Wildly excited, two men dashed out of a side door of Cambridge University's Cavendish Laboratory, cut across Free School Lane and ducked into the Eagle, a pub where generations of Cambridge scientists have met to gossip about experiments and celebrate triumphs. Over drinks, James D. Watson, then 24, and Francis Crick, 36, talked excitedly, Crick's booming voice damping out conversations among other Eagle patrons. When friends stopped to ask what the commotion was all about. Crick did not mince words. "We," he announced exultantly, "have discovered the secret of life!"
Brave words—and in a sense, incredibly true. On that late winter day in 1953, the two unknown scientists had finally worked out the double-helical shape of deoxyribonucleic acid, or DNA. In DNA's famed spiral-staircase structure are hidden the mysteries of heredity, of growth, of disease and aging—and in higher creatures like man, perhaps intelligence and memory. As the basic ingredient of the genes in the cells of all living organisms, DNA is truly the master molecule of life.
The unraveling of the DNA double helix was one of the great events in science, comparable to the splitting of the atom or the publication of Darwin's Origin of Species. It also marked the maturation of a bold new science: molecular biology. Under this probing discipline, man could at last explore—and understand—living things at their most fundamental level: that of their atoms and molecules. Once molecular biology was sardonically defined as "the practice of biochemistry without a license." Now it has become one of science's most active, exciting and productive arenas, taking the limelight (and some of the best talent) from that longtime favorite, nuclear physics.
Using laboratory skills that were unheard of a generation ago, scientists have isolated, put together and manipulated genes, and have come close to creating life itself. In 1967 Stanford University's Arthur Kornberg synthesized in a test tube a single strand of DNA that was actually able to make a duplicate of itself. Kornberg's "creation" was only a copy of a virus, a coated bit of genetic material that occupies a twilight zone between the living and inanimate. But many scientists have become convinced that they may eventually be able to create functioning, living cells.
Molecular biology, in part, is rooted in the science of genetics. Ever since Cro-Magnon man, parents have probably wondered why their children resemble them. But not until an obscure Austrian monk named Gregor Mendel began planting peas in his monastery's garden in the mid-19th century were the universal laws of heredity worked out. By tallying up the variations in the offspring peas, Mendel determined that traits are passed from generation to generation with mathematical precision in small, separate packets, which subsequently became known as genes (from the Greek word for race).