Just as precipitation before plants colonized land, denuded lands and , and transpiration no longer contributed to the hydrological cycle. Rampant deforestation contributed to flooded Mesopotamian rivers, and the region also became drier. The flood that survived, which , was probably related to deforestation, although a great deal of speculation exists regarding the origins of flood myths. The , where the rising interglacial global ocean flooded the lake to levels higher than during the glacial period. Another hypothesis has rising seas flooding the lower end of Mesopotamia. There are arguments that the legend of Atlantis related to a seashore civilization drowned under a rising interglacial ocean, but I think that an increasingly deforested Sumerian hinterland gave rise to the floods of legend.
Early elites claimed divine status, and the priesthood abetted the fiction, and a universal practice among early civilizations was erecting monumental architecture. The was the first such structure. Anthropologists think that monumental architecture may be a form of societal/elite , so that a society can flaunt the resources used to make such overawing showings, both to encourage submission to the society's obvious wealth and power, and to also discourage attempts to compete with it. In Sumer, ziggurats were not only the center of the , but also held precious metals such as gold. The priesthood directed mass economic activity, such as organizing irrigation projects. In some ways, the priesthood was only adapting to urbanization. Their professional ancestors developed calendars and other methods of synchronizing vital activities such as plantings and harvests, with their attendant festivals; mistimings by mere days could lead to famine. Sumerian temples had statues in their central place of worship, in human form, bedecked with jewels and other precious adornments. Offerings of food were presented to the statues, which temple personnel ate that night. In the third millennium BCE, temples owned land and had their own workforce, which was again a “voluntary” one that discharged religious obligations. Although those temples performed valuable societal functions such as taking in orphans, the earliest urban religions were obviously businesses and could become rackets, in a pattern that continues to this day.
I earlier compared people from different epochs. That stone tool Tesla what his/her invention would lead to a half-million years later, and members of the founding group could not have comprehended . Imagine a hunter-gatherer of 10 kya being dropped into Rome in 100 CE or London in 1500 CE. History has some relevant examples. When , about the last of his people, came out of hiding in his dying world and strode into civilization, it caused a sensation. He soon died of tuberculosis, but his encounters with civilization were recorded. He attended an opera, and the popular account portrayed his rapport with the diva, but Ishi actually stared in amazement at the , as he had never before seen so many people in one place. When he saw an airplane in flight, he laughed in amazement. Imagine a hunter-gatherer of 10 kya being dropped into imperial Rome. That hunter-gatherer had probably seen dogs, but horses, cows, sheep, and the like would have been astounding, and watching a horse or ox pull a cart would have been stunning. Crops would have been an amazing sight. Imagine that hunter-gatherer at the . The building and crowd alone would have boggled his mind, even if the festivities might have been horrifically familiar. Metals and glass would have seemed magical. Writing had not yet been invented in that hunter-gatherer’s world, so even the concept would have been difficult. Imagine him trying to learn math. There were no more singing and dancing religious rituals, and no wide-open spaces to hunt a meal. Imagine that hunter-gatherer visiting a Roman bath. Hot water alone would have been surreal, while the cavorting might have been delightful. What would his reaction have been to Rome’s markets? Rome was also loud and could be hellish, so the hunter-gatherer might have longed to flee to the countryside before long, but the countryside would have little resembled the one he knew. He obviously would not have understood anything that anybody said, but they were also all members of , so he would have seen many behaviors and traits that he eventually understood. But how long would his shock have lasted? Could he have really ever adapted to Roman society (if he did not quickly end up on the arena’s stage as a novelty)? Another surprise for that hunter-gatherer would be seeing people interact who did not know each other. People were interacting with members and not trying to kill them on sight, which became standard behavior in most hunter-gatherer societies that battled over territory (their food supply). Civilized life was all made possible by the local and stable energy source that agriculture provided, which led to an epoch that changed very little until the next energy source was tapped: the hydrocarbon energy that powered the Industrial Revolution. The next chapter will survey the developments that led to that momentous event. It is the only Epochal Event with historical documentation that showed how it developed, which is easier to reconstruct than examining stones and bones.
The methods of preindustrial civilizations, with deforestation and agriculture, were never really sustainable, as they disrupted ecosystems and even affected local climates. The only way that the system, for instance, was sustainable was that they let the land go fallow for eight years after two years of crops, in order to let the damage heal before farmers repeated the cycle. Only when practices were intermittent, to allow ecosystems to recover somewhat, could they be called sustainable, but even then the idea is somewhat misleading. It was an ecosystem commandeered for human benefit at the expense of the original ecosystem’s denizens, and the practice never approached true abundance. Those civilizations were all mired in scarcity, with only about one person in a thousand living to a ripe old age, and only about “making it” economically (the potentate). In such a world of scarcity, life was often cheap, and virtually every preindustrial civilization had , from to to chattel slavery to becoming a human sacrifice to other forms.
