Twenty-six autistic children, constituting a total population sample of children diagnosed in accordance with Rutter’s criteria as suffering from infantile autism, were assessed with regard to handedness and certain associated factors. They were compared with 52 age-, sex-, and IQ-matched controls. Sixty-two percent of the autistic children were non-right-handed compared with 37% of the controls. Left-handedness in autism was associated with an abundance of delayed echolalia. Heredity for left-handedness in some cases, and assumed brain damage and immature patterns of lateralization in others, were considered the cause of non-right-handedness in the autistic children. Computed tomographic (CT) brain scans and other neurobiological examinations did not provide evidence indicating clear-cut unilateral left hemisphere dysfunction in autism. Rather, a slight trend in the opposite direction (i.e., an association with right hemisphere dysfunction) was seen in the left-handed autistic children. The result points toward the need for further studies of handedness in autism. (Gillberg, C. (1983). Autistic children’s hand preferences: Results from an epidemiological study of infantile autism. Psychiatry Research, 10(1), 21-30.)
Twenty five years ago researchers observed the close connection between autism and handedess. A generation later and the connection between handedness and Marian Annett’s work regarding random handedness as an evolutionary precurser to contemporary right handedness has not been explored as related to autism. If autism is an evolutionary condition, and we understand evolution as a process deeply influenced by social structure and environmental effects, then perhaps we can understand what causes some forms of autism.
