Genome as a multipurpose structure built by evolution

International audienceThe publication in 2012 of the results of the ENCODE program generated an acrimonious debate about the role of junk DNA. This debate is a symptom of the difficulties of dovetailing functional and evolutionary descriptions of genomes. My argument is that extant genomes are the result of a progressive evolutionary construction. To the basic function – to give rise to RNA and proteins – have been successively added other functions – regulation by microRNA and epigenetic marks, for instance. This process of complexification was not a regular one, but the result of a complex evolutionary history, different for the different genomes