It is a deep question, from deep in our history: when did human language as we know it emerge? A new survey of genomic evidence suggests our unique language capacity was present at least 135,000 years ago. Subsequently, language might have entered social use 100,000 years ago.
I’ve heard about it. The hypothesis is probably false, but I still wish people developed it further, since it questions a lot of things people take for granted when it comes to the human mind (e.g. consciousness is innate).
If it is true, consciousness would’ve appeared practically yesterday, and considerably after the development of language. For example Jaynes claims that the Ancient Greeks still had a bicameral mind, instead of a single and unified conscience.
That said it’s tempting to analyse the origins of language in the absence of consciousness.