by Bill Bryson
Although there was no reliable way of dating periods, there was no shortage of people willing to try. The most well known early attempt was made in 1650, when Archbishop James Ussher of the Church of Ireland made a careful study of the Bible and other historical sources and concluded, in a hefty tome called Annals of the Old Testament, that the Earth had been created at midday on 23 October 4004 BC, an assertion that has amused historians and textbook writers ever since.2
There is a persistent myth, incidentally—and one propounded in many serious books—that Ussher’s views dominated scientific beliefs well into the nineteenth century, and that it was Lyell who put everyone straight. Stephen Jay Gould in Time’s Arrow cites as a typical example this sentence from a popular book of the 1980s: “Until Lyell published his book, most thinking people accepted the idea that the earth was young.” In fact, no. As Martin J. S. Rudwick puts it, “No geologist of any nationality whose work was taken seriously by other geologists advocated a timescale confined within the limits of a literalistic exegesis of Genesis.” Even the Reverend Buckland, as pious a soul as the nineteenth century produced, noted that nowhere did the Bible suggest that God made Heaven and Earth on the first day, but merely “in the beginning.” That beginning, he reasoned, may have lasted “millions upon millions of years.” Everyone agreed that the Earth was ancient. The question was simply: how ancient?
One of the better early ideas at dating the planet came from the ever-reliable Edmond Halley, who in 1715 suggested that if you divided the total amount of salt in the world’s seas by the amount added each year, you would get the number of years that the oceans had been in existence, which would give you a rough idea of Earth’s age. The logic was appealing, but unfortunately no-one knew how much salt was in the sea or by how much it increased each year, which rendered the experiment impracticable.
Eighteenth-century watercolour of the French naturalist Georges-Louis Leclerc, Comte de Buffon, who, in the late 1700s, became the first person to attempt to measure the age of the Earth. (credit 5.10)
The first attempt at measurement that could be called remotely scientific was made by the Frenchman Georges-Louis Leclerc, Comte de Buffon, in the 1770s. It had long been known that the Earth radiated appreciable amounts of heat—that was apparent to anyone who went down a coal mine—but there wasn’t any way of estimating the rate of dissipation. Buffon’s experiment consisted of heating spheres until they glowed white-hot and then estimating the rate of heat loss by touching them (presumably very lightly at first) as they cooled. From this he guessed the Earth’s age to be somewhere between 75,000 and 168,000 years old. This was of course a wild underestimate; but it was a radical notion nonetheless, and Buffon found himself threatened with excommunication for expressing it. A practical man, he apologized at once for his thoughtless heresy, then cheerfully repeated the assertions throughout his subsequent writings.
Scottish mathematician and physicist Lord Kelvin, who throughout his career produced revolutionary scientific theories and was arguably the first scientist to become wealthy by patenting his work. Despite his undoubted brilliance, he was chronically, and indeed dismally, unable to determine the age of the Earth. (credit 5.11)
By the middle of the nineteenth century most learned people thought the Earth was at least a few million years old, perhaps even some tens of millions years old, but probably not more than that. So it came as a surprise when in 1859, in On the Origin of Species, Charles Darwin announced that the geological processes that created the Weald, an area of southern England stretching across Kent, Surrey and Sussex, had taken, by his calculations, 306, 662, 400 years to complete. The assertion was remarkable partly for being so arrestingly specific but even more for flying in the face of accepted wisdom about the age of the Earth.3 It proved so contentious that Darwin withdrew it from the third edition of the book. The problem at its heart remained, however. Darwin and his geological friends needed the Earth to be old, but no-one could come up with a way to make it so.
Unfortunately for Darwin, and for progress, the question came to the attention of the great Lord Kelvin (who, though indubitably great, was then still just plain William Thomson; he wouldn’t be elevated to the peerage until 1892, when he was sixty-eight years old and nearing the end of his career, but I shall follow the convention here of using the name retroactively). Kelvin was one of the most extraordinary figures of the nineteenth century—indeed, of any century. The German scientist Hermann von Helmholtz, no intellectual slouch himself, wrote that Kelvin had by far the greatest “intelligence and lucidity, and mobility of thought” of any man he had ever met. “I felt quite wooden beside him sometimes,” he added, a bit dejectedly.
