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Fourier analysis of facial profiles of young twins
Author(s) -
Tangchaitrong Kanokwan,
Messer Louise Brearley,
Thomas C. David L.,
Townsend Grant C.
Publication year - 2000
Publication title -
american journal of physical anthropology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.146
H-Index - 119
eISSN - 1096-8644
pISSN - 0002-9483
DOI - 10.1002/1096-8644(200011)113:3<369::aid-ajpa7>3.0.co;2-u
Subject(s) - discriminant function analysis , twin study , fourier analysis , fourier transform , linear discriminant analysis , trait , mathematics , statistics , psychology , genetics , biology , heritability , mathematical analysis , computer science , programming language
Twins studies provide a powerful approach to determining the relative contribution of genetics and environment to observed variation. Such studies assume trait differences in monozygous (MZ) twins are due to environmental factors and those in dizygous (DZ) twins are due to both genetic and environmental factors. This study quantitated facial profiles of twins using Fourier equations, determining their value in profile analysis and the assessment of the genetic contribution to facial shape. Standardized profile slide photographs of 79 pairs of 4–6 year‐old twins (37 MZ pairs, 42 DZ pairs) were scanned and x and y coordinates were extracted from each profile using sellion and Camper's plane as references. The coordinates were subjected to Fourier analysis and the normalised vertex projection coefficients were studied. The means of the differences between coefficients for MZ co‐twins did not differ significantly from that of DZ co‐twins, although the DZ group showed higher mean differences in the higher harmonics. Subjective examination of superimposed reconstructions showed wider variation between DZ co‐twins than MZ co‐twins. Correct classification of twins by discriminant function analysis using Fourier coefficients was similar for both groups (MZ: 70.3%; DZ: 73.8%). Fourier analysis could quantitate facial profiles of young children and differentiate some details, but was unable to discriminate between genetic and environmental influences, and any possible interactions between these influences, on their overall facial profiles at this developmental stage. Am J Phys Anthropol 113:369–379, 2000. © 2000 Wiley‐Liss, Inc.