The traits of five types of tongue movement in Han of Shaanxi, China

Abstract The study sample consisting of 429 people (207males, 222 females) of Han nationality in Shaanxi, China.Five types of tongue movements were investigated,including tongue rolling, tongue folding, tongue twisting,pointed tongue and clover-leaf tongue. The results revealedthat the frequencies of tongue rolling, tongue folding,tongue twisting, pointed tongue and clover-leaf tonguewere 63.6, 14.0, 12.6, 54.8 and 0 %, respectively. Therewere no significant gender differences except with pointedtongue. Compared with other nationalities, tongue rolling,tongue folding, and pointed tongue of Han in Shaanxi hadan average frequency. Tongue twisting and clover-leaftongue had low frequencies. There were significant dif-ferences in frequency of clover-leaf tongue between Hanand another seven nationalities of China (P\0.01). Fur-thermore, only three pairs of trait correlations wereexhibited among ten pairs of types of tongue movementcombination traits when analyzed using Pearson’s corre-lation coefficient. The data indicated that the correlationsof tongue movement were between tongue rolling andtongue folding, between pointed tongue and tongue rolling,and also between tongue folding and pointed tongue,respectively. Additionally, there were significant differ-ences in frequency of tongue movements with age. Thepossible mechanism of variations of tongue movementswith aging may involve the degradation of tongue function,and differential gene activation and modulation, or proteintranslation.Keywords Han nationality Pearson’s correlationcoefficient Traits Tongue movementIntroductionThe tongue is the primary muscular organ of deglutition,taste and speech. Human beings have extrinsic and intrinsicmuscles of the tongue. Both sets of muscles are innervatedby the hypoglossal nerve and the vagus nerve. Undercoordination of extrinsic muscles in the tongue, contractionor relaxation of the intrinsic muscles can produce somespecial types of tongue movement, including tongue roll-ing, tongue folding, tongue twisting, pointed tongue andclover-leaf tongue. The special types of tongue movementare important classic indicators in human populationgenetics. Few researches on tongue movement have beenconducted previously (Hoch 1949; Whitney 1950; Bat-Miriam 1962). The ability to turn up the edges of thetongue (tongue upfolding/tongue folding) is conditioned atleast in part by heredity, and the dominant gene isresponsible for folding and rolling of the lateral edges ofthe tongue while the inability to roll and fold the tongue is