Photo 51 Reprinted by permission from Nature, Volume 171: 740-41, ©1953 Macmillan Publishers Ltd.

Photo 51 - Capturing the Science of Life

Long before the discovery of DNA, mankind knew of a phenomenon that allowed certain traits to be passed on from parents to offspring. For thousands of years, those involved in animal husbandry explored this concept by mating animals specifically for the production of quality offspring with distinctive traits. However, the science behind the heredity of these traits would not be known until the early 20th century.

In 1865, Gregor Mendel discovered that inherited traits are determined by discrete units, or 'genes,' that are passed on from the parents. Mendel's work was largely ignored at the time, and it wasn't until the turn of the 20th century that three European scientists independently confirmed Mendel's results and began to uncover the laws of inheritance.

Due to its simplistic sequence, DNA was at first deemed unqualified to be the code for all living things. However, in 1944, Oswald Avery and his colleagues, working in the New York Rockefeller Research Institute, classified DNA as the 'transforming principle' and determined that DNA is the carrier of genes.

Identifying DNA as the code of life was a remarkable discovery. However, uncovering the structure of DNA would prove to be the key to understanding the role it plays in the formation of life. While working at King's College in London in 1952, crystallographer Rosalind Franklin produced X-ray diffraction images of DNA that revealed its helical shape. One of Franklin's photos, 'Photo 51' as it was famously named, led to the discovery of the double helix by James Watson and Francis Crick in 1953. Photo 51 proved to be a driving force behind one of the greatest discoveries in the history of science.

Since the 1950s, the science of genetics has advanced at an impressive speed, always building upon those critical first steps of discovery made by Franklin, Avery, Morgan, Mendel and so many others. In 1985, a meeting was held at the University of California at Santa Cruz to discuss the possibility of sequencing the human genome. Proposals were introduced for a global Human Genome Project and 10 years later, full-scale decoding began with a target completion date of 2005. However, in the year 2000, a full five years ahead of schedule, the first draft of the human genome was completed.