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.
"To reduce these ideas to a very brief statement, I can say that for a long time before the evolutionary emergence of articulate vocal language, the early hominids probably communicated propositionally by means of hand and arm gestures, supplemented both by other nonverbal signs and by primate vocal calls not yet deserving of the term 'speech'. This proposal may seem at first hearing to be a case of creating a theory to fit some startling new experimental facts. However, the idea that articulate speech was preceded by a long phase of gestural language is quite old; by the eighteenth century, this idea had been considerably elaborated by Condillac and others. In the nineteenth century, the gestural hypothesis for the origin of language was favored by Alfred Russel Wallace and by Edward B. Tylor, one of the major figures in the formative period of scientific anthropology, and in the early twentieth century was further supported by Wilhelm Wundt, a comparably impressive figure in the history of psychology." (Menzel ed. (Hewes) 1973: 126, Precultural Primate Behavior)