Evolutionary Inference of the Human Facial Form: Insights from the Genotype-Phenotype Interface
Open Access
- Author:
- Zaidi, Syed
- Graduate Program:
- Genetics
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 09, 2016
- Committee Members:
- Mark Shriver, Dissertation Advisor/Co-Advisor
- Keywords:
- face
facial shape
nose
population genetics
selection
evolution
admixture mapping
climate
quantitative genetics
geometric morphometrics
3D
Fst
facial asymmetry
facial masculinity
sexual selection
heterozygosity
MHC - Abstract:
- The human face contains important organs which perform vital functions such as eating and breathing, sensory functions such as seeing and smelling, as well as signaling sex, emotions, and identity. It is also quite variable within and across human populations. Very little is known about the evolution of facial shape in humans, or the genetic architecture underlying the development of facial shape. In this dissertation, I have investigated the evolutionary genetics of certain aspects of the three-dimensional shape of the human face. In chapter one, I provide a literature review of the various hypotheses regarding the evolution of facial shape and the current evidence supporting them. In chapter two, I used a quantitative genetic framework to test the hypothesis that human variation in the shape of the nose seems to have been influenced by local adaptation to temperature. The results from this chapter suggest that the evolution of certain aspects of human nose shape, such as nostril size and nasal ridge may have been driven by local adaptation to temperature. In chapter three, I used an admixture mapping approach to identify three genomic loci associated with nose shape variation in a sample of individuals with mixed African and European ancestry. The nearest genes to the admixture peaks are LHX8 (LIM Homeobox 8), MITF (Micropthalmia-associated transcription factor), and, UACA (Uveal autoantigen with coiled-coil domains and ankyrin repeats). Chapter four is an investigation in the effects of genetic heterozygosity on traits such as facial asymmetry, facial masculinity, and height, which are thought to signal genetic quality and immunocompetence. Finally, in chapter five, I discuss the evolutionary implications of these results and future directions for this research.