Human Evolution

, Volume 4, Issue 6, pp 515–523 | Cite as

A critique of the «increasing population density effect»

  • K. R. Gibson
  • J. M. Calcagno


The «increasing population density effect» (IPDE) proposed by Macchiarelli and Bondioli (1986) represents one of the most recent attempts to account for dental reduction in modern human populations. Under the IPDE, the marked reduction in tooth size observed in post-Pleistocene human groups is seen as merely a side-effect of a more general reduction in body size, which resulted from an increase in population density. The model is dependent upon a strong correlation between tooth size and body size, which after numerous attempts has yet to be convincingly demonstrated in humans. This paper argues that the IPDE neglects the negative consequences on individual fitness of teeth which are too large to fit into diminishing jaws or are more susceptible to pathology, and that the worldwide reduction of tooth size is the result of selection for smaller teeth due to shifts to a softer and/or more cariogenic diet. Although increased population density may have intensified this selective effect by decreasing general fitness by lowering resistance to oral infections, it was not the primary cause of dental reduction. All proposed mechanisms of dental reduction, however, are in need of additional testing, and possible directions are offered for future studies of the phenomenon.

Key words

Dental Reduction Mechanisms Tooth Size/Body Size Natural Selection 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Anderson D.L. &Popovitch F., 1977.Dental reduction and dental caries. American Journal of Physical Anthropology, 47: 381–386.CrossRefGoogle Scholar
  2. Armelagos G.J., Van Gerven D.P., Goodman A.H. & Calcagno J.M., 1988.Post-Pleistocene facial reduction, biomechanics and selection against morphologically complex teeth: A rejoinder to Macchiarelli and Bondioli. Human Evolution.Google Scholar
  3. Avis V., 1959.The relation of the temporal muscle to the form of the coronoid process. American Journal of Physical Anthropology, 17: 99–104.CrossRefGoogle Scholar
  4. Avis V., 1961.The significance of the angle of the mandible. American Journal of Physical Anthropology, 19: 55–61.CrossRefGoogle Scholar
  5. Barber C.G., Green L.J. &Vox G.J., 1963.Effects of the physical consistency of diet on the condylar growth of the rat mandible. Journal of Dental Research, 42: 848–851.Google Scholar
  6. Begg P.R., 1954.Stone age man's dentition. American Journal of Orthodontics, 40: 298–312, 373–383, 462–475, 517–531.CrossRefGoogle Scholar
  7. Brace C.L., 1963.Structural reduction in evolution. American Naturalist, 97: 39–49.CrossRefGoogle Scholar
  8. Brace C.L., 1964.The probable mutation effect. American Naturalist, 98: 453–455.CrossRefGoogle Scholar
  9. Brace C.L., 1967.Environment, tooth form, and size in the Pleistocene. Journal of Dental Research, 46: 809–816.Google Scholar
  10. Calcagno J.M., 1984.Human Dental Evolution in Post-Pleistocene Nubia. Lawrence: PhD Dissertation, University of Kansas.Google Scholar
  11. Calcagno J.M., 1986a.Odontometrics and biological continuity in the Meroitic, X-Group, and Christian phases of Nubia. Current Antropology, 27: 66–69.CrossRefGoogle Scholar
  12. Calcagno J.M., 1986b.Dental reduction in post-Pleistocene Nubia. American Journal of Physical Anthropology, 70: 349–363.CrossRefGoogle Scholar
  13. Calcagno J.M., 1989.Mechanisms of Human Dental Reduction: A Case Study from Post-Pleistocene Nubia. Lawrence: University of Kansas Publications in Anthropology, 77: 505–517.Google Scholar
  14. Calcagno J.M. & Gibson K.R., 1988.Human dental reduction: Natural selection or the probable mutation effect. American Journal of Physical Anthropology, in press.Google Scholar
  15. Carlson D.S., 1976a.Temporal variation in prehistoric Nubian crania. American Journal of Physical Anthropology, 45: 467–484.CrossRefGoogle Scholar
