by Bill Bryson
You may not have heard of ATP, but it is what keeps you going. ATP molecules are essentially little battery packs that move through the cell providing energy for all the cell's processes, and you get through a lot of it. At any given moment, a typical cell in your body will have about one billion ATP molecules in it, and in two minutes every one of them will have been drained dry and another billion will have taken their place. Every day you produce and use up a volume of ATP equivalent to about half your body weight. Feel the warmth of your skin. That's your ATP at work.
When cells are no longer needed, they die with what can only be called great dignity. They take down all the struts and buttresses that hold them together and quietly devour their component parts. The process is known as apoptosis or programmed cell death. Every day billions of your cells die for your benefit and billions of others clean up the mess. Cells can also die violently--for instance, when infected--but mostly they die because they are told to. Indeed, if not told to live--if not given some kind of active instruction from another cell--cells automatically kill themselves. Cells need a lot of reassurance.
When, as occasionally happens, a cell fails to expire in the prescribed manner, but rather begins to divide and proliferate wildly, we call the result cancer. Cancer cells are really just confused cells. Cells make this mistake fairly regularly, but the body has elaborate mechanisms for dealing with it. It is only very rarely that the process spirals out of control. On average, humans suffer one fatal malignancy for each 100 million billion cell divisions. Cancer is bad luck in every possible sense of the term.
The wonder of cells is not that things occasionally go wrong, but that they manage everything so smoothly for decades at a stretch. They do so by constantly sending and monitoring streams of messages--a cacophony of messages--from all around the body: instructions, queries, corrections, requests for assistance, updates, notices to divide or expire. Most of these signals arrive by means of couriers called hormones, chemical entities such as insulin, adrenaline, estrogen, and testosterone that convey information from remote outposts like the thyroid and endocrine glands. Still other messages arrive by telegraph from the brain or from regional centers in a process called paracrine signaling. Finally, cells communicate directly with their neighbors to make sure their actions are coordinated.
What is perhaps most remarkable is that it is all just random frantic action, a sequence of endless encounters directed by nothing more than elemental rules of attraction and repulsion. There is clearly no thinking presence behind any of the actions of the cells. It all just happens, smoothly and repeatedly and so reliably that seldom are we even conscious of it, yet somehow all this produces not just order within the cell but a perfect harmony right across the organism. In ways that we have barely begun to understand, trillions upon trillions of reflexive chemical reactions add up to a mobile, thinking, decision-making you--or, come to that, a rather less reflective but still incredibly organized dung beetle. Every living thing, never forget, is a wonder of atomic engineering.
Indeed, some organisms that we think of as primitive enjoy a level of cellular organization that makes our own look carelessly pedestrian. Disassemble the cells of a sponge (by passing them through a sieve, for instance), then dump them into a solution, and they will find their way back together and build themselves into a sponge again. You can do this to them over and over, and they will doggedly reassemble because, like you and me and every other living thing, they have one overwhelming impulse: to continue to be.
And that's because of a curious, determined, barely understood molecule that is itself not alive and for the most part doesn't do anything at all. We call it DNA, and to begin to understand its supreme importance to science and to us we need to go back 160 years or so to Victorian England and to the moment when the naturalist Charles Darwin had what has been called "the single best idea that anyone has ever had"--and then, for reasons that take a little explaining, locked it away in a drawer for the next fifteen years.
25 DARWIN'S SINGULAR NOTION
IN THE LATE summer or early autumn of 1859, Whitwell Elwin, editor of the respected British journal the Quarterly Review , was sent an advance copy of a new book by the naturalist Charles Darwin. Elwin read the book with interest and agreed that it had merit, but feared that the subject matter was too narrow to attract a wide audience. He urged Darwin to write a book about pigeons instead. "Everyone is interested in pigeons," he observed helpfully.
