Baboons produce vocalizations comparable to vowels. This has been demonstrated using acoustic analyses of vocalizations coupled with an anatomical study of the tongue muscles and the modeling of the acoustic potential of the vocal tract in monkeys. The data confirm that baboons are capable of producing at least five vocalizations with the properties of vowels, in spite of their high larynx, and that they are capable of combining them when they communicate with their partners. The vocalizations of baboons thus point to a system of speech among non-human primates.