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.
"The Mark II predictions (post hoc in the present case) depend on a more general interpretation of the balanced polymorphism hypothesis explained above. This suggests that there are risks to intellectual development for those at both extremes of the asymmetry distribution. Problems in learning to read may be associated with overexpression as well as with underexpression of the rs + gene. Support for the view that the rs + + risk intellectual deficits beyond the visuospatial and practical ones hypothesized above comes from two sets of observations. First, the analysis of absolute hand speeds in hand preference groups (Kilshaw and Annett, 1983) suggested that hemisphere specialization might be achieved not be some boost to the left hemisphere but rather by some handicap to the right hemisphere. Among those of rs + + genotype there could be some who risk significant impairment of right hemisphere efficiency and who must rely, therefore, on the left hemisphere for all major intellectual skills."
(Annett, M. & Kilshaw D. (1984) Lateral preference and skill in dyslexics: Implications of the right shift theory. J Child Psychology and Psychiatry 25: 360)
"Evidence that the rs - - might have advantages in motor skills has been found in the discovery that in the large control samples of students and school children to be used below, left handers were faster than right handers for absolute peg moving times, and mixed handers were of intermediate skill.
(Kilshaw and Annett, 1983). (Annett, M. & Kilshaw D. (1984) Lateral preference and skill in dyslexics: Implications of the right shift theory. J Child Psychology and Psychiatry 25: 358)