Elwin's sage advice was ignored, and On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life was published in late November 1859, priced at fifteen shillings. The first edition of 1,250 copies sold out on the first day. It has never been out of print, and scarcely out of controversy, in all the time since--not bad going for a man whose principal other interest was earthworms and who, but for a single impetuous decision to sail around the world, would very probably have passed his life as an anonymous country parson known for, well, for an interest in earthworms.
Charles Robert Darwin was born on February 12, 1809, * 41 in Shrewsbury, a sedate market town in the west Midlands of England. His father was a prosperous and well-regarded physician. His mother, who died when Charles was only eight, was the daughter of Josiah Wedgwood, of pottery fame.
Darwin enjoyed every advantage of upbringing, but continually pained his widowed father with his lackluster academic performance. "You care for nothing but shooting, dogs, and rat-catching, and you will be a disgrace to yourself and all your family," his father wrote in a line that nearly always appears just about here in any review of Darwin's early life. Although his inclination was to natural history, for his father's sake he tried to study medicine at Edinburgh University but couldn't bear the blood and suffering. The experience of witnessing an operation on an understandably distressed child--this was in the days before anesthetics, of course--left him permanently traumatized. He tried law instead, but found that insupportably dull and finally managed, more or less by default, to acquire a degree in divinity from Cambridge.
A life in a rural vicarage seemed to await him when from out of the blue there came a more tempting offer. Darwin was invited to sail on the naval survey ship HMS Beagle, essentially as dinner company for the captain, Robert FitzRoy, whose rank precluded his socializing with anyone other than a gentleman. FitzRoy, who was very odd, chose Darwin in part because he liked the shape of Darwin's nose. (It betokened depth of character, he believed.) Darwin was not FitzRoy's first choice, but got the nod when FitzRoy's preferred companion dropped out. From a twenty-first-century perspective the two men's most striking joint feature was their extreme youthfulness. At the time of sailing, FitzRoy was only twenty-three, Darwin just twenty-two.
FitzRoy's formal assignment was to chart coastal waters, but his hobby--passion really--was to seek out evidence for a literal, biblical interpretation of creation. That Darwin was trained for the ministry was central to FitzRoy's decision to have him aboard. That Darwin subsequently proved to be not only liberal of view but less than wholeheartedly devoted to Christian fundamentals became a source of lasting friction between them.
Darwin's time aboard HMS Beagle, from 1831 to 1836, was obviously the formative experience of his life, but also one of the most trying. He and his captain shared a small cabin, which can't have been easy as FitzRoy was subject to fits of fury followed by spells of simmering resentment. He and Darwin constantly engaged in quarrels, some "bordering on insanity," as Darwin later recalled. Ocean voyages tended to become melancholy undertakings at the best of times--the previous captain of the Beagle had put a bullet through his brain during a moment of lonely gloom--and FitzRoy came from a family well known for a depressive instinct. His uncle, Viscount Castlereagh, had slit his throat the previous decade while serving as Chancellor of the Exchequer. (FitzRoy would himself commit suicide by the same method in 1865.) Even in his calmer moods, FitzRoy proved strangely unknowable. Darwin was astounded to learn upon the conclusion of
their voyage that almost at once FitzRoy married a young woman to whom he had long been betrothed. In five years in Darwin's company, he had not once hinted at an attachment or even mentioned her name.
In every other respect, however, the Beagle voyage was a triumph. Darwin experienced adventure enough to last a lifetime and accumulated a hoard of specimens sufficient to make his reputation and keep him occupied for years. He found a magnificent trove of giant ancient fossils, including the finest Megatherium known to date; survived a lethal earthquake in Chile; discovered a new species of dolphin (which he dutifully named Delphinus fitzroyi ); conducted diligent and useful geological investigations throughout the Andes; and developed a new and much-admired theory for the formation of coral atolls, which suggested, not coincidentally, that atolls could not form in less than a million years--the first hint of his long-standing attachment to the extreme antiquity of earthly processes. In 1836, aged twenty-seven, he returned home after being away for five years and two days. He never left England again.
