Geologists From The United States

"We may summarize the main line of this complexly meandering tale as a list of ironies - invoking the technical definition of irony as a statement where, for humorous or sarcastic effect, the intended meaning of a word becomes directly opposite to the usual sense..."

"Henry Fairfield Osborn, the dominant paleontologist of his era, and long time director of the American Museum of Natural History, gave the "standard version in his popular book of 1918, The Origin and Evolution of Life... "Lamarck attributed the lengthening of the [giraffe's] neck to the inheritance of bodily modifications caused by the neck-stretching habit. Darwin attributed the lengthening of the neck to the constant selection of individuals and races which were born with the longest necks. Darwin was probably right." …The version has held ever since."

"If we choose a weak and foolish speculation as a primary textbook illustration (falsely assuming that the tale possesses a weight of history and a sanction of evidence), then we are in for trouble - as critics properly nail the particular weakness, and then assume that the whole theory must be in danger if supporters choose such a fatuous case as a primary illustration."

"In his anti-Darwinian book... (and eponymously named The Neck of the Giraffe), Francis Hitching tells the story... "The need to survive by reaching ever higher for food is, like so many Darwinian explanations of its kind, little more than a post hoc speculation." Hitching is quite correct, but he rebuts a fairy story that Darwin was far too smart to tell - even though the tale later entered our high school texts as a "classic case" nonetheless."

"Eternal vigilance, as they say, is the price of freedom. Add intellectual integrity to the cost basis."

"Giraffes do use their long necks to browse leaves, at the tops of acacia trees - but such current function, no matter how vital, does not prove that the neck originally evolved for this purpose. The neck may have first lengthened in context of a different use, and then been coopted for better dining when giraffes moved into the open plains. Or the neck may have evolved to perform several functions at once. We cannot learn the reasons for historical origin simply by listing current uses."

"Why, then, have we been bamboozled into accepting the usual tale without questioning? I suspect two primary reasons: we love a sensible and satisfying story, and we are disinclined to challenge apparent authority (like textbooks!). But do remember that most satisfying tales are false."

"Darwinian evolution may be the most truthful and powerful idea ever generated by Western Science, but if we continue to illustrate our conviction with an indefensible, unsupported, entirely speculative, and basically rather silly story, then we are clothing a thing of beauty in rags - and we should be ashamed, "for the apparel oft proclaims the man.""

"Advocates for a single line of progress encounter their greatest stumbling block when they try to find a smooth link between the apparently disparate designs of the invertebrates and vertebrates."

"Arthropods and vertebrates share some broad features of general organization - elongated, bilaterally symmetrical bodies, with sensory organs up front, excretory structures in the back, and some form of segmentation along the major axis. But the geometry of major internal organs could hardly be more different... Arthropods concentrate their nervous system on their ventral (belly) side as two major cords running along the bottom surface of the animal. The mouth also opens on the ventral side, with the esophagus passing between the two nerve cords, and the stomach and remainder of the digestive tube running along the body above the nerve cords. In vertebrates, and with maximal contrast, the central nervous system runs along the dorsal (top) surface as a single tube culminating in a bulbous brain at the front end. The entire digestive system then runs along the body axis below the nerve cord."

"The inversion theory has a long and fascinating history in the discussion of vertebrate origins. The founding version dates to the early nineteenth century and became the centerpiece of a movement often called "transcendental biology," and centered on the attempt to reduce organic diversity to one or a very few archetypal building blocks that could generate all actual anatomies as products of rational laws of transformation. Some of Europe's greatest thinkers participated in this grand, if flawed enterprise. Goethe, Germany's preeminent poet-scientist, tried to explain the varied parts of plants as different manifestations of an archetypal leaf."

"In France, Étienne Geoffroy Saint-Hilaire attempted to portray the skeleton of vertebrates as a set of modifications upon an archetypal vertebra. In the 1820's, Geoffroy extended his ambitious plan to include annelids and arthropods under that same rubric. ...Vertebrates support their soft parts with an internal skeleton, but insects must live within their vertebrae (a reality, not a metaphor, for Geoffroy). This comparison led to... the claim that a vertebrate rib must represent the same organ as an arthropod leg - and that insects must therefore walk on their own ribs!"

"Geoffrey also recognized that the opposite orientations of gut and nervous system posed a problem for his claim that insects and vertebrates represent different versions of the same archetypal animal - and he proposed the first account of the inversion theory to resolve this threat to unification. ...Geoffroy pursued the... aim of establishing a "unity of type" that could generate both arthropods and vertebrates from the same basic blueprint. ...The single grand design includes a gut in the middle and the main nerve cords somewhere on the periphery."