  16. Carlson D.S., 1976b.Patterns of morphological variation in the human midface and upper face. In: (J.A. McNamara, Jr., ed.), Factors Affecting the Growth of the Midface, pp. 277–299. Ann Arbor: Center for Human Growth and Development, Craniofacial Growth Series, Monograph 6, University of Michigan.Google Scholar
  17. Carlson D.S. &Van Gerven D.P., 1977.Masticatory function and post-Pleistocene evolution in Nubia. American Journal of Physical Anthropology, 46: 495–506.CrossRefGoogle Scholar
  18. Carlson D.S. &Van Gerven D.P., 1979.Diffusion, biological determinism, and biocultural adaptation in the Nubian corridor. American Anthropologist, 81: 561–580.CrossRefGoogle Scholar
  19. Childs G.C. &Courville C.B., 1942.Thrombosis of cavernous sinus secondary to dental infection. Parts I, II, and III. American Journal of Orthodontics and Oral Surgery, 28: 367–373; 402–413; 458–468.CrossRefGoogle Scholar
  20. Dirks O.B. 1965.The distribution of caries resistance in relation to tooth surfaces. In: (G.E.W. Wolstenholme and M. O'Connor, eds.). Caries—Resistant Teeth, pp. 66–83. Boston: Little, Brown, and Co.Google Scholar
  21. Dixon O.J., 1929.Dental infections as cause of cavernous sinus thrombosis. Dental Cosmos, 71: 121.Google Scholar
  22. Filipson R. &Goldson L., 1963.Correlation between tooth width, width of the head, length of the head, and stature. Acta Odontologica Scandinavica, 21: 359–365.Google Scholar
  23. Garn S.M. &Lewis A.B., 1958.Tooth-size, body-size and «giant» fossil man. American Anthropologist, 60: 874–880.CrossRefGoogle Scholar
  24. Garn S.M., Lewis A.B., Kerewsky R.S., 1968.The magnitude and implications of the relationship between tooth size and body size. Archives of Oral Biology, 13: 129–131.CrossRefGoogle Scholar
  25. Ghafari J. &Heeley J.D., 1982.Condylar adaptation to muscle alteration in the rat. Angle Orthodontist, 52: 26–37.Google Scholar
  26. Grainger R.M., Paynter K.J., Honey L. &Lewis D.W., 1966.Epidemiologic studies of tooth morphology. Journal of Dental Research, 45: 693–702.Google Scholar
  27. Greene D.L., 1970.Environmental influences on Pleistocene hominid dental evolution. Bioscience, 20: 276–279.CrossRefGoogle Scholar
  28. Greene D.L., 1972.Dental anthropology of early Egypt and Nubia. Journal of Human Evolution, 1: 315–324.CrossRefGoogle Scholar
  29. Hanke M.T., 1933.Diet and Dental Health. Chicago: University of Chicago Press.Google Scholar
  30. Harvold E.P., 1975.Experiments on mandibular morphogenesis. In: (J.A. McNamara, Jr., ed.). Determinants of Mandibular Form and Growth, pp. 155–178. Ann Arbor: Center for Human Growth and Development, Craniofacial Growth Series, Monograph 4, University of Michigan.Google Scholar
  31. Harvold E.P., Vargervik K. &Chierici C., 1973.Primate experiments on oral sensation and dental malocclusions.American Journal of Orthodontics, 63:494–508.CrossRefGoogle Scholar
  32. Haymaker W., 1945.Fatal infections of the central nervous system after tooth extraction. American Journal of Orthodontics and Oral Surgery, 31: 117.CrossRefGoogle Scholar
  33. Henderson A.M. &Corruccini R.S., 1976.Relationship between tooth size and body size in American Blacks. Journal of Dental Research, 55: 94–96.Google Scholar
  34. Hinton R.J., 1983.Relationships between mandibular joint size and craniofacial size in human groups. Archives of Oral Biology, 28: 37–43.CrossRefGoogle Scholar
  35. Hoyte D.A.N. &Enlow D.H., 1966.Wolff's Law and the problem of muscle attachment on resorptive surface of bone. American Journal of Physical Anthropology, 24: 205–214.CrossRefGoogle Scholar
  36. Hunt E.E., 1960.The continuing evolution of modern man. Cold Spring Harbor Symposium on Quantitative Biology, 24: 245–254.Google Scholar
  37. Hunter W.S., 1967.Tooth size and approximal decay in human teeth. Archives of Oral Biology, 12: 313–316.CrossRefGoogle Scholar
  38. Keene H.J., 1964.Third molar agenesis, spacing and crowding of the teeth and tooth size in caries resistant naval recruits. American Journal of Orthodontics, 50: 445–451.CrossRefGoogle Scholar
