Читать книгу The Anthropocene - Christian Schwägerl - Страница 8

IN JANUARY 2013, American biologist and author Paul Salopek set off to trek around the world. He began his journey at a lake in the Great Rift Valley of Ethiopia, where remains suggest that modern man originated. Salopek’s goal, over a period of seven years, is to walk all the way to Tierra del Fuego— a region that lies the furthest from humanity’s birthplace—via the Middle East, Southeast Asia, China and North America. His planned hike is about 30,000 kilometers long (21,000 miles); he hopes to complete it in 2020. Salopek wants to retrace the path that humans have taken since starting out from Africa.

Before humans came on the scene, many animal species had already spread across the earth’s surface. Humans, however, were the start of something quite new. The biggest difference between us and other members of the Club of Revolutionaries such as cyanobacteria or algae is that we are able to act consciously with the help of a molecular electronic mirror image of ourselves and the world.²⁴ This difference, our uniquely precious ability, is what makes the Anthropocene completely new: human consciousness and geology forming a unity. By rights, there should be a UNESCO world cultural heritage site in East Africa named “The Origins of the Human Consciousness,” where Salopek’s journey started. The dimensions of this evolutionary event are simply colossal, extending from the first groups of humans who used pronouns like I, you and we, to online social networks connecting billions of people. They link the earliest humans who looked in awe at the sky to the builders of the Hubble Space Telescope, and the first stone tools to quantum computers of the near future.

Part of our emerging consciousness is an ever increasing awareness of our long march, how deeply rooted we are in the cosmos, the solar system, our planet and life. This awareness is not always present in our everyday lives, what with washing dirty dishes, chatting on social networks, or meeting deadlines. Part of the appeal and beauty of scientific research is to develop this awareness more thoroughly in ever greater detail.

Humans are the way we are because water, carbon, oxygen, minerals and metals were distributed across earth from the beginning in very specific proportions. We are the result of hundreds of millions of years of evolution, from individual unicellular organisms that began to cooperate, to the estimated 37 trillion cells combining to assemble organs as complex as the human brain.²⁵

Not only every stone but every person encapsulates the entire history of life and the universe.²⁶ The atoms making up our bodies have been traveling through the cosmos for billions of years. Each atom in our bodies has already served to build hundreds of other life forms before us; perhaps it swam in a fish long before humans appeared or lay deep in the soil or was a building block in a bacterium. Our bodies are gigantic zoos of evolutionary history. Hundreds of millions of years of evolution has shaped the way we think and perceive, from the first four-celled organisms with nerve endings on to fish, and from there to the first four-legged animals to primeval mouse-like mammals, on to the first primates who developed into early humans. After millions of years, a species of thinking, humanoid life forms rose to the challenge of survival in the vastness of Africa and developed characteristics similar to what we humans have today.

Modern-day people have brains that have been transformed by environment, long before people acquired the ability to change the environment. Nowadays, what we like or dislike, or fear or do not fear, or perceive to be or not, have much to do with the living conditions of our ancestors. These forebears include the squirrel-like Purgatorius that lived soon after the extinction of the dinosaurs; Eosimias, one of the earliest anthropoids that lived 41 million years ago; the chimpanzee-sized Kamoyapithecus that lived 25 million years ago, regarded by many researchers as the first hominoid and the last mutual ancestor before chimpanzees, that lived in Africa approximately 7 million years ago. This leads finally to the first hominids such as Sahelanthropus and Australopithecus that paved the evolutionary path for the genus Homo. Our lives today are linked by invisible threads to this past; each set of respective environmental circumstances, from the meteorite impact that doomed the dinosaurs, allowing for the era of mammals (who could otherwise have become the pets of highly intelligent dinosaur descendants) to the expansion of the savannah in East Africa due to natural climate change.

