The God Species: How Humans Really Can Save the Planet.... Mark Lynas

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СКАЧАТЬ ago, true Homo sapiens – the evolutionary descendant of Australopithecus, Homo habilis and later Homo erectus – appeared less than 500,000 years ago, and perhaps as recently as 200,000 years ago.

      Mitochondrial DNA passed through the maternal line suggests in fact that we are all descended from a single individual – the so-called Mitochondrial Eve – who lived in Africa 200,000 years ago. Further evidence comes from the remarkable homogeneity of human DNA: despite superficial differences in hair straightness, noses and skin colour, we are far more closely related than might be expected. (A single breeding group of chimpanzees will show more genetic variation than do all humans.⁷) This is strong evidence that modern humans did all descend from the same original group, and our dominance may have begun with a characteristic act of genocide, as the last Homo neanderthalensis survivors were ethnically cleansed from Europe and Asia by the new migrants. Since then, no other animal, whether on two legs or four, has challenged the dominance of Homo sapiens.

      The most striking biological characteristic of the human ancestral line over the last few million years is the extraordinary progress of its brain development. Chimpanzee brains measure about 360 cubic centimetres in volume. Early Australopithecus had expanded its brain to about 500 cm³, whilst Homo erectus measured up with a brain size of about 800 to 900 cm³. Half a million years ago, the brain was expanding at an extraordinary rate of 150 cm³ every hundred thousand years.⁸ Modern humans typically have a brain size of 1,350 cm³, nearly four times the size of those of our nearest relatives, the chimpanzees.

      One human innovation is often neglected in accounts of our evolution – and it may be one of the most important of all, because it allowed us to fuel our process of encephalisation (increased braininess). The brain is a very energy-hungry organ, consuming a quarter of all our energy use, as compared with 10 per cent in other primates and 5 per cent in most mammals.⁹ So how were the extra food requirements satisfied? Part of the answer is almost certainly the increasing amounts of animal protein in the human diet – hominid species quickly supplanted leopards as the dominant hunters on the African plains. But just as important was the advent of cooking, which enables food to be transformed into much softer and more calorific forms before being eaten. For over a million years humans have been eating cooked food, giving us a dietary advantage no animal has ever enjoyed before.

      Cooking, of course, needs fire. Indeed there is a strong biological case for seeing humans as a co-evolved fire species. Fire made us physically what we are, by allowing us to grow vastly bigger brains through eating cooked food. The human gut is much smaller, and uses far less energy, than the digestive system of comparable animals. We also have weak jaws, small mouths and underdeveloped teeth compared with other primates. That first acquisition of fire acted as a powerful evolutionary driver, enabling humans to become the first truly sentient beings in history.

      Fire, however, is a very special tool. Not for nothing is it identified in many human cultures as the preserve of the gods. Bonfires lit at the Celtic festival of Beltane symbolise the return of the sun to warm the Earth after the freezing nights of winter. In Navajo tradition, Coyote – who was a friend of humans – tricked two monsters on ‘fire mountain’ into letting him light a bundle of sticks tied to his tail, which he then took back to people. Perhaps the best-known fire tale of all is that of Prometheus, the Titan of the ancient Greeks (and son of Gaia, goddess of the Earth), who stole fire from the supreme god Zeus and brought it back to people. For this transgression he was punished by being chained to a rock and having his liver eaten out each day by an eagle.

      And rightly so, for fire dramatically changed our relationship with the natural world. Acquiring the power of gods separated humans permanently and irretrievably from all other species. As well as cooked food, it afforded protection against predators and warmth on cold nights, allowing early humans to spread north out of Africa during the depths of the last ice age. Fire may have facilitated the spread of genes for hairlessness, as the need for body insulation diminished. However, once our hair was lost and our guts had shrunk, we were tied to the hearth – we could no longer exist without it.

      No human can hope to survive in the wild today without fire, and this dependence marks a major qualitative shift in human relations with the biosphere. Other animals need only food. We are the only animal that has learned to harness an external energy source in a systematic way, through our reliance on fuel. It is this food–fuel relationship that most defines the fire-ape, Homo pyrophilus. Moreover, this innovation was perhaps the most important one in unbalancing our relationship with nature, for being armed with fire put the rest of the world at our mercy.

      However, our dependence on fuel could also be a weakness. Once the forests were chopped down and the landscape denuded, humans might no longer be able to flourish. The story of the modern era, however, is the story of our transcendence over even this limitation. For modern humans were to discover a new source of fuel that would allow us to expand both our numbers and our dominance dramatically. This new fuel, in the form of underground deposits of fossilised biological carbon, was to be the energy springboard that catapulted our species – and the planet – into an entirely new geological era, the Anthropocene. Using the tool of the gods, we were to become as gods. But unlike Zeus, we still live in ignorance about our true power. And time is running out, for the flames of our human inferno have begun to consume the whole world.

      Chapter Two

       The Biodiversity Boundary

      Our fire-sticks and engines have turned humans into extremely successful predators. We have poisoned, outcompeted or simply eaten so many other species that the Earth is currently in the throes of its most severe mass extinction event for 65 million years, and it is this crisis of biodiversity loss that arguably forms humanity’s most urgent and critical environmental challenge. Many of our other impacts on the Earth system are more or less reversible, but extinction is for ever, and a flourishing diversity of life is essential for the biosphere to function successfully during the Anthropocene and beyond. By removing species, we damage ecosystems, collapse food webs and ultimately undermine the planetary life-support system on which our species depends just as much as any other.

      The planetary boundaries expert group proposes a biodiversity loss boundary of a maximum of ten species lost to life per million species per year. The current rate of loss is already one or two orders of magnitude greater than this: conservationists estimate that 100 to 1000 species per million are currently wiped out annually. Meeting this boundary target is possible, but to do so will require a massive increase in the global attention and funding given to the issue and to solving it. We must create many more nature reserves, both on land and at sea. We must properly fund conservation, to defeat poachers and protect wildlife from direct threats. Above all we must alter our accounting systems so that living systems – from rainforests to polar tundra – are given the value they deserve as literally priceless assets of natural capital. This means using the power of markets, with most payments for biodiversity protection going to the local people who are always the best custodians of their local environment.

      If we are to save what remains of the glorious diversity of life on Earth, we will have to act fast. A quarter of the world’s mammals, a third of amphibians, about 13 per cent of birds, a quarter of warm-water corals, and a quarter of freshwater fishes are globally threatened with extinction. The rate of loss is accelerating, despite increasing concern about this brutal devastation of our planet’s natural history: whilst 36 mammals improved in terms of how threatened they were between the 2007 and 2008 Red Lists, 150 saw a deterioration, from vulnerable to endangered, from endangered to critically endangered, or critically endangered to extinct.¹

      In 2002 world governments agreed a target ‘to achieve by 2010 a significant reduction of СКАЧАТЬ