Department of Anatomy, Midwestern University
Friday 9:15-9:30, Galleria North
Somatic growth is constrained by several genetic parameters, but other factors, namely, locomotor stresses, can also influence morphological development. Scapular shape is closely related to locomotor activity, so it is plausible that ontogenetic behavioral changes might similarly engender intraspecific morphological differences. To test this, the ontogeny of scapular morphology was examined in taxa known to climb less frequently throughout development (Pan, Gorilla, and Macaca) and others that maintain a more stable locomotor pattern (Pongo, Hylobates, and Homo). If the development of some features corresponds with ontogenetic locomotor changes while also differing from the common developmental pattern displayed in other taxa, it would be reasonable to attribute the morphological shift to the aforementioned behavioral changes.
Suspensory hominoids were distinguished from Macaca and Homo by having more superiorly facing glenohumeral joints, obliquely oriented scapular spines, relatively narrow infraspinous regions, and expanded subscapularis fossae. Although some traits followed a generally common pattern of growth among all taxa, other features, like infraspinous fossa shape, did not change markedly within Pongo, Hylobates, or Homo, but became relatively broader throughout Pan, Gorilla, and Macaca ontogeny. This morphological shift deviates from the growth pattern observed in Pongo, Hylobates, and Homo, and also corresponds with what was predicted for such a transition to a less arboreal lifestyle. These results demonstrate that some scapular features may track subtle differences in locomotor behavior over the course of an organism’s lifetime, and supports the use of these characteristics for reconstructing behavior, particularly in fossil forms.
Support for this research was provided by the National Science Foundation IGERT Program (99875690), an NSF Doctoral Dissertation Improvement Grant (BCS-0824552), and a Wenner-Gren Foundation Dissertation Fieldwork Grant