The Reluctant Mr. Darwin (24 page)

For lucid accounts of those developments, if you happen to want them, you can turn to sources such as Ernst Mayr's readable (but not disinterested) history,
The Growth of Biological Thought
; or Peter J. Bowler's various books, including
The Non-Darwinian Revolution
; or Douglas Futuyma's excellent textbook,
Evolutionary Biology
; or Mark Ridley's,
Evolution
; or David J. Depew and Bruce H. Weber's dense survey,
Darwinism Evolving: Systems Dynamics and the Genealogy of Natural Selection
; or Stephen Jay Gould's ponderous but richly informative (it should be, at 1,433 pages) intellectual doorstop,
The Structure of Evolutionary Theory
; or…a passel of other books, some good and some merely useful. Darwin's theory, as I warned you at the start, has attracted a vast amount of scholarly nibbling and scribbling. But the fascinations and the implications of that theory are vast, too. And the story hasn't ended. It continues to unfold.

The central themes of the story, as told by Mayr or Gould or most of those others, are that evolution is real and wondrous, and that the idea of natural selection has survived and succeeded because it fits the observable facts better than any alternative idea, doing exactly what a scientific theory must do: explain material effects by way of material causes. As Darwin himself conceded—and as Sewall Wright, Motoo Kimura, and certain other biologists have since affirmed—natural selection isn't the sole mechanism of evolutionary change. But it's the primary mechanism. It's the lathe and the chisel that shape adaptations. It's the central concept of Darwinism, whatever else Darwinism might be taken to include. It's the starting point for understanding how evolution works.

When first published in
The Origin of Species
, according to Douglas Futuyma's textbook, Darwin's long argument was “based on logic and on interpretation of many kinds of circumstantial evidence, but he had no direct evidence.” Biogeography, paleontology, embryology, morphology—those could all be considered indirect, in that their puzzling patterns were explicable by Darwin's theory. More than seventy years had to pass before a synthesized understanding of Mendelian heredity and Darwinian selection would, in Futuyma's words, “fully vindicate his hypothesis.” But the vindication came. In 1959, the centennial of
The Origin
was celebrated in a spirit of confidence that Darwin, the crafty old boy, had gotten it right. Later discoveries have added further certainty. And more every year.

Not long ago I visited Futuyma in his office at the University of Michigan. A long narrow table, down the middle of a long narrow room, was strewn with journal papers. His shelves were full of books. No fruit flies in cages, no ammonoid fossils, no pickled barnacles. It was a place for thinking and chatting. Futuyma is a mild, urbane, and very smart man with short-clipped gray hair and wire-rim glasses. On this day he was wearing a bulky sweater. I had come to ask him about the evidence for evolution.

In response to my questions, he moved quickly through some familiar points—vestigial organs, the fossil record, patterns of biogeography—and talked mostly about molecular genetics. He reminded me that molecular biologists generally haven't concerned themselves with the same questions, let alone the same answers, that engage evolutionary biologists. For fifty years, since Watson and Crick discovered the structure of DNA, the molecular people have been interested in genes, proteins, and the ways they function within living cells, but not much in species and the ways they evolve. At the University of Michigan and many other universities, the two disciplines—molecular biology and evolutionary biology—don't even reside within one department. That said, Futuyma pulled out his heavily marked copy of
Nature
for February 15, 2001. It was a historic issue, fat with articles on the results of the Human Genome Project. Beside it he slapped down a more recent issue of
Nature
, also thick and important, this one devoted to the sequenced genome of the common mouse,
Mus musculus
. The particular strain of mouse under scrutiny was known as C57BL/6J, a laboratory lineage frequently used in research. The headline of the lead editorial announced:
HUMAN BIOLOGY BY PROXY
.

The mouse genome effort, according to
Nature
's editors, had revealed “about 30,000 genes, with 99% having direct counterparts in humans.” What they meant by “direct counterparts” was not identical genes (like the many identical genes that humans and chimpanzees share) but very similar ones. Such a high degree of similarity is nevertheless dramatic. Mice and humans possess about the same number of genes, almost all of them direct counterparts, “and we both like cheese,”
Nature
noted. “So why aren't mice more like us? The answer probably lies in the regulation of those genes.” Similar genes produce humans on the one hand, mice on the other hand, because of how they are turned on and off during each creature's embryonic development and growth.

