And us? Anatomically modern humans didn’t arrive until nearly 200,000 years ago and it was touch and go whether we would survive. But something pulled us through, the something that differentiated us from the other species in this shared biosphere and made us so successful that we now rule our world: the human brain. We’re more intelligent and use tools better than the other animals. And humans can make and control fire. Ever since the first human lit the first spark, our destiny as the most powerful species was assured. Having this external source of energy, which we could move wherever we chose, gave us power over the landscape, protection from other animals, allowed us to cook our food, keep warm and, ultimately, take over the world.
For thousands of years, humans shared the planet with Neanderthals and our other cousin species. A supervolcanic eruption at Toba in Indonesia 74,000 years ago nearly wiped us all out – the human population shrank to a few thousand. But, by 35,000 years ago, truly modern humans, indistinguishable from people alive today and littering caves and rocks with signs of their culture, had emerged and migrated out of Africa. Thus began the heroic ascent of man.
In the Stone Age, our impact as a species on the planet was limited to some extinctions – particularly of large mammals – and some local landscape changes, such as the burning of forests. Technologies were primitive and minimal, and were fashioned entirely from renewable materials. Over the following centuries, our impact grew. Farming was invented around 10,000 years ago (about 300 generations ago; world population: 1 million), transforming some regional landscapes as human-bred plant varieties replaced wild flora. Around 5,500 years ago (world population: 5 million), cities were built and the first great civilisations emerged. The Industrial Revolution in Europe and North America, which replaced the labour of humans and beasts with machines, started having a measurably global impact about 150 years ago (world population: 1 billion), as large volumes of carbon dioxide from fossil fuels were released into the atmosphere.
Nothing, however, compares to the scale and speed of our planetary impact since World War Two, driven by population expansion, globalisation, mass production, technological and communications revolutions, improved farming methods and medical advances. Known as the Great Acceleration, this rapid increase in human activity can be seen across a vast range of things, from the number of cars to water use.4 It took 50,000 years for humans to reach a population of 1 billion, but just the last ten years to add the latest billion.
This rapid transformation spurred social and economic development – a century ago, life expectancy in Europe was less than fifty years, now it’s around eighty years. But the Great Acceleration has been a filthy undertaking. Pea-souper smogs shrouded cities like London killing thousands, acid rain poisoned rivers, lakes and soils, eroding buildings and monuments, refrigerant chemicals ate away at the protective ozone layer, and carbon dioxide emissions changed in the global climate and acidified the oceans. Our voracious plundering of the natural world has led to massive deforestation, a surge in extinctions and destroyed ecosystems. It has produced a deluge of waste that will take centuries to degrade. In a single lifetime we’ve become a phenomenal global force and there is no sign of a slowdown – in fact, our extraordinary impact on the planet is only increasing.
Meanwhile, our closest relative, the chimpanzee, is living much as he did 50,000 years ago. Humans are the only creatures to have cumulative culture, allowing us to build on the past rather than continually reinvent the wheel. But, as we fumble about on Earth’s surface, hostage to the whims of our phenomenally powerful brains, humanity is undertaking a brave experiment in remodelling the physical and biological world. We have the power to dramatically shift the fortunes of every species, including our own. Great changes are already being wrought. The same ingenuity that allows us to live longer and more comfortably than ever before is transforming Earth beyond anything our species has experienced before. It’s a thrilling but uncertain time to be alive. Welcome to the Anthropocene: the Age of Man.
We live in epoch-making times. Literally. The changes humans have made in recent decades have been on such a scale that they have altered our world beyond anything it has experienced in its 4.5 billion-year history. Our planet is crossing a geological boundary and we humans are the change-makers.
Millions of years from now, a stripe in the accumulated layers of rock on Earth’s surface will reveal our human fingerprint just as we can see evidence of dinosaurs in rocks of the Jurassic, or the explosion of life that marks the Cambrian or the glacial retreat scars of the Holocene. Our influence will show up as a mass of species going extinct, changes in the chemistry of the oceans, the loss of forests and the growth of deserts, the damming of rivers, the retreat of glaciers and the sinking of islands. Geologists of the far future will note in the fossil records the extinctions of various animals and the abundance of domesticates, the chemical fingerprint of artificial materials, such as aluminium drinks cans and plastic carrier bags, and the footprint of projects like the Syncrude mine in the Athabasca oil sands of north-eastern Canada, which moves 30 billion tonnes of earth each year, twice the amount of sediment that flows down all the rivers in the world in that time.
Geologists are calling this new epoch the Anthropocene, recognising that humanity has become a geophysical force on a par with the earth-shattering asteroids and planet-cloaking volcanoes that defined past eras.5
Earth is now a human planet. We decide whether a forest stands or is razed, whether pandas survive or go extinct, how and where a river flows, even the temperature of the atmosphere. We are now the most numerous big animal on Earth, and the next in line are the animals we have created through breeding to feed and serve us. Four-tenths of the planet’s land surface is used to grow our food. Three-quarters of the world’s fresh water is controlled by us. It is an extraordinary time. In the tropics, coral reefs are disappearing, ice is melting at the poles, and the oceans are emptying of fish because of us. Entire islands are vanishing under rising seas, just as naked new land appears in the Arctic.
During my career as a science journalist, it became my business to take special interest in reports on how the biosphere was changing. There was no shortage of research. Study after study came my way, describing changes in butterfly migrations, glacier melt rate, ocean nitrogen levels, wildfire frequency . . . all united by a common theme: the impact of humans. Scientists I spoke to described the many and varied ways humans were affecting the natural world, even when it came to seemingly impervious physical phenomena like weather and earthquakes and ocean currents. And their predictions were of bigger changes to come. Climate scientists tracking global warming told of deadly droughts, heatwaves and metres of sea-level rise. Conservation biologists were describing biodiversity collapse to the extent of a mass extinction, marine biologists were talking of ‘islands of plastic garbage’ in the oceans, space scientists were holding conferences on what to do about all the junk up there threatening our satellites, ecologists were describing deforestation of the last intact rainforests, agro-economists were warning about deserts spreading across the last fertile soils. Every new study seemed to hammer home how much our world was changing – it was becoming a different planet. Humanity was shaking up our world, and as I and others reported these stories, people around the world were left in no doubt about the environmental crises we were responsible for.6 It was profoundly worrying and often overwhelming.
As I followed the latest research, I heard plenty of dire predictions about our future on Earth. But at the same time I was also writing about our triumphs, the genius of humans, our inventions and discoveries, about how scientists were finding new ways to improve plants, stave off disease, transport electricity and make entirely new materials. We are an incredible force of nature. Humans have the power to heat the planet further or to cool it right down, to eliminate species and to engineer entirely new ones, to resculpt the terrestrial surface and to determine its biology. No part of this planet is untouched by human influence – we have transcended natural cycles, altered the physical, chemical and biological processes of the planet. We can create new life in a test tube, bring extinct species back from the dead, grow new body parts from cells or build mechanical replacements. We have invented robots to be our slaves,
