Across all preindustrial civilizations, reacted in different ways to the energy surplus that domestication afforded, which usually depended on environmental variables, such as whether the arable land was bounded or whether shifting cultivation (as the soils were depleted) was feasible for relatively sedentary populations. The early states that arose where cultivation could be continual for a plot of land (through fertilizer and other methods) and were geographically bounded by barriers such as mountains, deserts, and bodies of water ( and ), were generally dominated by an elite in a steeply hierarchical society in what has been called the "exclusionary domination" model. The "corporate" model was more feasible where shifting cultivation could be practiced and geographical boundaries were minor (pre-state , the ancient culture in today's Nigeria) and less dominated by "great men" (monarchies) and more by groups that shared power (oligarchies, while constantly jockeying for it), and their control was more over labor than land. Most states arose where the arable land was both unbounded and permanent, or at least permanent. In anthropological circles, the corporate and exclusionary domination models of early civilizations often seemed to vie and interact, with one succeeding the other at times. However, whether it was monarchy or corporate oligarchy, the surplus was so small in agrarian civilizations that only a small elite and professional class could exist. Freedom was always a scarce commodity that primarily resided with the elite. While there was some variation in social organization across the world's agrarian cultures, the basics were identical for all of them, with elites and professionals riding atop the peasant class and extracting the agricultural surplus from them via a variety of carrots and sticks. Without the energy that agriculture provided, large sedentary populations were not possible, and without an agricultural surplus, civilization could not have formed. about the formation and trajectory of civilizations depended on those energy dynamics. Without those levels of energy generation, the game simply could not be played. In their most essential fundamentals, .
After Africa began colliding with Asia, about 18 mya Asian animals quickly invaded and dominated Africa. The two primary exceptions were , both of which prospered at home in Africa and in Eurasia. Proboscideans did even better; they did not only become prominent in Eurasia, but they also migrated to North America by 16.5 mya. , as soon as they could, and quickly succeeded in all South American biomes, from rainforest to grasslands to mountains. They beat apes to the Western Hemisphere by 16.5 million years. Elephants have and . Their huge size and prehensile trunks, as well as their ability to eat a wide variety of vegetation, let proboscideans flourish everywhere that they possibly could. They even as a force. Until humans arrived, proboscideans were the most intelligent, adaptable, and successful land mammals ever and arguably outperformed the dinosaurs. But after nearly 20 million years of global success, they nearly all went extinct soon after encountering behaviorally modern humans. They went extinct in the Western Hemisphere, and there has long been controversy among scientists whether humans caused it, although the debate is fading as evidence of human agency becomes clearer.
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Also, just as no fundamentally new body plans appeared after the Cambrian Explosion, modern ecosystems seem constrained by body size. Body sizes have similar “slots,” and body sizes outside of those slots are relatively rare. However, successful innovation usually happens at the fringes. The fringes are where survival is marginal and innovations carry a high risk/reward ratio. Most innovations fail, but a successful one can become universally dominant, such as those biological innovations that are considered to have happened only . There have been countless failed biological innovations during life’s history on Earth, many of which might have seemed brilliant but did not survive the rigors of living.