Shootout At The K/T Boundary

Several years ago, paleontologist Dewey M. McLean stepped to the podium at a conference on the climatological effects of volcanoes. The silver-haired professor from the Virginia Polytechnic Institute looked out over the packed house like a pastor surveying his flock. He was about to deliver a sermon— well, a paper actually—that would take on one of the exalted among his priesthood—the redoubtable Nobel laureate Luis W. Alvarez. Specifically, McLean was about to challenge Alva

Bruce Fellman
Oct 2, 1988

Several years ago, paleontologist Dewey M. McLean stepped to the podium at a conference on the climatological effects of volcanoes. The silver-haired professor from the Virginia Polytechnic Institute looked out over the packed house like a pastor surveying his flock. He was about to deliver a sermon— well, a paper actually—that would take on one of the exalted among his priesthood—the redoubtable Nobel laureate Luis W. Alvarez. Specifically, McLean was about to challenge Alvarez’s well-publicized theory that an asteroid had caused the extinction of the dinosaurs and thousands of other species 65 million years ago. The real angel of death, he would argue, was a “greenhouse effect” caused by intense volcanic activity.

The audience of scientists was looking forward to the talk; most of them were fellow heretics. But before McLean could begin, something started roaring outside the auditorium. The noise grew quickly, and as it reached near-deafening dimensions, McLean looked heavenward smiled, and said to the assembled multitude, “Here it comes.” Everyone laughed. It was only a torrential downpour. Even Alvarez, for all his supposed power, couldn’t order an asteroid to conveniently squash opposition to his controversial theory.

Still, there was a touch of nervousness to the audience’s laughter. At the time, there were dark rumors circulating that Alvarez would stop at nothing to stifle dissent. Even now, a number of vocal critics of the asteroid-impact theory are firmly convinced that the late Nobel laureate was pulling strings behind the scenes—and that the price of hewing to what they perceive as the scientific truth was loss of access to news coverage, grant money, the leading journals, and even tenure.

Today, Alvarez is no longer here to defend himself The brilliant physicist succumbed to complications of esophageal cancer (see accompanying story) on September 1 at the age of 77. With his passing, the rumors and recriminations may too be buried, but the legend of the man—both his feats of scientific discovery on a remarkably wide-ranging front and his reputation for feistiness, sometimes insensitivity, and perhaps even arrogance—will not die.

For Alvarez was not only one of science’s chosen few his Nobel Prize automatically bestowing enormous respect and power. He also ventured far from his original field of theoretical physics—and stirred up a ruckus that still rages. And it is this extraordinary aspect to the Alvarez career that makes the controversies he engendered a subject worthy of study by all those concerned about scientific propriety. In this vein, The Scientist recently embarked on an in-depth in- vestigation of Alvarez’s behavior during the last, and probably most contentious, period of his life: during the battle that some scientists have come to call the “shoot-out at the Cretaceous/Tertiary (K/T) boundary.” And what we found was that, despite all the cries of foul by his paleontological opponents, there is no evidence that Alvarez acted to damage the careers of those who disagreed with him. His opponents are still publishing they are getting funding like everyone and some are receiving tenure. None has been hit by an asteroid.

If Alvarez was guilty of anything, it was only of wielding a mighty blunt spoon as he stirred up the paleontological pot. Certainly, he didn’t shrink from criticizing his rivals: in a New York Times article earlier this year, McLean was dismissed as a “weak sister,” paleontologists in general were “really not very good scientists. They’re more like stamp collectors;” and one paleontologist in particular, Berke ley’s William A. Clemens, was “inept.” To top it off, the asteroid theory of dinosaur extinction, Alvarez wrote in his recent memoir, Alvarez: Adventures of a Physicist (Basic Books, 1987), is “most probably, ‘the only game in town.”’

Predictably, critics of the asteroid theory fought back with equal gusto. Dartmouth geologist Charles B. Officer, a de facto leader of the opposition, dismissed the impact hypothesis as a “tumbling house of cards,” the impactors as “bombardiers,” and Alvarez as a “bulldozer.” Texas A&M geophysicist Neville Carter called Alvarez’s public denunciation of his critics “an incredibly sick thing to do—the guy’s decided he’s God.” As David Raup, a paleontologist at the University of Chicago and a major sup- porter of Alvarez’s asteroid extinction theory, says, “Venom pervades the entire field.”

“Luis was not a gentle guy,” admits W. Peter Trower, a Virginia Polytech physicist and close friend of Alvarez who also edited the recent book, Discovering Alvarez: Selected Works of Luis W Alvarez, With Commentary by His Students and Colleagues (University of Chicago Press, 1988). “To him, something was either wrong or right. If he was wrong, he was very quick to retract. If he felt he was right, Luis put the full force of his considerable talents intellectually, as well as emotionally and politically, behind an idea.”

The acrimony of the whole debate has left many scientists reeling. “I like to think of science as pristine, pure, unsullied—with scientists doing their work for the same reasons that Mozart composed and Rembrandt painted,” says McLean, whose work has been roundly condemned by the impact camp. “But I’ve learned—and it’s been a terrible education—that there are very few angels in the Temple of Science.”

“We may look back on this episode and feel more than a little embarrassed,” adds Raup. “It’s been exhilarating, but it’s also been very upsetting. A lot of friendships have broken down as the result of this debate.”

Is this really the way science is supposed to work? Are rancor and personal animosity inevitable in the spread of new ideas? To some degree, the answer is yes, says sociologist Dorothy Nelkin, a visiting professor at New York University. “Good science can get rough,” she says. “How rough depends on the personalities and the stakes that are involved. But deep controversies are generated over every area of hot research. Their presence is actually a sign of a healthy science.”

