Human evolution theory utilizing concepts of neoteny & female sexual selection
An etiology of neuropsychological disorders such as autism and dyslexia, and the origin of left handedness.
"In studies employing both clinical patients and normal subjects, a large REA (left hemisphere superiority) is typically found for the discrimination of duration, temporal order, sequencing, and rhythm, leading to the suggestion that there is a fundamental left hemisphere capacity for discriminating between rapidly changing acoustic signals, and that this capacity underlies the traditional verbal superiority of the left hemisphere. Similar studies of normal subjects, brain-damaged individuals, and dyslexia and dysphasic children have demonstrated an important left hemisphere superiority in controlling fine, sequential, manipulative movements of the limbs, hands, fingers, and articulators, in terms of kinesthetic control towards internalized representations of sequential target positions. Although the right hemisphere may be responsible for an awareness of spatial interrelationships, the left organizes movement into correct sequences. Such considerations may account for the fact that motor sequential or segmental aspects may be more strongly lateralized than the perceptual, particularly if they are the more fundamental." (Bradshaw & Nettleton 1983: 186, Human Cerebral Asymmetry)
"A disproportionate number of sinistrals are found among a number of clinical populations, including mental retardates, epileptics, stutterers, and sufferers from dysarthria, cerebral palsy, developmental aphasia, and dyslexia (for reviews, see Carter-Saltzman, 1979; Hicks & Kinsbourne, 1978; Satz, Baymur, & Van der Vlugt, 1979; Springer & Searleman, 1980). There are even said to be more nondextrals among smokers (harburg, Feldstein, & Papsdorf, 1978) and criminals (Andrew, 1978)! Sinistrality is also said to be more common among the first- or late-born, those born of very young or old mothers, twins, males (who are larger at birth), and those known to be the products of complicated pregnancies." (Bradshaw & Nettleton 1983: 206-7, Human Cerebral Asymmetry)