The competence of humans to create and apply constructs of reality far exceeds that of any other animal species. Their ability to consciously manipulate such models seems unique, but it remains unknown how these abilities were initially acquired and then developed. Most individuals hold strong, culturally-anchored beliefs that their particular reality is true, a viewpoint challenged by the observation that all such constructs are different. They reflect not reality, but each individual’s life experiences. Collectively they facilitated the development of hominins (...) to unprecedented cultural and cognitive complexity. However, it remains entirely unknown how the human brain manages to create a model of the external world from the signals provided by sensory equipment and proprioceptors. This paper examines the roles of exograms in this development, as they are considered to be the only tangible connection between the brain, the faculties of sentience and the external world. Competency in exogram use became a crucial natural selection factor for humans and even overcame the human brain atrophy of the final Pleistocene and the Holocene. Under favourable conditions, some forms of exograms are capable of surviving from the deep time of human evolution. The paper follows their trail back in time to gain some insights into the developments that gave rise to human awareness, self-consciousness and Theory of Mind as we understand them. Specific archaeological finds and notions about sentient capabilities of hominins are presented in a search for exogram use in the course of human evolution. It results in a model that explains with clarity not only the course of the human journey but also the underlying reasons for the human condition as such: why we are the way we are. (shrink)