Center for Functional Anatomy and Evolution, Johns Hopkins
March 26, 2015 , Gateway Ballroom 2
The estimation of living body mass from skeletal material is an important component of the study of early hominins and more recent human archaeological remains. Most previous studies have concentrated on weight-bearing elements of the lower limb, in particular the femoral head. This study used new body mass estimation equations derived from measurements of the knee in a modern sample of known body mass to estimate body mass in 11 fossil hominin specimens (including Au. africanus, Au. afarensis, and early Homo). The reference sample consisted of 110 living humans who participated in the Baltimore Longitudinal Study of Aging. ML breadth measurements were taken from AP radiographs of the knee, and regressed against recorded body weight to generate body mass estimation equations. Knee dimensions were generally found to be good predictors of body mass in the modern human sample, with median absolute percent prediction errors of 7 to 8% (comparable to similar equations derived from the femoral head). Taxon average estimated body masses were 46kg for Au. afarensis, 42kg for Au. africanus, and 55kg for early Homo. Estimates for early Homo were similar to those generated previously from the femoral head. Estimates for australopiths, however, were larger than those generated from femoral head equations by an average of 8kg. This result supports the idea that relative loading of the femoral head may have differed between australopiths and Homo, perhaps due to subtle differences in gait.