Humans began to rapidly accumulate technological knowledge 600k years ago

You have to think that there were breakthroughs in communication technology — not just language in general but possibly also one individual who happened to be good at explaining things, either before or after language, who both taught more people, but also taught them how to teach — that led to step changes in technology.

Theory: there are no humans without language. Consider: what language do you think in?

Quite a lot of humans don't think in language, or do only some of the time, see e.g. https://www.iflscience.com/people-with-no-internal-monologue..., https://www.livescience.com/does-everyone-have-inner-monolog..., https://www.bustle.com/wellness/does-everyone-have-an-intern....

Indeed, there are two types of people in that regard, whose mind is blown (usually) that there is another type. One thinks in words, one has no words but a smooth stream of thought going.

> Indeed, there are two types of people in that regard

> One thinks in words

No. There are people who believe they think in words, because they haven't bothered to examine the question, but there are no people who think in words.

Think about the number of people you've ever seen do a double take at the idea that "I don't know how to put this into words".

I absolutely think in words. There are no pictures or whatever other mental model. There is literally a narrative of words and blackness inside head.