Sapiens: A Brief History of Humankind

by Yuval Noah Harari

Problem with this is that there is very little evidence that brain size is related to intelligence in mammals. https://pmc.ncbi.nlm.nih.gov/articles/PMC4685590/#:~:text=There%20is%20no%20clear%20correlation,definitely%20is%20not%20the%20case.