• • •
But what about simplicity versus complexity? What about stability versus fragility?
A tropical rainforest is undeniably complex, and presumably therefore quite stable. But stability is a relative value—relative to the magnitude of the disturbance inflicted. No ecosystem is invulnerable. And no ecosystem is immune to disturbances of the magnitude that humankind often inflicts. If you remove the canopy trees from a large area of the richest Amazon jungle, chances are that you will destroy the ecosystem there, for a very long time indeed, if not permanently. Likewise if you take a heavy enough toll—a subtle toll, maybe, but a critical one—on the complex community of a coral reef.
An ecologist named Ramón Margalef has written: “A strong exploitation of very mature ecosystems, like tropical forests or coral reefs, may produce a total collapse of a rich organization. In such stable biotopes, nature is not prepared for a step backward. Man has to be very careful in dealing with systems of high maturity.”
Certainly the Great Barrier Reef is one of our planet’s most mature ecosystems. And if it dies, under a crown of thorns, there may be no prospect of resurrection.
THE POSEIDON SHALES
One Family’s Quest Through the Strata of Time
In an inconspicuous brick building on the outskirts of the village of Holzmaden, in southern Germany, is a large female animal caught in the act of giving birth. The moment is frozen precisely, rather poignantly, as though by the snap of a shutter. The image is stark, nearly flat, black and white. This isn’t a photograph. It is a natural bas-relief executed in marine mud and bone and the awesome pressures of time and accreting rock—in other words, a fossil. Almost 200 million years old but preserved in all delicate filigree, like a maple leaf pressed lovingly in a book by the hand of a child who has long since grown old and wizened, this particular fossil is different from any other you are ever likely to see. The anatomy is unusual. The specimen is whole, intact, and breathtakingly vivid. The tableau contains a double share of silent drama, since in this case the moment of birth was also, evidently, the moment of death. Altogether it may be one of the world’s most eloquent fossils. The animal is called Stenopterygius crassicostatus. The inconspicuous building is called Museum Hauff.
This maternal beast is an ichthyosaur, a marine reptile from the age of the dinosaurs. She was not herself a dinosaur; she was something else, something other, something more than a little oxymoronic: a fish-like reptile that breathed air but lived all her life in the sea, shaped by evolution to the same body form and the same ecological role as a dolphin, all those millions of years before dolphinhood was reinvented by the mammals. She died at sea and was buried in sea-bottom mud, very gently, with her one newborn beside her and five embryos still in her abdomen. The cause of death can’t be known. Possibly it was childbirth itself. Finally in the year we call 1948 she was pried up from a shale quarry, right there at Holzmaden, and teased out of her slab by the painstaking efforts of two men, both of them named Bernhard Hauff. They were father and son, founder and first heir of a quiet dynasty that has supplied the twentieth century with ichthyosaurs.
“These ichthyosaurs were animals that evoluted very specially for water life,” says Rolf Bernhard Hauff, grandson in the same line and now director of the museum and its renowned fossil-preparation workshop. The young Herr Hauff is handsome and genial, no archetype of dour fossiliferous stodginess as one might expect but a contemporary man, dressed this morning in jeans and a scarlet sweatshirt. He is conducting a tour in English for a group of American teenagers, high school kids from a nearby Air Force base, and struggling amiably toward a compromise with the attention span of his audience, the scientific complexity of his subject, and the language. His English is good but imperfect and the word he wants is evolved.
These ichthyosaurs had indeed evolved very specially for life in the ancient seas. The fossil is the proof. It tells of an animal twelve feet in length, weighing perhaps half a ton, with a strikingly large eye socket that suggests a creature dependent on keen sight, and a long toothy beak suited for preying upon small fish and squid. It tells of streamlining, and the transformation of legs to flippers, and a powerful shark-like tail, and more.
