The aim of the present work is to identify the evolutionary origins of the ability to speak and understand a natural language. I will adopt Botha's "Windows Approach" (Language and Communication, 2006, 26, pp. 129–143) in order to justify the following two assumptions, which concern the evolutionary continuity between human language and animals' communication systems: (a) despite the uniqueness of human language in sharing and conveying utterances with an open-ended structure, some isolated components of our linguistic competence are shared with non-human primates, grounding a line of evolutionary continuity; (b) the very first "linguistic" utterances were holistic, that is, whole bunches of sounds able to convey information despite their lack of modern syntax. I will address such suppositions through the comparative analysis of three constitutive features of human language: syntax, the semantic value of utterances, and the ability to attribute mental states to conspecifics, i.e. the theory of mind.