The sentiment is understandable, for Kelvin really was a kind of Victorian superman. He was born in 1824 in Belfast, the son of a professor of mathematics at the Royal Academical Institution who soon afterwards transferred to Glasgow. There Kelvin proved himself such a prodigy that he was admitted to Glasgow University at the exceedingly tender age of ten. By the time he had reached his early twenties, he had studied at institutions in London and Paris, graduated from Cambridge (where he won the university’s top prizes for rowing and mathematics, and somehow found time to launch a musical society as well), been elected a fellow of Peterhouse, and written (in French and English) a dozen papers in pure and applied mathematics of such dazzling originality that he had to publish them anonymously for fear of embarrassing his superiors. At the age of twenty-two he returned to Glasgow to take up a professorship in natural philosophy, a position he would hold for the next fifty-three years.
In the course of a long career (he lived to 1907 and the age of eighty-three), he wrote 661 papers, accumulated sixty-nine patents (from which he grew abundantly wealthy) and gained renown in nearly every branch of the physical sciences. Among much else, he suggested the method that led directly to the invention of refrigeration, devised the scale of absolute temperature that still bears his name, invented the boosting devices that allowed telegrams to be sent across oceans, and made innumerable improvements to shipping and navigation, from the invention of a popular marine compass to the creation of the first depth sounder. And those were merely his practical achievements.
The common refrigerator, one of the most essential items of modern living, owes its creation to a practical suggestion made by the great Lord Kelvin in the nineteenth century—a fact acknowledged by the inventor of the first household mechanical refrigerator, Nathaniel B. Wales. By 1923, the Kelvinator Company held 80 per cent of the market share in electric refrigerators. (credit 5.12)
His theoretical work, in electromagnetism, thermodynamics and the wave theory of light, was equally revolutionary.4 He had really only one flaw and that was an inability to calculate the correct age of the Earth. The question occupied much of the second half of his career, but he never came anywhere near getting it right. His first effort, in 1862 for an article in a popular magazine called Macmillan’s, suggested that the Earth was 98 million years old, but cautiously allowed that the figure could be as low as 20 million years or as high as 400 million. With remarkable prudence he acknowledged that his calculations could be wrong if “sources now unknown to us are prepared in the great storehouse of creation”—but it was clear that he thought that unlikely.
With the passage of time Kelvin would become more forthright in his assertions and less correct. He continually revised his estimates downwards, from a maximum of 400 million years to 100 million years, then to 50 million years and finally, in 1897, to a mere 24 million years. Kelvin wasn’t being wilful. It was simply that there was nothing in physics that could explain how a body the size of the Sun could burn continuously for more than a few tens of millions of years at most without exhausting its fuel. Therefore it followed that the Sun and its planets were relatively, but inescapably, youthful.
The problem was that nearly all the fossil evidence contradicted this, and suddenly in the nineteenth century there was a lot of fossil evidence.
1 The
re will be no testing here, but if you are ever required to memorize them you might wish to remember John Wilford’s helpful advice to think of the eras (Precambrian, Palaeozoic, Mesozoic and Cenozoic) as seasons in a year and the periods (Permian, Triassic, Jurassic, etc.) as the months.
2 Although virtually all books find a space for him, there is a striking variability in the details associated with Ussher. Some books say he made his pronouncement in 1650, others in 1654, still others in 1664. Many cite the date of the Earth’s reputed beginning as 26 October. At least one book of note spells his name “Usher.” The matter is interestingly surveyed in Stephen Jay Gould’s Eight Little Piggies.
3 Darwin loved an exact number. In a later work, he announced that the number of worms to be found in an average acre of English country soil was 53,767.