Herr Hauff points to the rib cage of this great gravid Stenopterygius, hung in its gray slab on one museum wall. Five miniature skulls, five little bodies, show clearly between the ribs. “And inside we see very small ichthyosaurs. And these ichthyosaurs, we know then, they bring forth very small babies. They give live birth. Not like an alligator or a turtle, eh?, that lays eggs on a beach. And so we know that the ichthyosaurs were very well adapted to life in the sea.” A live-bearing sea reptile was one that never needed to go ashore, because its newborn could swim up to the surface for air, whereas an egg laid on the sea bottom would, literally, drown—this being an important point scientifically, if not one to draw gasps from school kids. Herr Hauff keeps his tour brisk and palatable, moving quickly across matters of evidence—captured in these extraordinary fossils—that have given the Hauff collection, and the Hauff workshop, a revered place in paleontology for the past ninety years.
He is good with this crowd of distracted, hormonal adolescents. He smiles, he looks them in the eyes, he makes jokes and quizzes them Socratically. He knows that they might hear half of what he tells them, and retain a twentieth overnight—or maybe they will retain a tenth, if he gets them involved. Maybe in a few years one or two of them will remember that once, on an escape from the classroom, they visited an astounding, tiny museum in some little town of south Germany. Herr Hauff cares about that possibility. He avowedly views his own efforts, his family’s ancestral mission, as directed not just toward science but also toward the public. Ichthyosaurs, he seems to believe, are a miracle that belongs to everyone.
He leans over a smaller specimen in a tabletop case. “This is the backbone. And this black line is not painted here,” he says. Flattened almost to two dimensions on its bed of gray shale, the skeleton is surrounded by a smooth coal-dark silhouette: the full outline of a body, left behind by chemical transformation of the animal’s skin. That outline is a rarity, an artifact as improbable as the face in Veronica’s veil, with scientific significance that a modest man like Rolf Hauff could scarcely exaggerate. It establishes that ichthyosaurs had almost precisely the same shape as dolphins, with a dorsal fin and a tall upper horn on the caudal fin that do not show up in the skeleton. “We find this only with very careful preparation. Soft-body parts preserved so good, we find only here in all the world. This takes very careful preparation. Almost a year to prepare one specimen.”
The tradition of fine craftsmanship in the Hauff workshop is only part of what has made these fossils so useful to science, and so beautiful. The other part involves geological accident. This area of southern Germany in which Holzmaden lies—just forty kilometers east of Stuttgart, at the base of a hilly upthrust known as the Swabian Alb—once lay at the bottom of a shallow sea. During the Jurassic period of Earth history, roughly between 190 and 136 million years ago, that inland sea covered a large portion of what is now western Europe. In the Holzmaden area, which was some distance off the coast, fine-grain muddy sediments were laid down upon the sea bottom, compressing and hardening finally into rock, and in the process entombing dead marine animals wherever the bodies fell. The sea bottom here was especially stable, undisturbed by currents, poor in oxygen, so that carcasses settling into the mud were often preserved free of dismemberment or rot. Laced richly with organic material (not just ichthyosaur bodies but various marine reptiles, fish, mollusks, and an abundance of other invertebrates), the hardening layers of mud eventually became strata of oil shale. Those dark carboniferous strata are known by geologists as the Black Jurassic. The sea retreated, the Swabian Alb was uplifted by pressures along the Earth’s crust, and erosion gradually stripped away other strata formed after the shale. Millions of years later, Rolf Hauff’s great-grandfather came to Holzmaden as an industrial chemist, with the notion of exploit
ing that oil shale. But his son, the founding grandfather of the fossil operation, was more interested in the shale as a mausoleum of vanished reptiles than for its sheer bitumen content.
