On February 28, 1953, Cambridge University scientists James D. Watson and Francis H.C. Crick announce that they have determined the double-helix structure of DNA, the molecule containing human genes.

Though DNA—short for deoxyribonucleic acid—was discovered in 1869, its crucial role in determining genetic inheritance wasn’t demonstrated until 1943. In the early 1950s, Watson and Crick were only two of many scientists working on figuring out the structure of DNA. California chemist Linus Pauling suggested an incorrect model at the beginning of 1953, prompting Watson and Crick to try and beat Pauling at his own game.