Bilateral Symmetry and Sexual Selection: A Meta-Analysis

Abstract

A considerable body of primary research has accumulated over the last 10 yr testing the relationship between developmental instability in the form of fluctuating asymmetry and performance of individuals in mating success itself or sexual attractiveness. This research comprises 146 samples from 65 studies of 42 species of four major taxa. We present the results of a meta-analysis of these studies, which demonstrates that there is indeed an overall significant, moderate negative relationship: for studies, the overall mean Pearson's r or effect size = -.42, P <.0005; for species, the overall mean r = -.34, .01 < P < .025. Based on calculated fail-safe numbers, the effect-size estimates are highly robust against any publication or reporting bias that may exist. There is considerable evidence that the magnitude of the negative correlation between fluctuating asymmetry and success related to sexual selection is greater for males than for females, when a secondary sexual trait rather than an ordinary trait is studied, with experimentation compared with observation, and for traits not involved with mobility compared with traits affecting mobility. There is also limited evidence that higher taxa may differ in effect size and that intensity of sexual selection negatively correlates with effect size.

Physical Attractiveness Bias in Employee Termination

“…As we touched on above, there is a large body of literature indicating that humans tend to be drawn to others who are more physically attractive. The origination of this phenomenon has been debated by psychologists of different origin; it may have an evolutionary beginning (attractiveness indicative of health and reproductive success; Moller & Thornhill, ) or it may be based, at least in part, from social learning at a very young age (Eagly et al., ). However, either origin leads to the conclusion that quite often there is a positive affective reaction to an attractive person and a negative affective reaction to an unattractive person (Lucker, Beane, & Helmreich, ).…”

Facial attractiveness, symmetry, and physical fitness in young women

“…Possible sources are genetic disturbances, toxics, and a high exposure to and/or a limited capacity to withstand parasites (see Thornhill and Moller 1997 for a review). Along the same line, Moiler and Thornhill (1998) provide meta-analytic evidence that, in many species, body symmetry is a valid cue for mate value that is utilized in mate choice. Concerning humans, several studies indicate that facial symmetry is positively linked to facial attractiveness (Grammer and Thornhill 1994;Hume and Montgomerie 2001;Mealey et al 1999;Rhodes et al 1998;Scheib et al 1999;Zebrowitz et al 1996; but also see Fink et al 2001;Rhodes et al 2001;Rikowski and Grammer 1998;Shackelford and Larsen 1997;Swaddle and Cuthill 1995 for mixed or contradictory results).…”

Preference for Symmetry: Only on Mars?

“…It has been established that humans prefer symmetrical patterns in numerous domains (Little et al 2007; Reber et al 2004), and preference for symmetrical visual features has been observed in creatures as simple as the bumblebee (Moller and Thornhill 1998; Rodriguez et al 2004). The widespread and robust influence of symmetry on aesthetic preference has resulted in several theories of its biological significance.…”