For hundreds of years the shale has been quarried also for decorative rock. Today that commercial quarrying continues, at a handful of sites around Holzmaden, with tools and methods nearly unchanged over the past century. Now you might see a dump truck or a power shovel helping to move shattered rock, but the delicate labor of prying up large sheets of shale, unbroken, suitable for paving the floor of a den or the wall of a fireplace, is still done by workmen using crowbars and picks. Occasionally one of those workmen will lift a slab and notice a brownish shape in the blue-gray shale—the hint of a fossil embedded there. Setting that slab aside, the workman will send a message to Herr Hauff, who will hurry out to the site. Other slabs will be pried up and inspected. The ideal is to capture a whole animal within just a few large pieces, then get those pieces back to the workshop and fit them together like a puzzle. Once that matrix is reassembled, the shale is chiseled and etched away—mainly again using hand tools, the fine finishing done with dental picks under a microscope—to liberate the fossil. For ninety years one Hauff or another has been responding to those messages from the quarries.
But the fossils have never been more than a by-product of Holzmaden quarrying. Nowadays, as in the past, it is not economically feasible to work the quarries purely for fossils. In this particular age, with humans and not reptiles dominating the Earth, raw fireplace stone carries more value than raw ichthyosaurs.
Once the Hauff craftsmen have intervened, of course, that balance tips. Museum Hauff is a private institution that supports itself largely through the sale of specimens, and a fully prepared ichthyosaur might bring $20,000. The customers are other museums (for specimens with unique scientific significance), as well as large corporations and private collectors (for decorative specimens with less scientific value), and this cottage industry allows the Hauff operation to remain independent, an old-fashioned family-run exercise in crazy devotion and pride. In this combined dedication to craftsmanship, private enterprise, and science, they seem like a cross between Harry Winston and the Leakeys.
The commercial Holzmaden stone comes from one particular layer of those Jurassic marine sediments, twenty feet below ground level and just seven inches thick. This buried seven-inch layer, which splits nicely and has an attractive surface, is what drives the quarry economy. The strata that are broken and pried out to reach that layer are cast aside as scrap—but from among that scrap, rescued from power shovel and dump truck, come the ancient reptiles. Paleontologists all over the planet know those fossil-rich Holzmaden strata as the “Middle Epsilon” division of the Black Jurassic period, and the slightly less formal label in German is “Posidonien-schiefer.” To you or to me: the Poseidon Shales. A sea god’s gift to posterity. Go to a good science museum in Stuttgart or Tübingen, or for that matter in Paris, Berlin, Cambridge, New York, and wherever you find ichthyosaurs you will probably also find a small plate saying, “Middle Epsilon, Black Jurassic. Holzmaden.” Or perhaps only “Posidonien-schiefer.” You may also see the name Hauff. Most of those specimens have passed through the family workshop.
But the Poseidon Shales are famous not only for ichthyosaurs. They have yielded a whole menagerie of marine life from the Jurassic period, and the walls of Museum Hauff display that life as a great stonework frieze, a portrait of the offshore community as it existed 160 million years before Christ. Besides ichthyosaurs there are two other seagoing reptiles, the plesiosaurs (resembling giant long-necked turtles, but without shells) and the steneosaurs (similar to the fish-eating gharials that survive in India and Nepal); there are also pterosaurs, those delicate flying reptiles, which sometimes died at sea and sunk to their graves in the underwater mud; and a selection of garish invertebrates, including the sea lilies (plant-like creatures with long stems and flowery heads, which were actually animals related to starfish) and the ammonites (a group of spiral-shelled mollusks that disappeared at the same time as the dinosaurs). All of these life forms—the giant and the small, the delicate and the robust, the predaceous and the benign—have been preserved in stunning detail by the gentle embrace of those Jurassic marine muds, and brought back to light by the methodical scraping of Hauff chisels.
One wall of the museum is filled by a huge panel of sea lilies, a parquetry of gray slabs stretching from the floor to a peaked roof fifty feet up, upon which a colony of these bizarre animals are frozen in ropey entanglement, like an orgy of giant sea worms with sunflower heads. This amazing thing turned up in a quarry back in 1908. For forty years it remained in the raw state, locked inside chunks of shale. The Hauff craftsmen began work on it, finally, in the 1950s. By then old Bernhard Hauff, the grandfather and founder, was dead. Fifteen years later, the sea lily panel was finished. Now it hangs here majestically, the largest community of fossil invertebrates exhibited anywhere in the world.