4 In particular, he elaborated the Second Law of Thermodynamics. A discussion of these laws would be a book in itself, but I offer here this crisp summation by the chemist P. W. Atkins, just to provide a sense of them: “There are four Laws. The third of them, the Second Law, was recognized first; the first, the Zeroth Law, was formulated last; the First Law was second; the Third Law might not even be a law in the same sense as the others.” In briefest terms, the second law states that a little energy is always wasted. You can’t have a perpetual motion device because no matter how efficient, it will always lose energy and eventually run down. The first law says that you can’t create energy and the third that you can’t reduce temperatures to absolute zero; there will always be some residual warmth. As Dennis Overbye notes, the three principal laws are sometimes expressed jocularly as (1) you can’t win, (2) you can’t break even, and (3) you can’t get out of the game.
Journals from the expedition of Meriwether Lewis and William Clark, who were sent by President Thomas Jefferson into the western wilderness of North America in 1803 partly in the hope that they would find herds of mastodons and other lost, ancient creatures grazing on the boundless prairies. Lewis and Clark found no mastodons, but they did find dinosaur bones—though without realizing what they were. (credit 6.1)
SCIENCE RED IN TOOTH AND CLAW
In 1787, someone in New Jersey—exactly who now seems to be forgotten—found an enormous thigh bone sticking out of a stream bank at a place called Woodbury Creek. The bone clearly didn’t belong to any species of creature still alive, certainly not in New Jersey. From what little is known now, it is thought to have belonged to a hadrosaur, a large duckbilled dinosaur. At the time, dinosaurs were unknown.
The bone was sent to Dr Caspar Wistar, the nation’s leading anatomist, who described it at a meeting of the American Philosophical Society in Philadelphia that autumn. Unfortunately, Wistar failed completely to recognize the bone’s significance and merely made a few cautious and uninspired remarks to the effect that it was indeed a whopper. He thus missed the chance, half a century ahead of anyone else, to be the discoverer of dinosaurs. Indeed, the bone excited so little interest that it was put in a storeroom and eventually disappeared altogether. So the first dinosaur bone ever found was also the first to be lost.
That the bone didn’t attract greater interest is more than a little puzzling for its appearance came at a time when America was in a froth of excitement about the remains of large, ancient animals. The cause of this froth was a strange assertion by the great French naturalist the Comte de Buffon—he of the heated spheres from the previous chapter—that living things in the New World were inferior in nearly every way to those of the Old World. America, Buffon wrote in his vast and much-esteemed Histoire naturelle, was a land where the water was stagnant, the soil unproductive, and the animals without size or vigour, their constitutions weakened by the “noxious vapours” that rose from its rotting swamps and sunless forests. In such an environment even the native Indians lacked virility. “They have no beard or body hair,” Buffon sagely confided, “and no ardour for the female.” Their reproductive organs were “small and feeble.”
Buffon’s observations found surprisingly eager support among other writers, especially those whose conclusions were not complicated by actual familiarity with the country. A Dutchman named Corneille de Pauw announced in a popular work called Recherches philosophiques sur les américains that native American males were not only reproductively unimposing, but “so lacking in virility that they had milk in their breasts.” Such views enjoyed an improbable durability and could be found repeated or echoed in European texts until near the end of the nineteenth century.
Not surprisingly, such aspersions were indignantly met in America. Thomas Jefferson incorporated a furious (and, unless the context is understood, quite bewildering) rebuttal in his Notes on the State of Virginia, and induced his New Hampshire friend General John Sullivan to send twenty soldiers into the northern woods to find a bull moose to present to Buffon as proof of the stature and majesty of American quadrupeds. It took the men two weeks to track down a suitable subject. The moose, when shot, unfortunately lacked the imposing horns that Jefferson had specified, but Sullivan thoughtfully included a rack of antlers from an elk or stag with the suggestion that these be attached instead. Who in France, after all, would know?
Meanwhile, in Philadelphia—Wistar’s city—naturalists had begun to assemble the bones of a giant elephant-like creature known at first as “the great American incognitum” but later identified, not quite correctly, as a mammoth. The first of these bones had been discovered at a place called Big Bone Lick in Kentucky, but soon others were turning up all over. America, it appeared, had once been the home of a truly substantial creature—one that would surely disprove Buffon’s foolish Gallic contentions.
