AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 65:259-266 (1984) The Chronological Distribution of Enamel Hypoplasias From Prehistoric Dickson Mounds Populations ALAN H. GOODMAN, GEORGE J. ARMELAGOS, AND JEROME C. ROSE Department of Orthodontics University of Connecticut Health Center, Farmington, Connecticut 06032 (A.H. G.), Department of Anthropology, Uniuersitv of Massachusetts, Amherst. Massachusetts 01003 (G.J.A.), and Department ’of Anthropology, University of Arkansas, Fayetteuille, Arkansas 72701 (J.C.R.) KEY WORDS Enamel hypoplasia, dentition, paleoepidemiology, weanling stress, development ABSTRACT The chronological distributions of enamel hypoplasias (indica- tors of nonspecific stress) are assessed for 111 individuals from two prehistoric populations from Dickson Mounds, Lewiston, Illinois. The earlier population (circa A.D. 950-1150) involves a transition from an indigenous gathering- hunting tradition to increasing adoption of Mississippian lifeways. The later population (circa A.D. 1150-1300) is fully Mississippian (MM). Based on the occurrence of hypoplasias on all permanent teeth except third molars, 14 half- year periods from birth to 7.0 years are graded for evidence of hypoplasia- stress. Both populations have a low frequency of hypoplasia which occur before 2 years of age and after 4 years of age. A common peak frequency of hypopla- sias between 2.0 and 4.0 years is suggestive of an elevated degree of stress at weaning. The peak frequency of hypoplasias is earlier in the MM (2.5-3.0 years versus 3.0-3.5 years in the pre-Mississippian population). In addition, the rise to and decline from peak frequency occurs approximately 0.5 years earlier in the MM. The earlier and sharper rise to peak frequency suggests earlier and more severe weanling-related stress. Hypoplasias chronologies are undoubtedly influenced by age-related host resistance factors (Sarnat and Schour, 1941). Nevertheless, these data demonstrate that populations may vary in their chronological distribution of hypoplasias and that these varia- tions may provide useful information on age-related patterns of exposure to environmental stressors. Enamel hypoplasia is a deficiency in en- nen and Edlund, 19671, neonatal asphyxia amel thickness resulting from a disruption (Grahnen et al., 19691, neonatal jaundice in amelogenesis (Sarnat and Schour, 1941). (Watson, 1964), nephrotic syndrome (Schus- This condition is readily observed in erupted terman and Fellers, 19691, and gastroenteri- teeth as a circumferential line, band, or pit- tis (Smith and Miller, 1979). In his summary ting of decreased enamel thickness (Fig. 1) of results from clinical and experimental (Goodman et al., 1980). studies, Kreshover states: tr. develop- Since the introduction of the term in 1893 mental tooth disturbances are generally non- by Zsigmondy (Sarnat and Schour, specific in nature and can be related to a 1941:1991), many investigators have studied wide variety of systemic disturbances. .” the etiology of this developmental defect. En- (1960:166). Any systemic disturbance may, amel hypoplasias have been associated with therefore, lead to an enamel defect if it is a wide variety of disease and nutritional de- sufficiently severe and long lasting to disturb ficiencies, including vitamin A deficiency (Wolbach, 1947), vitamin D deficiency (Niki- forouk and Fraser, 1981), fever (Kreshover and Clough, 1953), maternal diabetes (Grah- Received March 19,1984; accepted July 30, 1984. 0 1984 ALAN R. LISS, INC 260 A.H. GOODMAN, G.J. ARM LELAGOS. AND J.C. ROSE amelogenesis (cf. Kreshover, 1960; Pindborg, poplasias should be similar in all popula- 1970,1982; Yaeger, 1980). tions. Furthermore, it follows that if Because many different conditions may re- hypoplasia distributions are similar, they sult in an enamel hypoplasia, it is difficult to will not provide information on differences in determine their exact cause (Pindborg, 1982). the chronology of environmental events However, since hypoplasias provide a nearly which are causative of hypoplasia-stress. permanent record of stresses occurring dur- Giro (1947) supports the view that it is not ing enamel development, they may provide a the environmental event which is important general index of infant-childhood health in the determination of a hypoplasia but (Sarnat and Schour, 1941). The frequency of strictly the age of the individual at the time enamel hypoplasias has been successfully of the event. He argues for the universality used as an indicator of general health in of Sarnat and Schour’s (1941) results in stat- contemporary (Infante and Gillespie, 1974; ing: “It is a known fact that at least 68% of Sweeney et al., 1969) and prehistoric (Cook hypoplasias reported have occurred during and Buikstra, 1979, Swardstedt, 