Bully for Brontosaurus (52 page)

Moreover, all the Uranian moons are surprisingly active (except for Umbriel, odd man out in more ways than one, as the only non-Shakespearean entry) in a gradient of increasing turmoil from the outermost king of
Midsummer Night
to the innermost daughter of the
Tempest
. “As you move closer to Uranus,” Soderblom added, “we see an increasing ferocity, as though these bodies have been tectonically shuffled in a cataclysmic fashion.”

I must save the details for another time, but for starters, the surface of Miranda is a jumble of frozen geological activity—long valleys, series of parallel grooves, and blocks of sunken crust. Most prominent, and also most notable for their lack of any clear counterpart on other worlds, are three structures that seem related in their formation. One has been dubbed a stack of pancakes, the second a chevron, and the third a racetrack. They are series of parallel grooves, or cracks, shaped to different forms according to their nicknames and full of evidence for massive slumping, rifting, and cliff making.

In short, Io failed the size hypothesis by its position too close to Jupiter. Venus may not conform by a particular history that left it moon free and cloud covered. Miranda has failed, we know not why, by showing signs of a frantic past when the hypothesis predicted a passive compendium of impacts. The physical principle invoked by the size hypothesis—the law of surfaces and volumes—is surely correct, but not potent enough to overwhelm other influences and lead to confident predictions by itself. As we learn more and more about the historical complexity of the heavens, we recognize that where you are (Io) and what you have been (Venus and Miranda) exert as much influence over a planet’s surface as its size. After an initial success for our moon, Mercury, and Mars, the size hypothesis flunked all further tests.

The story of a theory’s failure often strikes readers as sad and unsatisfying. Since science thrives on self-correction, we who practice this most challenging of human arts do not share such a feeling. We may be unhappy if a favored hypothesis loses or chagrined if theories that we proposed prove inadequate. But refutation almost always contains positive lessons that overwhelm disappointment, even when (as in this case) no new and comprehensive theory has yet filled the void. I chose this tale of failure for a particular reason, not only because Miranda excited me. I chose to confess my former errors because the replacement of a simple physical hypothesis with a recognition of history’s greater complexity teaches an important lesson with great unifying power.

An unfortunate, but regrettably common, stereotype about science divides the profession into two domains of different status. We have, on the one hand, the “hard,” or physical, sciences that deal in numerical precision, prediction, and experimentation. On the other hand, “soft” sciences that treat the complex objects of history in all their richness must trade these virtues for “mere” description without firm numbers in a confusing world where, at best, we can hope to explain what we cannot predict. The history of life embodies all the messiness of this second, and undervalued, style of science.

Voyager
photograph of Miranda, showing fractured and reaggregated terrain.
PHOTO COURTESY NASA
/J
PL
.

Throughout ten years of essays firmly rooted in this second style, I have tried to suggest by example that the sciences of history may be different from, but surely not worse than, the sciences of simpler physical objects. I have written about a hundred historical problems and their probable solutions, hoping to illustrate a methodology as powerful as any possessed by colleagues in other fields. I have tried to break down the barriers between these two styles of science by fostering mutual respect.

The story of planetary surfaces illustrates another path to the same goal of lowering barriers. The two styles are not divisible by discipline into the hard sciences of physical systems and the soft sciences of biological objects. All good scientists must use and appreciate both styles since large and adequate theories usually need to forage for insights in both physics and history. If we accepted the rigid dichotomy of hard and soft, we might argue that as physical bodies, planets should yield to predictive theories of the hard sciences. The size hypothesis represented this mode of explanation (and I was beguiled by it before I understood history better)—a simple law of physics to regulate a large class of complex objects. But we have learned, in its failure, that planets are more like organisms than billiard balls. They are intricate and singular bodies. Their individuality matters, and size alone will not explain planetary surfaces. We must know their particularities, their early histories, their present locations. Planets are physical bodies that require historical explanations. They break the false barrier between two styles of science by forcing the presumed methods of one upon the supposed objects of the other.

