Evolution - Darwin's Struggle - BBC Documentary

In the late summer of 1859, Charles Darwin finally completed the last paragraph of his greatest work, "On the Origin of Species." But he wasn't drawing his inspiration from the exotic islands that he visited on his famous voyage on HMS Beagle; a chalk bank in Kent, near his house at Down, provided his metaphor for the laws that explain the diversity of life on our planet.

"It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other and dependent on each other in so complex a manner, have all been produced by laws acting around us."

Darwin was unleashing a new vision of nature where species evolved independently from the guiding hand of a Creator. The established vision of a harmonious world, divinely ordained to serve God's noblest creation, mankind, would be shattered. He was very aware that what he was dealing with was effectively intellectual dynamite, and he kept most of his thoughts about what he was doing, in terms of where man might come from and where new species might arise, effectively secret. It was a secret with which Darwin had wrestled for 20 years, 20 years of unflinching support from his wife, Emma, who feared that her beloved husband might be consigned to eternal damnation for challenging traditional beliefs. Together, they would endure two decades of debilitating illness, self-doubt, and family tragedy.

It was a life struggle that Darwin also saw among the animals and plants in the fields and tangled banks of the Kentish countryside—a struggle that is a founding principle of his theory of natural selection. The last paragraph of "On the Origin of Species" really goes out with a perfect bang. The whole book has been about the struggle for existence and what Tennyson had called "nature red in tooth and claw." The last paragraph gives, to me, a sense of hope; it sort of shows that this war of all against all actually has a result, and the result is the living world we see around us—the beauties of the tangled bank, the worms and the butterflies, and the grass and the orchids. All of these beauties of nature emerge from Darwin's simple idea: "There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one, and that whilst this planet has gone cycling along according to the fixed laws of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved."

Just as beauty and wonder emerge out of a war of nature, so too did Charles Darwin's great book evolve out of years of painstaking research and inner conflict. At the age of 33, Charles Robert Darwin was already an established gentleman naturalist. His substantial private income enabled him to pursue his particular interest: solving what have been called "the mystery of mysteries," how animals and plants might transmute or evolve. It was to find a quiet place to write that, in 1842, he and his burgeoning family had moved to a house just outside London, near the village of Down in Kent.

"After several fruitless searches in Surrey and elsewhere, we found this house and purchased it. I was pleased by the diversified appearance of the vegetation proper to a chalk district and so unlike what I had been accustomed to in the Midland counties, and still more pleased with the extreme quietness and rusticity of the place."

Darwin knew that in the country, there was space to expand his experiments, to walk, to observe nature. There was plenty of information there for him to draw on, and then there was a very important factor for Darwin: getting into a space where he felt safe with his secret theory of transmutation. In the early 1840s, transmutation, or evolution, was still a radical idea associated with social revolution. It was a secret that he shared with his wife and first cousin, Emma Wedgewood, whom he had married three years earlier.

"I marvel at my good fortune that Emma, so infinitely my superior in every single moral quality, should have consented to be my wife."

Emma was the precondition for everything that he did. She created a love-shaped space where he felt safe to work obsessively without fearing the loss of love or damaging their relationship. She was to nurse him through years of recurrent bouts of illness, the nature of which remains unclear to this day—possibly damage caused by a South American parasite inflamed by anxiety and nervous tension.

"25 years of extreme spasmodic daily and nightly flatulence, vomiting preceded by shivering, hysterical crying, dying sensations or half-faint, and copious and very palid urine. Air fatigues bring on head symptoms, nervousness. When Emma leaves me, I think..."

She was always concerned about his health. She was constantly trying to persuade him to have a day off, to go on a trip, not because she wanted his company, but because she felt if he carried on working at the pace at which he was going, then he would become more ill. Emma was to provide Charles with 10 children, seven of whom survived to adulthood. As a father, Charles Darwin did not conform to the standard Victorian stereotype of the distant and stern paterfamilias. Darwin was very much a family man.

He writes rather wryly one year that his wife hadn't been doing very well last year because she hadn't had a baby—okay, which is pretty rude for a Victorian, I have to say. But what's fascinating is that he used his children as experimental animals. He noted their expressions when they were crying, when they were angry, and he saw how similar they were to the expression of a dog, let's say. He saw his family as part of the human family, the human family as part of the mammal family, the mammal family as at one with the primroses. That really shows that he saw humankind as an intrinsic part of the living world and not apart from it.

