Easter Islander palmar dermatoglyphics: sexual dimorphism, bilateral asymmetry, and family polymorphism.

The palmar prints of 297 male and female Easter Islanders were analyzed according to the Penrose and Loesch topological classification system. While the frequencies of most pattern elements were not found to differ significantly between the sexes, the placement of the axial triradius was found to be highly significant (P less than 0.01). Both males and females were found to exhibit considerable bilateral asymmetry in the a-b count and in the atd angle, but there was no significant difference between the sexes in the amount of asymmetry expressed. Family data for a small subset of the sample (51 individuals) were subjected to further statistical analysis, from which significant results (P less than 0.05) were obtained both on chi-square tests for frequency of pattern elements and ANOVA tests for a-b counts, atd angle, and A-line exit. The implications of these results are considered from a developmental perspective. It is suggested that a particular pattern combination (termed a formula) could be used to represent a default value and that other formulae might then be considered as deviations from this default value. Such variation, theoretically at least, might be traced to genetic influences or to the embryological environment present during the time of dermatoglyphic formation.