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Body Image and Body Image Disorders
Published in Mark B. Constantian, Childhood Abuse, Body Shame, and Addictive Plastic Surgery, 2018
This latter point deserves elaboration. Averageness indicates similarity to a typical phenotype for a group and therefore signals genetic diversity (and presumably greater health and disease resistance). Symmetry seems obvious; in fact, studies across a number of species have shown that less “fluctuating asymmetry” (i.e., greater symmetry) is associated with both fitness and fertility. It is not simple youthfulness but neoteny that is particularly associated with facial attractiveness. A baby’s features (large eyes, small nose, round cheeks, smooth skin, glossy hair, and lighter skin tones) correlate with greater perceived attractiveness, more paternal attention, and even a lower incidence of child abuse. A preference for childlike facial features appears consistently across ethnic populations, regardless of sexual orientation.
Studying factors influencing facial developmental instability
Published in Annals of Human Biology, 2021
Humans are bilaterally symmetrical organisms. Individuals displaying a higher level of body symmetry exhibit better resistance to developmental stress than those with asymmetrical somatic features (Van Valen 1962; Parsons 1992; Thornhill and Møller 1997; Klingenberg and McIntyre 1998). In general, there are three types of body asymmetries visible in organisms – directional asymmetry, antisymmetry and fluctuating asymmetry (Van Valen 1962; Palmer and Strobeck 1986). All three can occur together in the same trait. Directional asymmetry (DA) is when a trait on one side of the body is consistently developed in a different manner than the equivalent trait on the other side of the body. Antisymmetry refers to a less common situation, where asymmetry is present, but the greater development of a feature is somewhat equally distributed between both body sides. As a result, a mix of “left-sided” and “right-sided” individuals are to be expected. In contrast, fluctuating asymmetry (FA) is a random developmental variation of a trait that is on average perfectly symmetrical. Fluctuating asymmetry occurs due to imprecisions in developmental processes (Van Valen 1962). Deviations from perfect symmetry are assumed to reflect genetic and environmental stress experienced throughout the development of an individual. While DA and antisymmetry are controlled developmentally and are likely to have adaptive significance (lateralisation of muscle load or other functional demands), fluctuating asymmetry is basically an accidental response to ecological hardship (Van Valen 1962).
Differential impacts of ionizing radiation on a sexually dimorphic trait in male and female Acheta domesticus
Published in International Journal of Radiation Biology, 2023
Tamara M. Fuciarelli, Selvi Patel, C. David Rollo
Fluctuating asymmetry was measured as a biomarker for environmental stress (Parsons, 1992; Beasley et al. 2013). To determine levels of fluctuating asymmetry a Procrustes ANOVA was completed separately for each control and radiation group for both the male and female dataset. To determine the affect of sex on FA, a 2-way ANOVA was conducted using a full model which included dose, sex, and interaction effects. A follow up Šídák’s multiple comparisons test was also used to determine significant differences in FA between sex and dose across each experimental group.