DP VAN GERVEN, Deptartment of Anthropology, University of Colorado, Boulder, CO  80309
SG SHERIDAN, Department of Anthropology, University of Notre Dame, Notre Dame, IN  46556
DB BURR, Department of Anatomy, Indiana University School of Medicine, Indianapolis, IN

While archaeological remains have played a major role in the study of adult-onset osteopenia, the study of subadults has been less extensive.  This is unfortunate in light of the strong association between bone loss and nutritional stress among living children.  The few studies of prehistoric children that have been done reveal the same association and have provided an important perspective on dietary stress in ancient populations.

This research examines the relationship between subadult bone loss and nutritional stress in a Classic Hohokam population.  The sample consisted of femora from 31 individuals aged birth thru 15 years.  Each femur was measured for diaphyseal length, percent cortical area, and AP and ML midshaft diameters.  Additionally, AP and ML cross-sectional moments of inertia (CSMI) were determined for each specimen.

The results indicate that while growth was well maintained, there were 2 periods of protracted cortical bone reduction.  The first occurred following birth.  While a degree of bone loss is common for well nourished newborns, the process is typically reversed by 9 months.  Bone loss at Pueblo Grande continued for 4 years and was associated with extensive enamel hypoplasia and porotic hyperostosis.  A second period of cortical bone loss (11%) occurred between ages 12 and 15 and was again associated with indicators of nutritional stress including porotic hyperostosis and diploic thickening.

The effect of bone loss on bone mechanics was assessed using AP and ML CSMI values.  While incremental increases in bending strengths occurred across the entire age range, including the period of infantile bone loss, the most dramatic increase occurred between ages 12 and 15 when cortical bone reduction was most substantial.  During this period there was a 310% increase in CSMI.  This resulted from a 60% increase in bone diameter associated with a 64% increase in bone length.

It appears that reductions in bone cortex may be of negligible consequence as long as normal trajectories of dimensional growth can be maintained.  Indeed, from a mechanical perspective, cortical bone reduction may have been adaptive.  Stressed and unable to maintain both dimensional and cortical bone growth, the infants and adolescents of Pueblo Grande appear to have diverted resources to that aspect of the growth process most critical to the structural integrity of their skeletal systems.