C KUZAWA, DP VAN GERVEN and SG SHERIDAN, Department of Anthropology, University of Colorado

Recent analyses of a Hohkam population from the site of Pueblo Grande has indicated a high rate of infant mortality suggesting high reproductive demands on the female segment of the population (Sheridan and Van Gerven, 1991).  In addition, trace elements analysis, as well as archaeological evidence suggests that a combination of nutritional deficiency, increased population density and resource depletion may have seriously taxed the population.  The present investigation provides a further opportunity to assess the general health at Pueblo Grande shortly before the Hohokam ceased to exist as a cohesive culture.

A sample of femoral midshafts from 24 females and 29 males was selected for analysis.  Measurements included percent cortical area, cortical thickness, antero-posterior (A-P) & medical-lateral (M-L) periosteal diameters.

Overall, females experienced a highly significant (p<0.01) reduction in percent cortical area of 30.4% by the oldest age category, compared to a reduction of 12.5% (p<0.05) among ales.  Although age changes in percent cortical area provide an excellent measure of overall bone loss, analysis of thickness changes in the A-P ad M-L quadrants provides additional information on the dynamics of the process related to mechanical as well as nutritional factors.  While male show no significant age change in cortical thickness in either the A-P or M-L quadrants, the female pattern is both significant and complex.  Because, in humans, the medical and lateral cortices are exposed to more frequent bending stresses than the anterior and postertior cortices, bone in the M-L quadrant is better maintained.  The Pueblo Grande females conform to this pattern.  Bone in the AP quadrants is reduced at an almost constant rate totaling 54%.  Bone in the M-L quadrants is predictability better maintained with an overall reduction of 27%.  The rate of loss, however is not constant.  Indeed, 95% of the reduction occurs between ages 30 and 40.

This female pattern appears related to factors of nutritional and reproductive stress.  During the early reproductive years and again after menopause (45+) bone loss among females is limited primarily to the A-P corticies.  However, during the later reproductive period dramatic reductions in cortical bone occur throughout the cortex.  We interpret this pattern to reflect the cumulative effects of continuing lactation and repeated pregnancy.