Darwin's Island

by Steve Jones

  Soil protection of this kind has a long and unexpected history. In most of the Amazon basin, the soil is bitter and thin for constant rain leaches goodness away, and the vegetation feeds on itself as it recycles nutrition from its own dead logs (which is why cleared forests are so infertile). Patches of the so-called Terra Preta (‘black soil’) lands, in contrast, are small islands of deep dark earth scattered among those starved soils. They were formed not long after the birth of Christ by native peoples who settled down, fed slow fires with rubbish and leaves, piled up excrement and added bones to the mix. They lived in large and scattered cities that recycled their rubbish and set up, in effect, precursors of the green belt that surrounds many modern towns. Over the centuries carbon levels shot up and the ground became filled with worms and their helpful friends. They chew up the ashes and excrete it as a muddy paste of carbon mixed with mucus. So fertile is terra preta, with ten times the average amount of nitrogen and phosphorus, that it is now sold to gardeners.

  In Amazonia, the United States and elsewhere, the worm has begun to turn, although perhaps too late. The new concern for the soil is manifest in many ways. Organic gardeners use ‘vermicompost’ - the end-product of species such as the red wriggler fed with waste from farms or factories - as a powerful boost to the garden. Real enthusiasts make their own in bins into which they throw household rubbish and old newspapers to be transformed into fertiliser. They are part of a global movement which sees commercial agriculture of the kind that destroyed the prairies as an enemy and tries, in a small way, to replace what has been lost.

  On the larger scale, too, the ploughman is going out of fashion and the burrowers and their fellows are allowed to work undisturbed. Farmers now scatter seed on undisturbed ground, or insert it through the previous year’s stubble. The world has a hundred million hectares of such ‘no-till’ agriculture, and even in places where the plough still rules, the land is treated with more care than before. Brazil, in particular, with its deep ant-built landscapes, has been a pioneer. No-till farming does its best to leave the hard work to Nature. Instead of clearing the ground of dried stalks or leaves, the remains of a crop are left behind. They are soon dragged underground. As a result the earth can take up more carbon and become more fertile. Weeds are suppressed by the mat of dead vegetation that appears, water runs away more slowly and the temperature of the surface is less variable, and better for planted seeds, than in a bare ploughed field. Farmers who once saw worms as a pest now realise that to let them flourish undisturbed does more to preserve the ground - and to make profits - than to use machines.

  The move away from technology and the return to Nature’s tillers has been a real success. In some places it reduces soil loss by fifty times, and the habit is spreading fast. In Canada, two-thirds of the crops now grow on earth left unploughed, or ploughed in such a way as to reduce the damage. An era in which millions of tons of mud are lost from fields may be succeeded by an age in which plants and animals - their efforts feeble as individuals, but all-powerful en masse - are allowed to regenerate the soil. Darwin, with his passion for the natural world, would be pleased; but there is still a lot to be done. The risk of a global Mesopotamia - a collapse in food production as the worms’ precious but forgotten products are squandered - has not gone away.

  The great naturalist himself, in old age, often spoke of joining his favourite animals in ‘the sweetest place on earth’, the graveyard at Downe. He was denied the chance to offer himself to their mercies for he was interred in Westminster Abbey, whose foundations kept them out. His remains may have been saved from the annelids but have no doubt been consumed by other creatures. Darwin’s simple idea - of the importance of gradual change in forming the Earth and all that lives upon it - has replaced the power of belief with that of science. Perhaps today’s science of the soil will return the compliment by allowing worms and their fellows to restore the damage done by his descendants to their most important product: the vegetable mould that keeps us all alive.

  ENVOI THE DARWIN ARCHIPELAGO

  When Charles Darwin moved to Down House in 1842 the population of England was fifteen million and London, the largest city in the world, had some two million inhabitants. At the time of his death, forty years later, the number of Londoners had doubled and the capital’s fringes were creeping towards his retreat. The city has multiplied by four times since then and his home has become a museum. It sits in a well-preserved enclave that pretends to be a village but is in fact part of the London Borough of Bromley. A few segments of countryside nearby have been preserved (and the ‘tangled bank’, the microcosm of life referred to at the end of The Origin, is almost unaltered) but the landscape around Down House has become suburban at best. A glance across the famous Sandwalk reveals the tailfins of planes parked a few hundred metres away. Biggin Hill Airport was a Battle of Britain fighter base whose pilots claimed to have shot down more than a thousand aircraft. Now the place is the most popular light aviation centre in England and its annual air fair attracts a hundred thousand visitors. A lot has changed in the Kentish countryside since Charles Darwin walked across what has become an oil-stained strip of tarmac.

  Many other places associated with the great man - and many of his subjects, from apes to earthworms and from insectivorous plants to Homo sapiens himself - have been transformed since his demise. That would be a surprise to the patriarch of Down House. Darwin looked at the past to understand the present. He scarcely considered what the future might bring, for in his view evolution was so slow, and flesh so stable, that no real changes in the world of life were to be expected for many generations to come. In the long term, no doubt, the outlook was bleak: as he wrote in a letter to his old friend Joseph Hooker: ‘I quite agree how humiliating the slow progress of man is, but every one has his own pet horror, and this slow progress and even personal annihilation sinks in my mind into insignificance compared with the idea or rather I presume certainty of the sun some day cooling and we all freezing. To think of the progress of millions of years, with every continent swarming with good and enlightened men, all ending in this, and with probably no fresh start until this our planetary system has again been converted into red-hot gas. Sic transit gloria mundi, with a vengeance.’

