Leonardo’s Mountain of Clams and the Diet of Worms by Stephen Jay Gould
I have focused this essay upon one of the great unconscious biases—our persisting preference for viewing history as a tale of linear progress—that so often stymie our interpretations of evolution and the history of life on Earth. But we should also recognize this other, rather more “homey” or obvious bias—our tendency to view a comfortable and well-known current situation as a generality rather than a potential exception. Such an attitude also has a highfalutin name in the history of science—uniformitarianism, or using the present as a key to the past.
As many scholars have pointed out (including yours truly in his very first published paper of 1965), uniformitarianism is a complex term with multiple meanings, some legitimate, but some potentially false and surely constraining. If we only mean that we will regard nature’s laws as invariant in space and time, then we are simply articulating a general assumption and rule of reasoning in science. But if we falsely extend such a claim to current phenomena (rather than universal laws)—and argue, for example, that continents must always be separated because oceans now divide our major landmasses, or that mass extinction by meteoritic bombardment cannot occur because we have never witnessed such an event during the short span of recorded human history—then we surely go too far. The present range of observed causes and phenomena need not exhaust the realm of past possibilities.
In this case, we shall be massively and seriously fooled if we extrapolate a current reality to a general situation in the history of human evolution. Most of hominid history has featured a bush, sometimes quite substantial, of coexisting species. The current status of humanity as a single species, maximally spread over an entire planet, is distinctly odd.
But if modern times are out of joint, why not make the most of it? I last visited Africa more than ten years ago, and that voyage (to lecture in Nairobi and do some fieldwork with Richard Leakey at Lake Turkana) led to some musings that culminated in an essay titled “Human Equality Is a Contingent Fact of History.” I argued that the happenstance of a surprisingly recent common ancestry for all modern humans had made our so-called races effectively equal in biological capacities (while individuals within all groups differ widely, of course).
I couldn’t help revisiting this theme as I surveyed many sites of human hope, disappointment, and struggle in Kenya, Malawi, and Zimbabwe. (I went to Africa in my role as a trustee of the Rockefeller Foundation, and we visited many of their social, medical, and agricultural projects—including a clinic for treating sexually transmitted diseases among prostitutes in one of the worst slums in Nairobi, and a series of schemes to improve corn yields in desperately poor agricultural villages of Malawi.)
In the most memorable event of this trip, we spent an entire morning talking with the women farmers of a small Malawian village. This ample time gave us leisure to explore in depth, and to listen and observe with great care. My mind wandered over many subjects, but I kept returning to a single theme. I could not imagine a greater difference between earthly communities—a senior American Ivy League professor, and an illiterate Malawian farmer, twenty-five years old, with five children (the oldest already eleven), and an annual family income of about eighty dollars. Yet her laughter, her facial expressions, her gestures, her hopes, her fears, her dreams, her passions, are no different from mine. One can understand the argument for human unity in a purely intellectual and scientific sense, but until this knowledge can be fleshed out with visceral experience, one cannot truly know in the deeper sense of compassion.
If our current times are peculiar in substituting the bushy richness of most human history with an unusual biological unity to undergird our fascinating cultural diversity, why not take advantage of this gift? We didn’t even have such an option during most of our tenure on Earth, but now we do. Why, then, have we more often failed than succeeded in the major salutary opportunity offered by our biological unity? We could do it; we really could. Why not try sistership; why not brotherhood?
IV
OF HISTORY AND TOLERATION
11
A CERION FOR CHRISTOPHER
IF CHINA HAD PROMOTED, RATHER THAN INTENTIONALLY SUPPRESSED, THE technology of oceanic transport and navigation, the cardinal theme for the second half of our millennium might well have been eastward, rather than westward, expansion into the New World. We can only speculate about the enormously different consequences of such an alternative but unrealized history. Would Asian mariners have followed a path of conquest in the Western sense? Would their closer ethnic tie to Native Americans (who had migrated from Asia) have made any difference in treatment and relationship? At the very least, I suppose, any modern author of a book printed on the American East Coast would be writing this chapter either in a Native American tongue or in some derivative of Mandarin.
But China did not move east, so Christopher Columbus sailed west, greedy to find the gold of Cathay and the courts of the grand Khan as described by his countryman Marco Polo, who had traveled by different means and from the other direction. And Columbus encountered an entire world in between, blocking his way.
I can think of no other historical episode more portentous, or more replete with both glory and horror, than the Western conquest of America. Since we can neither undo an event of such magnitude nor hope for any simple explanation as an ineluctable consequence of nature’s laws, we can only chronicle the events as they occurred, search for patterns, and seek understanding. When dense narrative of this sort becomes a primary method of analysis, detail assumes unusual importance. The symbolic beginning must therefore elicit special attention and fascination. Let us therefore take up an old and unresolved issue: Where did Columbus unite the hemispheres on October 12, 1492?