Futuyma helped me understand this in a broader context. The resemblance between our 30,000 human genes and the 30,000 mousey counterparts, he said, represents another form of homology, like the resemblance between a five-fingered hand and a five-toed paw. Now consider: Would any wise and busy God fabricate a human species, by special creation, that is similar to mice in 30,000 ways? Not likely. In fact, not rationally imaginable. Homology so intricate can be explained only by common descent. Flipping to the end of the main article, Futuyma read me a sentence: “Comparative genome analysis is perhaps the most powerful tool for understanding biological function.” He looked up. “That's a strong statement from molecular biologists.” Reading again: “Its power lies in the fact that evolution's crucible is a far more sensitive instrument than any other available to modern experimental science.” Evolution's crucible? In plain words: natural selection, preserving genes and discarding them, sometimes one by one.

Futuyma's point was that, after decades of increasing tension between two competing disciplines, even molecular biologists are now beginning to concede that
all
biology is evolutionary biology. “This is the future,” he said, “of biological and biomedical science.”

1876–1882

41

I
n his later years, Darwin's health improved, but he grew weary.

The old urgency was gone. He knew that the big works of his life were finished. Maybe that's why he vomited less frequently and suffered fewer attacks of bad, dizzy head. He resigned himself grumpily to the inconveniences of fame—worshipful visitors, letters from strangers, requests for his presence or his opinion or his expert testimony in court—though he would still claim incapacity by reason of invalidism when it suited him. For instance, he declined an invitation to go to Oxford for an honorary doctorate. Who needed that? Oxford was full of religious zealots such as John Henry Newman, and besides, Darwin himself was a Cambridge man. He declined to serve as a pallbearer for Charles Lyell, one of his oldest and most supportive friends, when Lyell was buried with great ceremony in Westminster Abbey. Darwin didn't even go up to London for the funeral. He had skipped other funerals and deathbed courtesies over the decades, putting his own needs for privacy and tranquility ahead of his human loyalties, but missing Lyell's interment in 1875 was a clear signal of his increasing disengagement from any community larger than family and village. When his brother Erasmus died several years later, after a lifetime of bachelor schmoozing in London, Darwin had the body brought to Downe for burial in the local churchyard. He probably assumed (but wrongly) that he would eventually lie there himself, elbow to elbow with Emma when she too passed, and not far from his lonely older brother.

Darwin was a selfish and ruthless man in some ways, but selfish and ruthless mainly in service to his work. He was also sweet-spirited and dutiful, with a strong sense of personal morality grounded only in his materialistic notions of how human social behavior had evolved. Occasionally he performed acts of quiet generosity, helping some worthy fellow get a job or a government pension, or sending a sizable check for a good cause. Near the end of his life, he still functioned as treasurer of the Downe Friendly Society, the cooperative savings-and-insurance club that he had helped found for the working people of the village. He also sat on the local school board for some years, and served as a magistrate, adjudicating small cases.

Of the letters that reached him from everywhere, some were weird or peremptory. Dear Mr. Darwin, what are your religious views? Dear Mr. Darwin, I'm trapped in a lunatic asylum, please get me out. Dear Mr. Darwin, I have two alligators in a mill pond here in Yorkshire; what would you like to know about them? He answered many of those letters, and usually with good grace. More than ever, he connected with the world only by publishing books and through the mail.

He enjoyed the small pleasures, distanced and non-disruptive, of being elected to national academies in Hungary, Russia, and the Netherlands, and of receiving (in absentia) a royal order,
Pour le Mérite
, from the king of Prussia. Karl Marx sent him a complimentary copy of
Das Kapital
, with salutations from a “sincere admirer.” By some combination of neglect and prudence on the part of successive prime ministers, in consultation with Queen Victoria, Darwin was never offered a knighthood, despite his international renown. (After his death, when it was too late, the government made gestures of rectification: Two of his sons were knighted for lesser achievements.) Pestered by his family, he allowed his portrait to be painted in oils, several times, and he posed for photographs looking patriarchal. People wanted a visual image of Britain's foremost living scientist—whether they had read his books, whether they understood and accepted his ideas, or not. He was a cultural icon by then, a celebrity, mildly notorious as celebrities should be. The most memorable of the photos were several shots taken by an unidentified man from the Elliott & Fry photographic company, who came down from London and captured Darwin, on the veranda, dressed for a bad-weather stroll around the Sandwalk. This was about a year before he died.

You can see his tired, chilly detachment in those photos today. He wears a black cape, pinched tightly around, and a black felt hat, like a bowler with a generous brim. His hands are invisible. His beard is white and shaggy, merging through unruly sideburns with his hair, which is scruffy down the back. His eyes are knowing and glum.

