The article's goal was to understand what set early humans apart from their closely related species, not simply to understand why modern human populations have exploded in the last couple of centuries. The answer to that seems to be that inter-generational co-operation in early human societies are what set them apart, enabled specialization and allowed the development of technology that frees up time, which led to more pop, and so on.

Perhaps these facts are not novel? I'm not sure how much of this is generally understood. Personally it seemed an interesting read. My education consisted of listing eras of human evolution (hunter gatherer, farmer, stone age etc), without much info on what human society looked like in the hunter gatherer stage. So this was novel to me at least.