There seems to be a natural progression in the size of associations and the complexities of activities of humans. The family must come first--the coming together of a father, mother, and child; this seems like an irreducible, biologically determined unit. Then extended families arise, leading to tribes of mutually beneficent individuals who share protection from predators and the elements, and share food that is hunted and gathered.
Historically (or pre-historically) such tribes must have been nomadic; they had to move on as they hunted-out or picked/gathered-out the resources of one area. If the resources were extensive, this would attract competitors who would be either (1) killed off, (2) driven off, (3) run away from, or (4) merged with to form bigger tribes.
Clearly the strongest of these four possible outcomes was merger. So, gradually, bigger and stronger tribes emerged. These stronger tribes could hold on to good resources, even cultivate crops (that is, plant seeds with the expectation that they would be around to harvest the results); and herd or corral game animals, even select the best grain seeds and breed the best meat animals.
The rise of agriculture led to the gathering of non-nomadic populations into villages. As agriculture became more efficient (through irrigation, crop rotation, fertilization, and seed selection), villagers had more time on their hands: if hunter-gatherers had to spend 90+% of their time and effort procuring food, farmers had to spend only 50% or 25% of their time securing nourishment. Or, conversely, only 1/4 or 1/2 of the population had to farm all the time and the rest could pursue other activities.
This led to the specialization associated with large-village or small-city life. People who developed skills at carving, or weaving, or entertaining, or a hundred other specialties, provided those services in exchange for food or in exchange for other services. In fact, as a system of barter or contractual exchange developed, city life became more and more specialized, and more and more stratified (some people's efforts and products were worth more than others'). Moreover, some medium of exchange (such as knives, cups of grain, or coins of gold) would be useful, as would a standardized system of weights and measures and a "graphic system," in other words, a written language system, numbers, and the physical technology for keeping track of accounts (such as marking on skins, bark, stones, clay, or papyrus).
Agreements on rules of engagement--on laws and codes of conduct, on principles of morality--also seem necessary, as do bureaucrats, enforcers, and overseers, in short, rulers and their staffs--a ruling class. And in addition to artisans, artists; in addition to arbiters and scribes, poets; in addition to teachers and caretakers, doctors and priests.
The first time this is known to have happened was the Sumerian civilization in Mesopotamia, the "Fertile Crescent," now southern Iraq. The Sumerian civilization extended from the first settlement in the late 6th millennium BCE until the rise of Babylon in the early 2nd millennium BCE. Other civilizations with complex social structures and high culture arose (and fell) in China and the Americas. In the Late Bronze Age, during the millennium leading up to about 1,000 BCE, high civilization and high culture emerged in large cities throughout what is now the Middle East. These collapsed with the advent of the Iron Age; the discovery of high-temperature forging of iron provided tools and weapons that were significantly cheaper and better than the bronze implements that preceded them. Most importantly, iron ore was widely available; the long-distance trade and peaceful negotiations between the sparse sources of copper and tin (needed to make bronze) were no longer needed.
After the collapse of Mesopotamian civilization at the end of the Bronze Age, there were, throughout the Levant and Middle East, several centuries without large cities, concentrated agriculture, irrigation and sanitation, uniform or enforced codes of law, philosophic and artistic works, and the other trappings of civilization. This Dark Age persisted until the rise of the Greek and then Roman empires. After the Roman Empire collapsed a few centuries after the birth of Christ, there followed, again, several centuries of fragmented and disorganized uncivil activity throughout the area now called Europe until the rise of our present civilization began a millennium or so ago.
Why did these prior civilizations collapse? Sometimes it was because they were invaded and overcome by larger population numbers and superior technologies. But often it was more because they outgrew (and polluted and exhausted) their agricultural base; their bureaucratic structures became top-heavy and laced with graft and corruption; and they could no longer sustain the legal and moral foundations on which their civilizations depended.
After each collapse there were outposts of barbarity from which, over several centuries, new seeds of civilization could arise.
In the 21st century, the entire globe is participating in a single, integrated civilization experiment. We see pollution and exhaustion of resources proceeding on a global scale. Rapidly developing technologies include briefcase-size weapons that can be used for very widespread mass destruction (spreading potent viruses and bacteria, radioactive materials, or super-toxins). We see markets and financial systems of international breadth teeter with rapid-fire information transfers and greedy inefficiencies. This time, the entire world is our backyard; every technologically sophisticated nation is interconnected with us; every downtrodden and hungry refugee is our neighbor. This time, when our civilization collapses, there may be few, if any, surviving remnants--few, if any, barbaric seeds in the hinterlands from which to rebuild.
Bun Gladieux, president of the Presssure Positive Company, has a blog with an interesting series of topics.
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