Fluctuating asymmetry and preferences for sex-typical bodily characteristics

William M. Brown, Michael E. Price, Jinsheng Kang, Nicholas Pound, Yue Zhao, Hui Yu

Research output: Contribution to journalArticlepeer-review

Abstract

Body size and shape seem to have been sexually selected in a variety of species, including humans, but little is known about what attractive bodies signal about underlying genotypic or phenotypic quality. A widely used indicator of phenotypic quality in evolutionary analyses is degree of symmetry (i.e., fluctuating asymmetry, FA) because it is a marker of developmental stability, which is defined as an organism's ability to develop toward an adaptive end-point despite perturbations during its ontogeny. Here we sought to establish whether attractive bodies signal low FA to observers, and, if so, which aspects of attractive bodies are most predictive of lower FA. We used a 3D optical body scanner to measure FA and to isolate size and shape characteristics in a sample of 77 individuals (40 males and 37 females). From the 3D body scan data, 360° videos were created that separated body shape from other aspects of visual appearance (e.g., skin color and facial features). These videos then were presented to 87 evaluators for attractiveness ratings. We found strong negative correlations between FA and bodily attractiveness in both sexes. Further, sex-typical body size and shape characteristics were rated as attractive and correlated negatively with FA. Finally, geometric morphometric analysis of joint configurations revealed that sex-typical joint configurations were associated with both perceived attractiveness and lower FA for male but not for female bodies. In sum, body size and shape seem to show evidence of sexual selection and indicate important information about the phenotypic quality of individuals.

Original languageEnglish
Pages (from-to)12938-12943
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume105
Issue number35
DOIs
Publication statusPublished - 2 Sep 2008

Keywords

  • 3D morphometrics
  • Body shape
  • Developmental stability
  • Sexual dimorphism
  • Sexual selection

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