A Multivariate Craniometric Analysis of Secular Change and Variation Among Recent North American Populations

This study presents an investigation of secular trends in craniometric variation among Afro-American and Euro-American North American populations from 1750 to the present. An additional analysis of collection specific cranial variation between two prominent anatomical collections is also undertaken. Both investigations address the question of crania variation in reference to the proper application of craniometric analysis to medico-legal identiciation of racial affiliation in forensic anthropology.

The craniometric data include individual historic specimens and cemetery populations from Canada, Philadelphia and New Orleans. Anatomical specimens are collected from the Hamann-Todd and R. J. Terry collections, and recent forensic cases are obtained from forensic laboratories across the nation.

Predicated on the idea that secular change in cranial size and shape contribute to the differentiation between temporally different crania series, it is suggested that temporally earlier cranial series are less appropriate as calibration samples for the identification of contemporary U.S. populations. Analyses were performed on eighty crania variables to document temporal differences among racial and ethnic groups, and to explore patterns of variation related to gender within each group. Group differences were examined by multivariate analysis of variance and temporal differences were investigated using multivariate analysis of covariance and canonical correlation. Specificity of collection association was examined by canonical discriminant analysis.

The multivariate analysis of cranial variation revealed similar temporal trends in size and shape between Afro-American female and male crania, while Euro-American gender differed somewhat in their direction of change. Temporal trends and collection specificity are both statistically significant. Collections are suggested to reflect ethnic differences, particularly within the Euro-American group.

It is found that significant temporal changes among Afro-American and Euro-American cranial series and ethnic specificity of individual skeletal collections can render problematic the application of earlier cranial series to the identification of recent forensic cases.

An alternative to present calibration standards for forensic identification of crania is offered. Two additional cranial series of Hispanic-American males and American Indian of both sexes were added to the sample to define a four group calibration sample.

Calibration standards were calculated using discriminant analysis for the separation of racial or ethnic groups. Four, three and two group discriminant function were calculated for a suple of post 1900 crania to conclude the analysis.