There are different theories about language evolution. Some authors claim that

language (and speech) evolved from monkey vocalization (Cheney & Seyfarth,

1990; Ghazanfar & Hauser, 1999; Hauser, 1996; MacLean, 1993). Others claim

that language/communicative behavior stems from gestural communication

(Armstrong et al., 1995; Corballis, 1992, 1999, 2002; Fogassi & Ferrari, 2004;

Kimura, 1993; Paget, 1963; Rizzolatti & Arbib, 1998). Some even deny a direct

evolution of language from some monkey precursor, considering the former as a

completely new acquisition of the human species, with characteristics that are

entirely different from any other animal cognitive function (Chomsky, 1986).