n the 1940s, biologists puzzled over an odd molecule they had found in the nucleus of living cells. Called deoxyribonucleic acid, or dna, the molecule seemed to be the stuff genes were made of. But researchers could not be sure, because no one had yet determined dna's structure. In 1951, James Watson, who had received a PhD in genetics from Indiana University at age 22, joined Francis Crick at Cavendish Laboratory in Cambridge, England. Crick, a physicist, was studying the structure of proteins. The two became intrigued by the work on DNA being done by Maurice Wilkins and Rosalind Franklin, both of King's College in London. Franklin thought DNA was shaped like a helix, but she wasn't certain. Watson and Crick proposed a model for DNA that Franklin quickly showed was incorrect.

     Then Watson got a look at a new DNA X-ray image made by Franklin, and in a brilliant flash of insight realized that DNA must be made of two helices—not one. He and Crick raced to work out the details of this curious double helix. In April, 1953, they published their findings in the British scientific journal Nature. It was without doubt the greatest biological discovery of the century. Once the structure was known, researchers could see how genetic information was encoded in DNA and how that information could be passed on from one cell to its daughter cells. Crick said he and Watson had found the secret of life. Watson was only 23 years old. Crick was 12 years his senior.

     For their discovery, Watson and Crick, along with Maurice Wilkins, were awarded the Nobel Prize in 1962. The award became tarnished in later years when the pivotal role of Rosalind Franklin became clear. Wilkins had shown her X-ray data to Watson. If Watson had never looked at the X-ray, he might never have happened upon the double helix. Franklin died in 1958. Nobels are not given posthumously, so Franklin did not share in the award.

     The importance of the work by Watson and Crick was never questioned, and both continue to be active in research. Watson taught at Harvard University and later directed Cold Spring Harbor Laboratory on Long Island, a distinguished center for basic biological research. He became the first director of the Human Genome Project, the ongoing effort to decode the entire human genetic code, and is now back at Cold Spring Harbor. Crick taught at Cambridge and is now at the Salk Institute for Biological Studies in La Jolla, Calif.

     Their discovery was one of the landmark innovations of the 20th century. And it could give rise to some of the greatest innovations of the 21st.

Related Links
- Cold Spring Harbor Laboratory
- DNA Research Center
- Salk Institute for Biological Studies

PHOTO 1953: A. BARRINGTON BROWN/PHOTO RESEARCHERS