Bully for Brontosaurus

by Stephen Jay Gould

  The tradition of simile begins at the very beginning. Richard Owen, the great British anatomist and paleontologist, described the genus Hyracotherium in 1841. He did not recognize its relationship with horses (he considered this animal, as his chosen name implies, to be a possible relative of hyraxes, a small group of Afro-Asian mammals, the “coneys” of the Bible). In this original article, Owen likened his fossil to a hare in one passage and to something between a hog and a hyrax in another. Owen’s simile plays no role in later history because other traditions of comparison had been long established before scientists realized that Owen’s older discovery represented the same animal that Marsh later named Eohippus. (Hence, under the rules of taxonomy, Owen’s inappropriate and uneuphonious name takes unfortunate precedence over Marsh’s lovely Eohippus—see Essay 5 on the rules of naming.)

  The modern story begins with Marsh’s description of the earliest horses in 1874. Marsh pressed “go” on the simile machine by writing, “This species was about as large as a fox.” He also described the larger descendant Miohippus as sheeplike in size.

  The rise to dominance of fox terriers as similes for the size of the earliest horses. Top graph: Increasing domination of dogs over foxes through time. Lower graph: Increase in percentage of fox terrier references among sources citing dogs as their simile. IROMIE WEERAMANTRY. COURTESY OF NATURAL HISTORY.

  Throughout the nineteenth century all sources that we have found (eight references, including such major figures as Joseph Le Conte, Archibald Geikie, and even Marsh’s bitter enemy E. D. Cope) copy Marsh’s favored simile—they all describe Eohippus as fox-sized. We are confident that Marsh’s original description is the source because most references also repeat his statement that Miohippus is the size of a sheep. How, then, did fox terriers replace their prey?

  The first decade of our century ushered in a mighty Darwinian competition among three alternatives and led to the final triumph of fox terriers. By 1910, three similes were battling for survival. Marsh’s original fox suffered greatly from competition, but managed to retain a share of the market at about 25 percent (five of twenty citations between 1900 and 1925 in our sample)—a frequency that has been maintained ever since (see accompanying figure). Competition came from two stiff sources, however—both from the American Museum of Natural History in New York.

  First, in 1903, W. D. Matthew, vertebrate paleontologist at the Museum, published his famous pamphlet The Evolution of the Horse (it remained in print for fifty years, and was still being sold at the Museum shop when I was a child). Matthew wrote: “The earliest known ancestors of the horse were small animals not larger than the domestic cat.” Several secondary sources picked up Matthew’s simile during this quarter century (also five of twenty references between 1900 and 1925), but felines have since faded (only one of fifteen references since 1975), and I do not know why.

  Second, the three-way carnivorous competition of vulpine, feline, and canine began in earnest when man’s best friend made his belated appearance in 1904 under the sponsorship of Matthew’s boss, American Museum president and eminent vertebrate paleontologist Henry Fairfield Osborn. Remember that no nineteenth-century source (known to us) had advocated a canine simile, so Osborn’s late entry suffered a temporal handicap. But Osborn was as commanding (and enigmatic) a figure as American natural history has ever produced (see Essay 29)—a powerful patrician in science and politics, imperious but kind, prolific and pompous, crusader for natural history and for other causes of opposite merit (Osborn wrote, for example, a glowing preface to the most influential tract of American scientific racism, The Passing of the Great Race, by his friend Madison Grant).

  In the Century Magazine for November 1904, Osborn published a popular article, “The Evolution of the Horse in America.” (Given Osborn’s almost obsessively prolific spate of publications, we would not be surprised if we have missed an earlier citation.) His first statement about Eohippus introduces the comparison that would later win the competition:

  We may imagine the earliest herds of horses in the Lower Eocene (Eohippus, or “dawn horse” stage) as resembling a lot of small fox-terriers in size…. As in the terrier, the wrist (knee) was near the ground, the hand was still short, terminating in four hoofs, with a part of the fifth toe (thumb) dangling at the side.