This was radically different from the established Christian view of the time, where mankind was God's special and separate creation. He kept his real opinions in a private notebook: "Man, in his arrogance, thinks of himself as a great work worthy of the interposition of a deity. More humble, and I believe true, to think him created from animals."

Charles and Emma did what animals do; only they had a bed to do it in upstairs. But then, because Darwin believed strongly in analogy, it's not only animals that do what people do, but it's also plants that do what people do in strange and complicated ways. So from the marriage bed to the flower bed was only 100 yards, and Darwin would go downstairs, out the back door, down to his flower beds where experiments were being performed and how these creatures—he even regarded some plants as simple animals—also reproduce themselves.

Just over a year after he arrived at Down, he felt bold enough to tentatively raise the issue of species change with his botanist friend, Joseph Hooker. "At last, gleams of light have come, and I'm almost convinced that species are not immutable." It is like confessing a murder. Hooker's response was non-committal. Darwin retreated into his shell. If Hooker wouldn't buy it, then his old teachers at Cambridge certainly wouldn't. Even the most progressive members of the Anglican clergy still saw nature's beauty and abundance as divinely ordained for the benefit of the Lord's highest creation, man.

The fundamental idea around nature for many people during the early part of the 19th century, particularly in Cambridge but throughout Anglican Britain, was that of design. The world was made for man, and probably the best way of explaining this is just to think about the 24-hour day. We think of that, of course, as just an outcome of astronomical chance and the way that the planets work and so forth. For people who were sitting in Cambridge, the idea was basically that the 24-hour day is because humans need to sleep for 8 hours, and everything around them is organized from that fact, from human need going outwards.

To suggest that mankind was merely a product of nature risked attack from the black-robed priests—the "black beasts," as Darwin called them. But what he possibly feared even more was the loss of respect from the Cambridge dons who had taught and inspired him—men such as the straight-spoken Yorkman, the Reverend Adam Sedgwick, professor of geology, who saw God's design in nature. Denying this might brutalize it and sink the human race into a lower grade of degradation than any into which it has fallen since records tell us of its history.

Sedgwick represents an uneasy union of science and religion that had prevailed since the 17th century in Britain, particularly a division of labor in which those who study nature offer to those who study God evidences of God's greatness, goodness, and wisdom in the world about us, and those who study God's revelation in the Bible offer reasons for believing in God, that he has revealed to us how to go to heaven. Nature doesn't tell us how to go to heaven, but it tells us that there is a God in heaven who has revealed himself and how to get there in the Bible.

It was with these traditional views in mind that, in early 1844, Darwin began to prepare a manuscript that he hoped would eventually show even men like Sedgwick that evolution was a reality and that he had found the mechanism that made it happen. But as a punctilious and cautious man, he needed to marshal his evidence. What he does there at Down is really create a living laboratory, you know, a laboratory for this to go along with his career, as it were. It's not just Darwin sitting alone looking out the window.

Darwin didn't just use his house and gardens to observe and learn from nature; he bred pigeons and orchids, raised 50 varieties of gooseberry, and to counter the creationists, he became a beekeeper in order to show that the near-perfect hexagons in honeycombs were made by instinct rather than divine design. "My habits are methodical; my love of natural science has been steady and ardent. I have the strongest desire to understand or explain whatever I have observed, to group all facts under some general laws."

He would also create a place to think. A rough oval-shaped path of gravel was laid down, and trees were planted to provide him with a half-kilometer walking circuit. He called it the Sandwalk. Darwin called the Sandwalk his thinking path. He watched the trees grow, and many of them are still there, in the knowledge and hope that he would be able to pace around this plot and escape the pressure of sitting in one place and writing and squeezing one's ideas out the point of a pen.

Darwin would lose himself in thought on the Sandwalk, so much so that the only way he could keep track of the time he spent there was to keep track of the laps. He kept track of the laps by a pile of flints, one of which he would kick to the side after a lap, and when the whole pile had been moved across the path, he knew he had completed his exercise. That was his thinking time for the day.

