Rana’s evolutionary study of the gene family of the odorant receptors (ORs) in ants was published in Genome Biology and Evolution! We found evidence for widespread positive selection following the extensive duplications of ORs in all ant lineages. Positively selected amino acid sites were especially concentrated around the putative ligand binding site, which indicates adaptive evolution of these receptors to recognize more diverse odors. We suggest that ant ORs evolved to recognize new and more diverse vocabulary of pheromones that they use for chemical communication.