The technique of measuring the human body for the purpose of describing or comparing individuals and groups of individuals is known as anthropometry. Anthropometry includes four basic subject matters: somatometry, cephalometry, osteometry, and craniometry. Craniometry is the measurement of the skull (cranium and mandible), especially measurements on dry bone. Craniometry has a long history in the biological sciences, as some of the earliest works on skeletal biology focused on measurements to complement descriptions of materials.
At the end of the 19th century, Anders Retzius created the cephalic index, sparking large-scale efforts to measure populations of living people. The cephalic index is a simple formula that divides the maximum head breadth by the maximum head length, and multiplies by 100. The cephalic index is used on living individuals and is distinguished from the cranial index, which is the same measurements on dry bone. On the basis of these measurements, attempts were made to differentiate between local populations from which an individual was descended. The basic premise underlying this methodology is that individuals with shared ancestry share similar cranial shape, due to morphology being strongly determined by genetics.
The data accrued from such studies was used for a variety of purposes, ranging from genuine scientific inquiry to justifying racial stereotypes, immigration laws, and arguments of racial superiority. There were even attempts to relate the shape of one’s head to criminality, and pseudosciences such as phrenology gained widespread use as a “civilized” tool for justifying racism. A backlash against misuse of biomeasurements led to many works that sought to dispel these notions, such as the research of Franz Boas and Ales Hrdlicka on Eskimo skeletal morphology. In the early 20th century, Boas published his seminal work, Changes in Bodily Form of Descendents of Immigrants, which compared cranial measurements of thousands of immigrants to those of their children, who had grown up in the United States. He concluded that the children of immigrants did not show sufficient affinities to their parents to support the notion that genetics played the major role in determining the shape of the skull of individuals. This work was a major blow to biological determinism and to the importance of cranial measurements as a distinguishing characteristic between populations.
Despite criticisms from various fronts, Boas’s work became a fundamental part of anthropology and modern society, underpinning such documents as the first United Nations Educational, Scientific, and Cultural Organization (UNESCO) statement on race. However, while his research has remained a strong component of the argument that the environment is the primary determinant of morphology (rather than genetics), the validity of craniometrics has become well established in the field of forensic anthropology, paleoanthropology, and archaeology. Forensic anthropology has developed a number of statistical methods using craniometric data that distinguish both sex and racial affiliation, and these interpretive frameworks have been used extensively in paleoanthropology to sex and type specimens and distinguish between closely related species. In addition, archaeological research uses these methods in the determination of group affiliations of skeletal material, in order to map migration patterns in prehistory.
Rather than simple measures of cranial length versus breadth, researchers have developed a suite of osteometric points that correspond to functional features of the cranium. Measurements are taken as chords between points, and multivariate analysis of the resulting measurements compares the shape of the skull with known samples in order to evaluate probably ancestry. The inherent limitation of this method is context, meaning that when particular regional variations (not necessarily correlated to “races”) have not been sampled, correct identification is impossible. Normal population variance also results in individuals that do not fit particularly well, since identification is based on probability rather than qualitative characters. In addition, individuals of mixed ancestry often do not fit well into a particular category when looking at cranial measures. Despite such limitations, craniometry remains extremely useful in forensic contexts for identification of human remains.
Craniometry is a probabilistic method of discriminating between possible ancestries of an individual. The utility for identification of human remains in forensic contexts has resulted in the continued refinement of formulae and procedures over more than a century, and the principles have extended into related aspects of physical anthropology, such as archaeology and the discrimination of paleontological species.
References:
- Bass, W. M. (1987). Human osteology: A laboratory and field manual. Columbia: Missouri Archaeological Society.
- Buikstra, J. E., & Ubelaker, D. H. (1994). Standards for data collection from human skeletal remains. Fayetteville: Arkansas Archeological Survey.
- Gill, G. W., & Rhine, S. (1990). Skeletal attribution of race. Albuquerque: University of New Mexico: Maxwell Museum of Anthropology.