  Osborn provides no rationale for his choice of breeds. Perhaps he simply carried Marsh’s old fox comparison unconsciously in his head and chose the dog most similar in name to the former standard. Perhaps Roger Angell’s conjecture is correct. Osborn certainly came from a social set that knew about fox hunting. Moreover, as the quotation indicates, Osborn extended the similarity of Eohippus and fox terrier beyond mere size to other horselike attributes of this canine breed (although, in other sources, Osborn treated the whippet as even more horselike, and even mounted a whippet’s skeleton for an explicit comparison with Eohippus). Roger Angell described his fox terrier to me: “The back is long and straight, the tail is held jauntily upward like a trotter’s, the nose is elongated and equine, and the forelegs are strikingly thin and straight. In motion, the dog comes down on these forelegs in a rapid and distinctive, stiff, flashy style, and the dog appears to walk on his tiptoes—on hooves, that is.”

  In any case, we can trace the steady rise to domination of dog similes in general, and fox terriers in particular, ever since. Dogs reached nearly 50 percent of citations (nine of twenty) between 1900 and 1925, but have now risen to 60 percent (nine of fifteen) since 1975. Meanwhile, the percentage of fox terrier citations among dog similes had also climbed steadily, from one-third (three of nine) between 1900 and 1925 to one-half (eight of sixteen) between 1925 and 1975, to two-thirds (six of nine) since 1975. Osborn’s simile has been victorious.

  Copying is the only credible source for these shifts of popularity—first from experts; then from other secondary sources. Shifts in fashion cannot be recording independent insights based on observation of specimens. Eohippus could not, by itself, say “fox” to every nineteenth-century observer and “dog” to most twentieth-century writers. Nor can I believe that two-thirds of all doginclined modern writers would independently say, “Aha, fox terrier” when contemplating the dawn horse. The breed is no longer so popular, and I suspect that most writers, like me, have only the vaguest impression about fox terriers when they copy the venerable simile.

  In fact, we can trace the rise to dominance of fox terriers in our references. The first post-Osborn citation that we can find (Ernest Ingersoll, The Life of Animals, MacMillan, 1906) credits Osborn explicitly as author of the comparison with fox terriers. Thereafter, no one cites the original, and I assume that the process of text copying text had begun.

  Two processes combined to secure the domination of fox terriers. First, experts began to line up behind Osborn’s choice. The great vertebrate paleontologist W. B. Scott, for example, stood in loyal opposition in 1913, 1919, and 1929 when he cited both alternatives of fox and cat. But by 1937, he had switched: “Hyracotherium was a little animal about the size of a fox-terrier, but horse-like in all parts.” Second, dogs became firmly ensconced in major textbooks. Both leading American geology textbooks of the early twentieth century (Chamberlin and Salisbury, 1909 edition, and Pirsson and Schuchert, 1924 edition) opt for canines, as does Hegner’s zoology text (1912) and W. Maxwell Read’s fine children’s book (a mainstay of my youth) The Earth for Sam (1930 edition).

  Fox terriers have only firmed up their position ever since. Experts cite this simile, as in A. S. Romer’s leading text, Vertebrate Paleontology (3d edition, 1966): “‘Eohippus’ was a small form, some specimens no larger than a fox terrier.” They have also entered the two leading high-school texts: (1) Otto and Towle (descendant of Moon, Mann, and Otto, the dominant text for most of the past fifty years): “This horse is called Eohippus. It had four toes and was about the size of a fox-terrier” (1977 edition); (2) the Biological Sciences Curriculum Study, Blue Edition (1968): “The fossil of a small four-toed animal about the size of a fox-
terrier was found preserved in layers of rock.” College texts also comply. W. T. Keeton, in his Biological Science, the Hertz of the profession, writes (1980 edition): “It was a small animal, only about the size of a fox-terrier.” Baker and Allen’s The Study of Biology, a strong Avis, agrees (1982 edition): “This small animal Eohippus was not much bigger than a fox-terrier.”

  You may care little for dawn horses or fox terriers and might feel that I have made much of nothing in this essay. But I cite the case of the creeping fox terrier clone not for itself, but rather as a particularly clear example of a pervasive and serious disease—the debasement of our textbooks, the basic tool of written education, by endless, thoughtless copying.