One thing Darwin didn't do on the voyage was propound the theory (or even a theory) of evolution. For a start, evolution as a concept was already decades old by the 1830s. Darwin's own grandfather, Erasmus, had paid tribute to evolutionary principles in a poem of inspired mediocrity called "The Temple of Nature" years before Charles was even born. It wasn't until the younger Darwin was back in England and read Thomas Malthus's Essay on the Principle of Population (which proposed that increases in food supply could never keep up with population growth for mathematical reasons) that the idea began to percolate through his mind that life is a perpetual struggle and that natural selection was the means by which some species prospered while others failed. Specifically what Darwin saw was that all organisms competed for resources, and those that had some innate advantage would prosper and pass on that advantage to their offspring. By such means would species continuously improve.
It seems an awfully simple idea--it is an awfully simple idea--but it explained a great deal, and Darwin was prepared to devote his life to it. "How stupid of me not to have thought of it!" T. H. Huxley cried upon reading On the Origin of Species . It is a view that has been echoed ever since.
Interestingly, Darwin didn't use the phrase "survival of the fittest" in any of his work (though he did express his admiration for it). The expression was coined five years after the publication of On the Origin of Species by Herbert Spencer in Principles of Biology in 1864. Nor did he employ the word evolution in print until the sixth edition of Origin (by which time its use had become too widespread to resist), preferring instead "descent with modification." Nor, above all, were his conclusions in any way inspired by his noticing, during his time in the Galápagos Islands, an interesting diversity in the beaks of finches. The story as conventionally told (or at least as frequently remembered by many of us) is that Darwin, while traveling from island to island, noticed that the finches' beaks on each island were marvelously adapted for exploiting local resources--that on one island beaks were sturdy and short and good for cracking nuts, while on the next island beaks were perhaps long and thin and well suited for winkling food out of crevices--and it was this that set him to thinking that perhaps the birds had not been created this way, but had in a sense created themselves.
In fact, the birds had created themselves, but it wasn't Darwin who noticed it. At the time of the Beagle voyage, Darwin was fresh out of college and not yet an accomplished naturalist and so failed to see that the Galápagos birds were all of a type. It was his friend the ornithologist John Gould who realized that what Darwin had found was lots of finches with different talents. Unfortunately, in his inexperience Darwin had not noted which birds came from which islands. (He had made a similar error with tortoises.) It took years to sort the muddles out.
Because of these oversights, and the need to sort through crates and crates of other Beagle specimens, it wasn't until 1842, six years after his return to England, that Darwin finally began to sketch out the rudiments of his new theory. These he expanded into a 230-page "sketch" two years later. And then he did an extraordinary thing: he put his notes away and for the next decade and a half busied himself with other matters. He fathered ten children, devoted nearly eight years to writing an exhaustive opus on barnacles ("I hate a barnacle as no man ever did before," he sighed, understandably, upon the work's conclusion), and fell prey to strange disorders that left him chronically listless, faint, and "flurried," as he put it. The symptoms nearly always included a terrible nausea and generally also incorporated palpitations, migraines, exhaustion, trembling, spots before the eyes, shortness of breath, "swimming of the head," and, not surprisingly, depression.
The cause of the illness has never been established, but the most romantic and perhaps likely of the many suggested possibilities is that he suffered from Chagas's disease, a lingering tropical malady that he could have acquired from the bite of a Benchuga bug in South America. A more prosaic explanation is that his condition was psychosomatic. In either case, the misery was not. Often he could work for no more than twenty minutes at a stretch, sometimes not that.
Much of the rest of his time was devoted to a series of increasingly desperate treatments--icy plunge baths, dousings in vinegar, draping himself with "electric chains" that subjected him to small jolts of current. He became something of a hermit, seldom leaving his home in Kent, Down House. One of his first acts upon moving to the house was to erect a mirror outside his study window so that he could identify, and if necessary avoid, callers.
