Eight Little Piggies Read online

  All these essays first appeared as columns in my monthly series, “This View of Life,” in Natural History magazine. I regard this volume as a true natural selection, since many have been dumped and the others improved and then organized into a sensible and coherent sequence, more organic than linear in its webs of cross referencing. The many that I now dislike or regard as substandard are on the scrap heap, so I will stand by all items in the present winnowing and reshaping. But some, inevitably, please me more than others, or at least serve as better exemplars of my chosen style. I think that I am condemned to like best the essays that are most difficult or most focused on particulars of little public knowledge or approbation. I am not hopelessly rarefied or ethereal, and I do feel quite warmly towards some of the most evident (if vital) themes and homely illustrations—as in musings on distortions of memory and myths of past golden ages (Essays 13 and 14). But I do so wish that some of the more complex pieces could receive some share of attention. I especially like Essay 29 because focusing on specimens rather than scientists so well highlights the crucial duality of all scientific activity—tension between the necessary social embeddedness of all scientific thinking and progress towards more adequate factual knowledge of an external reality (by pathways often tortuous and circuitous). If everyone knew the beauty and oddness of actual Cephalaspis fossils, this essay would be a sure winner, but knowledge is a prerequisite for this kind of love. For this reason, we need more “hands-on” science education, and we must resist the terrible current trend to confuse museums with theme parks (wonderful things in their proper domain), and to replace real specimens with large, throbbing, blinking glitz in order, ultimately, to pack more bodies into the gift shop. Also, please study Essay 25, even if you revile pigeons. C. O. Whitman was one of our greatest biologists and the key theme of his pigeon work really does speak to the nature of mind as a product of evolution.

  I adore all the odd animals and anatomical bits that I pack into these essays, but I have always liked my “people pieces” best (my favorite essays in the last three volumes are “The Titular Bishop of Titiopolis,” on Nicolaus Steno in Hen’s Teeth and Horse’s Toes, “Adam’s Navel,” on Gosse’s bizarrely magnificent treatise Omphalos in The Flamingo’s Smile, and “In a Jumbled Drawer,” on the conventional career of N. S. Shaler and the iconoclasm of William James in Bully for Brontosaurus).

  People ask how I keep finding honorable intent in reviled characters by the simple expedient of rediscovering either the full logic of their argument or the social context of their claims. Are all thinkers so worthy of respectful resurrection? Of course not; many are reviled in their own time for good reasons that remain equally cogent today. For the most part, I don’t choose to write about these people (though see my book The Mismeasure of Man for proof that I do not only seek virtue in historical figures). I praise Archbishop Ussher (Essay 12), so falsely labeled as a unique reactionary shoving his finger into the crumbling dike of revealed religion in order to hold back the flood of science, when he actually represented a large research tradition, humanistically motivated and successful in its own terms (though wrong about the age of the earth due to a false premise at the core of the argument). I warm to a paranoid dyspeptic like Eugene DuBois (Essay 8) when he fairly sticks to his guns in a noble (if losing) argument, but when posterity, not even trying to grasp the subtlety, invariably reports that he finally labeled his precious “ape-man” a giant gibbon, although he actually, by this trope of argument (and when you grasp his full system rather than picking at isolated straws), tried to affirm the immediately ancestral status of his Homo erectus.

  But the saints often need intellectual resurrection as well (though I’d rather be misunderstood in clouds of celestial music than bubbles of boiling magma). Halley is so tied to his eponymous comet that his work on the earth’s age is largely ignored and usually interpreted ass-backwards when mentioned at all (Essay 11). Goethe’s oracular reduction of all plant form to a leaf archetype needs to be read for its unconventional form of scientific excellence (Essay 10).

  I also like to find unusual entrées to important subjects generally treated under conventional formats. Thus I approach Darwin’s personal views on race and sex not by analyzing the Descent of Man (though I do not ignore this primary document), but by studying his very first publication, an article with Captain FitzRoy “On the Moral State of Tahiti” (Essay 18). As for the hottest topic of “modularity” in cognitive science, I never found a distinctive way in until I learned that an English dilettante named Daines Barrington had published an article in England’s leading scientific journal on Mozart’s musical abilities as a child of eight. (Barrington wrote when young Wolfgang represented a generic prodigy and had not yet become, so to speak, Mozart. Thus, he could be presented as a type, a general puzzle in why musical ability could be so hypertrophied in an otherwise ordinary boy). All this, in the propitious time of Mozart’s bicentennial year, led me to Darwin on mind, Tinbergen on the evolution of behavior and cognition in general, my own puzzling over Michelangelo’s stunning effect in using modularity to carve his statue of Moses, even, via Monty Python and back to Mr. Barrington, on the literary convention (and odd name) of litotes to mask wonderment—thus giving me a string to tie my beginning to a stylistically gentle end. Not bad.