Surrounded by hints of nearby land, yet faced with a crew on the verge of rebellion, Columbus knew that he must soon succeed or turn back. Then, at 2:00 A.M. on the morning of October 12, the Pinta’s lookout, Rodrigo de Triana, saw a white cliff in the moonlight and shouted the transforming words of human history: “Tierra! Tierra!”—land, land. But what land did Columbus first see and explore?
Why should such a question pose any great difficulty? Why not just examine Columbus’s log, trace his route, look for artifacts, or consult the records of people first encountered? For a set of reasons, both particular and general, none of these evident paths yields an unambiguous answer. We know that Columbus landed somewhere in the Bahama Islands, or in the neighboring Turks and Caicos. We also know that the local Taino people called this first landfall Guanahani—and that Columbus, kneeling in thanks and staking his claim for the monarchs of Spain, renamed the island San Salvador, or Holy Savior. But the Bahamas include more than seven hundred islands, and several offer suitable harbors for Columbus’s vessels. Where did he first land?
Navigation, in Columbus’s time, was far too imprecise an art to provide much help (and Columbus had vastly underestimated the earth’s diameter, thereby permitting himself to believe that he had sailed all the way to Asia). Mariners of the fifteenth century could not determine longitude, and therefore could not locate themselves at sea with pinpoint accuracy. Columbus used the two primary methods then available. Latitude could be determined (though only with difficulty on a moving ship) by sighting the altitude of Polaris (the North Star), or of the sun at midday. A ship could therefore sail to a determined latitude and then proceed either due east or west, as desired. (Columbus, in fact, was a poor celestial navigator, and made little use of latitudes. In one famous incident, he misidentified his position by nearly twenty degrees because he mistook another star for Polaris.)
In the other time-tested method, called dead reckoning, one simply takes a compass bearing, keeps track of time, judges the ship’s speed, and then plots the distance and direction covered. Needless to say, dead reckoning cannot be very precise—especially when winds and currents complicate any determination of speed, and when (as on Columbus’s ships) sailors measure time by turning a sandglass every half hour! Columbus, by all accounts, was an unusually skilled and spectacularly
We are further hindered by a paucity of documents. Columbus’s original log, presented to Queen Isabella, has been lost. A copy, given to Columbus before his second voyage, has also disappeared. Bartolomé de Las Casas, the Dominican priest who spoke so eloquently for the lost cause of kindness, made a copy of Columbus’s second version—and our modern knowledge derives from this document. Thus, we are using a copy of a copy as our “primary” text, and uncertainties therefore prevail on all crucial points.
The best possible source of evidence—artifacts and recorded histories kept by an unbroken line of original inhabitants—does not exist for another reason that motivated this essay. In the first case of New World genocide perpetrated by the Old, Spanish conquerors completely wiped out the native Bahamians within twenty years of contact, despite (or rather, one must sadly say, enabled by) the warm and trusting hospitality shown to Columbus by the peaceful Tainos.
With so little data to constrain speculation, virtually all major Bahamian islands have been proposed as San Salvador, the site of Columbus’s first landfall. (The Turks and Caicos Islands, just to the southeast of the Bahamas, form a politically separate entity. They are, however, geographically and ecologically continuous with the Bahamas, and therefore figure in this discussion as well.) The major contenders include Watling Island, Cat Island, Mayaguana, Samana Cay, Grand Turk, and several of the Caicos. Cat Island held an early advantage, and once even bore the name San Salvador in acknowledgment. But, in 1926, the Bahamian government, persuaded by a growing consensus, transferred Columbus’s designation to Watling Island—the favored site, and Columbus’s name bearer ever since.
Two traditional sources of evidence favor Watling as San Salvador: correspondence of size and topography with the fairly detailed descriptions of Columbus’s log (as known by the Las Casas copy), and nautical tracing of Columbus’s route for the rest of his first voyage, from San Salvador to other Bahamian islands, and finally to Cuba and Hispaniola. Samuel Eliot Morison’s “semiofficial” case, made in his 1942 classic, Admiral of the Ocean Sea, remains the standard expression of this favored hypothesis.
During the past twenty years, archaeology has provided a third source of evidence from excavations made by Charles A. Hoffman and others at Long Bay, within sight of the favored location for Columbus’s landfall. (A good account of this work, and of virtually all else connected with the discussion of Columbus’s initial landing, may be found in the Proceedings of the 1986 San Salvador Conference on Columbus and His World, edited by Donald T. Gerace and published by the Bahamian Field Station on San Salvador.) Along with native pottery and other Taino artifacts, several European objects were found, all consistent with Spanish manufacture at the right time, and all eminently plausible as items for trade—glass beads, metal buckles, hooks, and nails. One discovery exceeded all others in importance: a single Spanish coin of low value, known as a blanca—the standard “small change” of the times, and surely the most common coin in circulation among Columbus’s men. Moreover, this particular blanca was only issued between 1471 and 1474, and no comparable, copper-based coin was minted again until 1497.
Of course, these finds do not positively identify San Salvador as the first landfall for two reasons: Columbus visited several other Bahamian islands on this voyage, and the local Tainos moved freely among adjacent islands. In fact, three days after his first landing, and again on open waters, Columbus encountered a Taino in a canoe, carrying some beads and blancas received in trade on San Salvador.
