1Orthopaedic Surgery, University of California, San Francisco, 2Orofacial Sciences, University of California, San Francisco, 3Oral & Maxillofacial Surgery, University of California, San Francisco, 4Cell Biology & Anatomy, University of Calgary
Friday 4:15-4:30, Galleria South
Hominins exhibit significant evolutionary variation in facial shape and size, yet the genetic and developmental mechanisms involved in these interspecific differences remain poorly understood. For example, we know relatively few genes involved in human facial morphogenesis, what functional roles they may play during growth and development, and how heritable variation in their expression might contribute to the continuous phenotypes that selection acts upon. To better address these questions, we have initiated a project called “FaceSpace”, with the goals of characterizing normal human facial variation, identifying gene candidates involved in shape and growth, and testing their developmental contribution to variation via experimental analysis in model systems. We use as an example our analysis of the Sonic hedgehog (SHH) cell-signaling pathway, which has been implicated in both human facial birth defects and vertebrate brain and face evolution. We demonstrate that when experimentally modulated in the brain, variation in SHH-signaling activity contributes to integrated changes in vertebrate facial breadth that are relevant to human cranial evolution. Our results show how normal and abnormal human facial variation can be used to generate experimentally tractable hypotheses, and more importantly, how traditional anthropological strengths in quantitative morphometric analysis of variation can be combined with developmental biology to yield significant human evolutionary insights.
This research was funded by NIH F32DE018596 (NMY), R01DE018234, R01DE019638 (NMY, BH, RSM), the UCSF Academic Senate (JSL, JH), and NSERC #238992-02 (BH).