I can say goodbye to this particular forum because I know that I will never run out of unkept promises or miles to walk.
I loved Grammy and Papa Joe separately. Divorce, however legal and religiously acceptable, did not represent an option in their world. Unlike Hal and Nettie Huxley, I'm not at all sure they would have done it again. But they stuck together and prevailed, at least in peace, respect, and toleration, perhaps even in fondness. Had they not done so, I would not be here—and for this particular twig of evolutionary continuity, I could not be more profoundly grateful, in the most immediate of all conceivable ways. I also loved them fiercely, and I reveled in the absolute certainly of their unconditional blessing and unvarying support (not always deserved, of course, for I really did throw that rock at Harvey, even though Grammy slammed our front door on Harvey's father, after delivering a volley of Yiddish curses amidst proclamations that her Stevele would never do such a thing, while knowing perfectly well that I surely could).
The tree of all life and the genealogy of each family share the same topology and the same secret of success in blending two apparently contradictory themes of continuity without a single hair's breadth of breakage, and change without even a moment's loss of a potential that need not be exploited in all episodes but must remain forever at the ready. These properties may seem minimal, even derisory, in a universe of such stunning complexity (whatever its inexplicable eternity or infinity). But this very complexity exalts pure staying power (and the lability that facilitates such continuity). Showy statues of Ozymandias quickly become lifeless legs in the desert; bacteria have scuttled around all the slings and arrows of outrageous fortune for 3.5 billion years and counting.
I believe in the grandeur of this view of life, the continuity of family lines, and the poignancy of our stories—of Nettie Heathorn, grown old as Granmoo and passing Tasso's torch two generations after her initial lighting; of Papa Joe's ungrammatical landing as a stranger in a strange land, and my prayer that, in some sense, he might see my work as a worthy continuation, also two generations later, of a hope that he fulfilled in a different way during his own lifetime. I suspect we feel the poignancy in such continuity because we know that our small realization of an unstated family promise somehow mirrors the larger way of all life and, by this affirmation of totality, becomes "right" in a sense too deep for either words or tears. I can therefore say goodbye to this particular forum because I know that I will never run out of unkept promises or miles to walk and that I may even continue to sprinkle the journey remaining before sleep with a new idea or two. This view of life continues, flowing ever forward, while the current patriarch of one tiny and insignificant twig pauses to honor the twig's centennial in a new land by commemorating the first recorded words of a fourteen-year-old forebear.
Dear Papa Joe, I have been faithful to your dream of persistence and attentive to a hope that the increments of each worthy generation may buttress the continuity of evolution. You could write those wondrous words right at the beginning of your journey, amidst all the joy and terror of inception. I dared not repeat them until I could fulfill my own childhood dream—something that once seemed so mysteriously beyond any hope of realization to an insecure little boy in a garden apartment in Queens—to become a scientist and to make, by my own effort, even the tiniest addition to human knowledge of evolution and the history of life. But now, with my 300, so fortuitously coincident with the world's new 1,000 and your own 100, perhaps I have finally won the right to restate your noble words and to tell you that their inspiration still lights my journey: I have landed. But I also can't help wondering what comes next!
The "List or Manifest of Alien Immigrants" of the SS Kensington for September 11, 1901, shows the names of the author's relatives.
Hooking Leviathan by Its Past
The following essay was published in Dinosaur in a Haystack (1997).
By Stephen Jay Gould
he landscape of every career contains a few crevasses, and usually a more extensive valley or two — for every Ruth’s bat a Buckner’s legs; for every lopsided victory at Agincourt, a bloodbath at Antietam. Darwin’s Origin of Species contains some wonderful insights and magnificent lines but this masterpiece also includes a few notable clunkers. Darwin experienced most embarrassment from the following passage, curtailed and largely expunged from later additions of his book:
In North America the black bear was seen by Hearne swimming for hours with widely open mouth, thus catching, like a whale, insects in the water. Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered, by natural selection, more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale.
Why did Darwin become so chagrined about this passage? His hypothetical tale may be pure speculation and conjecture, but the scenario is not entirely absurd. Darwin’s discomfort arose, I think, from his failure to follow a scientific norm of a more sociocultural nature. Scientific conclusions supposedly rest upon facts and information. Speculation is not entirely taboo, and may sometimes be necessary faute de mieux. But when scientists propose truly novel and comprehensive theories — as Darwin tried to do in advancing natural selection as the primary mechanism of evolution — they need particularly good support, and invented hypothetical cases just don’t supply sufficient confidence for crucial conclusions.
Natural selection (or the human analogue of differential breeding) clearly worked at a small scale — in the production of dog breeds and strains of wheat, for example. But could such a process account for the transitions of greater scope that set our concept of evolution in the fullness of time — the passage of reptilian lineages to birds and mammals; the origin of humans from an ancestral stock of apes? For these larger changes, Darwin could provide little direct evidence, for a set of well known and much-lamented reasons based on the extreme spottiness of the fossil record.
