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Topic of Book
The impact of geology, particularly plate tectonics, on human history.
- The effect of the African and Indian continents slamming into Europe and Asia has had a profound impact on human history.
- Humans evolved in East Africa during a time of great climate variability.
- Glaciation during the Ice Age created the huge inland seaways of the Mississippi, Ohio, Missouri, Great Lake and St. Lawrence, a key geographical reason for the economic power of the United States.
- The flooding of the connection between Britain and France during the Ice Age made Britain an island, making it much easier for Britain to evolve into a Commercial society.
- The Himalayas, caused by the impact of India subducting under Asia, are the headlands for all the major rivers of East, South and Southeast Asia. These rivers were the foundation for almost every major Asian civilization.
- The Mediterranean and its jagged northern coastline, caused by Africa subducting under Europe, was the perfect environment for the Greek and Roman civilizations.
- The coal made during the formation of Pangea during the Carboniferous era was the foundation of the Industrial Revolution.
Important Quotes from Book
“I want to explore how the Earth made us.”
“humans didn’t evolve from apes – we are still apes, in the same way that we’re still mammals.”
“Plate tectonics is an overarching theme of the Earth we’ll return to throughout the book, but for now we’ll focus on how the climate change it drove over recent geological history produced the conditions for our own creation.
The past 50 million years or so have been characterised by a chilling of the global climate. This process is called the Cenozoic cooling, and it culminated 2.6 million years ago in the current period of pulsing ice ages… This long-term global cooling trend has been largely driven by the continental collision of India into Eurasia and the raising of the Himalayas. The subsequent erosion of this towering ridge of rocks has scrubbed a lot of carbon dioxide out of the atmosphere, resulting in a reduction of the greenhouse effect that was previously insulating the planet… and leading to declining temperatures. In turn, the generally cooler conditions drove less evaporation from the oceans to create a less rainy, drier world.”
“The upshot of all these tectonic processes – the creation of the Himalayas, the closing of the Indonesian Seaway, and in particular the uplift of the high ridges of the African Rift – was to dry out East Africa.”
“It was this long-term drying out of East Africa, reducing and fragmenting the forest habitat and replacing it with savannah, that was one of the major factors that drove the divergence of hominins from tree-dwelling apes. The spread of dry grasslands also supported a proliferation of large herbivorous mammals, ungulate species like antelope and zebra that humans would come to hunt.”
“Intelligence on the other hand is the evolutionary solution to the problem of an environment that shifts faster than natural selection can adapt the body. ”
“The three most recent periods of such extreme climatic variability occurred 2.7–2.5, 1.9–1.7, and 1.1–0.9 million years ago…The timing of when new hominin species emerged – often associated with an increase in brain size – or fell extinct again, tends to coincide with these periods of fluctuating wet–dry conditions. ”
“Overall, of the fifteen hominin species we know of, twelve first appeared during these three variable phases.32 What’s more, the development and spread of the different stages of tool technologies that we discussed earlier – Oldowan, Acheulean, Mousterian – also correspond with the eccentricity periods of extreme climate variability.33
And not only did the variable periods determine our evolution, they are also thought to have been the force driving several hominin species to migrate out of their birthplace and into Eurasia.”
“Like all species, we are a product of our environment. We are a species of apes born of the climate change and tectonics within East Africa”
“If you look at a map of the tectonic plate boundaries grinding against each other and superimpose the locations of the world’s major ancient civilisations, an astonishingly close relationship reveals itself: most are located very close to plate margins”
“There have been between forty and fifty ice ages over the past 2.6 million years,1 and they’ve been getting progressively longer and colder over time. In fact, the Quaternary is an exceptionally unstable time for the planet’s climate”
“The freeze-ups last on average 80,000 years, the shorter respites between ice ages only around 15,000 years”
“At the moment, the Earth is in something of a weird period of its lifetime. For around 80–90 per cent of its existence our planet has been significantly hotter than it is today; periods with ice caps at the poles are in fact something of a rarity.19 Over the last 3 billion years there have been perhaps only six eras with significant ice on the planet.20 Yet over the past 55 million years, the Earth has experienced a continued chilling and the global climate has shifted from hothouse to icehouse. This is known as the Cenozoic cooling, after the geological era during which it occurred.”
“the genetic diversity among the 7.5 billion humans living in the world today is astonishingly low.30 In fact, there’s more genetic diversity between two groups of chimpanzees living on opposite banks of a river in Central Africa than there is between humans on opposite sides of the world.31 Human genetic diversity is greatest within Africa,”
“Glaciation also had profound implications for the reshaping of North America’s geography and the subsequent history of the United States. Here the extensive ice sheet diverted the course of the mighty Missouri and Ohio rivers, and when the glaciation thawed these rivers continued to flow along what had been the edge of the ice sheet. Today, they meet the Mississippi in a huge Ψ shape and offer easy east-west transport right across the interior of the continent.”
“The Great Lakes of North America too are features left behind by the Ice Age, their deep basins gouged out by the advancing Laurentide ice sheet and then filled with its meltwater as it retreated again around 12,000 years ago. Once they were linked by canals, these extensive waterways became hugely important for inland transport from the Atlantic coast before the construction of long-distance railroads, and saw New York, Buffalo, Cleveland, Detroit and Chicago develop into major commercial centres”
“the frigid frontier of the North American ice sheets drove fierce winds, which picked up fine particles of silt, sand and clay that had been ground out of the bedrock, and deposited them further south to create the fabulously fertile loess farmland of the Midwest.”
“Half a million years ago, Britain was not an island. It was still part of continental Europe, physically connected to France”
“Britain had become permanently cut off from Europe.
The formation of the English Channel has had profound ramifications through history for Britain, as well as for Europe as a whole. The Channel has served as a natural defensive moat, protecting Britain throughout European history.”
