a risk factor for geohelminth infection: A longitudinal study of Kenyan primary schoolchildren. Trans. Royal Soc. Trop. Med. Hygiene 92:7–11.

    Google Scholar 

  • Geissler, P. W., Mwaniki, D. L., Thiong'o, F., Michaelsen, K. F., and Friis, H. 1998b. Geophagy, iron status and anaemia among primary school children in Western Kenya. Trop. Med. Int. Health 3:529–534.

    Google Scholar 

  • Geissler, P. W., Shulman, C. E., Prince, R. J., Mutemi, W., Mnazi, C., Friis, H., and Lowe, B. 1998c. Geophagy, iron status and anaemia among pregnant women on the coast of Kenya. Trans. Royal Soc. Trop. Med. Hygiene 92:549–553.

    Google Scholar 

  • Gilardi, J. D., Duffey, S. S., Munn, C. A., and Tell, L. A. 1999. Biochemical functions of geophagy in parrots: Detoxification of dietary toxins and cytoprotective effects. J. Chem. Ecol. 25:897–922.

    Google Scholar 

  • Heymann, E. W. and Hartmann, G. 1991 Geophagy in Moustached Tamarins, Saguinus mystax (Platyrrhini: Callitrichidae) at the Rio Blanco, Peruvian Amazonia. Primates 32:533–537.

    Google Scholar 

  • Holdridge, D. A. and Vaughan, F. 1957. The kaolin minerals (Kandites), pp. 98-139, in R. C. Mackenzie (ed.). The Differential Thermal Investigation of Clays. Mineralogical Society, London.

    Google Scholar 

  • Hunter, J. M. 1973. Geophagy in Africa and the United States: A culture–nutrition hypothesis. Geog. Rev. 63:173–195.

    Google Scholar 

  • Hunter, J. M. and de Kleine, R. 1984. Geophagy in Central America. Geog. Rev. 74:157–169.

    Google Scholar 

  • Johns, T. 1986. Detoxification function of geophagy and domestication of the potato. J. Chem. Ecol. 12:635–646.

    Google Scholar 

  • Johns, T. and Duquette, D. 1991a. Traditional detoxification of acorn bread with clay. Ecol. Food Nutr. 25:221–228.

    Google Scholar 

  • Johns, T. and Duquette, M. 1991b. Detoxification and mineral supplementation as functions of geophagy. Am. J. Clin. Nutr. 53:448–456.

    Google Scholar 

  • Keay, J. 1993. Eating dirt in Venezuela, pp. 342-350. in J. Keay (ed). The Robinson Book of Exploration. Robinson, London. (Taken from Alexander von Humboldt: Personal Narrative of Travels to the Equinoctial Regions of America. George Routledge and Sons, London).

    Google Scholar 

  • Ketch, L. A., Malloch, D., Mahaney, W. C., and Huffman, M. A. 2001. Comparitive microbial analysis and clay mineralogy of soils eaten by chimpanzees (Pan troglodytes schweinfurthii) in Tanzania. Soil Biol. Biochem. 33:199–203.

    Google Scholar 

  • Klaus, G., Klaus-hugi, C., and Schmid, B. 1998. Geophagy by large mammals at natural licks in the rain forest of Dzanga National Park, Central African Republic. J. Trop. Ecol. 14:829–839.

    Google Scholar 

  • Krishnamani, R., and Mahaney, W. C. 2000. Geophagy among primates: Adaptive significance and ecological consequences. Anim. Behav. 55:899–915.

    Google Scholar 

  • Kreulen, D. A. 1985. Lick use by large herbivores: A review of benefits and banes of soil consumption. Mammal Rev. 15:107–123.

    Google Scholar 

  • Kreulen, D. A., and Jager, T. 1984. The significance of soil ingestion in the utilization of arid rangelands by large herbivores with special reference to natural licks on the Kalahari pans, pp. 204-221, in F. M. C. Gilchrist and R. I. Mackie (Eds.). Herbivore Nutrition in the Subtropics and the Tropics. Science Press, Johannesburg.

    Google Scholar 

  • Mahaney, W. C. 1993. Scanning electron microscopy of earth mined and eaten by mountain gorillas in the Virunga Mountains, Rwanda. Primates 34:311–319.

    Google Scholar 

  • Mahaney, W. C., Aufreiter, S., and Hancock, R. G. V. 1995b. Mountain gorilla geophagy: A possible seasonal behavior for dealing with effects of dietary changes. Int. J. Primatol. 16:475–488.

    Google Scholar 

  • Mahaney, W. C., Bezada, M., Hancock, R. G. V., Aufreiter, S., and Perez, F. L. 1996a. Geophagy of Holstein hybrid cattle in the Northern Andes, Venezuela. Mount. Res. Dev. 16:177–180.

    Google Scholar 

  • Mahaney, W. C., Hancock, R. G. V., Aufreiter, S., and Huffman, M. A. 1996b. Geochemistry and clay mineralogy of termite mound soil and the role of geophagy in chimpanzees of the Mahale Mountains, Tanzania. Primates 37:121–134.

