This thought-the origin of thought, lends itself to the consideration of how past material remnants and culture would help us understand how thoughts evolved, and what thought systems existed in those past minds? The patterns of cultural evolution which left behind their symbolic representations of some "thoughts' of those times represents our traces of the history of mental evolution and cognitive developments by the passe of time. These patterns are artifacts of analysis, like bones, pits, potteries, tools of agriculture and carpentry, hearths, walls, buildings and many more, including mummies which are remnant of those minds who thought and whose thoughts were much correlated with the society and environment that prevailed at those times. When belief systems developed along with the origin and development of the state society, thoughts diversified, cultures specialized and human beings started to understand their own behavior, of how they should act, think and behave, are well studied by Cognitive Archaeologists like Colin Renfrew (Renfrew et al. 1993), Hodder (1993) and others.
Ref:
Wynn, T. (1979). The intelligence of later Acheulian hominids. Man 14:371-391.
We have been partly conscious since we became human, which is the larger question that would answer your question. Consciousness is largely collective, since we are all identically wired. However we are equally subconscious, likewise collectively. See my evidence from art and building sites at www.stoneprint.wordpress.com
Understood as the constant, permanent, selective and recurring memory of what has been memorized throughout life (autobiography), located within a broad development of the theory of mind (central self), and ordered by the symbolic and sequential structure of language.
Its development in historical time would occur with the gradual increase in cumulative culture within human niches, highlighting the development of the theory of mind, autobiography and language, used in the description and development of all human cultures.
Article ESTUDIO TRANSDISCIPLINARIO SOBRE LA AUTOCONCIENCIA