Illustration of an animal dissection from Buffon’s Histoire naturelle, in which he published his controversial theory that animals and humans of the New World were anatomically inferior to those of the Old. (credit 6.2)
In their keenness to demonstrate the incognitum’s bulk and ferocity, the American naturalists appear to have become slightly carried away. They overestimated its size by a factor of six and gave it frightening claws, which in fact came from a Megalonyx, or giant ground sloth, found nearby. Rather remarkably, they persuaded themselves that the animal had enjoyed “the agility and ferocity of the tiger,” and portrayed it in illustrations as pouncing with feline grace onto prey from boulders. When tusks were discovered, they were forced into the animal’s head in any number of inventive ways. One restorer screwed the tusks in upside down, like the fangs of a sabre-toothed cat, which gave it a satisfyingly aggressive aspect. Another arranged the tusks so that they curved backwards on the engaging theory that the creature had been aquatic and had used them to anchor itself to trees while dozing. The most pertinent consideration about the incognitum, however, was that it appeared to be extinct—a fact that Buffon cheerfully seized upon as proof of its incontestably degenerate nature.
Buffon died in 1788, but the controversy rolled on. In 1795 a selection of bones made their way to Paris, where they were examined by the rising star of palaeontology, the youthful and aristocratic Georges Cuvier. Cuvier was already dazzling people with his genius for taking heaps of disarticulated bones and whipping them into shapely forms. It was said that he could describe the look and nature of an animal from a single tooth or scrap of jaw, and often name the species and genus into the bargain. Realizing that no-one in America had thought to write a formal description of the lumbering beast, Cuvier did so, and thus became its official discoverer. He called it a mastodon (which means, a touch unexpectedly, “nipple-teeth”).
This skeleton of the first elephant-sized creature to be discovered in America took a long time to assemble, as naturalists initially over-estimated its size, ferocity and agility in their determination to disprove the damning theories of Buffon. (credit 6.3)
Inspired by the controversy, in 1796 Cuvier wrote a landmark paper, Note on the Species of Living and Fossil Elephants, in which he put forward for the first time a formal theory of extinctions. His belief was that from time to time the
Earth experienced global catastrophes in which groups of creatures were wiped out. For religious people, including Cuvier himself, the idea raised uncomfortable implications since it suggested an unaccountable casualness on the part of Providence. To what end would God create species only to wipe them out later? The notion was contrary to the belief in the Great Chain of Being, which held that the world was carefully ordered and that every living thing within it had a place and purpose, and always had and always would. Jefferson for one couldn’t abide the thought that whole species would ever be permitted to vanish (or, come to that, to evolve). So when it was put to him that there might be scientific and political value in sending a party to explore the interior of America beyond the Mississippi he leaped at the idea, hoping the intrepid adventurers would find herds of healthy mastodons and other outsized creatures grazing on the bounteous plains. Jefferson’s personal secretary and trusted friend Meriwether Lewis was chosen co-leader, with William Clark, and chief naturalist for the expedition. The person selected to advise him on what to look out for with regard to animals living and deceased was none other than Caspar Wistar.
In the same year—in fact, the same month—that the aristocratic and celebrated Cuvier was propounding his extinction theories in Paris, on the other side of the English Channel a rather more obscure Englishman was having an insight into the value of fossils that would also have lasting ramifications. William Smith was a young supervisor of construction on the Somerset Coal Canal. On the evening of 5 January 1796, he was sitting in a coaching inn in Somerset when he jotted down the notion that would eventually make his reputation. To interpret rocks, there needs to be some means of correlation, a basis on which you can tell that those carboniferous rocks from Devon are younger than these Cambrian rocks from Wales. Smith’s insight was to realize that the answer lay with fossils. At every change in rock strata certain species of fossils disappeared while others carried on into subsequent levels. By noting which species appeared in which strata, you could work out the relative ages of rocks wherever they appeared. Drawing on his knowledge as a surveyor, Smith began at once to make a map of Britain’s rock strata, which would be published after many trials in 1815 and would become a cornerstone of modern geology. (The story is comprehensively covered in Simon Winchester’s popular book The Map that Changed the World.)
