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Science's answers to these questions are changing, and changing rapidly, as fresh evidence pours in from fields as disparate as oceanography and molecular biology, geochemistry and astronomy. This summer a startling, if still sketchy, synthesis of the new ideas emerged during a weeklong meeting of origin-of-life researchers in Barcelona, Spain. Life, it now appears, did not dawdle at the starting gate, but rushed forth at full gallop. UCLA paleobiologist J. William Schopf reported finding fossilized imprints of a thriving microbial community sandwiched between layers of rock that is 3.5 billion years old. This, along with other evidence, shows that life was well established only a billion years after the earth's formation, a much faster evolution than previously thought. Life did not arise under calm, benign conditions, as once assumed, but under the hellish skies of a planet racked by volcanic eruptions and menaced by comets and asteroids. In fact, the intruders from outer space may have delivered the raw materials necessary for life. So robust were the forces that gave rise to the first living organisms that it is entirely possible, many researchers believe, that life began not once but several times before it finally "took" and colonized the planet. The notion that life arose quickly and easily has spurred scientists to attempt a truly presumptuous feat: they want to create life -- real life -- in the lab. What they have in mind is not some monster like Frankenstein's, pieced together from body parts and jolted into consciousness by lightning bolts, but something more like the molecule in that thimble-size test tube at the Scripps Research Institute. They want to turn the hands of time all the way back to the beginning and create an entity that approximates the first, most primitive living thing. This ancient ancestor, believes Gerald Joyce, whose laboratory came up with the Scripps molecule, may have been a simpler, sturdier precursor of modern RNA, which, along with the nucleic acid DNA, its chemical cousin, carries the genetic code in all creatures great and small.
Some such molecule, Joyce and other scientists believe, arose in the shadowy twilight zone where the distinction between living and nonliving blurs and finally disappears. The precise chemical wizardry that caused it to pass from one side to the other remains unknown. But scientists around the world are feverishly trying to duplicate it. Eventually, possibly before the end of the century, Joyce predicts, one or more of them will succeed in creating a "living" molecule. When they do, it will throw into sharp relief one of the most unsettling questions of all: Was life an improbable miracle that happened only once? Or is it the result of a chemical process so common and inevitable that life may be continually springing up throughout the universe?