    Google Scholar 

  • Mahaney, W. C., Hancock, R. G. V., and Inoue, M. 1993. Geochemistry and clay mineralogy of soils eaten by Japanese Macaques. Primates 34:85–91.

    Google Scholar 

  • Mahaney, W. C., Milner, M. W., Mulyono, Hs, Hancock, R. G. V., Aufreiter, S., Reich, M., and Wink, M. 2000. Mineral and chemical analyses of soils eaten by humans in Indonesia. Int. J. Environ. Health Res. 10:93–109.

    Google Scholar 

  • Mahaney, W. C., Milner, M. W., Sanmugadas, K., Hancock, R. G. V., Aufreiter, S., Wrangham, R., and Pier, H. W. 1997. Analysis of geophagy soils in Kibale Forest, Uganda. Primates 38:159–176.

    Google Scholar 

  • Mahaney, W. C., Stambolic, A., Knezevich, M., Hancock, R. G. V., Aufreiter, S., Sanmugadis, K., Kessler, M. J., and Grynpas, M. D. 1995a. Geophagy amongst Rhesus Macaques on Cayo Santiago, Puerto Rico. Primates 36:323–333.

    Google Scholar 

  • Mahaney, W. C., Watts, D. P., and Hancock, R. G. V. 1990. Geophagia by mountain gorillas (Gorilla gorilla beringei) in the Virunga Mountains, Rwanda. Primates 31:113–120.

    Google Scholar 

  • Mahaney, W. C., Zippin, J., Milner, M. W., Sanmugadas, K., Hancock, R. G. V., Aufreiter, S., Campbell, S., Huffman, M. A., Wink, M., Malloch, D., and Kalm, V. 1999. Chemistry, mineralogy and microbiology of termite mound soil eaten by the chimpanzees of the Mahale Mountains, Western Tanzania. J. Trop. Ecol. 15:565–568.

    Google Scholar 

  • Marlow, R. W. and Tollestrup, K. 1982. Mining and natural exploitation of mineral deposits by the desert tortoise, Gopherus agassizis. Anim. Behav. 30:475–478.

    Google Scholar 

  • Parham, W. E. 1969. Halloysite-rich tropical weathering products of Hong Kong, pp. 403-416, in Proc. Intern. Clay Conf., 1969, Tokyo, Vol. 1. Israel Universities Press, Jerusalem.

    Google Scholar 

  • Range, K. J., Range, A., and Weiss, A. 1969. Fireclay type kaolinite or fire-clay mineral? Experimental classification of kaolinite–halloysite minerals, pp. 3-13, in Proc. Internat. Clay Conf., 1969, Tokyo, Vol. 1. Israel Universities Press, Jerusalem.

    Google Scholar 

  • Robertson, R. H. S. 1996. Sadavers, cholera and clays. Mineralogical Society Bulletin, No. 113. September. pp. 3–7.

  • Schwertmann, U. and Taylor, R. M. 1989. Iron oxides, pp. 379-438, in J. B. Dixon and S. B. Weed (eds). Minerals in Soil Environments. Soil Science Society of America, Madison, Wisconsin.

    Google Scholar 

  • Setz, E. Z. F., Enzweiler, J., Solferini, V. N., Amendola, M. P., and Berton, R. S. 1999. Geophagy in the golden-faced saki monkey (Pithecia pithecia chrysocephala) in the Central Amazon. J. Zool. Soc. Lond. 277:91–103.

    Google Scholar 

  • Smith, B., Rawlins, B. G., Cordeiro, M. J. A. R, Hutchins, M. G., Tiberindwa, J. G., Sserunjogi, L., and Tomkins, A. M. 2000. The bioaccessibility of essential and potentially toxic trace elements in tropical soils from Mukono District, Uganda. J. Geol. Soc. Lond. 157:885–891.

    Google Scholar 

  • Stevens, D. E. and Carron, M. K. 1948. Simple field test for distinguishing minerals by abrasion pH. Am. Mineral. 33:31–49.

    Google Scholar 

  • Vermeer, D. E., and Ferrell, R. E. 1985. Nigerian geophagical clay: A traditional antidiarrheal pharmaceutical. Science 227:634–636.

    Google Scholar 

  • Wada, K. 1965. Intercalation of water in kaolin minerals. Am. Mineral. 50:924–941.

    Google Scholar 

  • Wiley, A. S. and Katz, S. H. 1998. Geophagy in pregnancy: A test of a hypothesis. Curr. Anthropol. 39:532–545.

    Google Scholar 

  • Ziegler, J. L. 1997. Geophagy: A vestige of palaeonutrition. Trop. Med. Int. Health 2:609–611.

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Macaulay Land Use Research Institute, Aberdeen, AB15 8QH, United Kingdom

    M. J. Wilson

Authors
  1. M. J. Wilson
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to M. J. Wilson.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Wilson, M.J. Clay Mineralogical and Related Characteristics of Geophagic Materials. J Chem Ecol 29, 1525–1547 (2003). https://doi.org/10.1023/A:1024262411676

Download citation

  • Issue Date:

  • DOI: https://doi.org/10.1023/A:1024262411676

  • Geophagy
  • clay minerals
  • halloysite
  • kaolinite
  • soils
  • clays