An extraordinary leap in the evolution of the human brain

Hello Rabbi,
I’m now watching a course in neuroscience by Prof. Idan Segev that you mentioned in your book The Science of Freedom. During the course, he showed an interesting graph of the weight of the human brain throughout history:
https://drive.google.com/open?id=1Fby3PTenFF4VEuqVEG030RVC9z8X-Nvy
It can be seen that there is a sudden decrease in brain weight that goes against the general trend over the last ten thousand years. This is also the period of the beginning of written history and the agricultural revolution. Do you think this sudden decrease can be seen as an indication of any intervention by God in the natural evolutionary process? This period also fits in terms of orders of magnitude with the age of the world in the Book of Genesis ~ 6000 years from the beginning of Adam to the present day.
Best regards,