We, the subsequent generation, love the Sandwalk because we can imagine Darwin on it and think about what he can see from the Sandwalk. He can see these climbing plants that grow in the hedge, for example—something he will write about. He can see the great plucking field where he will formulate a concept of biodiversity.

Secluded in his rural laboratory, Darwin's manuscript on what he was already calling natural selection developed into an essay suitable for publication. Some of his text drew on the experiences he had on his round-the-world Beagle expedition. Out of the five years he spent on the voyage, he had stayed just five weeks on the Galapagos. Specimens of plants and different species of mockingbirds and finches—the significance of his Galapagos experience was profound.

Now, at Down, he was able to draw on nine years of intellectual struggle. He'd set down some of his most brilliant insights in what would become known as the transmutation notebooks. It was in these pocketbooks that he first drafted the idea that the vast range of living species must have all evolved from a shared common ancestry—twigs and branches stemming from one tree of life.

He was brainstorming with total abandon—totally unorthodox, unacceptable to philosophers in his day. Maybe there were a few Enlightenment rationalists in France who would do that, but no one in Britain would countenance someone seriously trying to find out about the world by doing what Darwin did. He wasn't just tapping physics and theology; he was going to economics, he was going to animal breeding, he was reaching out in every direction for evidence and intuitions to build up the world as he sensed it existed.

And yet that vision of the world was changing all the while he was testing what he thought might be the case. This is the brainstorming aspect with what people were saying was the case. Darwin's 1844 manuscript was based on wide reading, from Milton's "Paradise Lost" to the evolutionary speculations of his grandfather Erasmus and the radical French biologist Jean-Baptiste Lamarck. His great geologist mentor, Charles Lyell, taught him that the Earth's surface had been formed gradually over countless ages.

But it was the political economist Thomas Malthus who would stimulate the closest parallel to a Eureka moment that Darwin would ever have. "In October 1838, 15 months after I had begun my systematic inquiry, I happened to read for amusement Malthus on population."

"In terms of natural selection, there's a crucial moment in Darwin's discovery, and that is, I think, when he reads Thomas Malthus's essay on the principle of population. Now, this was an incredibly controversial book. It was controversial basically because it argued that there were limits to growth. A lot of philosophers in the 18th century had said, you know, mankind can progress indefinitely; everything's going to be great. Malthus says, 'No, that's not the case. In fact, we've got a limited food supply, and effectively what happens is you're going to get this population exploding exponentially, and it's going to be cut off by the need for food.'

What Darwin does is turn this into a creative principle in nature. Death becomes the way of explaining life. And so what happens is you get this incredible idea that all of these thousands of forms, all these different slightly different species, are actually competing for these tiny spaces on the earth, and in nature, each one trying to live, and only those that are most fit—only those that are really going to match into that little spot—those are the ones that are going to survive, and all the thousands, the millions, the billions, the rest are going to die.

"It had once struck me that under these circumstances favorable variations would tend to be preserved and unfavorable ones destroyed. The result of this will be the formation of new species. Here then I had at last got a theory by which to work."

He says this population growth is like 100,000 wedges pounding into the face of nature, you know, pushing in stronger ones and throwing out weaker ones—therein capturing the essence of the struggle for existence, survival of the fittest.

He had a moment when he got it—very excited. You can definitely tell the excitement because it's very, very tight, very, very careful. It's controlled thrill, I would say—very, very detailed writing, layer upon layer, really of reaction to this.

By 1844, Darwin had placed Malthus's ideas on population at the core of his theory of natural selection as a mechanism by which evolution occurred. The war of nature destroyed the weaklings; only the best adapted went on to reproduce, passing on their successful characteristics to succeeding generations. In having so many children, Charles and Emma were effectively conducting their own Malthusian experiment.

By the time he had finished the manuscript, one baby child had died, and Emma was about to be pregnant with a fifth. William and Annie, their first two, were thriving. Elizabeth Darwin was born in March 1841. She became indispensable to her mother. By the time she was that wonderful age of eight or nine, she showed her parents great tenderness, and I think that that increased Emma and Charles's love for Annie.

She would pet them and stroke their hands, stroke their hair, and take her father's hair and plait it and fix it just so, then take his hand and walk around the Sandwalk, skipping ahead. She had her own little flower patch in the back—all these endearing things as they watched their eldest daughter become a young woman. Her joyousness and animal spirits radiated from her whole countenance and rendered every movement elastic and full of life and vigor.

