CAN SCIENCE CREATE A HISTORY OF EVERYTHING?
THE
DISCOVER
WALTER ALVAREZ
The geologist who figured out what killed the dinosaurs
talks about the stories hidden within rocks and what
they add to the grand narrative of “big history.”
BY PAMELA WEINTRAUB
PHOTOGRAPHY BY MISHA GRAVENOR
Geologist Walter Alvarez was on an expedition in Italy during the
early 1970s when he noticed something fascinating in the limestone
mountains outside Gubbio: two dark layers of rock sandwiching a
lighter, half-inch-thick seam. The darker sections were ;lled with fossils of microorganisms known as forams, while the center swath was
virtually devoid of fossil life. Alvarez and colleagues from Columbia
University’s Lamont-Doherty Earth Observatory later determined that
the middle layer was laid down at the exact time of the extinction of
the dinosaurs. More exciting, he and his father, Nobel Prize–winning
physicist Luis W. Alvarez, found that the fossil-free layer was rich in
iridium, an element that is rare on the earth but relatively abundant
in rocks from space. Piecing those clues together, the two Alvarezes
proposed a radical idea: The mass extinction that wiped out the dinosaurs 65 million years ago was caused by the impact of a giant asteroid, which unleashed a globe-spanning cloud of debris and plunged
the planet into darkness for months. In 1990, geologists found the
crater from this disaster off the north coast of the Yucatan peninsula,
validating the impact theory for most of the scienti;c world.
After that triumph, Walter Alvarez, now at the University of California
at Berkeley, began seeking other ways of using science to illuminate
history—not just remote geological epochs, but also the events of the
human era. “Naturally, a geologist thinks historically, and human history entangled itself with the work I was doing,” he says. That thinking
began to take concrete form one day when he received an e-mail from
Fred Spier, a sociologist at the University of Amsterdam. Spier was
working in the ;eld of “big history,” a uni;ed, multidisciplinary narrative of everything from the Big Bang to the present. He asked Alvarez if
he would be interested in teaching a course on this topic, and Alvarez
agreed. “It was a seed that fell on fertile ground,” he says.
Before long Alvarez was writing The Mountains of Saint Francis, a
book that traces Italy’s physical and cultural past going back 250 million years. He developed a wildly popular course at Berkeley that integrates cosmology and geology with world wars, sports, and Barack
Obama. And he expanded the scope of big history by adding to it
his concept of the contingency—the rare, unexpected event (like an
asteroid collision) that changes the world in a blink.
DISCOVER senior editor Pamela Weintraub interviewed Alvarez
in his Berkeley of;ce, a comfortable space decorated with his own
homages to the past: a black-and-white photo of his wife, Milly,
taken in her youth, and a piece of the Apennines that dates to
the demise of the dinosaurs. Soft-spoken and re;exively sunny,
Alvarez turns intense when it comes to the big message behind big
history. “Geology is the most important science of the 21st century
because there is only one earth, and it’s becoming clear that we
could damage it beyond the point where it could support us,” he
says. “Geologists are studying the historical record to understand
the controls before we tip into an unstable state.”
You seem to elevate geology above other sciences. Why?
Geology is a lot more complicated than astronomy and physics.
If you were an early astronomer, you looked at points of light in
the sky. The stars stayed in a ;xed arrangement and the planets
moved against that pattern. It didn’t make any difference what
happened a billion years before; all that mattered was what you
saw now. It took the genius of Tycho Brahe and Johannes Kepler
to ;gure out the movement of heavenly bodies and the genius of
Isaac Newton to give us the laws of motion, but these were tractable problems. If you look at a mountain range like the Alps or the