1966) popu- the first year of life” (1947:313). Further- lations. For examples, Sweeney and co-work- more, he contends that potential causes of ers (1969) found an association between the hypoplasias, which are not active during this occurrence of hypoplasias and infection in first year, can essentially be eliminated be- Guatemalan children, and Swardstedt (1966) cause of this “fact” that hypoplasias invari- found an increased frequency of hypoplasias ably occur during the first year (1947:313). in the lower classes of a medieval Swedish More recent dental references continue to ac- population. cept the relative universality of the Sarnat Since the age of individuals at the time of and Schour enamel hypoplasia chronology (cf. the development of hypoplasias can be deter- Pinborg, 1970:91-92; Spouge, 1973:152; Yae- mined, it is possible to reconstruct the chro- ger, 1980:lOO). nology of occurrence of hypoplasias for indi- In this paper we present chronological dis- viduals and populations (Sarnat and Schour, tributions of hypoplasias for time-successive 1941). An analyses of the chronological pat- populations from the Dickson Mounds, Lew- tern of hypoplasias should add a useful di- iston, Illinois (A.D. 950-1300). The distribu- mension to epidemiological studies which tion of hypoplasias in the Dickson popu- include hypoplasia data. However, while lations are compared with reference to the there is general acceptance that the fre- changing pattern of environmental stressor quency of hypoplasias may provide an indi- potentially resulting from the transition from cation of general health status in pop- an indigenous hunting and gathering tradi- ulations, interpretation of the chronological tion to increased use of maize agriculture distribution of hypoplasias is more con- and involvement in Mississippian lifeways. troversial. Our purposes are to demonstrate that the Sarnat and Schour (1941) constructed a fre- chronological distribution of enamel-hypo- quency distribution for enamel hypoplasias plasias in populations is not invariable and by age of occurrence for sixty hypoplastic that chronological differences reflect differ- individuals from the Chicago area. They ences in age-related patterns of exposure to found that most hypoplasias (67%) occurred environmental stressors. during the first year. Nearly another third occurred during the next 2 years and less than 2% occurred after this time. This chro- ARCHEOLOGICAL CONTEXT nology remains the only one for an industrial The Dickson Mounds site is located near or contemporary population. the confluence of the Illinois and Spoon Riv- The sparcity of further studies on the chro- ers, 4.8 km Southwest of Lewiston, Illinois. nology of hypoplasias may be due to Sarnat The site includes both habitation areas and and Schour’s conclusions that the distribu- burial mounds. The environment is one of tion of hypoplasias is due to the child’s bio- great diversity and potential for aboriginal logically determined developmental changes exploitation (Harn, 1971). in susceptibility to stressors (Sarnat and During the approximately 350 years in Schour, 1942:69; also see Massler et al., which the burial mounds were used, the 1941:42). Since these age changes in suscep- Dickson population underwent a great tibility to stressors are assumed to be a rela- change in lifeways. During the first century tively constant biological phenomena, this of occupation (A.D. 950-1050) the burial position implies that the distribution of hy- mounds were used by indigenous gatherer- AGE AT OCCURRENCE OF ENAMEL HYPOPLASIAS 261 hunters of the Late Woodland (LW) tradition population for an ecological study of the chro- (Conrad and Harn, 1972). Habitation sites nology of enamel hypoplasias. appear to have been seasonally occupied by a relatively small (75-125) group. During this time and into the next century, contact in- METHODOLOGY creased with Mississippian cultures to the The sample used in this analysis consists south, which had developed in the American of 111 adults and adolescents (Goodman et Bottom (Fowler, 1978). The period of greatest al., 1980). This includes all of the available transition (circa 1050-1150 A.D.) is often re- Dickson skeletons with complete or near ferred to as Mississippian Acculturated Late complete permanent dentition. Woodland (MALW) (Goodman et al., 1984). Of these 111 individuals, 48 are affiliated At this time there is evidence for long-dis- with either the Late Woodland or Mississip- tance trade and some use of maize pian Acculturated Late Woodland horizons agriculture. (circa 950-1150 A.D.). These individuals oc- By around 1150 A.D. the Dickson Mounds cupy the premound cemetery or the earliest inhabitants had become completely Missis- constructed burial mounds (A-E) and com-