The language void 10 years on: multimodal primate communication research is still uncommon

Abstract

Human language is thought to have evolved from non-linguistic communication systems present in the primate lineage. Scientists rely on data from extant primate species to estimate how this happened, with debates centering around which modality (vocalization, gesture, facial expression) was a likely precursor. In 2011, we demonstrated that different theoretical and methodological approaches are used to collect data about each modality, rendering datasets incomplete and comparisons problematic. Here, 10 years later, we conducted a follow-up systematic review to test whether patterns have changed, examining the primate communication literature published between 2011 and 2020. In sum, despite the promising progress in addressing some gaps in our knowledge, systematic biases still exist and multimodal research remains uncommon. We argue that theories of language evolution are unlikely to advance until the field of primate communication research acknowledges and rectifies the gaps in our knowledge.

KEY WORDS:

• multimodal
• vocalization
• facial expression
• gesture
• primates
• language evolution

ACKNOWLEDGEMENTS

We thank Federica Amici, Blanca Striegler, and Damilola Olaoba for their support with coding the data. We are also grateful to Jamie Whitehouse for creating the figures. Many thanks to the participants of the “Multimodal Communication Workshop” (Erica Cartmill, Kirsty Graham, Cat Hobaiter, Eithne Kavanagh, Jérôme Micheletta, Linda Oña) for our fruitful debates on terms and definitions of multimodal research.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.