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.
"What is striking about the mixed-handedness group is not only its prevalence among the autistic but also the fact that it has seldom, with one exception (Silva & Satz, 1979), been reported in mental retardation samples, who are also known to have a raised incidence of MLH [manifest left-handedness] (Silva & Satz, 1979; Bradshaw-McAnulty, Hicks, & Kinsbourne, 1984; Hardyck, Petrinovich, & Goldman, 1976). The prevalence of this phenotype found among the autistic has ranged from a low of 17% (Hauser, DeLong, & Roseman, 1975) to a high of 47% (Tsai, 1983), with a mean total frequency of 33.6% (130/387), as reported in a recent review by Satz et al. (1984). Virtually the same proportions were observed in an excellent recent review by Fein et al. (1984). If valid, these findings point to the existence of a neurobiological phenotype that not only is specific to infantile autism but may also, like PLH, represent a specific etiological subtype. In fact, two investigators (Tsai, 1982, Fein et al., 1984) have reported recently that this mixed-dominant subtype represents a more cognitively impaired subgroup compared to autistic children with established dominance (left- or right-handed)." (Soper HV, Satz P, Orsini DL, Henry RR, Zvi JC & Schulman M (1986) Handedness patterns in autism suggest subtypes. J of Autism and Developmental Disorders 16: 157)