engleski

Does dental arch asymmetry in Adriatic Island populations reflect developmental instability?

Developmental stability is reflected in the ability of a genotype to undergo stable development given the environmental conditions. Deviations from developmental stability may arise from the disruptive effects of environmental and genetic stresses ; they can be measured by the statistics of fluctuating asymmetry (FA), the most sensitive indicator of the individual's ability to cope with these stresses during ontogeny. Consequently, in an inbred Adriatic island population we hypothesize that dental arch asymmetry is higher than in any panmictic reference population, and it to increase within this population with both poor environmental circumstances and the extent of inbreeding. The data set consists of nearly 250 upper and lower dental casts from children (6-12 years of age), mainly from the Island of Hvar (Croatia). We digitized the 3D-coordinates of 40 landmarks on the arches. We used Geometric Morphometric methods for the statistical analysis quantifying overall asymmetry as the shape deviation (Procrustes distance) of a specimen from its mirrored form. The degree of asymmetry can be decomposed into 'directional' (DA) and 'fluctuating' asymmetry. The results generally support our hypotheses. Furthermore, we find a high variance in lateral size differences. Surprisingly, size asymmetries are also not consistent in upper and lower arches but seem to fluctuate independently, necessitating a novel modification of the decomposition algorithm. Since we think that Geometric Morphometrics is the method of choice to deal with the topic of bilateral symmetry which is why we apply it to 3D landmarks in the facial region. The problems and suggested solutions are of fundamental interest to physical anthropologists.

Asymmetry; Developmental instability; Dental arch; Inbreeding

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