  39. Keene H.J., 1965.The relationship between third molar agenesis and the morphologic variability of the molar teeth. Angle Orthodontist, 35: 289–298.Google Scholar
  40. Keene H.J., 1967.Dental evolution in the borderland between pathology and normality. American Journal of Physical Anthropology, 27: 245.CrossRefGoogle Scholar
  41. Keene H.J., 1971.Epidemiologic study of tooth size variability in caries free naval recruits. Journal of Dental Research, 50: 1331–1345.Google Scholar
  42. Klatsky M. &Fisher R.L., 1953.The Human Masticatory Apparatus: An Introduction to Dental Anthropology. Brooklyn: Dental Items of Interest Pub. Co. Inc.Google Scholar
  43. Koepf, S.W., Rosedale R.S. &Learni G.E., 1937.Infection of the Gasserian ganglion following tooth extraction. Journal of the American Dental Association, 24: 1843–1846.Google Scholar
  44. Macchiarelli R. &Bondioli L., 1986.Post-Pleistocene reductions in human dental structure: A reappraisal in terms of increasing population density. Human Evolution, 1: 405–417.Google Scholar
  45. McFarland P., (personal communication). Post-graduate School of Dentistry, University of Texas Dental Branch, Houston.Google Scholar
  46. McNamara J.A. Jr. (ed.), 1975.Determinants of Mandibular Form and Growth. Ann Arbor: Center for Human Growth and Development, Craniofacial Growth Series, Monograph 4, University of Michigan.Google Scholar
  47. Mead S., 1933.Oral Surgery. St. Louis: The CV Mosby Company.Google Scholar
  48. Oppenheimer A., 1964.Tool use and crowded teeth in Australopithecinae. Current Anthropology, 5: 419–421.CrossRefGoogle Scholar
  49. Paynter K.J. &Grainger R.M., 1961.Influence of nutrition and genetics on morphology and caries susceptibility. Journal of the American Medical Association, 177: 306–309.Google Scholar
  50. Paynter K.J. &Grainger R.M., 1962.Relationship of morphology and size of teeth to caries. International Dental Journal, 12: 147–160.Google Scholar
  51. Perzigian A.J., 1981.Allometric analysis of dental variation in a human population. American Journal of Physical Anthropology 54: 341–345.CrossRefGoogle Scholar
  52. Pratt L., 1943.Experimental masseterectomy in the laboratory rat. Journal of Mammology, 24: 204–211.CrossRefGoogle Scholar
  53. Scott J.H., 1957.Muscle growth and function in relation to skeletal morphology. American Journal of Physical Anthropology, 15: 197–234.CrossRefGoogle Scholar
  54. Stout B.F., 1931.Septic cavernous sinus thrombosis. Journal of Laboratory and Clinical Medicine, 17: 28.Google Scholar
  55. Sung C.C.W. &Sung R.Y., 1947.Some clinical observations concerning Noma. American Journal of Orthodontics and Surgery, 33: 284–289.CrossRefGoogle Scholar
  56. Thoma K., 1948.Oral Surgery, volumes 1 and 2. St. Louis: The CV Mosby Company.Google Scholar
  57. Van Reenen J.F., 1966.Dental features of a low-caries primitive population. Journal of Dental Research, 45: 703–713.Google Scholar
  58. Washburn S.L., 1947.The relation of the temporal muscle to the form of the skull. Anatomical Record, 99: 239–248.CrossRefGoogle Scholar
  59. Watt P.G. &Williams H.M., 1951.The effects of the physical consistency of food on the growth and development of the mandible and maxilla of the rat. American Journal of Orthodontics, 37: 895–928.CrossRefGoogle Scholar
  60. Wolpoff M.H., 1985.Tooth size-body size scaling in a human population: Theory and practice of an allometric analysis. In: (W.L. Jungers, ed.). Size and Scaling in Primate Biology, pp. 273–318. New York: Plenum Press.Google Scholar
  61. Wood B.A., 1979.An analysis of tooth and body size relationships in five primate taxa. Folia Primatologica, 31: 187–211.CrossRefGoogle Scholar

Copyright information

© Editrice Il Sedicesimo 1989

Authors and Affiliations

  • K. R. Gibson
    • 1
  • J. M. Calcagno
    • 2
  1. 1.Department of AnatomicalSciences University of Texas Dental BranchHoustonUSA
  2. 2.Department of Sociology/AnthropologyLoyola University of ChicagoChicagoUSA

Personalised recommendations