Besides our consciousness, what makes us humans uniquely able to create the Anthropocene, is our incredible generalism, that is, our ability to adapt not only to new circumstances but also to be the shapers of our habitat.²⁷

Our biological constitution is, for the most part, an echo from the past three million years when the earth was significantly colder than it is today. A factor that contributed to this cooling process was the formation of the Isthmus of Panama three million years ago, which connected North and South America and interrupted the flow of warm water from the Pacific Ocean over to Africa. Atlantic currents were forced northwards, eventually leading to the formation of today’s Gulf Stream. The Himalayan mountain range also continued to rise, which rerouted Asian rivers to flow northward rather than south. Flowing into northern seas diluted their salt concentration: water that is low in salt freezes more quickly, which led to the glaciation of the Arctic region. The sea level sank during these periods to an average of 426 feet because the water froze.

Then the level rose again as subsequent oceanic and atmospheric changes led to warming periods. The Great Rift Valley in East Africa, where early hominids lived, rose slowly but continuously during this epoch, creating a drier habitat and causing forests to change to savannahs—an environment where an upright gait was a significant advantage.²⁸

Early humans lived during times of sweeping change in the natural world that surrounded them. Whereas many species remained unchanged and only reacted to events, our ancestors were more flexible, innovative, and adaptable. Environmental changes even tended to foster flexibility and generalism in early humans. They developed an ability to survive under varied conditions, sustained by a wide variety of foods. The route to today’s world, wherein people can live in Arctic cold or tropical heat, on mountaintops or in river deltas, in Indian slums or in air-conditioned New York stockbrokers’ offices, arose a good two million years ago; omnivorous hominids proving to be very skilled at adapting. Due to genetic changes, brain size increased more rapidly, something that did not occur in close hominoid relatives whose numbers were much greater. These creatures began to use stone tools and began the evolutionary journey towards Homo; our branch on the tree of life.²⁹

That branch spread north two million years ago, from East Africa toward the Mediterranean and from there into Asia, even as far as present day Indonesia and China. These prehistoric peoples wandered only a few miles each generation, eventually reaching Europe where, as far as can be determined, they lit the first fires during the cold era that occurred about four hundred thousand years ago. Neanderthals were one of the first waves of this human expansion.

But a more significant revolution, a human “Big Bang,” also took place in Africa, about 220,000 years ago—a mere instant in geological terms—a lighter, more agile creature called Homo sapiens emerged. Everyone alive today is related to this “new kid on the block.” He is the most social yet egotistical, loving yet cruel, sensible yet emotional, far-sighted and narrow-minded, creative and destructive of all hominids. Our ancestors survived dangers and setbacks, and began a triumphal march out of Africa across the globe, the march Paul Salopek is following with his “Out of Eden Walk” project. A hundred thousand years ago, they settled in what is now the Middle East, seventy thousand years ago they arrived in Australia, about forty-four thousand years ago they came to Europe and entered the habitat of the Neanderthals and about thirty thousand years ago they came from the north, moving into the entire American landmass.³⁰

The spread of Homo sapiens had disastrous consequences for Neanderthals, human beings with artistic, cultural and even religious sensitivities. In their competition for land and resources, Neanderthal humans drew the short straw. Early Homo sapiens had already wiped out countless other species of animals—mostly large predators and some species they most enjoyed eating—a mere foretaste of the Anthropocene wave of extinctions to come, perhaps. According to recent findings, our direct ancestors cannot be held responsible for the extinction of the Neanderthals since there are no signs of massacres or widespread slaughter.³¹ There are even strong indications that Neanderthals and Homo sapiens had sex and that some Neanderthal genes persist today. But that didn‘t stop Neanderthals from going extinct. It may have been enough for our ancestors to be just a little more efficient at hunting and gathering in shared regions and in using up the resources that Neanderthals needed to survive. Thirty-seven thousand years ago, the trail of this fascinating alternate species of human disappears, whereas the spread of Homo sapiens truly kicked off.

The next decisive point in humanity’s ascent happened about twelve thousand years ago. The end of the last Ice Age and the beginning of a natural global warming created ideal conditions for a truly global expansion. Human ingenuity, fertile soil and a more favorable climate coalesced in a unique way. Independent of one another, human groups abandoned nomadic life and became agriculturalists, settling in fecund regions of the world, like the “Fertile Crescent,” the Andean Altiplano, Mesoamerica, China and New Guinea.