  I often wonder what I am doing every month. I can’t be just a dilettante or poseur, or the streak wouldn’t be continuing with such undiminished commitment and ardor, such love of each little new thing learned. I guess I see myself in the guise of Papageno, the bird catcher of Mozart’s Magic Flute. He captures (but does not harm) the most beautiful objects of nature. He is capable of naive wonder, counting as originality in breaking through conventional prejudice—as when frightened by the Moor Monastatos, he stops and upbraids himself: How foolish; black birds exist, so why not black men? He wins, at the end, the greatest Darwinian prize of continuity, as he finally gets his Papagena and the promise of many little Papagenos and Papagenas to follow (I think of them as essays). But do not doubt his overwhelming modesty amidst all the showy confidence. I sense how rich and complex it is out there, and what a tiny, tiny part any of us have been able to understand. And I feel much like Papageno as he struggles to sing but can produce no words (though he hums a lovely melody) because his mouth is padlocked.

  Nonetheless, if I could have but one Mozartian wish—although it be as unrealistic as the original claim itself, and although this series will stop, deo volente, in January 2001—I would request the time to write as many monthly essays as the Don had women in Spain. Ma in Ispagna…

  1 | The Scale of Extinction

  1 | Unenchanted Evening

  TAHITI IS THE STEREOTYPE, virtually the synonym, of enchantment in our legends. Nurse Forbush from Little Rock might have been a charmer (especially when played by Mary Martin), but the South Sea locale made a strong contribution to “some enchanted evening.” (And Ezio Pinza, that greatest of operatic Don Giovannis, slumming on Broadway, didn’t hurt the scene either.)

  Some aspects of the legend need correction. Point Venus, for example, still the landing spot for many tourists, is not named for the beauty of Tahiti’s women, but for astronomy and Captain Cook, who set up his instruments at the site to measure the transit of the planet Venus across the disk of the sun in 1769. Charles Darwin himself was beguiled both by the name and the place when he arrived on the Beagle in November 1835:

  …We landed to enjoy all the delights of the first impressions produced by a new country, and that country the charming Tahiti. A crowd of men, women and children, was collected on the memorable point Venus, ready to receive us with laughing, merry faces.

  Darwin, however, broke ranks with male convention in expressing a lack of enthusiasm for Tahiti’s women: “I was much disappointed in the personal appearance of the women; they are far inferior in every respect to the men.” He objected most of all to the current fad in coiffure:

  An unbecoming fashion in one respect is now almost universal: it
is the cutting of hair, or rather shaving it, from the upper part of the head, in a circular form, so as to leave only an outer ring of hair. The missionaries have tried to persuade the people to change this habit: but it is the fashion, and that is sufficient answer at Tahiti as well as at Paris.

  Darwin’s heterodox judgment had not been widely shared. Captain Bligh, who got such a bum rap from Charles Laughton, may not win any medals for grasping human psychology, but he was a great seaman and no more dictatorial than the normal run of British shipmasters. The celebrated mutiny on his Bounty owed as much to Fletcher Christian’s longing for Tahiti and the woman he left behind as to any of Bligh’s shipboard policies.

  Tahiti may be beautiful, but the title for “picture perfect paradise” has usually been awarded—and rightly so in my judgment (for I have just returned from my first visit to French Polynesia)—to the neighboring island of Moorea. Located just twelve miles northwest of Tahiti, Moorea is an extinct volcano, with a soaring crater rim, deeply dissected by later erosion into jagged peaks and draperies. Seen from Tahiti, especially when enshrouded by its usual entourage of seemingly personal clouds, Moorea becomes a most fitting symbol of beauty combined with mystery. One day on Tahiti, Charles Darwin scaled a local peak and received his dose of Moorea’s spell:

  From the point which I attained, there was a good view of the distant island of Eimeo [the old name for Moorea]…. On the lofty and broken pinnacles, white massive clouds were piled up, which formed an island in the blue sky, as Eimeo itself did in the blue ocean.

  This impression of beauty and mystery has certainly persisted. Oscar Hammerstein used Moorea as his model for Bali Ha’i, the off-limits paradise of delight in South Pacific:

  Rali Ha’i will whisper

  On the wind of the sea:

  “Here am I, your special Island

  Come to me, come to me!”

  Bali Ha’i. A photograph of Moorea from Crampton’s monograph on Partula. Carnegie Institution of Washington.

  Who could resist these enticements, especially for a few francs and a forty-minute ferry ride? So my son Ethan and I visited Moorea on our recent trip. We were not disappointed. Unfortunately, the lure of Bali Ha’i has attracted other guests, some not so harmless. This essay is a story of genocide in paradise, a preventable wholesale slaughter, just completed in one human generation. You do not know the tale only because it pitted snail against snail, rather than man against man. But do not breathe a sigh of relief for moral exculpation of our species. Snails killed snails, but humans imported the agent of death—consciously and for decent motives, but with tragic and easily avoidable misperception.

