Genetic Interrelationships of Dermatoglyphics

NVESTIGATORS of the relationships of dermatoglyphics and functional I handedness are in general agreement in finding slight but nevertheless 'real differences between the dermatoglyphics of right-handed and left-handed populations (BETTMANN 1932; BONNEVIE 1933; CUMMINS, LECHE, and MCCLURE 1931; LECHE 1933; NEWMAN 1934; KEITH'S unpublished data; CUMMINS 1940; CROMWELL and RIFE in press). Left-handers are characterized by slightly less bimanual asymmetry than are right-handers, rather than by outstanding differences in total pattern frequencies. The lowering of bimanual differences in left-handers is especially noticeable in females and is apparent in both palms and finger-tips. The investigation herewith reported is concerned with the ascertainment of possible genetic interrelationships of pattern development in palm and fingertip areas with each other and with functional handedness. Assortative mating, pleiotropy, and linkage may each result in certain types of association between biological traits. Obviously, handedness and dermatoglyphics are seldom, if ever, used as a basis for the selection of mates in man, so we need not consider assortative mating further. Pleiotropic genes result in correlations in the general population between the affected traits. As mentioned previously, several investigators have obtained such data for palmar and finger dermatoglyphics with handedness. WAITE (1915) made an exhaustive analysis of the finger prints of a population of adult males and found that positive correlations exist between pattern frequencies of different fingers. WENNICER (1935) observed an apparent negative correlation between the occurrence of patterns in thenar and hypothenar areas of palms. KEITH (1924) and BETTMANN (193 I) have made similar observations. CUMMINS in a communication to the writer previous to this investigation states his opinion to the effect that pattern occurrences in the thenar/first, second, third, and fourth inter-digital areas are positively correlated with each other and with transverseness of ridges, and also that there is a negative correlation between patterns in hypothenar and thenar2 areas. No literature has been found dealing with correlations between patterns on palms and on finger-tips. Linked genes result in inter-trait correlations within sibships, but not within the general population. Thus investigations dealing with the dermatoglyphics of right-handers as compared with left-handers selected from the general population tell us nothing concerning possible linkage relationships. RIPE (1941) obtained evidence for autosomal linkage of genes responsible for pattern