Variation in the Juvenile Bony Pelvis

Abstract

The human bony pelvis is important in many anthropological studies of archaeological populations and of human evolution as it balances two important human characteristics: upright walking and the birthing of large-brained infants. While it has been thought that the female pelvis is selectively constrained by these functions, research demonstrates the pelvis is also impacted by developmental plasticity and morphological variation. This thesis studies two archaeological human skeletal collections: Later Stone Age Southern African foragers, and semi- sedentary foragers from Indian Knoll, Kentucky. The sample consists of 60 juvenile individuals from 0-16 years of age as well as 10 adults (5 males, 5 females). The size and age range of the samples offers a look at growth and development in juveniles through maturation. This research explores when in pelvic growth morphological differences arise in the iliac crest and if there are differences between populations. In order to address pelvic growth and variability, geometric morphometric analysis of 3D semilandmark data was used to evaluate shape change during growth. This 3D approach is a novel way of exploring human bone adaptability and constraints in morphological variation. Morphological change was expected to occur between each developmental age cohort. The adult sample was expected to differ based on sex. Comparisons between the mean shape in the two populations was expected to differ based on their distinct geographic locations. When the results of the patterns of shape change were examined, the majority of landmark movement occurred in the mediolateral plane of the iliac crest. The greatest difference in mean shape occurred between the first and fourth developmental cohort, which was expected due to the large difference in age. Correlation tests revealed a positive relationship between shape and size. All results were the same between the two populations. The adult populations did not differ by sex but allowed maturation trajectories to be explored. Both size and shape maturation demonstrated highly significant positive correlations with age. This research was limited in its analysis by the fact it only examined the iliac crest. This represents only part of the entire human bony pelvis and may have limited the inferences that could be drawn from the results. Future studies should look at the entire shape of the pelvis over maturation and should further explore different populations to better understand the impact of developmental plasticity in different geographic contexts.