Language, Action and Thought

Non-human great apes inform one another in ways that can seem very humanlike. Especially in the gestural domain, their behavior exhibits many similarities with human communication, meeting widely used empirical criteria for intentionality. At the same time, great ape gesture does not appear to exhibit the same open-ended richness of human communication. How to account for these similarities and differences in a unified way remains a major challenge. Here we make a key distinction between the expression of intentions (Ladyginian) and the expression of specifically informative intentions (Gricean), and we situate this distinction within a ‘special case of’ framework for classifying different modes of attention manipulation. We reinterpret video footage of great ape gesture as Ladyginian, and we describe how the attested tendencies of great ape interaction—to be dyadic rather than triadic, to be about the here-and-now rather than ‘displaced’, to have a high degree of iconicity, and so on—are products of its Ladyginian but not Gricean character. We distinguish several varieties of meaning that are cognitively continuous with one another, and we conclude that the evolutionary origins of meaning lie in gradual shifts in what modes of attention manipulation are enabled by a species’ cognitive phenotype: first Ladyginian and in turn Gricean. The second of these shifts rendered humans, and only humans, language-ready.