Many notions of a mysterious “vitalism,” or “life force,” at the heart of the reproduction of living beings were exchanged for materialist (physical) accounts after James Watson and Francis Crick discovered the double helix in 1953. Watson and Crick’s discovery of the structure of DNA took the mystery out of the idea of life because it could account for the reproduction of genetic material in purely chemical terms. The double helix was a three-dimensional model of the twisted-ladder structure of deoxyribonucleic acid (DNA), which showed how sequences of acids and bases would replicate themselves through chemical reactions. Watson and Crick’s discovery paved the way for gene-based studies in heredity, culminating in the “mapping” of the human genome (totality of genes) by the early twenty-first century.