Abstract
An ethnically homogeneous group of Yakuts (Mongoloid race, Northeast Asia), aged 18–31, was studied to characterize the diversity of particular features between left- and right-handed individuals. A total of 52 left-handed (32 women and 20 men) and 100 right-handed (50 women and 50 men) individuals were studied. Testing included two sets of questions and tasks, dynamometry of the right and left hand, and fingerprint analysis. Left-handed and right-handed people were found to differ in functional asymmetry of psychophysiological and motor reactions. Right-handers were characterized by higher intragroup similarity, while, among left-handers, greater dispersion of these traits was observed. Asymmetry in hand grip strength was less pronounced in the left-handed people than in the right-handed; this difference was statistically significant, and the difference was greater in men than in women. This suggests that the non-dominant hand in the left-handed people was subjected to a greater load and indicates the forced adaptation of the left-handed people to “dextrastress”. No significant difference between sexes was found when analyzing fingerprint patterns. Left-handers had arches significantly more often than right-handers. Radial loops were most often found on the index finger, and, in the left-handers, their occurrence was significantly higher on three to five fingers of the left hand compared with the right-handers. The levels of fluctuating asymmetry in left-handers and right-handers were similar.
Highlights
The development of bilateral symmetry, along with the capability of adaptation to a rapid change in environmental conditions during movement, contributed to increasing “biological reliability”, i.e., the development of paired organs, one of which is capable of partially assuming the function of its partner if the latter is lost due to injury
No classification can fit the whole range of various phenomena into a rigid framework, and one such example is the manifestation of asymmetry in Symmetry 2018, 10, 728; doi:10.3390/sym10120728
Since it has been repeatedly mentioned above that both psychophysiological reactions and dermatoglyphic features are subject to high interpopulation variability, it is of interest to consider these features in a relatively small ethnicity that inhabits a vast area that is much farther north of the original area
Summary
The development of bilateral symmetry, along with the capability of adaptation to a rapid change in environmental conditions during movement, contributed to increasing “biological reliability”, i.e., the development of paired organs, one of which is capable of partially assuming the function of its partner if the latter is lost due to injury. There is the opinion that the number of people who write with their right hand is determined by genetic predisposition and by social pressure (that is, by the extent to which the society allows the individual to be unique) [15] This is why countries where, until recently, this pressure was the highest had the lowest percentage of left-handedness. The goal of our studies was to (1) evaluate the effectiveness of different testing approaches and the use of dermatoglyphic indicators to identify left-handed people and (2) assess the developmental stability of left-handed and right-handed people by establishing the level of fluctuating asymmetry of the fingerprints of a group of Yakuts (Mongoloids, Northeast Asia). Since it has been repeatedly mentioned above that both psychophysiological reactions and dermatoglyphic features are subject to high interpopulation variability, it is of interest to consider these features in a relatively small ethnicity that inhabits a vast area that is much farther north of the original area
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