The author of that book writes for the entertainment market and is not a particular expert in human evolution or speech generation either anatomical or neurological. There is little agreement among scientists on the topic and not a lot of real evidence to go on;) https://www.msn.com/en-us/news/technology/humanity-s-first-words-older-than-previously-believed/ar-BB1l1K3i?ocid=msedgntp&pc=NMTS&cvid=f2