Line of Sight in Hominoids.

OBJECTIVES

It remains unclear how the realignments of the face and basicranium that characterize humans were acquired, both phylogenetically and ontogenetically. The developmentally constrained nature of the skull has been previously demonstrated in other primates using Donald H. Enlow's mammalian craniofacial architectural relationships. Here, we compare crania of our closest relatives to gain greater understanding of how and why the relationship of the face and cranial base is developmentally constrained in order to inform instances of abnormal growth and clinical intervention.

STUDY DESIGN

A method for evaluating these fundamental architectural relationships using 3D landmark data was developed, thereby taking overall size and the geometric relationships among points into account. A sample of cone-beam computed tomography scans derived from humans and extant apes were analyzed (n=10 and n=6, respectively), as well as fossil hominid crania (n=7). Landmarks for 23 craniofacial architectural points were identified and recorded.

RESULTS AND CONCLUSIONS

Principal components analyses reveal that despite the similarities in craniofacial architecture between humans, extant apes and fossil hominids, appreciable trends in variation between the extant species suggest that the repositioning of the foramen magnum was only one of a constellation of traits that realigned the basicranium and face during the transition to bipedalism.