How is facial asymmetry related to gender and age?
No one is perfect, we all have at least a slightly asymmetrical face. Asymmetry arises during development and changes with age. We are most sensitive to asymmetry in the eye area because it's the first place people usually look. In the rest of the face, other asymmetrical places help us for example when assessing the attractiveness or health of an individual. How does facial symmetry change over the course of a lifetime? Is there a difference in facial asymmetry between the sexes? Katarína Harnádková from the Laboratory of 3D Imaging and Analytical Methods at the Faculty of Science, Charles University sought to answer these questions.
We have a constant need to check our faces in the mirror. We notice every change, every new wrinkle, whether it comes from a smile or worry. That is why we perceive the asymmetry of our face more in ourselves than in others. Soft tissues change throughout life. In addition to aging, facial asymmetry can also be caused by changes in the skull during adolescence or after tooth loss. Some facial asymmetries can be addressed with orthodontic approaches, while others can be addressed with plastic surgery. However, these interventions require knowledge of the "ideal" a/symmetry of the face, which is difficult to specify. This is where the results of a study and scans of 300 faces of healthy Czechs could be used.
Scientists have come up with the surprising finding that differences in facial asymmetry between the sexes can only be demonstrated up to the age of 40. In fact, after 40, the difference in facial asymmetry between men and women decreases, likely due to changes associated with aging. Facial asymmetry in females does not change significantly over adult life, whereas changes in males were significant. Another interesting finding was the average deviation from an ideally symmetrical face. The average line of the scanned faces (forehead-nose-chin) formed a slightly bent shape (the shape of the letter "C"). The upper part of the face was turned slightly clockwise and the lower part counterclockwise. The right eye was positioned slightly higher than the left one. The tip of the nose and lower jaw were tilted to the left.
What is behind the asymmetry of the human face? A preference for one side when chewing or using facial muscles is probably behind the differences in the shape of one of the faces. Sex hormones, particularly androgens (hormones regulating the development and maintenance of male characteristics), are also responsible for the asymmetry, and these hormones are likely to cause greater asymmetry in the faces of men than women. Our genes can also contribute to asymmetries – for example, changes in jaw asymmetry can be caused by mutations in specific genes. Some studies even point to specific patterns of facial asymmetry that characterise different groups of ancestors.
We are all asymmetrical in a way, some of us more and some less. Young men are more asymmetrical in the face than young women. But as we age, that difference disappears and the asymmetry itself fades slightly. In the future, facial 3D scanning may provide more interesting contexts that will be useful not only in forensic sciences but also in health care after the expansion of facial databases. Try looking in the mirror to see if your right eye is higher than your left or if your nose is turned slightly to the left.
Anežka Ševčíková
Harnádková K, Kočandrlová K, Kožejová Jaklová L, Dupej J, Velemínská J (2023) The effect of sex and age on facial shape directional asymmetry in adults: A 3D landmarks-based method study. PLOS ONE 18(8): e0288702. https://doi.org/10.1371/journal.pone.0288702
Published:
Oct 12, 2023 08:30 PM
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