Chimpanzee sign language points to universal laws of communication

Gestures akin to sign language used by chimpanzees follow several of the same fundamental principles as human language, in a code that extends far beyond mammalian communication and possibly to extraterrestrial life.

Researchers from the University of Roehampton performed a long-term analysis of 2,000 individual gestures of 58 different types used by chimpanzees in Uganda’s Budongo Forest Reserve to communicate when in close quarters, using quantitative linguistic methodologies.

Curiously, the chimp’s sign language obeyed both Zipf's law of abbreviation, in which commonly used words tend to be shortened, as well as Menzerath’s law, in which larger linguistic structures are constructed from shorter parts – think syllables in words – in both their vocal and non-vocal behavior.

The chimps combine hand and foot gestures with mouth noises, body postures and even facial expressions, depending on their proximity to each other. Previous research on chimpanzee hooting and panting showed the rules at work but didn’t delve as far into their non-verbal communication.

“Primate gestural communication is, of course, very different to human language, but our results show that these two systems are underpinned by the same mathematical principles,” lead researcher Raphaela Heesen said.

“We hope that our work will pave the way for similar studies, to see quite how widespread these laws might be across the animal kingdom.”

Both of the aforementioned laws are linked to compression, the concept of minimising code length, and the new research indicates that this concept applies not only to our human languages but to animal behavior and a wide variety of biological information systems, including, most notably, genes, proteins and genomes.

Chimpanzees aren’t the first animals to be observed in this way as scientists have previously determined that Formosan macaques, marmosets, certain species of bat and even dolphin all like to keep the chit-chat to a minimum and make communication as efficient as possible.

The current body of research points to some form of universal principle driving coding efficiency across the biological world which yields exciting realms of research and some interesting possibilities for breakthroughs in interspecies communication.

The researchers will next investigate bonobos to see how far these mathematical-linguistic underpinnings go following the logic that, if it does stem from chemistry, there may be an element of universality to communication that could extend to extraterrestrial life, if it exists.

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