"It was delightful and cheerful to behold her. Her dear face now rises before me as she used to sometimes come running downstairs with a stolen pinch of snuff for me, her whole form radiant with pleasure of giving pleasure."

As these children grew up, these were not only loved children, but they were creatures; they were little developing organisms. They were like the orangutan in the London Zoo, and Darwin would compare his son William and Annie growing up with the orangutan in the zoo at Down. Annie and her siblings provided an emotional relief from the constant struggle with his new and contentious theory.

But there was another long-term source of unease. Emma read his completed manuscript. Darwin must have known that she would find it uncomfortable reading. In a strong and loving relationship, his rejection of traditional religious teachings made her anxious about his salvation, although the manuscript acknowledged the existence of a Creator. Emma felt it undermined the belief that man was specially created by God.

If you put yourself in the mind of a 19th-century reader, the notion that species had evolved, that humans had evolved, would be deeply upsetting because of this presumption that humans are at the top of the ladder of the hierarchy—perfect, formed, noble—all of those things. To suggest that we had evolved from apes and before that from primitive sea creatures must have seemed deeply heretical.

Darwin was very aware that he needed to tell his wife the general tenor of the work that he was actually doing, but he was also quite aware too that she was going to be upset. I mean, Emma is quite liberal in her general outlook, but she also is a practicing Christian and a strong believer. Emma feared that her husband's religious doubts would mean that he might not be saved and join her in the afterlife.

"When I am with you, all melancholy thoughts keep out of my head, but since you are gone, some sad ones have forced themselves in—a fear that our opinions on the most important subject should differ widely. My reason tells me that honest and conscientious doubts cannot be a sin, but I feel it would be a painful void between us."

The big question for Emma was: were they going to spend eternity together? Or when she died and then he died, was that something where they were going to be apart? I think that was a terrible kind of burden for her, and it remained a burden right up till the end of their lives.

"I do not wish for any answers about all this. It is a satisfaction for me to write it. Don't think it's not my affair and does not signify much to me. Everything that concerns you concerns me, and I would be most unhappy if I thought that we would not belong to each other forever."

That became an item of unfinished business in their relationship. It was buried perhaps many times, but when a child was sick and dying, or when Darwin, as so often the case, fell ill and she had to care for him, it was the specter of being eternally without her beloved that haunted Emma and made her bring it up to him.

We don't know how many times in private. We do know that the issue weighed heavily on Darwin from a note he later added to Emma's letter: "When I am dead..."

No matter how many times I have kissed and cried over this. Whatever her personal misgivings, Emma loyally read and commented on the essay. Darwin was still not confident enough to have it published, and his anxieties about hostile attitudes to evolutionary ideas were soon to be confirmed.

He finishes this essay, and I think any decision that he had that he was thinking about publishing is certainly knocked on its head in October of 1844 when he learns through an advertisement in the London Times that a book has been published called "The Vestiges of the Natural History of Creation."

This is an anonymous book; who its author was was a subject of great guessing and uncertainty. It's a book which even the advertisements say deals with the whole range of phenomena and explains it through a natural law of development—in other words, there's some sort of evolution that will explain how everything in the universe came into being. It becomes one of the great sensations of the 1840s. Everybody reads it, from Queen Victoria to the poet Tennyson, most of Darwin's friends. It's discussed very extensively by a whole range of different people.

"The whole train of animated beings, from the simplest and oldest up to the highest and most recent, are then to be regarded as a series of advances of the principle of development. It has pleased Providence to arrange that one species should give birth to another until the second highest gave birth to man."

The identity of the author, Robert Chambers, a Scottish journalist, was not revealed for another 40 years. He had feared the inevitable backlash. In the vanguard of the attack was Darwin's old Cambridge teacher, the Reverend Adam Sedgwick. He detected the serpent coils of false philosophy in the book's vision of transmutation.

"People came down on it very hard," his Professor Sedgwick here at Cambridge referred to it as a "filthy abortion whose head ought to be crushed." Now, of course, that's consistent with seeing it as the offspring of a frail female mind.