Anasazi civilization also overtaxed its environment and collapsed in a drought, as did the . The lauding of Native American environmental conscience seems largely a romantic invention, like the “” fantasy. Although Native Americans obviously had a far gentler tenure on the land than what happened in the Old World, it may have been only a matter of time before they “progressed” with metal smelting, rampant deforestation, and the like. Without draft animals (bison were probably the only candidate for that, and turning them into domesticated draft animals may not have been feasible), their civilizations might have taken very different paths than the Old World’s. What kinds of civilizations might have emerged from the Western Hemisphere had Europe not intervened will always remain a tantalizing question, but we will never know; those civilizations show different ways to do it, even if what the Spaniards stumbled into seemed familiar, with cities, markets, elites, monumental architecture, warriors, priests, peasants, slaves, and so on.
Humans took a different path 2.5 mya. There are generally two schools of thought regarding the appearance of among scientists: one is called the Multiregional Model, and the other is called the . In their essence, the Multiregional Model had those migrants eventually evolving into today’s races, and the “Out of Africa” Model had humans evolve in Africa and then spread across the world and replace/displace all other members of the genus. The rise of has largely resolved the issue in favor of the “Out of Africa” Model. There are also intermediate views and variations of each hypothesis, which generally relate to the invaders mating with the natives, even if they could be classified as separate species. For instance, Neanderthal DNA is part of the human genome, which reflects interbreeding. Since Neanderthals were largely confined to Europe and what became the Fertile Crescent, and the migration of the original was from Africa, sub-Saharan Africans . Africans also have the most genetic divergence, which reflects the idea that humans have lived longer in Africa than anywhere else. There is virtually no doubt that evolved in Africa.
From the initial appearance of about 2.0-1.8 mya, Europe was periodically buried under the ice sheets that began growing and receding when the first stone tools were made, so tended to appear and disappear in Europe. The fact that humans evolved and spread during an ice age has led to competing hypotheses about many aspects of humanity’s rise. Although , and there have been 17 identified episodes of advancing and retreating ice sheets, particularly in North America and northern Eurasia, the early ones were not as severe, and they did not achieve , as the diagram below shows. (Source: Wikimedia Commons)
Did the control of fire to , ? Or did merely use it to begin dominating the world? Was cooking the seminal event in the appearance of humans? Those questions may not be definitively answered in my lifetime, and led to the somewhat uncertain title of this chapter. Highly transformative developments coincided with the appearance and dispersal of , which was a radical break from all that came before – biologically, technically, and culturally – and strongly implies great cognitive enhancements. I believe that the control of fire and cooking would leave deep cultural and biological impacts on the human journey, and because barely changed during its nearly two-million year tenure on Earth, both in biology and in Acheulean artifacts, I favor Wrangham’s hypothesis, at least until the Next Big Finding. Just as Einstein said that and that his theories would one day become obsolete, but that their best parts would survive in the new theories, I suspect that significant aspects of Wrangham’s hypothesis will live on in successor hypotheses, and other scientists have been following Wrangham’s lead.
The energy from controlled fire allowed humans to , , and socially organize in new ways. Humans commandeered energy that otherwise and used it for immediate human benefit. It was also the first great human robbery. All heterotrophs “” energy from other life forms to live. The primary exception is the symbiosis that . But no animal had ever robbed energy from ecosystems on that scale before. By making fires, humans were liberating many times the energy that their biological processes used - energy that could have fed forest ecosystems. While humans were only using deadwood, it was the least destructive to forest ecosystems. But when humans began burning forests to flush out animals to kill and make biomes suitable for animals to hunt, they were destroying and altering ecosystems on a vast scale. A cord of wood provides about four years of the calories that fuel a human adult’s body, and one hectare can provide a sustainable annual harvest of about ten years of human calories. A family of four using a hectare for firewood on a sustainable basis would be using more than twice their caloric intake for burning wood. Very little of that released energy would benefit humans if they burned it over a campfire, as humans did for the entire epoch of the hunter-gatherer; that liberated energy largely went straight into the sky. The direct benefit to humans would be the energy that went into cooking food, what warmed human flesh, what was used to make tools, and the benefits of scaring off predators and providing light at night. More indirect benefits would have been ecosystem changes to provide human-digestible calories, such as American Indians burning the woodlands and plains to make environments conducive to animals that they could easily hunt. In , the earliest epochs are the most uncertain, but saying that hunter-gatherer humans used 2.5 times their dietary calories in their economy is probably, perhaps greatly, understating the case. That 5% efficiency number is also a rough estimate, and both numbers could be refined by a scientifically performed effort. Maybe somebody has already done it. The numbers in that table for subsequent epochs are more accurate, and the most accurate of all are those for , and I live in one. The increases in efficiency became more modest with each epoch as the limits of were approached.
During that boring million years, changed from into hunter. They did not their biomes, but they were also respected by local predators and feared by what they hunted with their primitive weapons. At what stage big cats and other megafauna in Africa learned to avoid and its descendants is not clear, but it happened, and is thought by most scientists today to be why Africa retained its megafauna, and to a lesser extent Eurasia, when the other continents quickly lost them soon after humans appeared, which is a subject for the next chapter. But an early indicator of what probably happened, repeatedly in the coming rise and dominance of humanity, is when (or ) first made it to Flores Island about 900 kya (scientists have found tools but no human-like fossils), perhaps by rafting: a pygmy elephant, a giant tortoise, and a giant lizard all quickly went extinct. Today, it appears that once the migrants made it to Flores Island they stayed and forgot how to leave. They eventually became and lived on Flores for nearly the next million years, and went extinct soon after arrived.