On this day in history, February 28th 1953, Cambridge University scientists James D. Watson and Frances 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. On the morning of February 28, they determined that the structure of DNA was a double-helix polymer, or a spiral of two DNA strands, each containing a long chain of monomer nucleotides, wound around each other. According to their findings, DNA replicates itself by separating into individual strands, each of which becomes the template for a new double helix.