"Later evolutionary theorists of linear progress had to advance the overtly physical and historical claim that an ancestral lineage of arthropods actually turned over to become the first vertebrates (for the classical statement of the inversion theory, see William Patten, The Grand Strategy of Evolution, 1920)."

"Gaskell could not abide this indecorous version of his beloved linear progress theory. He could not bear to imagine that the grand procession from jellyfish to man, orchestrated by an ever-increasing mass of nervous tissue, once paused in its stately and orderly march toward human consciousness in order to execute a fancy little flip, a clever jig of inversion, just at the sublime and definitive moment of entrance into the vertebral home stretch."

"Gaskell... had to keep his stately soldiers upright and uniformly oriented... by crafting the brain and spinal cord from an arthropod digestive tube, while forming a completely new gut below. ...Gaskell thought that his move would rescue the theory of linear progress, with its necessary transition of arthropod into vertebrate, from the absurdities of the old inversion theory."

"How ironic. In order to avoid the "nutty" theory of inversion, Gaskell invented the even odder notion of stomachs turning into brains with new guts forming below. No wonder then, that later biologists cast a plague on both speculative houses and opted instead for the obvious alternative: arthropods and vertebrates do not share the same anatomical plan at all, but rather represent two separate evolutionary developments of similar complexity from a much simpler common ancestor that grew neither a discrete gut nor a central nerve cord."

"Independent derivation meshed beautifully with the triumph, from the 1930's on, of a strict version of Darwinism based on the near ubiquity of adaptive design built by natural selection... Arthropods and vertebrates do share several features of functional design. But those similarities only reflect the power of natural selection to craft optimal structures independently in a world of limited biomechanical solutions to common functional problems - an evolutionary phenomenon called convergence."

"This new consensus seemed so compelling that Ernst Mayr, the dean of modern Darwinians, opened the ashcan of history for a deposit of Geoffrey's ideas about anatomical unity."

"Darwin himself told us in his last book (The Formation of Vegetable Mould Through the Action of Worms) that we should never underestimate the power of worms on the move. ...The inversion of a humble worm, especially when disturbed, may bring down empires. Shakespeare told us that "the smallest worm will turn being trodden on." And Cervantes wrote in his author's preface to Don Quixote that "even a worm when trod upon, will turn again." …Geoffrey, it seems, was correct after all - not in every detail, of course, but at least in basic vision and theoretical meaning. And the triumph of surprise, the inversion of nuttiness to apparent truth, stands as a premier example of the most exciting general development in evolutionary theory during our times."

"We can now determine, easily and relatively cheaply, the detailed chemical architecture of genes; and we can trace the products of these genes (enzymes and proteins) as they influence the course of embryology. In so doing we have made the astounding discovery that all complex animal phyla - arthropods and vertebrates in particular - have retained, despite their half-billion years of evolutionary independence, an extensive set of common genetic blueprints for building bodies."

"Many similarities of basic design among animal phyla, once so confidently attributed to convergence, and viewed as testimony to the power of natural selection to craft exquisite adaptation, demand the opposite interpretation that Mayr labeled as inconceivable: the similar features are homologies, or products of the same genes, inherited from a common ancestor and never altered enough by subsequent evolution to erase their comparable structure and function. The similarities record the constraining power of conserved history, not the architectural skills of natural selection independently pursuing an optimal design in separate lineages. Vertebrates are, in a certain sense, true brothers (or homologs) - not mere analogs - of worms and insects."

"Evolving life must experience a vast range of possibilities, based on environmental histories so unpredictable that no realized route - the pathway to consciousness in the form of Homo sapiens or Little Green Men, for example - can be construed as a highway to heaven, but must be viewed as a tortuous track rutted with uncountable obstacles and festooned with innumerable alternative branches. Any reasonably precise repetition of our earthly route on another planet therefore becomes wildly improbable even in a trillion cases."

"Since the universe must contain millions of appropriate planets, consciousness in some form - but not with the paired eyes and limbs, and the brain built of neurons in the only example we know - may evolve frequently. But if only one origin of life in a million ever leads to consciousness, then Martian bacteria most emphatically do not imply Little Green Men.)"

"We now live, as Earth always has (see my 1996 book Full House), in an Age of Bacteria. These simplest organisms will dominate our planet (if conditions remain hospitable for life at all) until the sun explodes. During our current, and undoubtedly brief, geological moment, they watch with appropriate amusement as we strut and fret our hour upon the stage. For we are, to them, only transient and delectable islands ripe for potential exploitation."

