Arm folding, hand clasping and dermatoglyphic asymmetry in Bulgarians.

Arm folding and hand clasping have been analysed in 2100 Bulgarians, 1050 of either sex. In both traits, significant preponderance of the left type over the right one was revealed. Also, in both traits the excess of the left type is more pronounced in females but this sexual heterogeneity is significant only in the arm folding. Examination of the possible association between arm folding and hand clasping showed the independence between both asymmetries. On the other hand, the comparison between both sexes concerning distributions of the four possible combinations of types revealed statistically significant sexual dimorphism in this respect. Two kinds of dermatoglyphic asymmetry, directional and relative, have been investigated and comparisons have been made between right and left claspers and between right and left folders, each sex separately and finger-by-finger. Although statistically significant differences are not numerous, they have been discussed from the point of view of the importance of relationships between functional and morphological asymmetries.