Some of these early farmers settled in an area comprising modern-day Azerbaijan, Iran, Iraq, Turkey and Syria. They discovered that grass seeds are not only edible but can also replicate. Precious calories could be gained from this food source, supplementing the hunting of gazelles and the gathering of nuts and berries. Once under way, the agricultural revolution could not be stopped.

Farming had some grave disadvantages: each calorie yielded from the land took more time and effort compared to hunting for meat.³² Farmers had less free time than hunters and gatherers. Yet, farmers found it worthwhile to work the land since it enabled them to stock up food in case of hard times. Surplus food meant that more children survived their first few months of life but also there were now more mouths to feed.

Layer upon layer, this history is evident at the village of Abu Hureyra, an ancient settlement on the upper reaches of the Euphrates River, in present-day Syria. British archaeologist Andrew Moore examined the village before it disappeared under floodwaters caused by the construction of Syrian president Hafez al-Assad’s massive new dam.³³ People of the Natufian culture lived here around twelve thousand years ago. Remains of hundreds of different plants have been discovered beside the residents’ simple homes. Einkorn and emmer wheats, rye, lentils and fava beans play a central role in life. These people were very innovative: they discovered ways of maintaining the fertility of the land, by planting pulses which return nitrogen to the soil, and they domesticated animals such as goats, sheep and later cattle, brought down from the nearby Zagros Mountains. The symbiosis between humans and farm animals had begun to develop.

We have now arrived at a critical moment in our high-speed review of human history. The Holocene is the period of earth’s history in which we currently, officially live, based on geological calculations. Before modern humans were the children of the Holocene, our closest ancestors inhabited the Pliocene, a geological epoch that began 5.3 million years ago and ended 2.6 million years ago when the Pleistocene era began. If the Pleistocene Ice Age had simply continued, it is conceivable that humans would have remained hunters and gatherers. But something “new” happened, which is what “Holocene” means (from the Greek, holos, whole or entire and kainos, new). As far back as seventy thousand years ago, our ancient relatives had already produced paintings on the walls of South African caves, and thirty thousand years ago, they had fashioned pipes from bones, made sculptures, needles, and ceramics. In many places, such as the Chauvet cave in the south of France, they created paintings that would rival those by Picasso or Franz Marc. Humans are artists, masters at imagining, at creating, at reshaping their environment. Embedded in the favorable Holocene climate, these abilities have changed the world.

The start of the warming after the last Ice Age, approximately eleven thousand seven hundred years ago, prepared the conditions for “modern” life. Since the Holocene began, our biological make-up has changed very little. What has changed radically is our social, economic and technological make-up.

A few hundred agricultural pioneers in the Middle East have become a billion farmers who produce an inconceivable assortment of edible crops. The first fields and pastures have changed into a gigantic agricultural area of approximately 20 million square miles, which is larger than the entire surface area of the whole American continent. From scattered herds of sheep, goats and cattle, a global herd of livestock has grown, consisting of more than 50 billion animals, making up 90 per cent of the biomass of all the mammals on the Earth.³⁴

Where once there were small villages, megacities have now grown; from the simplest tools, there are now coal excavators, 3D printers and plasma screens; from characters and symbols scratched on tablets, the World Wide Web. However, spears have evolved into missiles and combat drones. In amongst our anthropogenic burgeonings some very dark flowers have also sprouted.

If we fast-forward past the first cities, the culture of Imperial China, the great empires of antiquity, the development of global trade routes, the European conquest of the world, scientific breakthroughs and medical and technological progress—then the Holocene appears to be one extended, magnificent gift to humanity.³⁵

No matter how tough the Holocene may have been for many people, it was characterized by boundless natural resources that could be discovered, extracted and utilized. Despite thunderstorms and weather extremes, earth’s climate during the Holocene has been astonishingly stable, permitting us to build villages, towns and cities, and to farm. The last glaciation left behind wonderfully fertile soils like loess. Nature’s services, by the thousand, providing water, soil or the air we breathe, have been available free of charge, without requiring any favor in return. Imagine if we were merely the second intelligent primate species and had to earn our living and obtain our resources in fierce competition with an entire civilization of other technology freaks, But we were lucky: the gold seams in California, the emeralds in India and the diamonds in Russia were all found untouched, for the first time, by humans. Our civilization has been one big treasure hunt.