Some splendid cases began to accumulate in years following the Origin of Species, most notably the discovery of Archaeopteryx, an initial bird chock-full of reptilian features, in 1861; and the first findings of human fossils late in the nineteenth century. But Darwin had little to present in his first edition of 1859, and he tried to fill this factual gap with hypothetical fables about swimming bears eventually turning into whales — a fancy that yielded far more trouble in easy ridicule than aid in useful illustration. Just two years after penning his bear-to-whale tale, Darwin lamented to a friend (letter to James Lamont, February 25, 1861), “It is laughable how often I have been attacked and misrepresented about this bear.”
The supposed lack of intermediary forms in the fossil record remains the fundamental canard of current antievolutionism. Such transitional forms are sparse, to be sure, and for two sets of good reasons — geological (the gappiness of the fossil record) and biological (the episodic nature of evolutionary change, including patterns of punctuated equilibrium, and transition within small populations of limited geographic extent). But paleontologists have discovered several superb examples of intermediary forms and sequences, more than enough to convince any fair-minded skeptic about the reality of life’s physical genealogy.
The first “terrestrial” vertebrates retained six to eight digits on each limb (more like a fish paddle than a hand), a persistent tailfin, and a lateral-line system for sensing sound vibrations underwater. The anatomical transition from reptiles to mammals is particularly well documented in the key anatomical change of jaw articulation to hearing bones. Only one bone, called the dentary, builds the mammalian jaw, while reptiles retain several small bones in the rear portion of the jaw. We can trace, through a lovely sequence of intermediates, the reduction of these small reptilian bones, and their eventual disappearance or exclusion from the jaw, including the remarkable passage of the reptilian articulation bones into the mammalian middle ear (where they became our malleus
and incus, or hammer and anvil). We have even found the transitional form that creationists often proclaim inconceivable in theory — for how can jawbones become ear bones if intermediaries must live with an unhinged jaw before the new joint forms? The transitional species maintains a double jaw joint, with both the old articulation of reptiles (quadrate to articular bones) and the new connection of mammals (squamosal to dentary) already in place! Thus, one joint could be lost, with passage of its bones into the ear, while the other articulation continued to guarantee a properly hinged jaw.
Still, our creationist incubi, who would never let facts spoil a favorite argument, refuse to yield, and continue to assert the absence of all transitional forms by ignoring those that have been found, and continuing to taunt us with admittedly frequent examples of absence. Darwin’s old case for the origin of whales remains a perennial favorite, for Darwin had to invent a fanciful swimming bear, and if paleontologists haven’t come to the rescue by discovering an intermediary form with functional legs and potential motion on land, then Jonah’s scourge may gobble up the evolutionary heathens as well. God’s taunt to Job might be sounded again: “Canst thou draw out leviathan with a hook?” (The biblical Leviathan is usually interpreted as a crocodile, but many alternative readings favor whales.)
Every creationist book on my shelf actually cites the absence of and inherent inconceivability of transitional forms between terrestrial mammals and whales. Alan Haywood, for example, writes in his Creation and Evolution (see bibliography):
Darwinists rarely mention the whale because it presents them with one of their most insoluble problems. They believe that somehow a whale must have evolved from an ordinary land-dwelling animal, which took to the see and lost its legs … A land mammal that was in the process of becoming a whale would fall between two stools — it would not be fitted for life on land or at sea, and would have no hope for survival.
Duane Gish, creationism’s most ardent debater, makes the same argument in his more colorful style (Evolution: The Challenge of the Fossil Record):
There simply are no transitional forms in the fossil record between the marine mammals and there supposed land mammal ancestors … It is quite entertaining, starting with cows, pigs, or buffaloes, to attempt to visualize what the intermediates may have looked like. Starting with a cow, one could even imagine one line of descent which prematurely became extinct, due to what might be called an “udder failure.”
The most “sophisticated” (I should really say “glossy”) of creationist texts, Of Pandas and People by P. Davis, D. H. Kenyon, and C. B. Thaxton says much the same, but more in the lingo of academese:
The absence of unambiguous transitional fossils is strikingly illustrated by the fossil record of whales … If whales did have land mammal ancestors, we should expect to find some transitional fossils. Why? Because the anatomical differences between whales and terrestrial mammals are so great that innumerable in-between stages must have paddled and swam the ancient seas before a whale as we know it appeared. So far these transitional forms have not been found.
Three major groups of mammals have returned to the ways of distant ancestors in their seafaring modes of life (while smaller linkages within several other mammalian orders have become at least semiaquatic, often to a remarkable degree, as in river and sea otters): the suborder Pinnepedia (seals, sea lions, and walruses) within the order Carnivora (dogs, cats, and Darwin’s bears among others); and two entire orders — the Sirenia (dugongs and manatees) and Cetacea (whales and dolphins). I confess that I have never quite grasped the creationists’ point about inconceivability of transition — for a good structural (though admittedly not a phylogenetic) series of intermediate anatomies may be extracted from these groups. Otters have remarkable aquatic abilities, but retain fully functional limbs for land. Sea lions are clearly adapted for water, but can still flop about on land with sufficient dexterity to negotiate ice floes, breading grounds, and circus rings.
