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Bodily symmetry increases across human childhood
David Hope1, Timothy C Bates, Dominika Dykiert
1Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, UK.
Background:
Although bodily symmetry is widely used in studies of fitness and individual differences, little is known about how symmetry changes across development, especially in childhood.
Aims:
To test how, if at all, bodily symmetry changes across childhood.
Study Design:
We measured bodily symmetry via digital images of the hands. Participants provided information on their age. We ran polynomial regression models testing for associations between age and symmetry.
Subjects:
887 children attending a public science event aged between 4 and 15 years old.
Outcome Measures:
Mean asymmetry for the eight traits (an average of the asymmetry scores for the lengths and widths of digits 2 to 5).
Results:
Symmetry increases in childhood and we found that this period of development is best described by a nonlinear function.
Conclusion:
Symmetry may be under active control, increasing with time as the organism approaches an optimal state, prior to a subsequent decline in symmetry during senescence. The causes and consequences of this contrasting pattern of developmental improvement in symmetry and reversal in old age should be studied in more detail.
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