https://www.quora.com/Is-the-nondual-perspective-real-or-just-group-think-based-on-abnormal-mental-experiences/answer/Frank-Heile?srid=uUQ8

“About 50,000 years ago, the vocabulary of the humans at that time crossed over a threshold where the vocabulary had increased to the point where language became a universal representational system. Existing words could give a very accurate model of the world and new words could be easily created and defined in terms of existing words so that language became a universal representational system. The system also included a rich and detailed model of the person itself. Thus this new language representational system became a language consciousness.”