"If we make this readjustment to view Homo sapiens as an ultimate in oddball rarity, and life at bacterial grade as the common expression of a universal phenomenon, then we could finally ask the truly fundamental question raised by the prospect of Martian fossils. If life originates as a general property of the material universe under certain conditions (probably often realized), then how much can the basic structure and constitution of life vary from place to independent place?"

"All life on earth - everything from bacteria to mushrooms to hippos - shares an astonishing range of detailed biochemical similarities, including the structure of heredity in DNA and RNA, and the universal use of ATP as an energy-storing compound. Two possible scenarios, with markedly different implications for the nature of life, might explain these regularities: either all earthly life shares these features because no other chemistry can work, or these similarities only record the common descent of all organisms on earth from a single origin that happened to feature this chemistry as one possibility among many."

"Unfortunately, all life on earth - the only life we know - represents, for all its current variety, the results of a single experiment, for every earthly species evolved from the common ancestry of a single origin. We desperately need a repetition of the experiment (several would be better, but let's not be greedy!) in order to make a judgement. Mars represents our first real hope for a second experiment - the sine qua non - for any proper answer for the question of questions."

"Darwinian natural selection only yields adaptation to changing local environments, and better function in an immediate habitat might just as well be achieved by greater simplicity in form and behavior as by ever-increasing complexity."

"Consider one of the standard "laments" or "stories of wonder" in conventional tales of natural history: the mayfly that lives but a single day (a sadness even recorded in the technical name for this biological group - Ephemoptera). Yes, the adult fly may enjoy only a moment in the sun, but we should honor the entire life cycle and recognize that the larvae, or juvenile stages, live and develop for months. Larvae are not mere preparations for a brief adulthood. We might better read the entire life cycle as a division of labor, with larvae as feeding and growing stages, and the adult as a short-lived reproductive machine. In this sense, we could well view the adult fly's day as the larva's clever and transient device for making a new generation of truly fundamental feeders."

"This essay treats the most celebrated story in the extreme simplification in an adult parasite - in the interests of illuminating, reconciling, and, perhaps, even resolving two major biases that have so hindered our understanding of natural history: the misequation of evolution with progress, and the undervaluing of an organism by considering only its adult form and not the entire life cycle."

"What constitutes the primordium of the adult parasite [ Rhizocephala ]? What can be injected through the narrow opening of the dart's hypodermic device? ...Imagine going through such complexity as nauplius, cyprid, and kentrogon - and then paring yourself down to just a few cells for a quick and hazardous transition to the adult stage. What a minimal bridge at such a crucial transition! ...But other species have achieved the ultimate reduction to a single cell! The dart injects just one cell into the host's interior, and the two parts of the life cyle maintain their indispensable continuity by an absolutely minimal connection - as though, within the rhizocephalan life cycle, nature has inserted a stage analogous to the fertilized egg that establishes minimal connection between generations in ordinary sexual organisms."

"The parasite has somehow evolved to turn off the host's defenses, presumably by disarming the crab's immune response with some chemical trickery that fools the host into accepting the parasite as part of itself. ...The adult parasite castrates the host, not by directly eating the gonadal tissue, but by some unknown mechanism probably involving penetration of the interna's roots around and into the crab's nervous system."

"Lernaeodiscus porcellanae turns control of the host into a fine art. After castration by the parasite, male crabs develop female characteristics in both anatomy and behavior, while females become even more feminized. The emerging externa then takes the same form and position as the crab's own egg mass... The crabs then treat the externa as their own brood. In other words, the parasite usurps all the complex care normally invested in the crab's own progeny."

"In short, the root-head turns the crab into a Darwinian cipher, a feeding machine working entirely in the parasite's service. The castrated crab can make no contribution to its own evolutionary history; its "Darwinian fitness" has become flat zero. ...But ever so carefully, for the parasite must maintain the crab in constant and perfect servitude - not draining the host enough to kill this golden goose, but not letting the crab do anything for its own Darwinian benefit."

"The intricate and different life cycles of both male and female root-heads, and the great behavioral sophistication shown by the female in reconfiguring a host crab as a support system, all underscore the myopia of our conventional wisdom in regarding rhizocephalans as degenerate parasites because the adult anatomy of internal roots and external sac seem so simple."

"Our indirect methods have taught us a mountain of things about horses, but if you wished to learn even more, would you rather be Whirlaway in the stretch, than interview Eddie Arcaro afterwards?"