Nonetheless, and all other things considered, the archaeological evidence supports the usual view that San Salvador has now been correctly identified. Still, everything cited so far relies upon European impressions or artifacts. Wouldn’t we welcome some hard data from the other side for corroboration? How about one distinctive item of local history, either natural or cultural?
I do not mean to exaggerate the current uncertainty in this debate. Most experts seem satisfied that Columbus first landed on the island now called San Salvador by the Bahamian government. Nonetheless, several dogged and knowledgeable opponents still advocate their alternatives with gusto, and the issue remains vigorously open. I recently spent a week on San Salvador, where I sifted through all the evidence and visited all the sites. I found no reason for dissatisfaction with the conventional view. Nonetheless, if only because we prefer near certainty to high probability, I write this essay to announce that I could truly resolve any remaining doubt about Columbus’s first landfall if only the good admiral had added one little activity to the usual drill of kissing the ground, praising God, raising the flag, claiming sovereignty, and trading with the locals. If Christopher Columbus had only picked up (and properly labeled, of course) a single shell of my favorite animal, the land snail Cerion—and they are so common that he was probably kneeling on one anyway!—I would know for sure where he had landed.
No one can be objective about his own children, but Cerion truly ranks as a natural marvel, and an exemplar of evolution for a particular reason well illustrated by its potential utility for identifying San Salvador. In shell form, Cerion may be the most protean land snail in the world—and evolutionists thrive on variation, the result and raw material of biological change. Cerion ranges in size from dwarfs of 5 millimeters to giants more than 70 millimeters in length (for folks wedded to good old ways, 25.4 millimeters make an inch)—and in shape from pencil-thin cylinders to golf balls.
Naturalists have named more than six hundred species from Cerion’s two major geographic centers in Cuba and the Bahama Islands. Most of these names are technically invalid because members of the respective populations can interbreed, but the designations do record a striking biological reality—that so many local populations of Cerion have evolved unique and clearly recognizable shell forms. In particular, nearly every Bahamian island can be identified by a distinctive kind of Cerion. Thus, bring me a single shell, and I can usually tell you where you spent your last vacation.
Marine species, by contrast, generally maintain much larger and more-continuous populations. Broader patterns of variation preclude any pinpoint definition of island coastlines (at Bahamian scale) by distinctive shapes or sizes of clams, snails, corals, or other oceanic forms. Terrestrial species, therefore, offer our only real hope for distinguishing islands by unique biological inhabitants. Individual Bahamian islands might house an endemic insect, or perhaps a plant, but Cerion surely provides the best biological marker for specifying particular locales. Insects and plants are less distinctive and harder to preserve; but if Columbus had just slipped a nearly indestructible Cerion shell into his vest pocket, his trusty scabbard, or his old kit bag, then we would know. Moreover, Cerion must have been the first terrestrial zoological object to enter Columbus’s field of vision in the New World (unless a lizard darted across his path, or a mosquito drew first Caucasian blood)—though I cannot guarantee that the Admiral of the Ocean Sea had eyes to see at this scale. For Cerion lives right at the coastline in large populations. As they say, you can’t miss ’em. And all putative landing sites on San Salvador sport large and obvious populations of my favorite snail.
While I was on San Salvador attending a biennial conference on Caribbean geology at the Bahamian Field Station, I played extensive hooky to do a survey of the local Cerion. San Salvador houses two major species of Cerion—a large, robust, whitish shell, pointed at the top, and found on promontories on the windward east coast; and a smaller, ribbier, brownish shell, barrel-shaped at the top, and found all along the leeward west coast (and most of the island interior). A single shell of either form can easily be distinguished from the characteristic Cerion of all other favored sites for Columbus’s initial landfall.
Cerion piratarum, Mayaguana’s species, belongs to the same basic group as the east-coast Cerion of San Salvador, but is bigger, whiter, entirely different in shape, and quite distinct from the San Salvadorian form. S
Erection of monuments at putative landing sites has been something of a cottage industry on San Salvador for more than a century. Three major markers now adorn the island, each located amid a large population of Cerion (and all shown in the preceding photographs). The Chicago Herald built the first monument in 1891, in preparation for the four-hundredth-anniversary celebrations of Columbus’s landing and the great Chicago Columbian exposition, held a year late, in 1893. This monument, constructed largely of exotic stones and featuring a limestone globe set within the base of an obelisk, is now eroding away on the largely inaccessible promontory of Crab Cay (a two-mile walk from the nearest path, along a beautiful beach, but then up a narrow and treacherous slope). The monument sits amid one of the densest Cerion populations on San Salvador. I don’t think that anyone would now advocate this reefy, windward site as a conceivable landing place (though the cliff might have reflected moonlight for Rodrigo’s first sight of land)—yet the monument reads: “On this spot Christopher Columbus first set foot upon the soil of the New World. Erected by The Chicago Herald. June, 1891.”