"This book, this filthy abortion—that's hard talk from the Reverend Adam Sedgwick, fellow of Trinity College, Cambridge. I cannot but think the work is from a woman's pen; it's so well dressed and so graceful in its externals. This mistake was woman's from the first; she longed for the fruit of the tree of knowledge, and she must pluck it, right or wrong."

Sedgwick absolutely loathed "Vestiges." For him, it was, for many evangelical Christians, "Vestiges," which was bound in red, the Scarlet Harlot. It's a book that has the beautiful attraction of a woman. What you need to do, he says, is rip off the pretty clothes and reveal underneath the foul mass of corruption within.

"If the book be true, the labors of sober induction are in vain; religion is a lie, human law is a mass of folly and a base injustice, morality is moonshine, our labors for the black people of Africa were works of madmen, and men and women are only better beasts."

Darwin reads this, as he says, in fear and trembling. It also, I think, serves a very useful role for Darwin, though, because when he reads the review, when he looks at what Sedgwick has to say, in many ways he's able to start ticking off the kinds of things that he needs to look into, the kinds of questions he needs to answer in order to make sure that his theory is safe, that it has the right kind of armor around it so that it can go forward in the world without having the same kind of reaction against it that "Vestiges" actually had.

Still reeling from the savage response to "Vestiges," Darwin seems to have gone into a period of self-doubt. His fears of being regarded as a lightweight speculator were possibly raised by some words of advice from his botanist friend, Joseph Hooker. Hooker said to him that he thought that no one had the right to pronounce on species unless they had examined many—throwaway line in a letter from Hooker to his friend, and yet clearly a remark that haunted Darwin.

He knew absolutely that Hooker was right; that if anyone was going to believe this enormous claim that he was going to make, then he really had to do the examining of many. He had to really do the work with the microscope and with the dissection tools, and once he had done that, and once people admired him for the detail of that work, then he would have a better chance with the big idea.

Darwin decided to embark on a comprehensive description of an entire subclass of marine organisms: barnacles. It was a project he anticipated would take a matter of months. It was to take him eight years. There are two types of barnacles mainly: there's the coned barnacles, the little white volcanic tiny cones that cover every rock. Inside the cone, there's a little creature which is cemented to the rock by its head and which fishes with its feet. So when the tide comes in, the feet come out through the little hole, and there's this wonderful pulsing movement, like feathers almost, as the feet fish for tiny plankton.

They also, barnacles—coned barnacles—have the largest penises proportionate to size in the entire animal kingdom. So every now and again, you can also see coming out of one of the tops of these cones an enormous penis which will come out the top and then go into the top of another valve, maybe four or five barnacles away.

So he quite quickly comes to see and express this sense of wonder that here they were, seemingly ordinary, you know, covering every shoreline of the temperate world, and yet when you go in really, really close, what seems like a simple organism becomes a very sophisticated one. You see that pattern over and over again in Darwin's early work—that sense of we must stop talking about higher animals and lower animals, that actually the lower animals are often very sophisticated, almost fantastic in the way that they've adapted to their conditions.

You can almost hear him gasp, you know, as he goes further and further in at the beauty of these things. There was another payoff: Darwin's barnacle research relied on people sending him specimens from all over the world. Down House developed into the hub of a network of contacts which would supply vital evidence for writing "On the Origin of Species."

Darwin's communication networks are absolutely remarkable. They're partly a tribute to the sophistication of the Victorian postal service, without which most 19th-century science would simply have collapsed. Pigeon breeders and orchid fanciers, colonial physicians and royal naval officers were badgered by Darwin from his study at Down, so that flowing onto that desk were piles and piles of paper.

It was while he was still laboriously dissecting his way through hundreds of barnacle specimens that one more of Darwin's children was struck down with what is now thought to have been tuberculosis. When Annie was about nine years old, she began to have tummy troubles, which isn't surprising in a house where the father was periodically throwing up in his study and doing all kinds of odd things to keep himself from becoming violently physically ill.

It was one of the ways one got attention at Down House: to be sick, very sick, preferably. Finally, her illness became so acute that while Emma was seriously pregnant—she was having her ninth child—Charles put Annie under his own doctor, and the doctor immediately diagnosed a grave situation that was bound to get worse. Finally, over the Easter weekend, she died.

"Her eyes sparkled brightly; she often smiled. Her step was elastic and firm; she held herself upright and often threw her head backwards as if she defied the world in her joyousness."

