In This Article Skeletal Age Estimation

  • Introduction
  • General Overviews
  • Textbooks
  • Trajectory of Research
  • Age Estimation across the Lifespan
  • Age Estimation and Paleodemography
  • Sample Origin
  • Sample Composition
  • Sample Representativeness
  • Combinations of Anatomical Units

Anthropology Skeletal Age Estimation
by
George Milner, Sara M. Getz
  • LAST MODIFIED: 28 November 2016
  • DOI: 10.1093/obo/9780199766567-0159

Introduction

Knowing—more properly, estimating—the ages of skeletons from archaeological and forensic contexts is essential, but often exceedingly difficult. It is a fundamental aspect of investigating the mortality characteristics and disease experience of past populations; that is, paleodemography and paleoepidemiology. In medico-legal investigations, age is an essential part of the individual identification process. There are three critical features of a good skeletal age indictor: (1) the trait must go through unidirectional change, (2) the feature must be easily identified with little and known observer error, and (3) the observable changes in morphology must take place at roughly the same time in all people, or at least readily identifiable groups of them, such as when separated by sex or ancestry. While seemingly straightforward, the three requirements are actually hard to satisfy. The development and subsequent evaluation of procedures designed to meet these requirements have occupied the attention of researchers for many decades, with mixed results. Of particular concern are estimate accuracy (correspondence between estimated and true age) and precision (length of age intervals). There are real limitations in what can be done using existing methods, especially for middle-age and older adults. Many common procedures use an open-ended terminal interval, often something similar to fifty or more years. For people in this category, little can be said other than that the individual was old. Compounding that problem are well-documented biases in estimates, notably an underestimation of adult age from middle age onward. Taken together, these difficulties compromise what can be said about past populations and the contributions of skeletal analyses to medico-legal investigations. Despite such problems, there is room for optimism. It stems from an increasingly detailed appreciation of the analytical problems associated with age estimation, the development of procedures to deal with them, and the use of a wider array of skeletal characteristics as age indicators. Here we emphasize procedures that rely on simple visual observations of bone or tooth morphology, as opposed to those that require destructive analyses. Visually based methods are widely used and are of great practical value in forensic and archaeological investigations. At present, age estimates based on simply looking at skeletons work as well as, if not better than, those that involve sectioning bones and teeth.

General Overviews

Much has been written on age estimation from bones and teeth that originated in archaeological and forensic contexts. Overviews in Buikstra and Ubelaker 1994; Garvin, et al. 2012; Latham and Finnegan 2010; Liversidge 2008; Milner and Boldsen 2012a; Milner and Boldsen 2012b; Scheuer and Black 2000; and Uhl 2013 address how age at death is an essential element of medico-legal, paleodemographic, and paleoepidemiological investigations. Also, these publications detail how estimation procedures have developed and changed over time, and provide summaries of generally accepted methods. Standard methods (i.e., those most commonly used) are also routinely covered in bone identification manuals and textbooks. Perhaps the most influential recommendations for best practices, especially for archaeological skeletons, are found in Buikstra and Ubelaker 1994, often referred to simply as Standards. Collectively, these references cover what can be done to estimate age from the skeleton, identify procedures that should be employed to meet current standards of reporting and analysis, and highlight areas where improvements are needed. Reviews of skeletal age estimation, just like primary research articles, differ in part because of the related, but distinct, goals of archaeological and forensic investigations. Although individual skeletons, or just a few of them, are sometimes of interest to bioarchaeologists, many studies focus on understanding the characteristics of past populations as inferred from examinations of many skeletons. Usually what is of interest is what life was like in a particular time and place, and how it might have differed from the experiences of temporally, geographically, or culturally distinct groups of people. Interpretations drawn from mortuary materials about social organization and ritual practices in ancient societies are likewise impoverished without a proper accounting of age. In forensic investigations, the primary focus is often individual identification, which is typically a two-step process. First, skeletons are classified according to their general biological characteristics, including age at death, to narrow the range of possible matches to known missing people (e.g., males in their forties or fifties). Second, an effort is made to identify a specific person through matching the skeletal remains to personal descriptions, photographs, medical records, or other documentation. Although individual identification through DNA analysis is becoming increasingly common, the biological profile developed from morphological features remains a critical part of many investigations.