Darwin kept his theory to himself because he well knew the storm it would cause. In 1844, the year he locked his notes away, a book called Vestiges of the Natural History of Creation roused much of the thinking world to fury by suggesting that humans might have evolved from lesser primates without the assistance of a divine creator. Anticipating the outcry, the author had taken careful steps to conceal his identity, which he kept a secret from even his closest friends for the next forty years. Some wondered if Darwin himself might be the author. Others suspected Prince Albert. In fact, the author was a successful and generally unassuming Scottish publisher named Robert Chambers whose reluctance to reveal himself had a practical dimension as well as a personal one: his firm was a leading publisher of Bibles. Vestiges was warmly blasted from pulpits throughout Britain and far beyond, but also attracted a good deal of more scholarly ire. The Edinburgh Review devoted nearly an entire issue--eighty-five pages--to pulling it to pieces. Even T. H. Huxley, a believer in evolution, attacked the book with some venom, unaware that the author was a friend. * 42
Darwin's manuscript might have remained locked away till his death but for an alarming blow that arrived from the Far East in the early summer of 1858 in the form of a packet containing a friendly letter from a young naturalist named Alfred Russel Wallace and the draft of a paper, On the Tendency of Varieties to Depart Indefinitely from the Original Type , outlining a theory of natural selection that was uncannily similar to Darwin's secret jottings. Even some of the phrasing echoed Darwin's own. "I never saw a more striking coincidence," Darwin reflected in dismay. "If Wallace had my manuscript sketch written out in 1842, he could not have made a better short abstract."
Wallace didn't drop into Darwin's life quite as unexpectedly as is sometimes suggested. The two were already corresponding, and Wallace had more than once generously sent Darwin specimens that he thought might be of interest. In the process of these exchanges Darwin had discreetly warned Wallace that he regarded the subject of species creation as his own territory. "This summer will make the 20th year (!) since I opened my first note-book, on the question of how & in what way do species & varieties differ from each other," he had written to Wallace some time earlier. "I am now preparing my work for publication," he added, even though he wasn't really.
In any case, Wallace failed to grasp what Darwin was trying to tell him, and of course he could have no idea that his own theory was so nearly identical to one that Darwin had been evolving, as it were, for two deca
des.
Darwin was placed in an agonizing quandary. If he rushed into print to preserve his priority, he would be taking advantage of an innocent tip-off from a distant admirer. But if he stepped aside, as gentlemanly conduct arguably required, he would lose credit for a theory that he had independently propounded. Wallace's theory was, by Wallace's own admission, the result of a flash of insight; Darwin's was the product of years of careful, plodding, methodical thought. It was all crushingly unfair.
To compound his misery, Darwin's youngest son, also named Charles, had contracted scarlet fever and was critically ill. At the height of the crisis, on June 28, the child died. Despite the distraction of his son's illness, Darwin found time to dash off letters to his friends Charles Lyell and Joseph Hooker, offering to step aside but noting that to do so would mean that all his work, "whatever it may amount to, will be smashed." Lyell and Hooker came up with the compromise solution of presenting a summary of Darwin's and Wallace's ideas together. The venue they settled on was a meeting of the Linnaean Society, which at the time was struggling to find its way back into fashion as a seat of scientific eminence. On July 1, 1858, Darwin's and Wallace's theory was unveiled to the world. Darwin himself was not present. On the day of the meeting, he and his wife were burying their son.
The Darwin-Wallace presentation was one of seven that evening--one of the others was on the flora of Angola--and if the thirty or so people in the audience had any idea that they were witnessing the scientific highlight of the century, they showed no sign of it. No discussion followed. Nor did the event attract much notice elsewhere. Darwin cheerfully later noted that only one person, a Professor Haughton of Dublin, mentioned the two papers in print and his conclusion was "that all that was new in them was false, and what was true was old."