Science + Technology



UCLA paleobiologist J. William Schopf has been awarded the 2000 Phi Beta Kappa Award in Science for his 1999 book, "Cradle of Life: The Discovery of Earth's Earliest Fossils" (Princeton University Press). The annual award is presented for "outstanding contributions" to the literature of science at a Phi Beta Kappa Senate dinner in Washington, D.C., on Dec. 1.

Previous recipients of the award include Linus Pauling, Stephen Jay Gould, E. O. Wilson, and Jared Diamond, UCLA professor of physiology and winner of the 1999 National Medal of Science.

In "Cradle of Life," Schopf showed that for all its achievements, science has also been spectacularly wrong. "Facts always prevail eventually," Schopf said, "but sometimes they don't emerge for decades."

"Cradle of Life" recounts the discovery over the last three decades of a vast, ancient fossil record, unknown and thought to be unknowable. This immense fossil record fills in gaping holes in our knowledge of the earliest 85 percent of the history of life on Earth, and changes our understanding of how evolution works. In addition to writing about this remarkable success story, however, Schopf also detailed a few of science's stunning failures, including the "discovery" in the early 1700s of a skeleton of a human said to have drowned in Noah's Flood — taken for many decades as proof of Biblical truth. Hailed as irrefutable evidence of Noah's Flood, it was shown — almost a century later — to be a misidentified huge fossil salamander.

Schopf, director of UCLA's Center for the Study of Evolution and the Origin of Life, drew the following lesson from science's mishaps: "Who are we to smugly sit in judgment? Though it is now harder to be fooled since so much more is known, it's a sure bet that some of what passes as 'known' today will eventually turn to dust."

Following two accounts from the 18th century, Schopf concluded with a chapter on the NASA scientists who claimed in 1996 that they had found evidence of life on Mars in a meteorite that landed in Antarctica 13,000 years ago. His implication is that these respected scientists may be modern successors to those of the 18th century.

Schopf, who first assessed the evidence for life on Mars a year-and-a-half before the 1996 press conference produced worldwide headlines, offered this judgment: "The evidence was (and still is) inconclusive. Crucial questions had not been asked. Articles published earlier and critically relevant to the authors' contentions had been ignored. More plausible ways to explain the findings were given short shrift. The claim of 'evidence for primitive life on early Mars' seemed overblown, ill-conceived.

"I want there to be life on Mars more than anyone else — but it doesn't matter what I want! The evidence isn't there. That does not mean Mars contained no life — just that these scientists didn't find any."

Mostly, however, "Cradle of Life" addresses one of science's great successes.

As an honors student at Oberlin College in Ohio in the 1960s, Schopf learned in great detail about the most recent 500 million years of the planet's history. But geologic time covers more than 4.5 billion years, and Schopf's textbooks and professors taught virtually nothing about the Earth's first four billion years. The reason this period was neglected, Schopf learned, was that nobody knew much about it. He vowed to fill that black hole of knowledge, and he explained in "Cradle of Life" how he and other scientists succeeded in doing so.

What significant events occurred in that first 85 percent of the Earth's history? Among other things, the first living organisms, the modern food chain, photosynthesis, the ability to breathe oxygen, the development of the atmosphere and oceans, various types of cell division, and sexual reproduction all date from this enormously long period of time, Schopf said.

"Think how extraordinary it is that the earliest 85 percent of life's history has until now remained a mystery," Schopf said. "What would it be like if more than four-fifths of America's past were unknown? Imagine if history professors said that 'a pre-1963 historical record ought to exist, but there are no facts to go on. No one knows what happened, or why the record's been wiped out.' And then imagine if researchers discovered conclusive evidence of the earliest 85 percent of U.S. history: a Declaration of Independence, a Constitution, Washington, Franklin, Jefferson, Lincoln, a Civil War, electricity, telephones, radio, television, a Great Depression, World War I, World War II, the nuclear age … Astounding!"

In "Cradle of Life," Schopf told an "even more mind-boggling tale," scaled in millions and billions of years, dealing with "all of life, over all of time, over the entire globe" — a tale that reveals "where we have come from and who we are."

The tracing of life's earliest history is an acrimonious story of false starts, embarrassing mistakes, and ultimately, dogged persistence and remarkable success. Schopf showed why it took so long for the hidden record to emerge. The early fossil record is richly complex and full of surprises. One such surprise: Evolution itself evolved.

"Everyone had expected early organisms would be smaller, simpler, perhaps less varied, but they were universally thought to have evolved in the same way and at the same pace as later life," Schopf wrote. "This turned out not to be true. That evolution itself evolved is a new insight."

The pivotal point in evolution's own evolution turned out to be the advent of sex about 1.1 billion years ago. The origin of sex caused monumental change. Sex increased variation within species, diversity among species, and the speed of evolution and genesis of new species — and brought not only the rise of organisms specially honed to particular settings, but because of this specialization, the first appearance of life-destroying mass extinctions.

The first organisms to engage in sexual activity were single-cell floating plankton. They started to appear about 1.1 billion years ago with a pore-like mechanism that permits the release of sex cells into the environment. Before this time, organisms reproduced by asexual division, as do human body cells. Data from the fossil record clearly show that there appeared many new types of species at about 1.1 billion years ago, evidently when sexual activity first began.

"The start of sexuality," Schopf said, "had an enormous effect on the world's biodiversity. The pre-sex world was monotonous, dull, more or less static, but every organism born from sexual reproduction contains a genetic mix that never existed before."

Among the lessons Schopf draws is one that might surprise many high school students: "Science is enormous fun, and the greatest adventure ever devised. The past, present, even the future of life, Earth and all beyond are within its scope. There's hardly anything better than having a novel idea and finding that it makes sense."



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