Finally, we should not lament that simple explanations have failed and that the “messy” uniqueness of each planet must be featured in any resolution. We might despair if the individuality of planets dashed all hope for general explanation. But the message of Io, Venus, and Miranda is not gridlock, but transcendence. We think that we understand Io, and we strive to fathom the moons of Uranus. Historical explanations are difficult, damned interesting, and eminently attainable by human cleverness. Whoever said that nature would be easy?

Prospero, after saving his foes from the tempest, asserts that he cannot relate the history of his life too simply, for “’tis a chronicle of day by day, not a relation for a breakfast.” The tale is long and intricate, but fascinating and resolvable. We can also know the richness of history in science. Proper explanation may require a tapestry of detail. Our stories may recall the subtle skills of Scheherazade rather than the crisp epitome of a segment in
Sixty Minutes
, but then who has ever been bored by Sinbad the Sailor or Aladdin’s magic lamp?

THE ARGUMENTS
of “iffy” history may range from the merely amusing to the horribly tragic. If Mickey Owen hadn’t dropped that third strike, the Dodgers might have won the 1941 World Series. If Adolf Hitler had been killed in the Beer Hall Putsch, the alliances that led to World War II might not have formed, and we might not have lost our war fleet at Pearl Harbor just two months after Owen’s miscue.

I don’t think that we would be so fascinated by conjectures in this mode if we felt that anything could happen in history. Rather, we accept certain trends, certain predictabilities, even some near inevitabilities, particularly in war and technology, where numbers truly count. (I can’t imagine any scenario leading to the victory of Grenada over the United States in our recent one-day conflict; nor can I conjecture how the citizens of Pompeii, without benefit of motorized transport, could have escaped a cloud of poisonous gases streaming down Mount Vesuvius at some forty miles per hour.) I suspect, in fact, that our fascination with iffy history arises largely from our awe at the ability of individuals to perturb, even greatly to alter, a process that seems to be moving in a definite direction for reasons above and beyond the power of mere mortals to deflect.

In opening
The Eighteenth Brumaire of Louis Bonaparte
, Karl Marx captured this essential property of history as a dynamic balance between the inexorability of forces and the power of individuals. He wrote, in one of the great one-liners of scholarship in the activist mode: “Men make their own history, but they do not make it just as they please.” (Marx’s title is, itself, a commentary on the unique and the repetitive in history. The original Napoleon staged his
coup d’état
against the Directory on November 9–10, 1799, then called the eighteenth day of Brumaire, Year VIII, by the revolutionary calendar adopted in 1793 and used until Napoleon crowned himself emperor and returned to the old forms. But Marx’s book traces the rise of Louis-Napoleon, nephew of the emperor, from the presidency of France following the revolution of 1848, through his own
coup d’état
of December 1851, to his crowning as Napoleon III. Marx seeks lessons from repetition, but continually stresses the individuality of each cycle, portraying the second in this case as a mockery of the first. His book begins with another great epigram, this time a two-liner, on the theme of repetition and individuality: “Hegel remarks somewhere that all facts and personages of great importance in world history occur, as it were, twice. He forgot to add the first time as tragedy, the second as farce.”)

This essential tension between the influence of individuals and the power of predictable forces has been well appreciated by historians, but remains foreign to the thoughts and procedures of most scientists. We often define science (far too narrowly, I shall argue) as the study of nature’s laws and their consequences. Individual objects have no power to shape general patterns in such a system. Walter the Water Molecule cannot freeze a pond, while Sarah the Silica Tetrahedron does not perturb the symmetry of quartz. Indeed, the very notion of Walter and Sarah only invites ridicule because laws of chemical behavior and crystal symmetry deny individuality to constituent units of larger structures. What else do we mean when we assert that hydrogen and oxygen make water or that silica tetrahedra sharing all their corner oxygen ions form quartz? (We could scarcely speak of a law if Ollie Oxygen willingly joined with Omar but refused to share with Oscar because they had a fight last Friday.) No actual quartz crystal has a perfect lattice of conjoined retrahedra; all include additions and disruptions known as impurities or imperfections—but the very names given to these ingredients of individuality demonstrate that scientific content supposedly lies in the regularities, while uniquenesses of particular crystals fall into the domain of hobbyists and aestheticians.

