Fluctuating asymmetry

Bilateral features in the face and body, such as left and right eyes, ears, lips, wrists and thighs, often show some extent of fluctuating asymmetry. Some individuals show greater asymmetry than others.

Fluctuating asymmetry (FA), is a form of biological asymmetry, along with anti-symmetry and direction asymmetry. Fluctuating asymmetry refers to small, random deviations away from perfect bilateral symmetry.[1][2] This deviation from perfection is thought to reflect the genetic and environmental pressures experienced throughout development, with greater pressures resulting in higher levels of asymmetry.[1] Examples of FA in the human body include unequal sizes (asymmetry) of bilateral features in the face and body, such as left and right eyes, ears, wrists, breasts, testicles, and thighs.

Research has exposed multiple factors that are associated with FA. As measuring FA can indicate developmental stability, it can also suggest the genetic fitness of an individual. This can further have an effect on mate attraction and sexual selection, as less asymmetry reflects greater developmental stability and subsequent fitness.[3] Human physical health is also associated with FA. For example, young men with greater FA report more medical conditions than those with lower levels of FA.[4] Multiple other factors can be linked to FA, such as intelligence[3] and personality traits.[5]

  1. ^ a b Valen, Leigh Van (June 1962). "A Study of Fluctuating Asymmetry". Evolution. 16 (2): 125–142. doi:10.2307/2406192. JSTOR 2406192.
  2. ^ Tomkins, J. L.; Kotiaho, J. S. (2001). Fluctuating Asymmetry. London: Macmillan Publishers Ltd. pp. 1–5.
  3. ^ a b Cite error: The named reference :1 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Fluctuating asymmetry and physical health among young adults was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference :2 was invoked but never defined (see the help page).