All this came to a head in the eighteenth century, at another civilizational watershed, when people learned how to use the energy made available by earlier members of the Club of Revolutionaries: energy from the sun that led to the formation of coal and crude oil or natural gas. This is the moment Paul Crutzen suggests represents the transition from the Holocene to the Anthropocene—the emergence of humans as a veritable geological force.

When our great-great-great-grandparents discovered how to use this energy to power machines, humanity’s potential increased, at a stroke. It was as if people had been given a collective potion that harnessed the strength of millions of horses and workers in the form of black chunks of coal and viscous oil. So much is taken for granted these days that we hardly notice. But if you’ve ever sweated to shovel a cubic meter of soil and then watched a backhoe do the same job, you too have experienced the Industrial Revolution, in one instant. Using fossil-based fuels and machines that could be powered by them, humanity really started to accelerate.

And this is why Paul Salopek’s “Out of Eden Walk” confronted him with an entirely new reality just a few days after leaving the origins of humanity behind him: “Moving north and then east, we abandon the desert and stub our toes on the Anthropocene—the age of modern humans. Asphalt appears: the Djibouti-Ethiopia road, throbbing with trucks. We drift through a series of gritty towns. Dust and diesel. Bars. Shops with raw plank counters. Garlands of tin cups clink in the wind outside their doors. Then, near Dubti: a sea (no, a wall) of sugarcane. Miles of industrial irrigation. Canals. Diversion dams. Bulldozed fields. Levees crawling with dump trucks.”³⁶

^24. Recommended literature on the evolutionary history of consciousness: Giulio Tononi, Phi: A Voyage from the Brain to the Soul, New York: Pantheon, 2012.

^25. Eva Bianconi et al., “An estimation of the number of cells in the human body,” Annals of Human Biology, 5 July 2013.

^26. Excellent further reading on this subject in: Jan Zalasiewicz, The Planet in a Pebble: A Journey into Earth‘s Deep History, Oxford University Press, 2010.

^27. See also Erle Ellis’ article “Conserving a Used Planet: Embracing Our History as Transformers of Earth,” Snap Magazine, http://www.snap.is/magazine/embracing-our-history-as-transformers-of-earth/.

^28. For a general depiction of the history of the climate, see Jan Zalasiewicz and Mark Williams, The Goldilocks Planet: The Four Billion Year Story of the Earth’s Climate, Oxford University Press, 2012.

^29. For a comprehensible description of human evolution, see Alice Roberts, Evolution —The Human Story, Dorling Kindersley, 2011.

^30. On the first modern humans in Europe, see Stefano Benazzi et al., “Early dispersal of modern humans in Europe and implications for Neanderthal behaviour,” Nature, vol. 479, no. 7374, November 2 (2011): 525–528. On the first modern humans in Australia, see Morten Rasmussen et al., “An Aboriginal Australian Genome Reveals Separate Human Dispersals into Asia,” Science, vol. 334, no. 6052, October 7 (2011): 94–98.

^31. Dálen, Love, “Partial genetic turnoverbin neandertals,” Molecular Biology and Evolution, February 23, 2012.

^32. David R. Montgomery, Dirt: The Erosion of Civilizations, Berkeley: University of California Press, 2007.

^33. Andrew Moore et al., Village on the Euphrates: From Foraging to Farming at Abu Hureya, Oxford University Press, 2000.

^34. See Gowri Koneswaran and Danielle Nierenberg, “Global Farm Animal Production and Global Warming: Impacting and Mitigating Climate Change,” Environmental Health Perspectives, vol. 116, no. 5 (January 2008):578–582 and Food and Agriculture Organization of the United Nations (FAO), “World agriculture–towards 2015/2030,” Rome, 2002 and FAO and OECD, “Agricultural Outlook 2009–2018”, Rome, 2009.

^35. A very good overview of the ascent of human civilization in Asia and Europe can be found in Ian Morris’s book with the slightly misleading title, Why the West Rules for now: The Patterns of History and What They Reveal About the Future, Profile Books, 2011.

^36. Paul Salopek keeps a fascinating online journal about his project, see www.outofedenwalk.com.