The existence of what 20th century geneticists had already perceived (and wrongly described as "junk DNA"!) was confirmed by the sequencing of the first complex genomes, including that of Homo sapiens. A large part of what defines a living thing is not unique, but repeated, sometimes a very large number of times, increasing in complexity with successive duplications and multiplication.
Understanding and defining the many functions of this myriad of repeated sequences, as well as their evolution through natural selection, has become one of the major challenges for 21st century genomics.
Guy-Franck Richard is a research director at Institut Pasteur, France. He also leads a team within the CNRS unit Génétique des génomes. His research focuses on the stability and evolution of repeated DNA sequences in eukaryotic organisms.