Two origins of language evolution: Unilateral gestural language and bilateral vocal language, hypotheses from IQ test data

Journal/Book: Mankind Quart. 1999; 39: 1133 13Th St NW, #C-2, Washington, DC 20005, USA. Inst Study Man. 399-436.

Abstract: This report reviews sex differences in the hemispheric organization of language revealed in standardized data from IQ tests. IQ test data support the notion that language is more bilaterally represented in females than in males. Test data also suggest that females matures faster than males. The factorial pattern of females' IQ, which shows bilateral representation, remains the same throughout life, but the pattern of males' IQ changes from bilateral representation at early childhood to unilateral representation at adolescence and after. Females seeking partners evolved vocal language for emotional and affective communication. Neotenic males were exposed to the vocal language transmitted from nursing females. Vocal language announced from the vocal organ located at the median line was originally bilateral. Gestural language, which is announced from unilateral upper extremities, is another origin of language evolution. Use of hands and arms as language produced ''Name Relation'' and ''Truth Value'' through matching between object and hand. The hands are under contra hemispheric unilateral control of the brain. Gestural language is the origin of unilateral hemispheric organization of language.

Note: Article Hattori K, Natl Rehabil Ctr Disabled, 4-1 Namiki, Tokorozawa, Saitama 3590042, JAPAN

Keyword(s): sex difference; laterality; IQ; r-selection; K-selection; gestural language; vocal language; language evolution; sexual precocity; neoteny; HUMAN CORPUS-CALLOSUM; SEX-DIFFERENCES; PREOPTIC AREA; BRAIN; INTELLIGENCE; NUCLEUS; RAT

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