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


Documented secular change in epiphyseal union timing and dimensions of the clavicle

NATALIE R. SHIRLEY1 and SANDRA CRIDLIN2.

1Anatomy Department, Lincoln Memorial University DeBusk College of Osteopathic Medicine, 2Health Sciences Department, South College

Saturday Afternoon, Forum Suite Add to calendar

This presentation synthesizes data on secular change in clavicle fusion and dimensions in the American population from 1840-1980 birth cohorts to provide a comprehensive assessment of developmental and morphological change in the clavicle. Langley-Shirley and Jantz (2010) documented secular changes in fusion timing of the medial clavicular epiphysis in Americans during the past century. They found that fusion commenced four years earlier in mid to late 20th century birth cohorts (1955-1985) compared to late 19th and early 20th century cohorts (1880-1935). Shirley and Cridlin (2011) noted an increase in clavicle length in birth cohorts from 1850-1920 and a decrease from 1920-1970.

The combined sample for this analysis consists of the Forensic Data Bank (n=1239), a modern autopsy sample from East Tennessee (McCormick Clavicle Collection, n=1137), McKern and Stewart Korean War males (n=341), and 354 individuals from the Hamann-Todd Collection. The total sample size is 3071 (2277 males, 794 females). LOESS regression was used to examine overall trends in clavicle length, and piecewise regression was applied to determine breakpoints in the data. Piecewise regressive models indicate a breakpoint around 1910-1920 in both sexes. Fluctuations in clavicle length are in general agreement with fluctuations in cranial and facial breadth. This is not unexpected, as certain genetic disorders (craniocleido-dysostosis) indicate a likely developmental link between the clavicle and cranium.

This preliminary analysis suggests that (1) earlier fusion timing and decreased clavicle length are not linked or (2) further refinement of the sample groups will elucidate the relationship between maturation timing and adult morphology.

This researh was funded by NIJ Grant No.2007-DN-BX-0004, the William M. Bass Endowment, and a Knebeg-Lewis Grant (University of Tennessee Anthropology Department).

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