The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)


Cranial change in America: 1815 to 1980

RICHARD L. JANTZ and LEE M. JANTZ.

Anthropology, University of Tennessee

Saturday Afternoon, Forum Suite Add to calendar

The American population has experienced remarkable change in cranial morphology. Some of these have already been documented, but this paper expands on previous results by increasing the time frame, sample sizes and attempting to identify points in time when change begins, or proceeds most rapidly, which in turn may provide clues to reasons for the changes. Data sets employed are those from the Forensic Anthropology Data Bank, the University of Tennessee Donated collection, the Terry and Todd Anatomical collections, Civil War, and crania from historical cemeteries. All have documented birth and death dates, allowing calculation of birth year. Five standard vault and two face measurements from over 1500 crania were available. The analysis was limited to Americans of European ancestry. Size was defined as the geometric mean of the measurements, treating the vault and face measurements separately. Dividing each of the variables by size created shape variables. Cranial size shows significant increase, but the most marked change occurs in shape. Cranial vaults become higher (basion-bregma), bases become longer (basion-nasion), and bases become narrower (biauricular breadth). Most changes begin occurring mid to late 19th century and continue through the 1980s. There is negative interaction in the shape variables of breadth and those of height and base length. Face changes are less pronounced, but faces become significantly narrower and higher. An explanation of why these changes take place cannot yet be offered, but their timing offers a place to begin the search for correspondence with changes in quality of life.

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