Darwin's Island (33 page)

In fact, such suspicions are misplaced. Surveys of on-line daters show impressive levels of accuracy in their descriptions of themselves, for almost all say something close to the truth about age, body build, wealth, education, politics, marital history and more (admittedly, men tell slightly more lies about their income and women about their weight). The daters disapprove strongly of anyone who did not live up to their claims on a first meeting and swore that they would go no further with them. Deception is not an effective sexual strategy. For men and women, honesty pays and the fraudulent are rejected as partners as soon as they are detected.

 

In the dating game, on the other hand, there are few disappointments that a bunch of orchids will not put right.

CHAPTER IX

THE WORMS CRAWL IN

The fields of Britain are criss-crossed by earnest men with metal-detectors. Despised by archaeologists for the damage they cause, the ‘discoverists’, as they call themselves, have found thousands of coins, swords, belt buckles and the like. Some of the objects were hidden, or buried by their owners in times of danger, but most simply sank from sight. Why?

Charles Darwin, as usual, got it right. The past had been entombed by worms. He hymns their praises in his last book,
The Formation of Vegetable Mould, through the Action of Worms, with Observations on their Habits
: ‘The plough is one of the most ancient and most valuable of man’s inventions; but long before he existed the land was in fact regularly ploughed, and still continues to be thus ploughed by earth-worms. It may be doubted whether there are many other animals which have played so important a part in the history of the world.’ His literary swansong discusses the anatomy and habits of such creatures, their intellectual life (such as it is) and, most of all, their ability to disturb the surface of the Earth, to aerate, turn over and improve the soil, and to sink any object that lies upon it. At the time its author claimed that he had produced no more than ‘a curious little book’ on a matter that ‘may appear an insignificant one’, but the ravages of the plough since it was invented thousands of years ago and the damage done to the surface of our planet by today’s agriculture mean that the work of the worms is crucial not just to the history of the world but to its future.

The power of such small beings to seal the fate of objects far larger than themselves shows, once again, the huge consequences that can emerge from what may appear to be the trivial efforts of Nature. Darwin was aware of the potential of the worm as proof of the might of slow change; as he said of their efforts: ‘the maxim
de minimis non curat lex
does not apply to science’. They were the final test of his obsession with the cumulative potential of the small and he was proud of his results. He dismissed the arguments of a Mr Fish, who denied the animals’ talents, as ‘an instance of that inability to sum up the effects of a continually recurrent cause, which has often retarded the progress of science, as formerly in the case of geology, and more recently in that of the principle of evolution’.

The elderly savant’s attraction to such creatures had started long before he thought of science. In his autobiography he notes that, as a child, he had been so upset by their contortions when impaled on fish-hooks that, as soon as he heard that it was possible to euthanise them with salt and water, he never again ‘spitted a living worm, though at the expense, probably, of some loss of success!’ His later studies introduced a new world beneath our feet, gave life to the idea of animals as a geological force and, as an incidental, showed how even simple animals have a rich mental life of their own. His work became the foundation of a science which has now, almost too late, noticed the dire state of the world’s vegetable mould and has begun to do something about it.

In 1837, just a year after the
Beagle
voyage, Charles Darwin presented a paper on worms to the Royal Geological Society. Later he published a few notes on the subject, which occupied him at odd moments for forty years. At last, at the age of seventy-two, he wrote
Vegetable Mould
, which was published at nine shillings in 1881, just six months before his death. The book was received with what he called ‘almost laughable enthusiasm’ and sold nearly as many copies in its first few years as had
The Origin.

Soil is where geology and biology overlap. Adam’s name comes from
adama
- the Hebrew for soil - and Eve from
hava
, or living: an ancient statement of the tie between our own existence and that of the ground we stand on (‘
Homo
’ and ‘humus’ also share a root). The epidermis of the Earth is no more than around one part in twenty million of its diameter while our own skin, in contrast, is about a five-thousandth as thick as the average human body. Leonardo da Vinci wrote that ‘We know more about the movements of the celestial bodies than of the soil underfoot’, and until
Vegetable Mould
that was still almost true.

Since then, earthworms and their relatives have been studied by geologists, ecologists, molecular biologists and many others. Archaeologists, too, have reason to be grateful for their efforts, for without the animals our insight into history would be far less complete than it is, for most of the evidence left by our ancestors would not be buried but washed away. More important, perhaps, without worms we would starve.

Vegetable Mould
built upon an observation Darwin had made as a young man. Twelve months after his return to his native island from his famous voyage, he visited his uncle - and future father-in-law - Josiah Wedgwood, at Maer Hall in Staffordshire. Wedgwood took him to a field upon which had been scattered, fifteen years earlier, a mass of lime, cinders and burnt marble, the detritus of his Etruria pottery works nearby. The material had, over that period, been covered by a layer of earth. Wedgwood suggested to his nephew that perhaps worms had done the job. The young scientist agreed, but saw this at first as little more than a ‘trivial gardening matter’. In time, as the notion that - for both rocks and flesh - small means could give rise to large ends grew in his mind, he saw in those humble creatures a real chance to experiment on the measured actions of Nature.

Darwin continued to study the animals as he travelled across England with his wife and children. They were not the only tourists of those days. The Victorians were fond of excursions, and many were, like the modern discoverists, anxious to cart off relics for their own delight. In 1877, in a brief respite from ill health, Charles took his wife to visit Stonehenge. He dug pits around several of the ‘Druidical stones’, as the monoliths were then called, and noted that even the largest had been sunk several centimetres deep by the worms. Emma worried that her husband might have sunstroke as he sported with the relics, and she recorded her conversation with the site’s guardian, ‘an agreeable old soldier’. ‘Sometimes,’ the venerable trooper told her, ‘visitors came who were troublesome, and once a man came with a sledge-hammer who was very troublesome to manage.’