A week after Annie died, this is what's most remarkable: Charles sat down and, in a single draft—you can tell by reading it—wrote a magnificent tribute for this loved and sorely missed child in which he describes Annie's human nature in all of its physicality.

This is not just a struggle for existence in which a vulnerable life is crushed; this is a loved person who is their offspring. "We have lost the joy of the household and the solace of our old age. She must have known how we loved her. Oh, that she could now know how deeply, how tenderly we do still and shall forever love her dear, joyous face."

Annie's death came just three years after Darwin's father had died, an unbeliever, with his own belief in the Christian God already shaken. Darwin now severed his ties with traditional faith. "Disbelief crept over me at a very slow rate, but it was at last complete. I indeed hardly see how anyone ought to wish Christianity can be true, for if so, the plain language seems to show that men who do not believe will be everlastingly punished, and this is a damnable doctrine."

There it seems to me is the quintessence of any anger that he felt—that Annie's being torn away at Easter focused into a single moral statement, and it's the statement of a non-believer, a non-Christian, but still a believer in God—just a God who will not punish.

Ten-year-old's death in the war in nature had been the driving force in Darwin's theory of evolution. From the time he read Malthus, eight years after her death, Darwin would weave his daughter into that vision. Annie is in Chapter 3 of "On the Origin of Species," where Darwin talks about the struggle for existence.

In that chapter, Darwin, he's now writing five, six, seven years after Annie's death, describes for us nature as it appears and then nature how it really is. He refers to the smiling face of nature; he refers to the nature that we look out upon and is so celebrated—the green and pleasant land of England, the insects flitting through the air, the birds sporting themselves.

"We do not see," he says, "beneath the surface. It's a continual state of war. Under this surface of nature, the young are dying young, and the rest of the animal life struggles to survive. And then he says that this struggle for existence is like—and he uses the old notebook figure of wedges being driven into the face.

"We behold the face of nature bright with gladness. Every single organic being around us may be seen to be striving to the utmost to increase in numbers, that each lives by a struggle at some period of its life, that heavy destruction inevitably falls either on the young or old during each generation or at recurrent intervals. The face of nature may be compared to a yielding surface with 10,000 sharp wedges packed close together and driven inwards by incessant blows—sometimes one wedge being struck and then another with greater force."

And there's this nature with a smiling face and then there are wedges being driven in. It's the most horridly anthropomorphic figure, and when I first read that after studying Annie's death, I thought, could it be her face? And of course, when you read his account of her a week after she died, over and over again, her brilliant face, her beaming face, her smiles that he remembers with the picture of the dear type sat next to him in writing this chapter in the struggle for existence in "On the Origin of Species."

He's portraying Annie's fate in falling victim to a remorseless struggle that gives rise to higher forms of life. "She suffered at Easter that others may live."

Darwin now lost himself in barnacles again, taking three more years to finish his huge study. At last, he now felt able to return to his big theory, but for some time, something had been nagging him: how did a group like barnacles evolve, consisting as they did of thousands of slightly different species, many living side by side? Was his idea of natural selection enough by itself to explain the extraordinary diversity of living things?

"At that time, I overlooked one problem of great importance: the problem is the tendency in organic beings descended from the same stock to diverge in character as they become modified."

There's a place in the autobiography where he talks about the moment of discovery of the principle of divergence. You can see a chain, a small piece of paper among many that are dated the same date, November '54, in which his handwriting is extremely jagged in pencil.

"I can remember the very spot in the road whilst in my carriage when, to my joy, the solution occurred to me. The solution, as I do believe, is that the modified offspring of all dominant and increasing forms tend to become adapted to the many and highly diversified places in the economy of nature."

What Darwin realized was that the more individuals differed from each other, the better able they would be to take advantage of the particular environment in which they lived. Just as importantly, species would diverge even more as they adapted to each other.

This interdependence had a parallel in what would eventually become the Victorian factory system. He uses, I would call him more like the Adam Smith phase of Darwin's encounter with the political economists because, you know, Adam Smith had this idea of the division of labor—that you can produce more wealth if you have people who are specialists. You know, instead of everybody being a farmer, if some people become tailors and some become leather workers, you can produce more wealth.

