Two Origins of Language Evolution: Unilateral Gestural Language and Bilateral Vocal

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. Key words: sex difference, laterality, IQ, r-selection, K-selection, gestural language, vocal language, language evolution, sexual precocity, neoteny. Emotional Language is Neglected in Linguistics Children during Piaget's stage of preoperational thought, which ranges from 2 to 7 years, develop their abilities to represent objects and events (Wadsworth, 1971, p.70). Language at "this stage is studied linguistically. However, language at Piaget's sensory motor stage as spoken by fragile children is generally regarded as somewhat primitive or incomplete. "Children prior to this stage (stage of preoperational thought) of development may use words. They may use 'mama' or 'dada' during the first year. These early words are not usually used to represent objects, or the early words are not language in the representational sense" (Wadsworth, ibid., p.74). See Figure 1. Language at the sensory motor stage is possibly an `emotional language' (Code, 1987, pp.104-106) which "functions as a link between the outside world and our most private inner selves" (Code, ibid., p.106). Adults strengthen emotional language by complex prosody "the expletive, the soft loving tone, the harsh angry tone, the emotional break in the voice, the wink and the smile" (Code, ibid., p.106-107) - after the acquisition of representational language. Emotional language does not require componential or sequential synthesis or analysis: its impact is immediate and its meaning is fundamental (Code, ibid., p.107). This very human function of language had been neglected as baby talk, but emotional language is closely related to the sexual behavior of females seeking to acquire partners (Hattori, 1998), and could have evolved before representational language. Sex Differences of IQ and Age Dependence Lynn (1998) wrote that language processing by females is performed bilaterally, in contrast to male language which is performed unilaterally. The sexual difference found in psychometrics is possibly correlated with the sexual dimorphism revealed by brain science (Breedlove, 1994; Kelly, 1991; de Lacoste, et al., 1986; de Lacoste-Utamsing & Holloway, 1982). Sexual dimorphism is also age dependent. Allen et al. (1991) found that the midsagittal area of the corpus callosum increased with maturation and decreased with advancing age. Blatter et al. (1995) reported sexual differences in the shrinkage of cortex with age. Hattori (1999) examined standardization data of IQ tests conducted in Japan, ranging from 3 years to 74 years, and found different patterns in sex difference of IQ. The study of sex differences in IQ should record age (Halpern, 1997). Hattori's study reviewed three IQ tests with different administration age ranges in relation to human growth (Deacon, 1992; Love & Webb, 1996; Wadsworth, 1984, pp. …