Fluctuating asymmetry

symmetry
As a form of biological asymmetry, fluctuating asymmetry (FA), along with anti-symmetry and direction asymmetry, refers to small, random deviations away from perfect bilateral symmetry.wikipedia
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Physical attractiveness

physiquephysically attractiveattractive
Symmetry has been shown to affect physical attractiveness.
Low facial and body fluctuating asymmetry may indicate good health and intelligence, which are desirable features.

Extra-pair copulation

extra-pair copulationsextra-pair matingextra pair copulation
Research has also provided evidence that FA is linked to extra-pair copulation, as women have been shown to prefer men with lower levels of FA as extra-pair partners.
Firstly, males with low levels of fluctuating asymmetry are more likely to have EPCs.

Orgasm

sexual gratificationfemale orgasmclimax
Research has shown that the female partners of men with lower levels of FA experience a higher number of copulatory orgasms, compared to the female partners of males with higher levels of FA.
Research by Randy Thornhill et al. indicates that female orgasm is more frequent during intercourse with a male partner with low fluctuating asymmetry.

Facial symmetry

facial asymmetrysymmetricalEchoism (facial symmetry)
Facial bilateral symmetry is measured via fluctuating asymmetry of the face comparing random differences in facial features of the two sides of the face that develop and accumulate throughout one's lifetime as a result of stressors.

Symmetry in biology

bilateral symmetryradial symmetrybilaterally symmetrical
As a form of biological asymmetry, fluctuating asymmetry (FA), along with anti-symmetry and direction asymmetry, refers to small, random deviations away from perfect bilateral symmetry.

Breast

breastsbosombreast tissue
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.

Testicle

testestestistesticles
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.

Health

human healthphysical healthwellness
Human physical health is also associated with FA.

Developmental biology

developmentdevelopmental biologistdevelopmental
Fluctuating asymmetry (FA) is often considered to be the product of developmental stress and instability, caused by both genetic and environmental stressors.

C. H. Waddington

Conrad Hal WaddingtonConrad WaddingtonC.H. Waddington
The notion that FA is a result of genetic and environmental factors is supported by Waddington's notion of canalisation, which implies that FA is a measure of the genome's ability to successfully buffer development to achieve a normal phenotype under imperfect environmental conditions.

Canalisation (genetics)

canalizationcanalisationcanalised
The notion that FA is a result of genetic and environmental factors is supported by Waddington's notion of canalisation, which implies that FA is a measure of the genome's ability to successfully buffer development to achieve a normal phenotype under imperfect environmental conditions.

Genome

genomesgenetic materialgenomic
The notion that FA is a result of genetic and environmental factors is supported by Waddington's notion of canalisation, which implies that FA is a measure of the genome's ability to successfully buffer development to achieve a normal phenotype under imperfect environmental conditions.

Phenotype

phenotypicphenotypesphenotypically
The notion that FA is a result of genetic and environmental factors is supported by Waddington's notion of canalisation, which implies that FA is a measure of the genome's ability to successfully buffer development to achieve a normal phenotype under imperfect environmental conditions.

Infection

infectious diseaseinfectious diseasesinfections
Various factors causing developmental instability and FA include infections, mutations, and toxins.

Mutation

mutationsgenetic mutationmutated
Various factors causing developmental instability and FA include infections, mutations, and toxins.

Toxin

toxinstoxicbiotoxin
Various factors causing developmental instability and FA include infections, mutations, and toxins.

Twin

identical twintwinsfraternal twin
Research on twins suggests that there are genetic influences on FA, and increased levels of mutations and perturbations is also linked to greater asymmetry.

Inbreeding

inbredlinebreedinglinebred
There is some speculation that inbreeding contributes towards FA.

Poverty

poorlow-incomeindigent
Some evidence suggests that poverty and lack of food during development may contribute to greater levels of FA.

Malnutrition

malnourishednutritional deficienciesmalnourishment
Some evidence suggests that poverty and lack of food during development may contribute to greater levels of FA.

Oxidative stress

oxidative damageoxidant stressoxidative
Fluctuating asymmetry in human males is also seen to positively correlate with levels of oxidative stress.

Morning sickness

nausea and vomiting of pregnancypregnancy sicknessMorning nausea
Pregnancy sickness is argued to be an adaptation for avoiding toxins during foetal development.

Adaptation

adaptedadaptationsadaptive
Pregnancy sickness is argued to be an adaptation for avoiding toxins during foetal development.

Prenatal development

prenatalperinatalfetal development
Pregnancy sickness is argued to be an adaptation for avoiding toxins during foetal development.

Pollution

pollutedenvironmental pollutionpollution control
Greater exposure to pollution may also be a fundamental cause of FA.