When and how are fair questions to ask about many things. But when it comes to where humans came from and their history over the millennia we are still finding our way about the remains that are left and the potential interpretations.
These interpretations and the ideas, assumptions and guesses we make in what we call politics, philosophy, economics and history, ancient and modern are not just an academic matter. A good deal of the present thinking is derived from our notions about the past.
The past may be different than that what most of us have been led to believe. This book review by Steven Mithen in the latest London Review of Books, titled "Why Did We Start Farming" summarises the book by James C, Scott titled "Against The Grain; A Deep History of Earliest States". It is literally food for thought.
This is a long read and not something to click, scan and rush off to the football scores or latest media thing. One of the many ideas that are questioned is why ancient cities built high walls. We have always assumed that they were to keep the outsiders out. Possibly, it might be that they were more designed to keep people in.
What interests me is that one factor little considered by historians etc. more interested in Kings, wars and elites, is disease, which perhaps mattered a lot more than we think.