Referential gestures sounds like something we might perform when paying obeisance to something, but the term actually describes what might be called ‘sign language’. For a gesture to be considered ‘referential’, it must have the following five attributes: it is directed towards an object; it is mechanically ineffective; it is directed towards a potential recipient; it receives a voluntary response and it demonstrates hallmarks of intentionality.
A study published in Nature Communications suggests that the practice of referential gesturing might not be limited to the species we currently acknowledge as performing ‘sign language’, namely, humans, other primates, and ravens. The study authors found evidence that some coral reef fish of different species – groupers and moray eels, Napoleon wrasses and octopuses, work together to optimize hunting. The fish see a prey fish hide in the coral, they signal to the eels or octopuses that a fish is hiding in a crevice, the eel or octopus reaches in and grabs the prey, which the hunters then share.
For me, this not only demonstrates that we have a lot to learn about the abilities of other species to communicate; it also shows that some animals are as good or better than humans at cross-species collaboration.
Nature Communications study – Referential gestures in fish collaborative hunting by A.L. Vail, A. Manica, R. Bshary
LiveScience article on the study