Still, the controversy that Alvarez started has been more heated than most. Its origins date back to 1980 when Alvarez, his paleontologist son Walter, and their colleagues at Berkeley first proposed the impact theory in Science (Vol 208: 1095-1108). The researchers had discovered enormous concentrations of the rare element iridium in a layer of clay that marked the abrupt transition between the Cretaceous and Tertiary geological epochs in Gubbio, Italy. In what everyone, critics included, counts as a brilliant bit of science, the Alvarez camp concluded that a large iridium-rich asteroid had collided with the Earth and left its elemental signature at the K/T boundary.

But the impactors moved on to shakier ground when they also theorized that the collision kicked up an enormous dust cloud that blotted out the sun, stopped photosynthesis,’lowered worldwide temperatures, and left many of the planet’s inhabitants—including the dinosaurs—to freeze and starve to death in the dark.

The apocalyptic vision captured the imagination of scientists (although only a minority of paleontologists) and the public alike. Wal- ter Alvarez’s talks on the hypothesis played to packed houses at annual meetings of the American Association for the Advancement of Science, and a painting of the menacing asteroid even made the cover of Time magazine.

From the outset, however, plenty of reputable scientists did not buy the various aspects of the hypothesis. A number of them invoke volcanoes as the cause of the iridium layer and other peculiarities of the K/T boundary, while others accept the reality of the asteroid impact but not its cataclysmic biological and climatological consequences. But these opponents had a tough row to hoe because of the theory’s enormous popularity and the influence of Luis Alvarez, its leading proponent.

Was Alvarez to blame for the acrimonious debate that followed? Some scientists have suggested, for example, that his entry into the fray was an example of the so-called “Nobel Syndrome,” a foot-in-mouth condition that results from external and internal pressures on Nobel laureates to comment on a wide variety of matters that are outside their areas of expertise.

“They come to be defined as contemporary seers and sages,” says Harriet Zuckerman, a Columbia University sociologist who has written about the syndrome. “But this was clearly not a case of it. Alvarez, even though a physicist, made himself as qualified as anyone else. He had the energy and imagination to start a new line of research.”

Of course, Luis Alvarez’s caustic comments about paleontologists didn’t exactly pour oil on troubled waters. “Dad made some remarks that he shouldn’t have made,” admits son Walter, adding that the “shoot-out” was caused by far more than a few “uncharitable comments. It’s the result of a clash of scientific cultures.”

For one thing, Alvarez’s foray into paleontology aroused a certain amount of jealousy, admits Yale paleontologist Leo Hickey, an expert on K/T plant communities who accepts the reality of the impact but does not see it as a world--wide “angel of death.” Although the traditionally “low-tech” world of paleontology had often been invaded by “higher-tech” machines and methods, this newest assault by a pushy Nobelist—and an outsider, at that—who wielded the most advanced technology, denigrated paleontological researchers, and declared the K/T debate over, “was bound to cause some resentment,” says Hickey.

In addition, the controversy was fueled by fundamental differences between scientific disciplines. Alvarez followers tend to view data with a kind of precision that is part and parcel of chemistry and physics, but which is alien to the tradition of paleontology, explains Hickey. “One of Luie’s points was that if we see a trend in physics— say, the coincidence of an extinction and a spike of iridium—the conclusion is incontrovertible: the two events are linked,” Hickey says. “But the essence of the paleontological argument is that however soft and wishy-washy it sounds, biotic systems are extremely complex. They often respond to environmental stress in a nonlinear and unpredictable fashion. It’s the height of hubris to say that changes in the record are caused by specific spikes.”

The impactors have an easy response to this charge. “There’s no reason that a simple answer can be right,” says Raup.

Another problem is that many paleontologists have wrapped entire scientific careers around the assumption that earth history can be explained by ongoing, earthly processes. The suggestion that the evolution of life was greatly influenced by sudden extraterrestrial events, therefore, smacks of heresy. “Remember, a lot of science is really a belief system,” Nelkin explains. The inevitable result, says William Glen, a geologist currently at work on a book about the impact controversy, is an almost religious clash between two fundamental theories about how the planet and its life evolved.

And so, the consensus among those who have observed the K/T imbroglio is that the high level of acrimony was probably unavoidable. Hot, contentious areas of science, the observers explain, inevitably arouse strong passions and stimulate pitched battles. “Unpleasant as it may be, controversy is important for the refinement of scientific ideas,” says sociologist Zuckerman. “They rarely get straightened out without it.”

Zuckerman points to past battles that make the asteroid debate seem like a pillow fight. The debate over the theory of continental drift, for example, raged on for years, prompting all sorts of wild accusations, and leaving Alfred Wegener, who originally proposed the idea, a bitter, broken man.

So it may be fruitless to chide Luis W. Alvarez or his critics for their bad manners. In fact, the strong passions aroused by the clash are probably directly responsible for rapid advances in the science, since both sides are so anx- ious to prove their opponents wrong. As historian Glen says, “There’s so much good science being done. The debates over impact theory, mass extinctions, periodicity, and volcanism have rejuvenated virtually quiescent fields.”

Perhaps Hickey said it best, a few months before Alvarez’s death. “While I decry the nasty, bigoted, opinionated, cantankerous, crusty old bastard Luis Alvarez, he really has helped open up the thinking in paleontology." Hickey said. “His is a major contribution.”

—Bruce Fellman