Asymmetry and intraindividual diversity in digital dermatoglyphics of Bulgarians.

A random sample of 2,130 apparently healthy Bulgarians, 1,065 of each sex, was investigated to obtain a detailed picture of finger dermatoglyphic asymmetry and intraindividual diversity in the population examined. Both sexes showed an almost equal pattern of asymmetry and diversity. Relative pattern asymmetry, taking into account the pattern type frequencies, tends to be higher in males, being especially pronounced on fingers which show a low asymmetry in other aspects. Like other populations so far examined, Bulgarians display higher rates in males than in females concerning the total, ulnar, and radial ridge-counts, their asymmetries, and intraindividual diversities. However, the more analysis of the ridge-count asymmetry is worked out in detail, the more it becomes evident that both sexes are asymmetrical not so much to a different degree as in a different manner. As a whole, the ambidirectional, directional, fluctuating, and relative asymmetries are practically consistent in both sexes. Important sex differences are revealed in the structure of the directional and fluctuating asymmetries concerning contrasts between their radial and ulnar levels. The sex differences in directional asymmetry are discussed in the light of possible effects of the sex chromosomes upon the mediolateral developmental gradients. Expressed modulation of the fluctuating asymmetry by finger is interpreted as evidence for considerable differences between separate finger pairs in their sensitivity to stressful factors. Presented results are relevant to anthropology and population genetics and could have implications in medical genetics and teratology, serving as normative data in pathological conditions.