Sex Estimation

by

Natalie Langley, Beatrix Dudzik

• LAST REVIEWED: 28 September 2016
• LAST MODIFIED: 28 September 2016
• DOI: 10.1093/obo/9780199766567-0152

Introduction

Sex estimation is the process of assessing whether skeletal remains are biologically male or female. Biological anthropologists, forensic anthropologists, bioarchaeologists, and paleoanthropologists may be called upon to determine sex from skeletal remains. Sex estimation is vital in establishing an accurate biological profile from the human skeleton, as sex influences the analysis of other elements (e.g., stature and age). The terms sex and gender are not to be confused in this context. Gender is a sociocultural construct, and sex is a biological trait. Sex estimation is based on the premise that male and female skeletal morphology differs in size and shape. This difference is referred to as sexual dimorphism. Although humans are less dimorphic than their nonhuman primate relatives, sexual dimorphism in Homo sapiens is sufficient to facilitate sex estimation from skeletal morphology. Practitioners distinguish between estimating sex by visually examining skeletal features (nonmetric methods) versus estimating sex using equations based on skeletal dimensions (metric methods). Experienced practitioners can quickly and easily assess sex by examining nonmetric traits, particularly those of the pelvis. Males have more robust muscle attachment sites and cranial features. Female skeletons are more gracile and smaller in overall size, but female pelvic traits collectively contribute to a wider pelvis. This morphology directly relates to parturition, or child-bearing. For this reason, the pelvis yields the most accurate sex estimates, followed by postcranial bones. Sex assessments from cranial traits generally are the most variable and least accurate. A growing concern about the subjectivity of nonmetric sex assessments has led to the implementation of ordinal scoring systems, statistical methods, and the quantification of discrete trait morphology with geometric morphometric techniques that examine shape differences. Metric sex estimation is favored because of the objectivity associated with osteometric data but is only possible if equations from geographically and temporally appropriate reference samples are available. The most popular statistical method for sex estimation is discriminant function analysis. Since degrees of sexual dimorphism vary between populations worldwide, population-specific equations are most accurate for metric sex estimation. Furthermore, significant skeletal sexual dimorphism is not present prior to puberty. Attempts to develop methods for subadult sex estimation have met with varying degrees of success, but, as a rule, it is not possible to determine sex accurately prior to the onset of puberty, especially when dealing with infants and children.

General Overviews

Most general overviews on sex estimation are covered in textbooks (see Textbooks). Braz 2009 and Garvin 2012 offer an introductory overview of the topic. Moore 2012 and Berg 2012 present comprehensive summaries for the intermediate to advanced level audience. Scientific Working Group for Forensic Anthropology (SWGANTH) 2010 constitutes a document on sex estimation that provides a cursory overview of the topic with an emphasis on best practices.

• Berg, Gregory E. 2012. Determining the sex of unknown human skeletal remains. In Forensic anthropology: An introduction. Edited by MariaTeresa A. Tersigni-Tarrant and Natalie R. Shirley, 139–160. Boca Raton, FL: CRC.

  The chapter on sex estimation provides a thorough introduction and overview of various methodologies.

• Braz, Valeria S. 2009. Anthropological estimation of sex. In Handbook of forensic anthropology and archaeology. Edited by Soren Blau and Douglas H. Ubelaker, 201–207. Walnut Creek, CA: Left Coast.

  This chapter briefly summarizes sexual dimorphism, visual sex assessment, and osteometric techniques used for sex estimation.

• Garvin, Heather M. 2012. Adult sex determination: Methods and application. In A companion to forensic anthropology. Edited by Dennis Dirkmaat, 239–247. Malden, MA: Wiley-Blackwell.

  DOI: 10.1002/9781118255377.ch12

  This chapter provides a brief summary of the traditional morphoscopic and osteometric techniques used for sex estimation.

• Moore, Megan K. 2012. Sex estimation and assessment. In Research methods in human skeletal biology. Edited by Elizabeth DiGangi and Megan Moore, 91–114. Oxford: Academic Press.

  This chapter provides an in-depth review of current and historical approaches to sex estimation by specific skeletal elements and gives a thorough review of sexual dimorphism.

• Scientific Working Group for Forensic Anthropology (SWGANTH). 2010. Sex assessment. Washington, DC: Federal Bureau of Investigation Laboratory, US Department of Justice.

  Provides a brief overview of sex assessment and includes commentary on approaches, factors, best practice, and unacceptable practices. The document is intended primarily for practitioners.