miRNA regulatory variation in human evolution.

Recent advancements have revealed a complex post-transcriptional regulatory network in humans involving miRNAs. However, the contribution of miRNAs to human evolution, especially interindividual variation associated with miRNAs, is only beginning to be studied. In this article, we illustrate the extent of variation in miRNA-mediated post-transcriptional regulation in humans. Based on evidence from recent studies, we argue that the evolution of post-transcriptional control may be adaptive, and that it not only complements the primary transcriptional regulation by transcription factors (TFs), but also diversifies gene expression phenotypes, thereby generating genetic novelty on which natural selection subsequently acts. Given that current evolutionary analyses and genotype-phenotype mapping are primarily focused on protein-coding genes and TF-mediated regulations, comprehensive examination of post-transcriptional variations should be included in future studies to add a new dimension to understanding of human phenotypic evolution.