Darwin uses essentially the same idea and applies it to these little plots of ground, and his view is that more life can be sustained on a square plot if the organisms use different parts of the environment. If you think about this in terms of this kind of lawn plot experiment, you've got grasses and other plants growing, and its roots might go down to a certain depth, so we can take nutrients from that level, but another might grow to a deeper depth.

You can sustain more life that way than if they're all growing to the same depth, if they're all one kind. And he's seeing that as a process of divergence. Darwin set up innovative trials to test out his ideas, leaving a few square feet of his lawn unmowed for three years. He regularly noted the changing composition in the struggle for life among 20 plant species, recording 11 winners and nine losers.

In Great Parkland's Meadow, he counted 142 different species—the first-ever survey of its kind. The chalk fields and banks around Down support as many as 40 different species per square meter—an abundance explained by natural selection and the principle of divergence.

His applications of Adam Smith's ideas of capitalist manufacture were not lost on the inventor of the idea of class struggle, Karl Marx. Darwin discovers among the beasts and plants the society of England, with its division of labor, competition, opening up of new markets, invention, and the Malthusian struggle for existence.

Certainly, Darwin, when he looks at those tangled banks where new varieties and eventually new species are preferentially being produced by competition and the physiological division of labor, Darwin calls those "manufacturies of species." The very phrase "factory system" is about 30 years old, and it had first been applied to this new system of economy based on industrial production, ferocious division of labor, automation, and mechanization.

Now, Darwin was using those principles to try and make sense of what was happening when competition was particularly vigorous and therefore adaptations peculiarly intensely favored. It was at this time that Darwin began to feel confident enough to come out in public with his theory. He started to prepare a masterwork where every possible criticism could be anticipated and every assertion backed up by evidence.

He wanted to win over his Victorian readers with striking and familiar examples. Understanding their fascination with domestic animals, he chose a particularly popular species, the pigeon, in order to make an analogy. Fancy pigeon breeding by artificial selection showed how natural selection worked in the wild.

He was especially concerned with just the sheer diversity of pigeons—all the different forms, the amazing types of pigeons, and how those related then to a single ancestor. On the one hand, you had fantails—really beautiful birds with beautiful feathers—down to the almond tumblers, very small birds with beaks so small that they could hardly get out of their eggshells. Carrier pigeons were very large; they had big ugly beaks.

They really show this incredible diversity. How could they all come from one ancestor? Just as pigeon breeders bred different varieties, so nature acted in the same way over longer periods of time, naturally selecting different varieties, each passing on their own inherited characteristics.

So in some sense, what Darwin was saying was just as the pigeon fanciers had a fancy, nature had a fancy, and that fancy was to produce these incredible varieties—all these different kinds of forms and types of animals and plants that we see around us—that the diversity could actually be explained by looking at something as simple as pigeons.

Pigeons were to be one example amongst many in a work that might have amounted to three heavy volumes had Darwin not been interrupted. "My plans were overthrown, for early in the summer of 1858, Mr. Wallace, who was then in the Malay Archipelago, sent me an essay on the tendency of varieties to depart indefinitely from the original type, and this essay contained exactly the same theory as mine."

Alfred Russell Wallace had been supplying Darwin and other rich collectors with animal and plant specimens from the Indonesian archipelago. Now Darwin, what has to say was tough; there's no question of it. Wallace was exactly the opposite. He had a few years of schooling; he was kicked out, and he went to the University of Life—it's all he could afford.

He decided to set up shop as a collector of animals, and he had an extraordinarily adventurous life. He went to Indonesia and had a tremendously challenging and difficult time. I mean, he was living out in the jungle for year after year after year, and then suddenly one day he had a good idea. Like Darwin, Wallace had been struck by Thomas Malthus's essay on population. His theory came to him while he was lying incapacitated with malaria, struggling for life.

So he wrote with a certain amount of trepidation to the grand and already famous fellow of the Royal Society, Charles Darwin, with this idea, and of course, it landed on Darwin's breakfast table, ringing down with the force of a hand grenade.

"So all my originality, whatever it may amount to, will be smashed, though my book, if it will ever have any value, will not be deteriorated, as all the labor consists in the application of the theory."

Darwin was distraught. Also, his daughter Henrietta was sick, and his infant son Charles gravely ill. He put his trust in his friends Joseph Hooker and Charles Lyell to decide the fate of his theory. With Wallace far away in Indonesia, they resolved to have papers by both naturalists presented at a meeting of the Linnean Society in London.

