Estimating Age From Adult Occlusal Wear: A Modification of the Miles Method Cassandra C. Gilmore* and Mark N. Grote Department of Anthropology, University of California, Davis; Davis, CA 95616 KEY WORDS tooth wear; age estimation; hunter-gatherers ABSTRACT The Miles method of age estimation relies on molar wear to estimate age and is widely used in bioarcheological contexts. However, because the method requires physical seriation and a sample of subadults to estimate wear rates it cannot be applied to many samples. Here, we modify the Miles method by scoring occlusal wear and estimating molar wear rates from adult wear gradients in 311 hunter-gatherers and provide formulae to estimate the error associated with each age estimate. A check of the modified method in a subsample (n 5 22) shows that interval estimates overlap in all but one case with age categories estimated from traditional methods; this suggests that the modifications have not hampered the ability of the Miles method to estimate age even in heterogeneous samples. As expected, the error increases with age and in populations with smaller sample sizes. These modifications allow the Miles method to be applied to skeletal samples of adult crania that were previously only amenable to cranial suture age estimation, and importantly, provide a measure of uncertainty for each age estimate. Am J Phys Anthropol 149:181–192, 2012. V V C 2012 Wiley Periodicals, Inc. The ability to estimate adult age-at-death from skele- tal remains is critical to bioarcheological studies (e.g., paleodemography and paleopathology) and in forensic contexts. As such, a staggering volume of literature is devoted to methods of age estimation; commonly used methods include scoring the degeneration of the pubic symphysis (e.g., Acsa ´di and Nemeske ´ri, 1970; Meindl et al., 1985; Brooks and Suchey, 1990) and auricular sur- face (e.g., Lovejoy et al., 1985b; Buckberry and Chamber- lain, 2002; Igarashi et al., 2005), cranial suture fusion (e.g., Meindl and Lovejoy, 1985), and dental wear (e.g., Miles, 1962; Brothwell, 1981; Walker et al., 1991). Given the superior preservation of dental tissues and the his- toric preference of early anthropologists to collect skulls over postcranial elements (Walker et al.1991), the ability to estimate age from the dentition alone can be particu- larly useful for researchers studying past populations. Age estimation from dental wear is further distinguished from other methods in that it is based on an indicator (enamel) that does not have the potential to remodel (Boldsen, 2005), and that it can be calibrated to the pop- ulation in question, rather than requiring the applica- tion of aging standards from a reference population (Lovejoy et al., 1985a). This combination of qualities likely explains why dental wear was found to be the best single age indicator when compared with pubic symphy- sis, auricular surface, femoral radiographs, and cranial suture closure in a known-age sample (Lovejoy et al., 1985a). Though researchers have long noted the value of den- tal wear to classify individuals into broad age categories, Miles (1962, 1963, 1969, 2001) was the first to use molar wear to estimate age systematically by progressively extrapolating wear rates from younger individuals—for whom age can be estimated with relative certainty—to older individuals where the determination of age is more problematic. The Miles method, or the aging chart accompanying the original publication, is commonly used to estimate age in bioarcheological contexts (Wolpoff, 1971; Griffin et al., 1979; Ruff, 1981; Kieser et al., 1983; Levers and Darling, 1983; Lovejoy, 1985; Whittaker et al., 1985, 1987; Harper, 1994; Visser, 1994; Borrman et al., 1996; Sullivan, 2004, 2005; Papageorgopoulou et al., 2009; Sagona et al., 2010; Cole and Waldron, 2011) and tests of the method routinely suggest that it per- forms as well or better than other methods of skeletal age estimation (Nowell, 1978; Kieser et al., 1983; Love- joy, 1985; Lovejoy et al., 1985a; but see Santini et al., 1990). Practically, the Miles method requires that the entire collection be seriated by tooth wear (Helm and Prydso, 1979) and that it include roughly 20 juveniles to make reliable wear rate estimates (Nowell, 1978). Unfortunately, many skeletal collections are curated by separate institutions and therefore cannot be seriated together according to wear. Furthermore, juvenile remains are more fragile than those of adults and are of- ten less well preserved in archaeological assemblages. This study was necessitated by just such a situation: while collecting data to compare antemortem tooth loss frequencies in hunter-gatherers, one of us (CCG) was obliged to use collections composed primarily (sometimes exclusively) of adult crania and curated by diverse repo- Grant sponsors: The L.S.B. Leakey Foundation, the University of California, Davis, Department of Anthropology Summer Fellow- ships, and the UC Davis Institute of Governmental Affairs. *Correspondence to: Cassandra Gilmore, Department of Anthro- pology, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA. E-mail: ccbrown@ucdavis.edu Received 1 December 2011; accepted 22 May 2012 DOI 10.1002/ajpa.22106 Published online 5 July 2012 in Wiley Online Library (wileyonlinelibrary.com). V V C 2012 WILEY PERIODICALS, INC. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 149:181–192 (2012)