  A moment of hindsight on his two hundredth birthday shows that he was badly out in his timing of the coming apocalypse, at least when it came to biology. Every continent is indeed swarming with men, but ‘progress’ (if such it is) has not been slow, but meteoric. A great deal has happened in the evolutionary instant since 1809. In the next two centuries, plants, animals and people will see an upheaval greater than anything experienced for thousands of years. For most plants and animals the prospect of biological annihilation is far closer than the certainty of the heat death of the universe.

  In the last few weeks of his voyage, in July 1836, the young explorer had a brief vision of what lay ahead. The Beagle dropped anchor at St Helena, halfway between Africa and South America. The island, first occupied by the Portuguese in the sixteenth century, is among the most isolated places in the world. Darwin was delighted by it: a hundred square kilometres of volcanic mountain rose ‘like a huge black castle from the ocean’. He admired the ‘English, or rather Welsh, character of the scenery’ and noted to his surprise that St Helena’s vegetation, too, had a British air, with gorse, blackberries, willows and other imports, supplemented by a variety of species from Australia. Over seven hundred plants had been described - but nine out of ten were invaders. They had driven the original inhabitants to extinction or to refuges high in the mountains. A sweep of thin pasture near the coast was known to locals as the ‘Great Wood’ - which is what it had been until a hundred years before, when the trees were felled and herds of goats and hogs consumed their seedlings and killed the forest. Plagues of rats and cats had come and gone as they ate themselves to extinction. On his first day ashore, he found the dead shells of nine species of ‘land-shells of a very peculiar form’ (one of the few mentions of snails in his en
tire oeuvre) and - in an early hint of evolution - noted that specimens of a certain species ‘differ as a marked variety’ from others of the same species picked up a few kilometres away. All those molluscs apart from one had been wiped out and replaced by the common brown snail of English gardens.

  Two centuries or thereabouts after his visit, life on St Helena is worse. The island once had forty-nine unique species of flowering plant and thirteen of fern. Seven have been driven to destruction since the arrival of the Portuguese, two survive in cultivation and many more are on the edge. The last St Helena Olive died of mould in 1994. Parts of the tree-fern forest of the high mountains - still in robust health at the time of the Beagle - remain, but other unique habitats visited by Darwin, such as the dry gumwood, have gone and of the ebony thickets just two bushes remain. The island’s giant earwig (at eight centimetres the world’s largest), its giant ground beetle and the St Helena dragonfly, all common in the 1830s, have not been seen for years and Darwin’s snail of peculiar form is now reduced to a population of no more than a few hundred. The St Helena Petrel is extinct and a solitary endemic feathered creature, the Wire Bird, is left. That too is under threat.

  Three months after the farewell to St Helena, the naturalist’s diary records that ‘we made the shores of England; and at Falmouth I left the Beagle, having lived on board the good little vessel nearly five years’. His account of the expedition ends with a spirited enjoinder to all naturalists ‘to take all chances and to start on travels by land if possible, if otherwise on a long voyage’. Charles Darwin never left British shores again.

  He had no need to, for, as this book has shown, the plain landscapes of his own country gave him the raw material needed for a life filled with science. Darwin’s fifty years of work on his homeland’s worms, hops, dogs and barnacles changed biology for ever. Since then the British Isles have provided another useful lesson for students of wild Nature, for their modest archipelago is a microcosm of the global upheavals that have taken place since the naturalist came home.

  Bartholomew’s Gazetteer of the British Isles, in its edition published just after the great naturalist’s death in 1882, describes Kent, ‘the Garden of England’, as a paradise: ‘The soil is varied and highly cultivated … All classes of cereals and root produce are abundant, as is also fruit of choice quality and more hops are grown in Kent than in all the rest of England. The woods are extensive … Fishing is extensively prosecuted … of which the oyster beds are especially famous.’

  A lot has changed since then. The local farms bring in half what they did even a decade ago. The oysters are almost gone and the salmon fishery of the Thames Estuary, which fed the apprentices of London with such abundance that they refused to eat fish more than once a week, has collapsed. Bucolic pursuits have been replaced by that invaluable product, ‘services’, which accounts for three-quarters of the county’s contribution to the nation’s wealth. Kent is a dormitory of London and London has become a staging post for the world. The flow of people, power and cash has carved up its landscape with motorways, rail links and webs of power lines. The oast houses that once stored hops have become commuter homes and the hops themselves - the raw material of so many experiments - cover a fraction of the fields he knew. So far, the Great Wen has been kept in part at bay by the Green Belt, but plans for a ‘Thames Gateway’ mean that yet more of the Garden of England will soon be a bland suburb.