(I don’t mean to paint the world of science as a heartless place of perfect predictability under immutable laws. We permit a great deal of play and doubt under the guise of randomness. But randomness is equally hostile to the idea of individuality. In fact, classically random systems represent the ultimate denial of individuality. Coin-flipping and dice-throwing models rest upon the premise that each toss or each roll manifests the same probabilities: no special circumstances of time or place, no greater chance of a head if the last five tosses have been tails, or if you blow on the coin and say your mantra, or if Aunt Mary will die as a consequence of your failure to score—in other words, no individuality of particular trials. Individuality and randomness are opposing, not complementary, concepts. They both oppose the idea of clockwork determinism, but they do so in entirely different ways.)

Natural history does not share this consensus that individual units with particular legacies cannot shape the behavior and future state of entire systems. Our profession, although part of mainstream science since Aristotle, grants to individuals the potential for such a formative role. In this sense, we are truly historians by practice and we demonstrate the futility of disciplinary barriers between science and the humanities. We should be exploring our marked overlaps in explanatory procedures, not sniping at each other behind walls of definitional purity.

Natural history stands in the crossfire and should provoke a truce by reaching in both directions. Individual organisms can certainly set the local history of populations and may even shape the fate of species. Walter the Walrus and Sarah the Squirrel are friendly and congenial, rather than risible, concepts (and may be actual creatures at the municipal zoo). Two recent cases of extraordinary (although not particularly likable) individuals have led me to consider this theme and to grant more attention to the vagaries of one in my profession.

1. Jane Goodall’s quarter century with the chimpanzees of Gombe will rank forever as one of the great achievements in scientific dedication combined with stunning results. With such unprecedented, long-term knowledge of daily history, Goodall can specify (and quantify) the major determinants of her population’s fate. Contrary to our intuitions and expectations, the demography of the Gombe chimps has not been set primarily by daily rhythms of birth, feeding, sex, and death, but by three “rare events” (Goodall’s words), all involving mayhem or misfortune: a polio epidemic, a carnage of one sub-band by another, and the following tale of one peculiar individual.

With odd and unintended appropriateness as we shall see, for the word means “suffering,” Goodall named one of the Gombe females Passion. Goodall met Passion in 1961 at the outset of her studies. In 1965, Passion gave birth to a daughter, Pom, and, as Goodall remarks (all quotes from
The Chimpanzees of Gombe
, Harvard University Press, 1986), “thereby gave us the opportunity to observe some extraordinarily inefficient and indifferent maternal behavior.”

Nonetheless, Pom and Passion formed a “close, cooperative bond” as the daughter matured. In 1975, Passion began to kill and eat newborn babies of other females in her band. She could not easily wrest a baby from its mother and failed when acting solo, but Passion and Pom together formed an efficient killing duo. (Goodall observed three other “cannibalistic events” during nearly thirty years of work, all directed by males toward older chimps of other bands; Passion’s depredations are the only recorded incidents of cannibalism within a band.) During a four-year period, Passion and Pom, in sight of observers, killed and ate three infants by seizing them from their mothers and biting through the skull bones (sorry, but nature isn’t always pretty, and I hate euphemisms). They may have been responsible for the deaths of seven other infants. During this entire period, only one female successfully raised a baby. In studying Goodall’s curves of Gombe demography, the depredations of Passion have as great an impact as any general force of climate or disease. Moreover, the effects are not confined to the short years of Passion’s odd obsession (for reasons unknown, she stopped killing babies in 1977), but propagate well down the line. Since only one female was raising a baby in 1977, nearly all were in estrus, thus prompting a baby boomlet and sharp rise in population when Passion stopped her cannibalism.

Such observational work on the behavior of animals in their natural habitat requires a personal pledge to maximal noninterference. Passion taxed this principle to its absolute limit. Goodall told me that when Passion died “of an unknown wasting disease” in 1982, she (Jane, not Passion) watched with renewed faith in noninterference and some legitimate sense of moral retribution.