  My younger son started high school last month. For a biology text, he is using the 4th edition of Biology: Living Systems, by R. F. Oram, with consultants P. J. Hummer and R. C. Smoot (Charles E. Merrill, 1983, but listed on the title page, following our modern reality of conglomeration, as a Bell and Howell Company). I was sad and angered to find several disgraceful passages of capitulation to creationist pressure. Page one of the chapter on evolution proclaims in a blue sidebar: “The theory of evolution is the most widely accepted scientific explanation of the origin of life and changes in living things. You may wish to investigate other theories.” Similar invitations are not issued for any other well-established theory. Students are not told that “most folks accept gravitation, but you might want to check out levitation” or that “most people view the earth as a sphere, but you might want to consider the possibility of a plane.” When the text reaches human history, it doesn’t even grant majority status to our evolutionary consensus: “Humans are indeed unique, but because they are also organisms, many scientists believe that humans have an evolutionary history.”

  Yet, as I argued at the outset, I find these compromises to outside pressure, disgraceful though they be, less serious than the internal disease of cloning from text to text. There is virtually only one chapter on evolution in all high-school biology texts, copied and degraded, then copied and degraded again. My son’s book is no exception. This chapter begins with a discussion of Lamarck and the inheritance of acquired characters. It then moves to Darwin and natural selection and follows this basic contrast with a picture of a giraffe and a disquisition of Lamarckian and Darwinian explanations for long necks. A bit later, we reach industrial melanism in moths and dawn horses of you-know-what size.

  What is the point of all this? I could understand this development if Lamarckism were a folk notion that must be dispelled before introducing Darwin, or if Lamarck were a household name. But I will lay 100 to 1 that few high-school students have ever heard of Lamarck. Why begin teaching evolution by explicating a false theory that is causing no confusion? False notions are often wonderful tools in pedagogy, but not when they are unknown, are provoking no trouble, and make the grasp of an accepted theory more difficult. I would not teach more sophisticated college students this way; I simply can’t believe that this sequence works in high school. I can only conclude that someone once wrote the material this way for a reason lost in the mists of time, and that authors of textbooks have been dutifully copying “Lamarck…Darwin…giraffe necks” ever since.

  (The giraffe necks, by the way, make even less sense. This venerable example rests upon no data at all for the superiority of Darwinian explanation. Lamarck offered no evidence for his interpretation and only introduced the case in a few lines of speculation. We have no proof that the long neck evolved by natural selection for eating leaves at the tops of acacia trees. We only prefer this explanation because it matches current orthodoxy. Giraffes do munch the topmost leaves, and this habit obviously helps them to thrive, but who knows how or why their necks elongated? They may have lengthened for other reasons and then been fortuitously suited for acacia leaves.)

  If textbook cloning represented the discovery of a true educational optimum, and its further honing and propagation, then I would not object. But all evidence—from my little story of fox terriers to the larger issue of a senseless but nearly universal sequence of Lamarck, Darwin, and giraffe necks—indicates that cloning bears an opposite and discouraging message. It is the easy way out, a substitute for thinking and striving to improve. Somehow I must believe—for it is essential to my notion of scholarship—that good teaching requires fresh thought and genuine excitement, and that rote copying can only indicate boredom and slipshod practice. A carelessly cloned work will not excite students, however pretty the pictures. As an antidote, we need only the most basic virtue of integrity—not only the usual, figurative meaning of honorable practice but the less familiar, literal definition of wholeness. We will not have great texts if authors cannot shape content but must serve a commercial master as one cog in an ultimately powerless consortium with other packagers.

  To end with a simpler point amid all this tendentiousness and generality: Thoughtlessly cloned “eternal verities” are often false. The latest estimate I have seen for the body size of Hyracotherium (MacFadden, 1986), challenging previous reconstructions congenial with the standard simile of much smaller fox-terriers, cites a weight of some twenty-five kilograms, or fifty-five pounds.

