The family Caricaceae comprises 35 species in currently 6 genera. Thirty-two species occur in Central and South America and two in Africa. The species occur in a wide range of tropical habitats, and growth forms range from rhizomatous herbs to tall trees. Most species are dioecious, with strictly male and female individuals. During the last decades, the highland papayas (Vasconcellea spp.) were considered the closest relatives of papaya. However, a molecular phylogeny based on nuclear and plastid sequences from all species shows that Carica papaya is sister to a Mexican clade of four herbaceous species in the genera Jarilla and Horovitzia. This unexpected discovery has important implications for the improvement of papaya by plant breeders, and as a first step, we here summarize the currently sparse knowledge concerning the morphology and ecology of the Mexican Caricaceae. We also discuss the molecular phylogeny of family and its biogeographic implications, such as transatlantic dispersal, diversification concomitant with the Miocene uplift of the Andes, expansion along the Isthmus of Panama, and adaptation of species in the genus Jacaratia to the drier climates and more open vegetation that predominated during the Late Miocene, 12–7 Ma ago.