Language’s intentional nature has been highlighted as a crucial feature distinguishing it from other communication systems. Specifically, language is often thought to depend on highly structured intentional action and mutual mindreading by a communicator and recipient. Whilst similar abilities in animals can shed light on the evolution of intentionality, they remain challenging to detect unambiguously. We revisit animal intentional communication and suggest that progress in identifying analogous capacities has been complicated by (i) the assumption that intentional (that is, voluntary) production (...) of communicative acts requires mental-state attribution, and (ii) variation in approaches investigating communication across sensory modalities. To move forward, we argue that a framework fusing research across modalities and species is required. We structure intentional communication into a series of requirements, each of which can be operationalised, investigated empirically, and must be met for purposive, intentionally communicative acts to be demonstrated. Our unified approach helps elucidate the distribution of animal intentional communication and subsequently serves to clarify what is meant by attributions of intentional communication in animals and humans. (shrink)

In this study of the functionally referential alarm calls in the meerkats, we tested the hypothesis that the ability to refer to a specific location was an important factor in the evolution of discrete vocalizations. We investigated what information receivers gained about the location of the predator from alarm calls with high stimulus specificity compared to alarm calls with low stimulus specificity. Furthermore, we studied whether visual cues about the localization of the predator may be available from the posture of (...) the caller. We described the general behaviour of the caller, the caller’s posture, and in particular its gaze direction. We then observed receivers responding to the different call types, to determine whether the acoustic structure of the calls was enough for them to respond in the appropriate way, or whether they used additional visual cues from the caller. We tested this with specific manipulation experiments, using three set ups of playback experiments: no caller visible; model guard with specific gaze direction; and live sentinel. Natural observations and experiments confirmed that in high urgency situations the meerkats have enough information from the acoustic structure of the call to respond appropriately. When hearing low urgency calls that are less stimuli specific, meerkats used visual cues as an additional source of information in a few cases. This may indicate that functionally referential calls evolved to denote the location of the predator, rather than the predator type or its velocity of approach. However, when discussing this result in comparison to other functionally referential calls, such as the food associated calls and recruitment calls, this localization hypothesis does not appear to apply to the functionally referential calls in general. (shrink)