"I can only look from the outside (or cut into the inside, but flesh and genes do not reveal organic totality). I am stuck with a panoply of ineluctably indirect methods - some very sophisticated to be sure. I can atomize, experiment, and infer. I can record reams of data about behaviors and responses. But if I could be a beetle or a bacillus for that one precious minute - and live to tell the tale in perfect memory - then I might truly fulfill Darwin's dictum penned into an early notebook containing the first full flowering of his evolutionary ideas during the late 1830's: "He who understands the baboon would do more towards metaphysics than Locke.""

"The classical argument for why a supposedly decent and moral creature like Homo sapiens can mistreat and even extirpate other species rests upon an extreme position in a continuum. The Cartesian tradition, formulated explicitly in the seventeenth century, but developed in "folk" and other versions throughout human history no doubt, holds that other animals are little more than unfeeling machines, with only humans enjoying "consciousness," however defined."

"I am willing to believe that my unobtainable sixty seconds within a sponge or a flatworm might not reveal any mental acuity that I would care to call consciousness. But I am also confident […] that vultures and sloths, as close evolutionary relatives with the same basic set of organs, lie on our side of any meaningful (and necessarily fuzzy) border—and that we are therefore not mistaken when we look them in the eye and see a glimmer of emotional and conceptual affinity."

"South America had been an island continent, far bigger and far more diverse than Australia, for tens of millions of years before the Isthmus of Panama rose just a couple of million years ago. The resulting flood of North American mammals across the new land bridge corresponds in time with the decimation of the native South American fauna. In fact, most large mammals generally considered distinctly South American... are all recent migrants from North America."

"If I could have those sixty seconds within Bradypus... would I not receive a plea for humans to pause, reassess - and above all, slow down?"

"Natural historians tend to avoid tendentious preaching in this philosophical mode (although I often fall victim to such temptations in these essays). Our favored style of doubting is empirical: if I wish to question your proposed generality, I will search for a counterexample in flesh and blood. Such counterexamples exist in abundance, for they form a staple in a standard genre of writing in natural history — the “wonderment of oddity” or “strange ways of the beaver” tradition."

"Flies can eat toads! (Although astonishment may be lessened in noting that the tiny toads are much smaller than enormous fly larvae.) Unusually large insects and maximally small vertebrates have also been featured in the few other recorded cases of such reversals - frogs, small birds, even a mouse, consumed by praying mantids, for example."

"No one supposed that dinoflagellates might actively kill fish as an evolved response for their own specific advantage, including a potential nutritional benefit for the algal cells. And yet the dinoflagellates do seem to be killing and eating fishes in a manner suggesting active evolution for this most peculiar reversal."

"In our struggle to understand the history of life, we must learn where to place the boundary between contingent and unpredictable events that occur but once and the more repeatable, lawlike phenomenon that may pervade life's history as generalities."

"Will we ever again be able to view a public object with civic dignity, unencumbered by commercial messages? Must city buses be fully painted as movable ads, lampposts smothered, taxis festooned, even seats in concert halls sold one by one to donors and embellished in perpetuity with their names on silver plaques?"

"The skein of human continuity must often become this tenuous across the centuries (hanging by a thread, in the old cliché), but the circle remains unbroken if I can touch the ink of Lavoisier's own name, written by his own hand. A candle of light, nurtured by the oxygen of his greatest discovery, never burns out if we cherish the intellectual heritage of such unfractured filiation across the ages. We may also wish to contemplate the genuine physical thread of nucleic acid that ties each of us to the common bacterial ancestor of all living creatures, born on Lavoisier's ancienne terre more than 3.5 billion years ago—and never since disrupted, not for one moment, not for one generation. Such a legacy must be worth preserving from all the guillotines of our folly."

"Christopher Wren, the leading architect of London's reconstruction after the great fire of 1666, lies buried beneath the floor of his most famous building, St. Paul's cathedral. No elaborate sarcophagus adorns the site. Instead, we find only the famous epitaph written by his son and now inscribed into the floor: “si monumentum requiris, circumspice”—if you are searching for his monument, look around. A tad grandiose, perhaps, but I have never read a finer testimony to the central importance—one might even say sacredness — of actual places, rather than replicas, symbols, or other forms of vicarious resemblance."

"No one should feel at all offended or threatened by the obvious fact that we are not all born entirely blank, or entirely the same, in our mixture of the broad behavioral propensities defining what we call “temperament.”"