A recent study explored the genome-wide variation of tandem repeats (TRs) within and across natural populations of humans and five other primate species. Analysis of 83 genomes and gene expression data revealed an association between the presence of TRs in the promoters, 3′ untranslated regions (UTRs), introns or exons of genes and increased gene expression divergence. Furthermore, genes with promoters that contained polymorphic small repeats exhibited more divergent expression than those that contained fixed or no TRs. These studies highlight the potential contribution of TRs to primate evolution.