  Oceanic islands are our great natural laboratories of evolution, the source of so many ideas about organic change and of so many classical examples from finches on the Galápagos to flies on Hawaii. The combination of geographic isolation and difficult access, with frequent absence of predators or competitors, provides explosive possibilities for creatures who manage to reach these bounteous havens. (On the Galapagos, for example, finches radiated into a series of ecological roles usually filled by several families of birds on continents. Some species eat seeds of varying sizes; others act like woodpeckers; one species uses cactus needles to pry insects out of crevices. Darwin was bamboozled during his celebrated visit and classified these birds into several groups. He only learned the true story and significance when a professional ornithologist surveyed his collection in London and recognized the anatomical signature of finches beneath all the diversity.)

  Land snails provide some of our finest and most intensely studied examples—and for obvious reasons. Few manage to make the long and fortuitous ocean voyage (by such odd means of transport as natural rafts, mud on birds’ feet, or hurricanes if the distances are not too great). The lucky immigrants often find an open world divided into numerous separate pieces (the islands of a chain), each available for colonization and each the eventual source of an evolutionary radiation. Moreover, with their legendary lack of range and their hermaphroditic nature, small founding populations of snails (right down to the absolute minimum of one) can readily become the source of isolated colonies and, eventually, new species. One rat on an island is a transient memory (unless she is a pregnant female); one snail, any snail, may be the progenitor of a vast and changing population.

  The high islands of the Pacific are the most promising places of all, for they combine maximal isolation with ecological diversity (the full range from seashore to volcanic mountain top). Many of these islands are formed by single and fairly symmetrical volcanoes. The volcano sides are often dissected into a series of radiating valleys from crater rim to sea. Since most land snails prefer moisture, they often live on the valley floors, but not on the intervening ridges. This common geography adds yet another ingredient to the evolutionary caldron—a source of isolation within islands, as each valley becomes its own separate pocket. On the most diverse of oceanic islands, almost every valley may house a separate species of a particularly prolific snail.

  The great radiations of Pacific island land snails are a glory of evolution and a source of joy and knowledge to those of us who have followed Darwin’s footsteps into a profession. (I must confess to some jealousy here, for I have devoted my career to the less diverse land snails of low Atlantic islands—to Poecilozonites on Bermuda, and Cerion on the Bahamas). Darwin’s own Galápagos house a classic example—more than sixty endemic species of the family Bulimulidae. Even more famous (to cognoscenti, for I do not expect a general murmur of recognition here) are two great radiations on more isolated central Pacific islands—the several hundred species of Achatinellidae in the Hawaiian islands and the one hundred or so species of the genus Partula on Tahiti, Moorea, and their far-flung neighbors.

  These high-island Pacific snails occupy an honored place in the history of evolutionary thought as foci for one of our great and extended debates. No animals seemed better suited for resolving a major issue about causes of organic change: What is the role of environment in evolution? In particular, do organisms change their form to fit altered conditions? And, if so, does environment work its influence directly by Lamarckian inheritance of characters acquired during life, or does form map environment through the indirect route of Darwinian adaptation by natural selection of the most fit in a random spectrum of variation?

  Against these two different versions of adaptation—Lamarckian and Darwinian—other evolutionists asserted that form would not match environment in any clear way. The grossly maladapted will die, of course, but if variation arises only rarely and in definite directions, and if most alternatives are well enough suited to local environments, then adaptation will not shape the differences among populations. “Internal causes” (direction of rare mutations), rather than external shaping (by natural selection), will then predominate in the production of evolutionary change.

  What better test of these issues than the high-island Pacific snails? For if every valley housed a different population, think of the natural experiment thus provided. Many valleys would have nearly identical environments, but be colonized by only distantly related snails. If adaptation ruled, and climate shaped evolution in predictable ways, then the different snails of separate but similar valleys should evolve strong likenesses as adaptations to common conditions. But if “internal factors” predominated, then no correlation of form and environment should be found among populations.

  John T. Gulick (1832–1923), son of an American missionary who worked in Hawaii, fired the first important salvos in a series of works published between 1872 and 1905. Although Gulick spent most of his adult life as a missionary in China and Japan, he had, as a young man in his parents’ parish, amassed an enormous collection of Hawaiian achatinellids. Gulick came down strongly for “internal factors” and against control by natural selection or any other form of environmental influence. He could find no correlation between the forms of shells and the local environments of their valleys. Places with apparently identical vegetation,
moisture, and temperature might harbor shells of maximally different form.

  A map of Moorea taken from Crampton’s monograph and indicating the original distribution of the Partula species. Carnegie Institution of Washington.

  Gulick, who so strongly opposed (and primarily for religious reasons) the dominant determinism of the late nineteenth century, triumphantly concluded that the unpredictability of snail shells could be fully generalized to an overall defense of contingency in history, including human free will:

  If my contention [that different forms arise in identical environments] is in accord with the facts, the assumption which we often meet that change in the organism is controlled in all its details by change in the environment, and that, therefore human progress is ruled by an external fate, is certainly contrary to fact. (From Gulick’s famous 1905 treatise, Evolution, Racial and Habitudinal)