[Sometimes we review stuff that ain’t new, cuz why not? Maybe you ain’t read it.]
Like a psychohistorian in Asimov’s Foundation (which Guns, Germs, and Steel, especially the Epilogue, makes me want to reread), I feel that, armed with Diamond’s theories, you could drop me on any planet during its prehistory, and I could predict who would rise to power and when and how. He is thorough and convincing. Here’s my simplified version:
When humans spread over the planet, gathering nuts and whacking animals, it was the ones who developed a more or less controllable food supply that could start spending time doing things other than gathering nuts and whacking animals. These other things included discovering metal, inventing writing, and making more babies, (that they could now feed but not have to carry around, following a mammoth herd, for instance.) Those humans started clumping together in larger and larger groups, and they had to get organized. Some, very painfully, figured out how. All of these hot! new! trends spread to wherever they were useful or necessary: an area with people to feed, a group who now needed metal to survive, a tribe that needed to manage its growth. Sometimes a less trendy group was straight-up conquered by a more trendy group. But go back a second – what about that “controllable food supply” thing? That would be key; that would be farming (and herding). Not exactly cutting-edge now, but in 8500 BC, farming was the new black. It’s the sine qua non, but begs the question of who figured it out and why? According to Jared Diamond, certain areas of the planet, because of native fauna and climate, are conducive to this reliable production of food. This would be Eurasia – in a vast east (China) – west (Fertile Crescent) belt of relatively similar climates and seasons. Those first little wheat grass seeds (or rice or barley, etc) snowball down through many millennia into wheeled carts, trade routes, record-keeping, empires. Without the right environment or native fauna, humans gather nuts and whack animals: a great way to survive, but not much use for building a civilization. The successors of those first farmers have inherited a set of overwhelming advantages over their gather/whacking cousins in other parts of the planet.