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Unformatted text preview: 2005 Nature Publishing Group Dance reveals symmetry especially in young men William M. Brown 1 , Lee Cronk 1 , Keith Grochow 2 , Amy Jacobson 1 , C. Karen Liu 2 , Zoran Popovic 2 & Robert Trivers 1 Dance is believed to be important in the courtship of a variety of species, including humans, but nothing is known about what dance reveals about the underlying phenotypicor genotypic quality of the dancer 16 . One measure of quality in evolutionary studies is the degree of bodily symmetry (fluctuating asymmetry, FA), because it measures developmental stability 7,8 . Does dance quality reveal FA to the observer and is the effect stronger for male dancers than female? To answer these questions, we chose a population that has been measured twice for FA since 1996 (ref. 9) in a society (Jamaican) in which dancing is important in the lives of both sexes. Motion-capture cameras created controlled stimuli (in the form of videos) that isolated dance movements from all other aspects of visual appearance (including FA), and the same population evaluated these videos for dancing ability. Here we report that there are strong positive associations between symmetry and dancing ability, and these associations were stronger in men than in women. In addition, women rate dances by symmetrical men relatively more positively than do men, and more-symmetrical men value symmetry in women dancers more than do less-symmetrical men. In summary, dance in Jamaica seems to show evidence of sexual selection and to reveal important information about the dancer. Darwin was the first to suggest that dance is a sexually selected courtship signal 1 . If so, it should reveal genetic or phenotypic quality of the dancer. One such indicator of quality is degree of fluctuating asymmetry (FA), because it is inversely correlated with degree of developmental stability, which is an organisms ability to reach an adaptive end point despite ontogenetic perturbations 7,8,10,11 . Across diverse taxa, increased FA is associated with increased morbidity, mortality, poor fecundity and other variables linked to natural and sexual selection 7,8 . Most germane to the hypothesis that dance reveals underlying developmental stability is evidence that reduced fluctuating asymmetry is associated with locomotory traits or their functional effectiveness in several species, including humans 1219 . Likewise, bodily FA is inversely associated with attractiveness based on a persons odour 20 , voice 21 and facial appearance 22 . (Note that associations between FA and measures of sexual selection may sometimes be overestimated owing to publication bias and problems associated with small sample size 23 .) There are no studies in humans (or any other species) linking variation in dance quality with genetic and/or phenotypic quality....
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