A few years earlier a hammer and chisel had been provided at Stonehenge for the use of those who wanted a curio of ancient times. Their intellectual descendants still agitate the nation’s soil. A hobby that began with chunks chipped off monuments has become an electronically powered craze, with, at its peak, almost two hundred thousand enthusiasts in Britain (they include Bill Wyman of the Rolling Stones, who markets his own metal detectors for ‘Treasure Island UK’). For a time the 1960s Prime Minister, Harold Wilson, was an honorary patron of the detectorists’ organisation. The numbers are well down from those frenzied days and in most of Europe the practice remains illegal, but in 1997 the British government bowed to reality and changed the law to reward those who report their finds; they are, said the minister for culture of the time, ‘the unsung heroes of the UK’s heritage’. The Portable Antiquities Scheme, as it is called, applies to England and Wales alone, for Scots must still give up their treasures to the Crown. South of the Border, the number of objects reported has risen from fewer than a hundred per year to thousands. The scheme now lists more than three hundred thousand items. Recent triumphs include the discovery of a four-thousand-year-old gold cup at Ringlemere, in Darwin’s home county. Its finder shared a £250,000 reward.

The Ringlemere cup was concealed by men anxious to placate the gods but many other objects have been hidden by humbler creatures with simpler motives. Electronic sweeps of the fields around Down House reveal many coins, necklaces, buckles and the like. Vast numbers more remain, no doubt, to be uncovered. They were buried by worms as they searched for shelter and for food.

 

The earthworm has undoubted charm. It belongs to a group known as the annelids, which include the leeches and lugworms and is related to less agreeable creatures such as the parasites that cause elephantiasis in tropical Africa. The creatures are more distant kin of snails and slugs. Their ancient roots are best revealed by patterns of DNA similarity, as soft-bodied creatures do not leave many fossils (even if the remains and the tracks of a few primitive annelids are found as far back as the Cambrian). Today, three thousand or so species are known, and, given our ignorance of tropical nature, many more must remain to be found. Most are small and unassertive, but a certain Australian kind grows to three metres long and ejects a jet of fluid half a metre into the air when annoyed. Britain has a just over a couple of dozen sorts while France has six times as many. A rain forest has far more.

A 2005 survey at Down House, in the woods by the famous Sandwalk - the site of its owner’s regular stroll - and in a nearby meadow in which Darwin had noted that stones were soon buried by worms, revealed that his home was still a hotbed for the creatures. Nineteen of the twenty-eight British species were found there or nearby. The most abundant species nowadays, and no doubt in Victorian times, was the black-headed worm, which is smaller than the familiar lobworm found in city gardens and used as bait by fishermen. The animals were most abundant in the kitchen garden, probably because of its many decades of fertiliser and a strict ban on pesticides.

A worm is an animated intestine. The body is divided into segments, each with an outer layer of muscle that encircles it and an inner muscle sheet that runs parallel to the axis. Each segment bears a simple kidney with a series of even simpler hearts distributed along the animal’s length. The body is hollow and filled with fluid and down the centre runs a long digestive tube. Many species have internal glands filled with lime - calcium carbonate. Some have coloured blood while others are almost transparent. Certain kinds smell of garlic, perhaps to put off predators.

The skin is covered with stiff spines that help the creature move through the soil as it eats its way onwards, pumping out waste from the rear end as it goes. In some kinds, the slime made as it burrows hardens into a solid wall that keeps a track open for a possible return while in others the soil collapses behind the questing worm as it travels. Some worms live on or just below the surface and in leaf litter, while others hide deeper, sometimes six metres down. A few prefer rotten wood. Those most important to farmers roam the top metre or so of soil. Some species reuse their burrows while others set out instead to build new homes. The common lobworm makes a single excavation, with one or two branches, while others make a network with several exits.

Most earthworms spend most of their time at rest in their underground fortresses and venture forth only when conditions are suitable. In winter they dig down and hibernate and in dry summers build a cocoon in which to rest until the rains come. After a downpour, they can travel in vast concourses across the surface. Darwin noted that many species do not like to leave the doors to their burrows open, and sealed them by pulling in leaves. Others made piles of digested earth - casts - on the ground, and in some tropical forms these could be several centimetres high. The creatures excrete with some care, for the tail, he noted, was used almost like a trowel to make a neat heap of ordure. A careful look at the body waste revealed many fine grains of silt that had been broken down from larger particles within the soil.

Worms live for no longer than two years or so, and most die younger than that. They get us all in the end, but some creatures get their retaliation in first. Many animals eat them. Badgers and hedgehogs are fond of a diet of worms, and as Alfred Russel Wallace had noticed, the natives of South America appreciated them too. In the Orinoco Basin of Venezuela smoked earthworms still form an important part of the local Indians’ cuisine.

Many species regenerate their tails when cut off, and a few do the same for a head, but - in spite of myths to the contrary - none of the familiar kinds can develop into two individuals when cut into pieces (an amputated tail may grow a mirror image of itself, but then it starves). A few do reproduce by simple fission; the back breaks off and forms a new worm, and - in some - the animal splits into a dozen or more pieces, each of which gives rise to a new individual. The ability to multiply by breaking into fragments is common in the lower reaches of the animal kingdom, but the worms are the most advanced creatures to possess that talent.