2.
Notornis
, the New Zealand ornithological journal, does not show up in the scientific equivalent of the corner drug store; I was therefore delighted when Jared Diamond alerted me (via
Nature
, which does appear at our watering holes) to a fascinating article by Michael Taborsky entitled “Kiwis and Dog Predation: Observations in Waitangi State Forest” (see the bibliography). The Waitangi Forest houses the largest “known and counted” population of the brown kiwi
Apteryx australis
—some 800 to 1,000 birds. In June and July of 1987, Taborsky and colleagues tagged twenty-four birds with radio transmitters “so that their spacing and reproductive activities could be studied” (all quotations come from Taborsky’s paper cited above).

On August 24, they found a dead female, evidently killed by a dog. Thus began a tale worthy of
The Hound of the Baskervilles
. By September 27, thirteen of the tagged birds had been killed. All showed extensive bruising, and most had defeathered areas; ten of the thirteen birds “were found partly covered or completely buried under leaf litter and soil.” Scientists and forestry workers found ten more carcasses without transmitters, all killed and buried in the same way, and all dispatched during the same period.

It didn’t take the sleuthing genius of Mr. Holmes to recognize that a single dog had wreaked this reign of terror. Distinctive footprints of the same form appeared by the carcasses, along with “dog droppings of one type and size.” On September 30, a female German shepherd, wearing a collar but unregistered, was shot in the forest. Her “long claws suggested that she had not been on hard surfaces for some time, i.e., was probably living in the forest.” The killings abruptly stopped. Taborsky tagged several more birds with transmitters, bringing the total to eighteen; all these birds survived to the end of the study on October 31.

This Rin Tin Tin of the Dark Side had killed more than half of the tagged birds in six weeks. As “there is no reason to believe that birds with transmitters were at greater risk than those without,” the total killed may range to 500 of the 800 to 1,000 birds in the population. Lest this seem a staggering and unbelievable estimate, Taborsky provides the following eminently reasonable defenses. First, given the remote chance of finding a buried, untagged kiwi carcass, the ten actually located during the interval of killing must represent the tiny pinnacle of a large iceberg. Second, other evidence supports a dramatic fall in total population: Taborsky and colleagues noted a major drop in calling rates for these ordinarily noisy birds; a dog trained to find, but not to kill, kiwis could not locate a single live individual (although she found two carcasses) in a formerly well-inhabited section of the forest. Third, kiwis, having evolved without natural enemies and possessing no means of escape, could not be easier prey. Taborsky writes:

As to why a dog would kill so many animals “for sport,” or at least not for food, who knows? We do, however, understand enough to brand as romantic twaddle the common litany that “man alone kills for sport, other animals only for food or in defense.” The kiwi marauder of New Zealand may have set a new record for intensity of destruction, but she followed the killing pattern of many animals. In any case, she surely illustrated the power of individuals to alter the history of entire populations. Taborsky estimates that, given the extremely slow breeding of kiwis, “the population will probably need 10–20 years and a rigorous protection scheme to recover to previous densities.”

These two stories may elicit both fascination and a
frisson
, but still strike some readers as unpersuasive regarding the role of individuals in science. To be sure, both Passion and the austral hell hound had a disturbing effect on their populations. But science is general pattern, not ephemeral perturbation. The Gombe chimps recovered in a few years, as a subsequent baby boom offset Passion’s depredations. On the crucial issue of scale, individuals still don’t set patterns in the fullness of time or the largeness of space. Predictability under nature’s laws takes over at an amplitude of scale and a degree of generality meriting the name “science.” I would offer three rebuttals to this argument.

First, scale is a relative concept. Who can set the boundary between perturbations in systems too small to matter and long-term patterns of appropriate generality? Human evolution is a tiny twig among millions on the tree of earthly evolution. But do all the generalities of anthropology therefore count only as details outside the more ample scope of true science? Earthly evolution may be only one story of life among unknown cosmic billions; are all the laws of biology therefore nothing but peculiarities of one insignificant example?

Second, small perturbations are not always reined in by laws of nature to bring systems back to a previous equilibrium. Perturbations, starting as tiny fluctuations wrought by individuals, can accumulate to profound and permanent alterations in much larger worlds. Much of the present fascination for chaos theory in mathematics stems from its attempt to model such agents of pattern, even in large systems operating under deterministic laws. The Gombe chimps may feel no long-term effect of Passion’s cannibalism, but the Waitangi kiwis may never recover.