  Lassie come home!

  11 | Life’s Little Joke

  I STILL DON’T UNDERSTAND why a raven is like a writing desk, but I do know what binds Hernando Cortés and Thomas Henry Huxley together.

  On February 18, 1519, Cortés set sail for Mexico with about 600 men and, perhaps more important, 16 horses. Two years later, the Aztec capital of Tenochtitlán lay in ruins, and one of the world’s great civilizations had perished.

  Cortés’s victory has always seemed puzzling, even to historians of an earlier age who did not doubt the intrinsic superiority of Spanish blood and Christian convictions. William H. Prescott, master of this tradition, continually emphasizes Cortés’s diplomatic skill in making alliances to divide and conquer—and his good fortune in despoiling Mexico during a period of marked internal dissension among the Aztecs and their vassals. (Prescott published his History of the Conquest of Mexico in 1843; it remains among the most exciting and literate books ever written.)

  Prescott also recognized Cortés’s two “obvious advantages on the score of weapons”—one inanimate and one animate. A gun is formidable enough against an obsidian blade, but consider the additional impact of surprise when your opponent has never seen a firearm. Cortés’s cavalry, a mere handful of horses and their riders, caused even more terror and despair, for the Aztecs, as Prescott wrote,

  had no large domesticated animals, and were unacquainted with any beast of burden. Their imaginations were bewildered when they beheld the strange apparition of the horse and his rider moving in unison and obedient to one impulse, as if possessed of a common nature; and as they saw the terrible animal, with “his neck clothed in thunder,” bearing down their squadrons and trampling them in the dust, no wonder they should have regarded him with the mysterious terror felt for a supernatural being.

  On the same date, February 18, in 1870, Thomas Henry Huxley gave his annual address as president of the Geological Society of London and staked his celebrated claim that Darwin’s ideal evidence for evolution had finally been uncovered in the fossil record of horses—a sequence of continuous transformation, properly arrayed in temporal order:

  It is easy to accumulate probabilities—hard to make out some particular case, in such a way that it will stand rigorous criticism. After much search, however, I think that such a case is to be made out in favor of the pedigree of horses.

  Huxley delineated the famous trends to fewer toes and higher-crowned teeth that we all recognize in this enduring classic among evolutionary case histories. Huxley viewed this lineage as a European affair, proceeding from fully three-toed Anchitherium, to Hipparion with side toes “reduced to mere dew-claws [that] do not touch the ground,” to modern Equus, where, “finally, the crowns of the grinding-teeth become longer…. The phalanges of the two outer toes in each foot disappear, their meta
carpal and metatarsal bones being left as the ‘splints.’”

  In Cat’s Cradle, Kurt Vonnegut speaks of the subtle ties that can bind people across worlds and centuries into aggregations forged by commonalities so strange that they must be meaningful. Cortés and Huxley must belong to the same karass (Vonnegut’s excellent word for these associations)—for they both, on the same date, unfairly debased America with the noblest of animals. Huxley was wrong and Cortés, by consequence, was ever so lucky.

  Horses evolved in America, through a continuity that extends unbroken across 60 million years. Several times during this history, different branches migrated to Europe, where Huxley arranged three (and later four) separate incursions as a false continuity. But horses then died in America at the dawn of human history in our hemisphere, leaving the last European migration as a source of recolonization by conquest. Huxley’s error became Montezuma’s sorrow, as an animal more American than Babe Ruth or apple pie came home to destroy her greatest civilization. (Montezuma’s revenge would come later, and by another route.)

  During our centennial year of 1876, Huxley visited America to deliver the principal address for the founding of Johns Hopkins University. He stopped first at Yale to consult the eminent paleontologist Othniel C. Marsh. Marsh, ever gracious, offered Huxley an architectural tour of the campus, but Huxley had come for a purpose and would not be delayed. He pointed to the buildings and said to Marsh: “Show me what you have got inside them; I can see plenty of bricks and mortar in my own country.” Huxley was neither philistine nor troglodyte; he was simply eager to study some particular fossils: Marsh’s collection of horses.