Scientists have solved Leonardo da Vinci's human heart mystery by studying trabeculae, a branching structure first described by the artist. The study involved combining genetics and fractal theory to determine the anatomical function of these structures. The researchers found that this branching muscle layer plays a part in the risk of heart disease. They identified 16 significant loci that contain genes associated with haemodynamic phenotypes and regulation of cytoskeletal arborization. This discovery could lead to a more complex understanding of the trabECulae.