But I admit, of course, that the transition to manatees and whales represents no trivial extension, for these aquatic mammals propel themselves to powerful, horizontal tail flukes and have no visible hind limbs at all — and how can a lineage both develop a flat propulsive tail from the standard mammalian length of rope, and then forfeit the usual equipment of back feet so completely? (Sirenians have lost every vestige of back legs; whales often retain tiny, splintlike pelvic and leg bones, but no foot or finger bones, embedded in musculature of the body wall, but with no visible expression in external anatomy.)
The loss of back legs, and the development of flukes, fins, and flippers by whales, therefore stands as a classical case of a supposed cardinal problem in evolutionary theory — the failure to find intermediary fossils for major anatomical transitions, or even to imagine how such a bridging form might look or work. Darwin acknowledged the issue by constructing a much criticized fable about swimming bears, instead of presenting any direct evidence at all, when he tried to conceptualize the evolution of whales. Modern creationists continue to use this example and stress the absence of intermediary forms in this supposed (they would say impossible) transition to land to sea.
Goethe told us to “love those who yearn for the impossible.” But Pliny the Elder, before dying of curiosity by staying too close to Mount Vesuvius at the worst of all possible moments, urged us to treat impossibilities as a relative claim: “How many things, too, are looked upon as quite as impossible until they have been actually effected.” Armed with such wisdom of human ages, I am absolutely delighted to report that our usually recalcitrant fossil record has come through in exemplary fashion. During the past fifteen years, new discoveries in Africa and Pakistan have greatly added to our paleontological knowledge of the earliest history of whales. The embarrassment of past absence has been replaced by a bounty of new evidence — and by the sweetest series of transitional fossils an evolutionist could ever hope to find. Truly we have met the enemy and he is now ours. Moreover, to add blessed insult to the creationists’ injury, these discoveries have arrived in a gradual and sequential fashion — a little bit at a time, step by step, from a tentative hint fifteen years ago to a remarkable smoking gun early in 1994. Intellectual history has matched life’s genealogy by spanning gaps in sequential steps. Consider the four main events in chronological order.
CASE ONE: Discovery of the oldest whale. Paleontologists have been fairly confident, since Leigh Van Valen’s demonstration in 1996, that whales descended from mesonychids, an early group of primarily carnivorous running mammals that spanned a great range of sizes and habits from eating fishes at river edges to crushing bones of carrion. Whales must have evolved during the Eocene epoch, some 50 million years ago, because Late Eocene and Oligocene rocks already contain fully marine cetaceans, well past any point of intermediacy.
In 1983, my colleague Phil Gingerich from the University of Michigan, along with N. A. Wells, D. E. Russell, and S. M. Ibrahim Shah, reported their discovery of the oldest whale, named Pakicetus to honor its country of present residence, from Middle Eocene sediments some 52 million years old in Pakistan. In terms of intermediacy, one could hardly have hoped for more from the limited material available, for only the skull of Pakicetus has been found. The teeth strongly resemble those of terrestrial mesonychids, as anticipated, but the skull, in feature after feature, clearly belongs to the developing lineage of whales.
Both the anatomy of the skull, particularly in the ear region, and the inferred habitat of the animal in life, testify to transitional status. The ears of modern whales contain modified bones and passageways that permit directional hearing in the dense medium of water. Modern whales have also evolved enlarged sinuses that can be filled with blood to maintain pressure during diving. The skull of Pakicetus lacks both these features, and this first whale could neither dive deeply nor hear directionally with any efficiency in water.
In 1993, J. G. M. Thewissen and S. T. Hussain affirmed these conclusions and added more details on the intermediacy of skull architectur
e in Pakicetus. Modern whales achieve much of their hearing through their jaws, as sound vibration pass through the jaw to a “fat pad” (the technical literature, for once, invents no jargon and employs the good old English vernacular in naming this structure), and thence to the middle ear. Terrestrial mammals, by contrast, detect most sound through the ear hole (called the “external auditory meatus,” which means the same thing in more refined language). Since Pakicetus lacked the enlarged jaw hole that holds the fat pad, this first whale probably continued to hear through the pathways of its terrestrial ancestors. Gingerich concluded that “the auditory mechanism of Pakicetus appears more similar to that of land mammals than it is to any group of extant marine mammals.”
As for place of discovery, Gingerich and colleagues found Pakicetus in river sediments bordering an ancient sea — an ideal habitat for the first stages of such an evolutionary transition (and a good explanation for lack of diving specialization if Pakicetus inhabited the mouths of rivers and adjacent shallow seas). My colleagues judged Pakicetus as “an amphibious stage in the gradual evolutionary transition of primitive whales from land to sea … Pakicetus was well equipped to feed on fishes in the surface waters of shallow seas, but it lacked auditory adaptations necessary for a fully marine existence.”
Verdict: In terms of intermediacy, one could hardly hope for more from the limited material of skull bones alone. But the limit remains severe, and the results therefore inconclusive. We know nothing of the limbs, tail, or body form of Pakicetus, and therefore cannot judge transitional status in these key features of anyone’s ordinary conception of a whale.
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