  • Buikstra, Jane E., and Douglas H. Ubelaker, eds. 1994. Standards for data collection from human skeletal remains. Arkansas Archeological Survey Research Series 44. Fayetteville: Arkansas Archeological Survey.

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    Widely used recommendations for data collection, including indicators of age, are presented. Examples of forms for documenting that information are included.

  • Garvin, Heather M., Nicholas V. Passalacqua, Natalie M. Uhl, Desina R. Gipson, Rebecca S. Overbury, and Luis L. Cabo. 2012. Developments in forensic anthropology: Age-at-death estimation. In A companion to forensic anthropology. Edited by Dennis C. Dirkmaat, 202–223. Blackwell Companions to Anthropology 10. Chichester, UK: Wiley-Blackwell.

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    Standard procedures for aging adult skeletons are reviewed along with complications of particular importance in forensic investigations. The future of age-at-death estimation lies in the exploration of new anatomical areas and the development of more advanced statistical procedures.

  • Latham, Krista E., and Michael Finnegan, eds. 2010. Age estimation of the human skeleton. Springfield, IL: Charles C. Thomas.

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    Concise chapters focus on different aspects of age estimation from immature and adult bones and teeth. Much of the volume focuses on dental and skeletal methods based on macroscopic features, but estimation methods that rely on histological sections are also covered.

  • Liversidge, Helen M. 2008. Dental age revisited. In Technique and application in dental anthropology. Edited by Joel D. Irish and Greg C. Nelson, 234–252. Cambridge Studies in Biological and Evolutionary Anthropology 53. Cambridge, UK: Cambridge Univ. Press.

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    The means of estimating age from tooth development, problems with doing so, and the relative effectiveness of several common procedures are discussed.

  • Milner, George R., and Jesper L. Boldsen. 2012a. Estimating age and sex from the skeleton, a paleopathological perspective. In A companion to paleopathology. Edited by Anne L. Grauer, 268–284. Blackwell Companions to Anthropology 14. Chichester, UK: Wiley-Blackwell.

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    Approaches to skeletal age estimation and difficulties associated with how it is done are reviewed. So too are implications for paleopathological studies, which should incorporate more accurate information on age to estimate age-specific risks of having various pathological conditions.

  • Milner, George R., and Jesper L. Boldsen. 2012b. Skeletal age estimation: Where we are and where we should go. In A companion to forensic anthropology. Edited by Dennis C. Dirkmaat, 224–238. Blackwell Companions to Anthropology 10. Chichester, UK: Wiley-Blackwell.

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    Age estimation, especially pertaining to medico-legal applications, is covered, as are likely future directions applicable both to archaeological and forensic work. Improvement in adult age estimation will require simultaneous research on a wider array of skeletal characteristics and the development of quantitatively rigorous statistical procedures to utilize that information.

  • Scheuer, Louise, and Sue Black. 2000. Developmental juvenile osteology. San Diego, CA: Academic Press.

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    Data on bone dimensions, epiphyseal union, and dental development for fetuses to adolescents are gleaned from various sources and are accompanied by a thorough discussion of the juvenile skeleton.

  • Uhl, Natalie M. 2013. Age-at-death estimation. In Research methods in human skeletal biology. Edited by Elizabeth A. DiGangi and Megan K. Moore, 63–90. Boston: Academic Press.

    DOI: 10.1016/B978-0-12-385189-5.00003-0E-mail Citation »

    This concise chapter summarizes basic concepts necessary for understanding age estimation from bones and teeth, along with commonly used techniques. It covers key sources on age-estimation methods.

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