Comparison of non-coding and coding genes across different genomes. (A) Venndiagram illustrates numbers and percentages of known genes in human and mouse genomes (adapted from GENCODE, 2015 update). (B) Increased complexity of organisms is associated with marked expansion of genome size and non-coding RNA. X-axis is genome size in bp and Y-axis is size of the genome encoding mRNA or ncRNA (adapted from: Liu, G, Mattick, JS, Taft, RJ. ‘A meta-analysis of the genomic and transcriptomic composition of complex life’. Cell Cycle 12:2061–2072, 2013).