“It has also been argued that it was this reduced threat of invasion and sense of security from external threats that allowed the progressive dispersion of power away from the autocratic monarch to a more balanced democratic system, beginning with Magna Carta in 1215 and leading to the parliamentary system in place today”
“While anatomically modern humans had appeared in Africa by around 200,000 years ago, our ancestors only became behaviourally modern between 100,000 and 50,000 years ago.”
“The Holocene is the first interglacial period that modern humans have experienced, and almost immediately after it began peoples around the world started developing agriculture.”
“And the three most important systems of agriculture that have spread across most areas of the globe are wheat originating in the Fertile Crescent, rice in China, and maize in Mesoamerica. Today, these three cereals alone provide around half of all the human energy intake around the world.
Cereal crops are all species of grass. The astonishing truth is that we are no different from the cattle, sheep or goats that we leave out to pasture – humanity survives by eating grass.”
“virtually all the plants we consume are members of one particular group, known as the angiosperms.”
“Our evolution as primates and our development as hunter-gatherers depended on the fruit, tubers and leaves of angiosperm plants. And the agriculture we adopted is also almost entirely reliant on angiosperms. Cereals are angiosperms: in fact, the grain we harvest is botanically the fruit of the grass plant. And virtually every other plant we eat is also a member of one of eight different families of angiosperm.”
“The three major orders of mammals that dominate the world today, however, did not emerge and begin diversifying until 10 million years later. These are the artiodactyls, perissodactyls and primates – collectively known as APP mammals.”
“The surprising fact is that the artiodactyl and perissodactyl orders, along with the primates, all emerged suddenly within a period of about 10,000 years, in a burst of evolutionary diversification that occurred 55.5 million years ago. ”
“And the event that seems to have triggered the rapid emergence of these crucial APP mammals was a singular planetary spasm – an extreme spike in the world’s temperature known as the Palaeocene–Eocene Thermal Maximum – PETM for short. ”
“If this extreme temperature blip drove the emergence of the APP orders, it was the global cooling and drying over the last few tens of millions of years that created the ecosystems the artiodactyls and perissodactyls came to dominate. As the grasslands spread around the desiccating continents, the herbivorous ungulates followed and diversified into a large number of different species,”
“the uneven distribution of domesticable plant and animal species around the world, as well as the fundamental orientation of the continents, came to exert a deep influence on the patterns of history.”
“Successful agriculture is utterly reliant on intercepting fresh water as it cycles around the world – evaporating from oceans, falling as rain, percolating underground and then flowing back to the sea. Rivers are often the most reliable stage of this water cycle, and they remain critical for feeding many people around the world today.”
“Tibet is the highest and largest plateau in the world, and within its tens of thousands of glaciers it holds the largest store of glacial ice and permafrost outside the Arctic and Antarctic. This high plateau is often referred to as the planet’s Third Pole. The meltwater from these glaciers and snow forms the headwaters of ten of the largest rivers fanning out across the whole of South East Asia, including the Yellow River, Yangtze, Mekong, Indus, Brahmaputra and Salween. All these great rivers carry huge amounts of sediment eroded from the mountains to fertilise their flood plains and the rice paddies that have been established here.
The Tibetan plateau thus serves as the water tower of the entire continental region”
“The Mediterranean region is one of the most complex tectonic environments on Earth. Here the African plate is shunting northwards and being subducted beneath the Eurasian, with a jumbled array of several smaller plates trapped in between, to drive a flurry of mountain-building and volcanic activity. ”
“the segmentation of the northern coast into many small pockets of land, separated by the relatively calm waters of the Mediterranean, was of huge assistance to the movement of people and goods between city states and kingdoms. The northern coastlines also provided a great selection of good natural harbours. In short, the northern Med is ideally set up for maritime activity and consequently many ancient cultures thrived along these northern shores.”
“The story of civilisation is the story of humanity digging up the fabric of the planet beneath our feet and piling it up to build our cities.”
“Metals have been so revolutionary in human history because they offer a range of properties that no other materials provide. They can be extremely hard and strong, but unlike brittle ceramics or glass they are also flexible and shatter-resistant.”
“The universe created by the Big Bang contained mainly the simplest element, hydrogen, with some helium and a tiny amount of lithium thrown in. All the other elements in our periodic table were made by nuclear fusion in stars”
“Iron is the star-killer element.”
“So overall, in each hemisphere the atmosphere enveloping the planet is divided into three great circulation cells, like giant tubes wrapped around the world, each rolling in place and shifting north and south slightly with the seasons. These produce the major wind zones of the planet – easterly trade winds, westerlies and polar easterlies – which in turn drive the circulating ocean currents. Pretty much the entire wind pattern on Earth can therefore be explained by three simple facts: the equator is hotter than the poles, warm air rises, and the world spins.”
“The Age of Exploration was therefore not just a process of filling in the world map with strange new lands, but also of discovering invisible geographies. European sailors learned how to use the alternating bands of planetary winds and wheeling ocean currents like a great interlinked system of conveyor belts, to carry them where they wanted to go.”
“It was coal that built the modern world.”
“And this is what’s so important about the ongoing formation of Pangea during the Carboniferous: continental collisions kept the basins warping down at roughly the same rate that the coal built up, allowing enormously thick successions of coal seams to accumulate.
It is this chance coincidence of several factors all acting at the same time and place that made the Carboniferous such a unique period in Earth’s history for creating the massive deposits of coal that we came to rely upon.”
“The process of plate tectonics was the ultimate force behind all this. ”
“This confluence of planetary factors ultimately fuelled the Industrial Revolution. Without the great Carboniferous coal measures humanity might have stalled in its technological development three centuries ago. ”