Our data strongly support the gestural flexibility hypothesis according to which our closest primate relatives use brachiomanual gestures more flexibly across contexts than they do facial expressions and vocalizations. Gestures seem less closely tied to particular emotions, such as aggression or affiliation, hence possess a more adaptable function. Gestures are also evolutionarily younger, as shown by their presence in apes but not monkeys, and likely under greater cortical control than facial/vocal signals (see Introduction). This observation makes gesture a serious candidate modality to have acquired symbolic meaning in early hominins. As such, the present study supports the gestural origin hypothesis of language.