He grew weary, in particular, of his efforts to advance and defend evolutionary thinking, with all its subsidiary theories and ramifications. Natural selection was just part of that, albeit a central part. Under attack by Fleeming Jenkin, William Thomson, and others, Darwin had trimmed his claims about natural selection in successive revisions of
The Origin
, giving more emphasis to Lamarckian use-and-disuse, and to the direct action of external conditions. He never abandoned his brave, scary idea, but he hedged it dispiritedly; in 1880, he wrote to the editor of
Nature
, responding to one more critique with the indignant rejoinder that he had never claimed evolution depends
only
on natural selection. It was true, he never had, not even in his first edition of
The Origin
. But insisting on that point was a sad and unnecessary comedown. He didn't know that Mendel's insights, and radioactivity, and other discoveries would later vindicate his earliest, strongest assertions about natural selection.

Other portions of his later work, from the twenty years of continued productivity after
The Origin
first appeared, addressed hard questions that were still being contested now as Darwin himself faded away. There was his (incorrect) theory of inheritance, as articulated in
The Variation of Animals and Plants under Domestication
. He imagined a process, which he labeled “pangenesis,” whereby millions of tiny particles zoom through the body and carry heritable traits, quantitatively, into descendants. There was his (valuable) concept of sexual selection, as propounded in
The Descent of Man
. There were his ideas about the sources of variation, the importance of cross-fertilization as opposed to self-fertilization in hermaphroditic plants, the evolution of moral instincts in humans, and much more.

Although he still cared about those subjects, he found himself unable or unwilling to argue them every time some energized crank dropped a gauntlet. To a man who wrote to him with probing assertions about human behavior, Darwin pleaded that in recent years he'd been working only on plant physiology, and that all other subjects had slipped from his head. It fatigued him, he admitted, to try to bring them back. He thanked another man for his “interesting letter” about hairiness on the ears of infant humans and monkeys, then confessed: “I am so old that I am not likely ever again to write on general and difficult points in the theory of Evolution.” It was a polite way of saying:
Leave me the hell alone
. And he was always polite.

The work on plants was quieter, more soothing, less intricately conceptual, and less inflammatory. Some of it carried evolutionary implications—regarding, for instance, the ways by which plants reproduce, acquire variations, and adapt. But writing about heterostyled dimorphic primroses (never mind what those are) didn't seem nearly so provocative as writing about the
os coccyx
, that rudimentary hint of a human tail, as he had done in
The Descent of Man
. By now he'd had a bellyful of being provocative, which brought stress and provocation in return. With help from his son Francis, who had finished Cambridge and gravitated back to Downe village, he continued his ingenuous style of botanical experimentation, keeping sundews and Venus's-flytraps in pots, feeding them insects and raw meat, tormenting them with salts of ammonia to test the sensitivity of their leaves. This led to his book
Insectivorous Plants
, published in 1875. Francis and another son, George, helped with the illustrations. Despite the wonderful luridness of the subject, flesh-eating vegetation, Darwin's treatment was sober and technical, and
Insectivorous Plants
didn't sell so well as his evolutionary volumes. He wasn't deterred. He liked messing around in the greenhouse and the garden. In his study, the potted creatures were good company.

Also in 1875, he brought out
The Movements and Habits of Climbing Plants
, a commercial (but not very) edition of a long paper he'd published ten years earlier through the Linnean Society. John Murray was still glad to be his publisher for general interest books, even when the topics seemed narrow and the sales potential limited, as they increasingly did. A year later came
The Effects of Cross and Self Fertilisation in the Vegetable Kingdom
, which Darwin considered a sort of companion piece to his earlier book on the fertilization of orchids. Within the next several years he produced a new edition of
Orchids
and two other plant books, both containing small insights and discoveries in which he took special pride; but those books were little noticed during his lifetime, and have seldom been reprinted since. “It has always pleased me to exalt plants in the scale of organised beings,” he wrote. He didn't care much anymore whether his books astonished the world and earned bagfuls of money. He was immune to ambition now and enamored, as ever, with the beautiful significance of tiny details and the big truth of interconnectedness.