  Much of Charles Darwin’s work on insectivorous plants, on self-fertilisation and on orchids took place in Ashdown Forest in the adjacent county of Sussex, where his cousin Sarah Wedgwood had a house and where he often walked, mused and botanised. It shows how fast the wild can retreat. In his day the forest was just one of several vast belts of English heath, successors of ancient tracts of trees felled thousands of years ago (Cobbett saw its thin soils as ‘the most villainously ugly spot I ever saw’). Ashdown Forest was used by the Normans as a game preserve and was closed off with a thirty-kilometre bank. In time most of the trees were cleared and burned, in iron foundries as much as domestic hearths, and it became heathland, a semi-natural part of the semi-natural landscape that is England. Since the date of publication of The Origin, nine-tenths of the nation’s heaths have been lost. The forest, at two and a half thousand hectares, is the largest piece left but even that is a shadow of what it was. The acid grass and marshes have been taken over by bracken or have dried out as water is pumped away to slake the thirst of millions. Many once familiar species - gentians, asphodels, sundews, orchids and more - are rare where once they were abundant and some of his favourite walks have become suburbs, farms or golf courses.

  Ashdown Forest is a microcosm of the modern age. The Common Plants Survey keeps count of sixty-five of Britain’s most abundant flowers, from primroses to bluebells and foxgloves, in five hundred random plots scattered across the nation. A century ago, those species were almost everywhere. By 2007, a quarter of the study sites had none of them at all. Most of the empty plots were in huge fields of corn or on wide pastures without hedgerows. Others were in woodlands. England’s forests - preserved by the Woodland Trust, the Royal Society for the Protection of Birds and the National Trust as they may be - have lost large parts of their diversity. A stable ecology maintained by the labours of woodmen has been replaced by museums of elderly trees in which bluebells and foxgloves, sparrows, cuckoos and jackdaws are in decline. Across England - and across Europe - the fields are even more starved of life. Subsidies have made a desert and called it farming.

  Kent’s sorry tale is repeated in many of Darwin’s favourite British places, from Stonehenge to Shrewsbury and from Wales to the Highlands. In a further blow to the products of evolution, the world has come to Kent and the animals - and people - of Kent have migrated to the world. Darwin’s archipelago has been united with the globe, which has become a single giant continent rather than a series of islands, real or metaphorical. For his own county the Channel Tunnel makes that reality. Humankind, too, has been homogenised, for even genteel Bromley now has a tenth of its citizens from ethnic minorities. The struggle to exist for both man and beasts has become a worldwide conflict rather than a series of local skirmishes. No longer does evolution mould the natives of each corner of the planet to fit their own domain. Some creatures thrive in the international arena; but many more are doomed.

  Evolution generates difference. One species and one alone has put the process into reverse. Man has instituted a simplification almost as grand as that brought by the catastrophe that destroyed the dinosaurs. The Galapagos themselves are a stark reminder of what he has done in less than two centuries. HMS Beagle visited the island of James in 1835. Food was plentiful: ‘We lived entirely on tortoise meat … the young tortoises make excellent soup.’ In those inelegant creatures, Darwin saw, without realising it, his first hint of evolution, for the animals from that island were distinct from those on Indefatigable and Albemarle nearby. In a rare conjunction of taxonomy with gastronomy, he noted that the James specimens were ‘rounder, blacker and had a better taste when cooked’ - which at the time seemed little more than a curiosity but was in fact an introduction to the biology of change.

  Now, the tortoises of James and its fellows have been driven almost to extinction. From a quarter of a million in the Beagle’s day, their numbers have dropped to fifteen thousand. Three of the fourteen unique races have gone and a solitary animal, the famous Lonesome George, is left from another (now, at the age of ninety or so, he has been persuaded to mate with a female of a different race in the hope of preserving his genes). Pigs, as much as men, have done the job, for they love to feast on tortoise eggs. Less obvious pests have also made their way to the archipelago. The cotton cushiony scale insect invaded twenty years ago. It has reached across the whole archipelago and attacks dozens of kinds of native plants.

  Pigs and scale insects are dangerous because they have Epicurean tastes. They are happy to try anything once and - like the young explorer with the tortoises - will try a novel source of f
ood if their usual diet is not available. They can, as a result, snack on the last specimens of an endangered species without eating themselves out of house and home. Such generalised predators, as they are called, are a real threat to diversity. On the Galapagos, goats and cats are a plague, pigeons have pushed out their feathered relatives and alien wasps have done terrible damage to the insects. The islands face an era in which specialists, evolved to fit their own small place in nature, have fallen to loutish strangers able to cope more or less anywhere. A tourist on the Galapagos today - and a hundred thousand arrive each year - has less to admire than did the crew of the Beagle. Next century’s visitors will find the place more or less indistinguishable from South America for many of its natives will be gone. The products of millions of years of isolation have been destroyed by man, the most generalised predator of all.

  The Galapagos are the icons of evolution and their problems get plenty of attention. Many other oceanic islets across the globe - rare, specialised and fragile as their natives are - face the same cataclysm or worse, but not many people notice. From St Helena to Tahiti and from Hawaii to the Cape Verdes, the alarm has at last been raised. It is too late to save the majority of such places, most of which began their decline long before the Beagle arrived.