One of the major moments in the journey occurred in the 1940s, when cytogeneticist Barbara McClintock discovered transposable elements (TE), also known as “jumping genes.” Decades later, The Human Genome Project found that these elements made up a staggering 45 percent of the human genome, and managed to proliferate over millions of years thanks to a “copy-and-paste” mechanism. Today, scientists believe that TEs play a role in genome function, chromosome evolution, speciation, and diversity. So, the team used a technique known as “lentiviral massively parallel reporter assay,” or lentiMPRA, to measure 7,000 MER11 sequences using human stem cells and early-stage neural cells. By tracking the evolution of this group, scientists have shown that DNA originally inherited from ancient viruses can actively participate in the form and function of primate DNA. Even though the journey of understanding the human genome is more than 150 years in the making, it still has the remarkable ability to surprise us at seemingly every turn.