Remarkably, the joint presentation stirred up little interest. Darwin too was absent from the event; his infant son had died. Once recovered, he resolved to publish his book as soon as possible.

The great thing that Wallace did, I think, in many ways was to make sure that Darwin basically finished his book and wrote it in such a way that was actually readable to a much wider audience than it would have otherwise been. Darwin was basically writing a three-volume treatise on natural selection, with all the evidence—pigeons, bees, ants, everything—all put in there. There was going to be a chapter on man; it was everything all together.

What Wallace did was organize Darwin. He recaptured much of the energy he had when he was working on the Beagle voyage, and he suddenly started writing just with a real passion.

"In September 1858, I set to work on the strong advice of Lyell and Hooker to prepare a volume on the transmutation of species. It cost me 13 months and 10 days of hard labor. It was published under the title of 'On the Origin of Species' in November 1859."

Darwin was to describe his book of nearly 500 pages as one long argument. He gently and tentatively coaches his reader through a developing series of observations and examples. Throughout, the same pattern is repeated of moving from specific details to grand overarching conclusions.

"I often think that the theory of evolution by natural selection is a bit like the grammar of biology. You can't learn the language without understanding at least something about its grammar, and you couldn't be a biologist before 1859 because none of the facts seemed to fit together. You could be studying flowers, or you could be studying earthworms, you could be collecting birds on the Galapagos, but none—they were all sort of independent discoveries. But suddenly, 'On the Origin of Species' made it all make sense. It gave you a framework onto which you could bolt all these facts. So it really was, and still is, the central book of the science of biology."

The book appealed to a new breed of professional men of science who were prepared to accept that all nature was governed by fixed laws—the "Origin of Species" as much as the motions of the planets. But Darwin had invested so many years developing the book because he also hoped to win over his old Anglican mentors.

"On the Origin of Species" only twice refers to the origins of mankind, but for old naturalists such as his respected teacher, Professor Adam Sedgwick, the implications were obvious and odious. Adam Sedgwick wrote him a letter. This old man sat down and sorrowfully told his geological student how much he disapproved of this book, "The Origin of Species," which in places, Sedgwick said, attempts to break the link between the world of nature and the reality of God.

"I have read your book with more pain than pleasure. Parts of it I admired greatly; parts I laughed at till my sides were almost sore; parts I read with absolute sorrow because I think them utterly false and grievously mischievous."

Sedgwick hoped that they would see each other in heaven, and that said it all, didn't it? Sedgwick realized perfectly well what was at stake and what Darwin himself always knew was at stake. Sedgwick saw the fabric tottering and falling—that is, the fabric of salvation and eternal life.

"If you make a man out of a monkey..." That all comes down. The family was really quite upset about this. I think it is probably for Darwin the most upsetting letter he gets about "On the Origin of Species" because it represents, at some level, his failure in a certain way to be able to reach the kind of person that Sedgwick actually was.

It's particularly upsetting, I think, also for Emma, because Sedgwick is somebody that she particularly admired and whose views she respected quite heavily. So there's quite a lot of sense that there's upset in the household as a result of Sedgwick's intervention in the debate.

Whatever the personal setbacks, Emma steadfastly supported Charles throughout the years of controversy that followed, enabling him to write nine more books despite further breakdowns and mounting exhaustion. But he was later to call "On the Origin of Species" the chief work of his life.

The book has never been out of print. In it, he immortalized a chalk bank at Down to illustrate the extraordinary diversity and interdependence of living beings that result from the process of natural selection. It might also serve as a metaphor for his struggle to write the book, and of course, the tangled bank that he describes at the end is also a vision of his own life.

You know, the tangled bank that he sees, central to his vision of nature, is also the world that he's lived in, and there's a sense of worship in that—of worship of nature as he sees it fully. That he accepts the war, the destruction, the famine, the pain, suffering, the loss of children, but nonetheless, you put all of that together—the death and the suffering and the beauty and the miracle of it—and you end with wonder.

"There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one, and that whilst this planet has gone cycling along according to the fixed laws of gravity, from so simple a beginning, endless forms most beautiful and most wonderful have been and are being evolved."

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