42

The family home, Down House, was a quieter place in early 1876 than it had been for years. On February 12, Darwin turned sixty-seven. He and Emma weren't quite empty-nesters but, as events would unfold, they were as close to that circumstance as they'd ever get. William, the oldest son, was a banker down in Southampton, wise with his money, going bald like his father, and unmarried. Annie was dead and buried at Malvern. Little Charles and the infant daughter from the early 1840s, Mary Eleanor, were planted in the churchyard at Downe. Henrietta, the oldest surviving daughter, had married a slightly peculiar man named Litchfield and settled in London. After five years, the Litchfields were childless. George and Francis (usually called Frank) and by now even Horace, the youngest surviving son, had finished Cambridge and were variously groping, as their father had groped, toward serious interests and careers; only Frank, with a medical degree but no desire to practice, had returned to live near his parents. Leonard, who considered himself the dolt of the family, went to Woolwich Military Academy instead of Cambridge, then off on travels as a military engineer. That left just Bessy, the youngest daughter, unmarried at twenty-nine and destined to remain that way. Never educated outside the house, Bessy was “not good at practical things,” according to one loving relative, and couldn't have managed her own life without help. Even Henrietta bullied her. She was so overlooked and inconsiderable, poor woman, that she scarcely gets mentioned in even the most thorough Darwin biographies. The record doesn't seem to tell Bessy's whereabouts in early 1876, but there's nowhere she could have been except at home.

The place didn't clatter with youth and energy, as it once had. There were no grandchildren to renew the cheerful chaos. Darwin worked on his plants and played backgammon with Emma in the evenings. The backgammon was an old tradition. Over the years he had won (as he bragged, self-mockingly) 2,795 games to her piddling 2,490. Frank, after hours, walked back down the lane to the little house where he lived with his wife, Amy. Even the faithful old butler, Parslow, was gone. He'd retired on a modest Darwin-paid pension.

Darwin himself, the elderly invalid, depended more than ever on Emma, the caregiver, doting spouse, and emotional pillar of the family. He might tease her about backgammon, but his devotion to this woman, which had started so tepidly back in 1838, had grown warm and fervent with passing time. She didn't share his intellectual interests; she didn't share his disdain for religion or his materialistic view of the world; she still worshiped a Christian God and worried for the soul of her husband; and he, for his part, loved her to the moon. He couldn't pretend to endorse her beliefs, or to accept his own deepest sorrows (such as the loss of Annie) and illnesses in a spirit of pious surrender, as Emma wanted him to do. But he venerated her goodness and was sensitive to her feelings. For forty years, he had saved—somewhere amid his portfolios and papers—that earnest letter she had written to him around the time of their marriage, after hearing his confession of wild and heretical ideas. “Don't think that it is not my affair,” she'd insisted, “and that it does not much signify to me.” It did signify, she wrote, arguing firmly but lovingly against his apostasy. Everything that concerned him concerned her also, and she would be “most unhappy if I thought we did not belong to each other for ever.” Over all the years since, she had been left to nurture her hope of eternal togetherness, in an afterlife, without receiving any affirmation of that hope from him. Darwin could only sympathize, or avoid the subject; it wasn't in him to lie. But sometime along the way he had scribbled a note at the bottom of her letter. It was found there, among his other papers, after the end:

They were an old married couple, cousins and lovers and friends, hearing the echo of their own steps in a large cold house, as they moved inexorably toward death and separation.

And then, in the spring, came a bit of good news: Amy, Frank's wife, was pregnant. This provided some incentive for Darwin's next literary project. Faced with the prospect of a grandchild at last, he began to draft his private autobiography, hoping it “might possibly interest my children or their children.” He wrote the first pages in late May 1876, during a visit at the country home of Emma's brother, and he continued back at Downe, spending an hour or so on the manuscript most afternoons through the summer. He searched his memory for signal facts and episodes, without consulting (for a change) any notebooks, portfolios of data, or diaries. My mother died when I was eight years old, Darwin wrote, and “it is odd that I can remember hardly anything about her” except her deathbed and one black velvet gown. But he recalled the time when, as a small boy, he stole apples from an orchard; he recalled his early collections of shells, birds' eggs, and minerals; he recalled, with indelible guilt after sixty years, having once been cruel to a puppy; and he recalled his undistinguished performance in boarding school, bad at Greek, bad at Latin, conscientious but never much engaged. He remembered his passion for bird-hunting, especially the moment of trembling excitement after he'd killed his first snipe. And he couldn't forget that caustic remark by his father, probably made when Charles was a teenager: “You care for nothing but shooting, dogs, and rat-catching, and you will be a disgrace to yourself and all your family.” He remembered Robert Grant's guiding influence in Edinburgh, and then the rowdy gang of boozing cardplayers he fell in with at Cambridge. He remembered some loftier diversions during the Cambridge years, too—learning botany from Henslow, hearing the choir at King's College Chapel. “But no pursuit at Cambridge was followed with nearly so much eagerness or gave me so much pleasure,” Darwin wrote, “as collecting beetles.”