On the wall just opposite hangs an oil portrait of Bernhard Hauff. He seems, as always, to be taking the long view. Dreaming the dream of time.
This museum itself is a private dream, a heartfelt and heritable whimsy, that exists to amuse and to edify the public. It expresses one family’s quixotic conviction: that the history of life on our planet is not only intriguing but beautiful, a miracle that belongs to everyone.
“So, you will find nearly nowhere on the world where you can take out information and fossils like we have it here in Holzmaden,” Herr Hauff tells the American teenagers. He has not exaggerated. He smiles. The students have listened and stared at his fossils for nearly an hour, a great feat of prolonged attention, and Herr Hauff knows he dare not try to hold them five minutes longer. He pushes his hands into the pockets of his jeans, and shrugs. He is an optimist. He believes that one or two of them will remember.
THE BEAUTIFUL AND DAMNED
Genetics and Aesthetics in the Life of a Dashing Animal
Beauty is one of the lies we live by. The joys of success is another. God knows, we have been offered enough minacious parables over the centuries to discourage both of these stubborn delusions—from The Iliad and Oedipus Rex to The Picture of Dorian Gray and “Richard Cory”—but still they survive, eternal inverities. Evidently we need them at least as much as we need mere truth. The latest increment of counterevidence against that pair of sleek cheery falsehoods came and went recently as an article in the journal Science, and unless you were watching closely, you may have missed it.
Based on the experimental work of a team led by S. J. O’Brien, a geneticist from the National Cancer Institute, this article presents a technical assessment of the unusually low genetic diversity within a certain species. O’Brien’s study is noteworthy to a broad audience not so much because of its results (“we found a total absence of genetic polymorphism in forty-seven allozyme loci and a low frequency of polymorphism in proteins”) as because of the test subject in question. That species was Acinonyx jubatus, the cheetah.
Every schoolchild in America knows that the cheetah is the world’s fastest mammal. Anyone who has seen and studied these creatures in the field is liable also to argue that they are the most beautiful of all carnivores, and the most successful of all wild cats. A dozen years ago I spent one lucky hour watching four cheetahs stalk game on the East African savanna, and I still haven’t begun to forget their gorgeous, prepossessing grace. But the cheetah today, despite appearances, is not well. It is genetically depauperate.
Though there may still be as many as 20,000 cheetahs at large on the plains of Africa, the gene pool of A. jubatus appears to be much smaller than it should be for that number—too small, perhaps, to carry the species through any sudden adversities. Insufficient genetic options equals insufficient adaptability. So far, admittedly, only one of the two remaining large populations has been investigated: the South African cheetah, not the East African. In the course of O’Brien’s study, blood tests were done on fifty-five animals, some o
f those from the Transvaal, some from Namibia, a few that had previously been exported to zoos in the United States. This scattered group of cats turned out to have all the genetic diversity of a palace full of incestuous Romanovs.
Cheetahs are currently an endangered species. Twenty thousand is not such a large total, and the real number may be much less, possibly as low as 1,500. No one really knows, because the elusive habits of these animals make them very hard to count. Though officially protected in some of the countries where they occur, they are still occasionally threatened by fur poachers and stock-raising peoples. They are threatened even more by habitat loss. But the worst threat they face may be the genetic one. They are just dangerously short on genetic variety.
And that’s one threat that we humans can’t rectify. All we can do is give them time. A depleted population of animals can sometimes recover quickly. A depleted gene pool cannot. Thousands of new generations must be born and grow and achieve successful reproduction themselves, before the slow process of mutation will have restored a previous level of gene variations. Populations fall and rise again at geometric rates but, like some morbidly hurtful memory, genetic impoverishment lingers afterward.
• • •
Where did those missing cheetah genes go?
O’Brien and his coauthors are cautious about offering speculation, but their work, together with what is known of the history of this species in both the recent and the distant past, suggests a couple of sad possibilities.
The Flight of the Iguana Page 14
