Facial symmetry

This article is about the physiognomical concept. For other uses, see Symmetry (disambiguation).

Facial symmetry, is one element of bodily symmetry, including fluctuating asymmetry. Along with traits such as averageness and youthfulness it influences judgements of aesthetic traits of physical attractiveness and beauty, and is associated with fitness-linked traits including health, It is also hypothesized as a factor in both interpersonal attraction and interpersonal chemistry.

Health and physical attractiveness

British orthodontist R.J. Edler cited research supporting the claim that bilateral symmetry is an important indicator of freedom from disease, and worthiness for mating. Random differences between the two sides, known in biological terms as Fluctuating asymmetry, and not deliberate asymmetrical structures found in some animals, develops throughout the lifespan of the individual and is a sign of the phenotype being subjected to some levels of stress.

The ability to cope with these pressures is partly reflected in the levels of symmetry. A higher degree of symmetry indicates a better coping system for environmental factors. While the visible signs of this may not be particularly apparent, it is thought that they have at least an unconscious effect on people's perception of their beauty. Zaidel et al. in an empirical study upholds the claim that facial symmetry may be critical for the appearance of health. Their study disputes, however, the beauty or attractiveness claim.

Interpersonal attraction

A large body of work has been conducted relating symmetry to attractiveness, though this is not yet incorporated in this article. Symmetry may act as a marker of phenotypic and genetic quality and is preferred during mate selection in a variety of species^{[citation needed]}.

Experimentally, when the shape of facial features is varied (with skin textures held constant), increasing symmetry of face shape increases ratings of attractiveness for both male and female faces^{[citation needed]}. These findings imply facial symmetry may have a positive impact on mate selection in humans.

Non-scientific theories of attraction and symmetry abound. For instance the conjunction "of similar and related parts that are to some extent contrasted to one another" has been considered to have the most aesthetic appeal. Likewise shared features echoism, proportions and similarity to people the person bonded to early in life (prima copulism) have been suggested as relevant.

Etiology of facial asymmetry

^{[citation needed]}

Congenital defect

• Facial hemi-trophy or hypertrophy of superfacial tissue , muscle & bone.
• Mandibular Condylar hypoplasia due to intrauterine or birth trauma.
• TMJ Ankylosis, the mandible moves to the affected side.
• Mandibular body or ramus hyperplasia, the mandible moves to the unaffected side.

Traumatic

Zygomatic process fracture & followed infra orbital depression.

Inflammatory

Abscess - cellulitis - cyst

Muscular

a- Atrophy of facial musculature following Bell's palsy.

b- Hyperplasia of masseter muscle in clenching habit.

c- Patients using only one side in chewing

Salivary Glands

Inflammatory as mumps or neoplastic.

Neoplastic

Ameloblatoma - lipoma - osteoma

References

• Fink, B.; Manning, J. T.; Neave, N.; Grammer, K. (2004). "Second to fourth digit ratio and facial asymmetry". Evolution and Human Behavior 25 (2): 125–132. doi:10.1016/S1090-5138(03)00084-9. 

• Oral diagnosis 402 by Dr.Gihane Gharib Madkour

Lecturer of Oral Medicine, Oral Diagnosis & Periodontology Cairo University

Further reading

• Fink, B.; Grammer, K.; Thornhill, R. (2001). "Human (Homo sapiens) facial attractiveness in relation to skin texture and color". Journal of comparative psychology (Washington, D.C. : 1983) 115 (1): 92–99. PMID 11334223. 
• Johnston, V.; Hagel, R.; Franklin, M.; Fink, B.; Grammer, K. (2001). "Male facial attractiveness: evidence for hormone-mediated adaptive design". Evolution and Human Behavior 22 (4): 251. doi:10.1016/S1090-5138(01)00066-6. 

External links

• "Teeth, Beauty, Biology, and Health" – a class handout on dentition and facial symmetry at the College of Dentistry – University of Illinois at Chicago.
• "Chimeric Face Experiment" – Perform a facial symmetry and attractiveness experiment by uploading a photo
• FaceResearch – Online studies on facial symmetry by researchers affiliated with University of Aberdeen (Scotland) School of Psychology, and University of St. Andrews (Scotland).
• "A facial symmetry plugin for the GIMP" -- Try experimenting with facial symmetry, using open source software.