What is communication?

Communication is contact which shares cognition or emotion. By this definition, telepathy is a kind of communication. In situations where telepathy does not work, cognition and communication can only be shared by the transmission of signs, which is then a covert condition of the definition. The transmission of signs may be intended by the communicators. This applies to many animals, but not to plants. If intention is part of the definition, ‘communication among trees’ is a metaphor.

Cognitive and communicative abilities have developed in different branches of the animal kingdom in mutual independence. Elephants, apes, dogs and rats show empathy with their peers. Elephants cooperate. Dolphins and parrots achieve remarkable complexity in their communication. Thus, man is far from being the only animal to possess cognition and communication (Lehmann, K. 2024).

Effability includes the possibility of displaced reference, i.e. speaking about topics that are remote in space and/or time. Animal communication is situation-bound. This mostly means it is bound to the speech situation, to the ‘here and now’. Some animals can communicate about the wider situation directly related to the speech situation. The waggle dance of bees refers to nectar just found in the immediate environment and is limited to that. Similar constraints apply to the communicative abilities of ants and birds.

Visual signs

Animals communicate by all of the senses that humans use to this purpose, and some more. Communication by visual signs includes the peacock fanning its tail or a dog wagging its tail. Communication by gestures is common among primates; see below. However, the pointing gesture so basic to human communication is not widely understood; and if it is, e.g. by dogs and dolphins, this is probably an achievement of domestication.

Auditory signs

Sound signals are used for communication in two segments of the animal kingdom (Lehmann, K. 2024: 191):

• Birds produce sound signals by their beak. Songbirds have species-specific rules for their song, which are learnt during the maturation phase. In some of these songs, recursion is observed (Lehmann, K. 2024: 193). Hummingbirds produce chirps, whistles and produce chattering sounds to chase others away from what they consider their territory. Parrots make many different sounds to warn, threaten or signal contentment.
• Mammals produce sound signals with their snout. Apart from primates, this includes elephants, which produce a rumble as a 'let's go!' sign or trumpet through their trunk in aggression. Seals have a wide repertoire of cries. Whales have elaborate songs. A dolphin has a signature whistle which identifies it. It also remembers the names of its peers.

Primate communication

For the evolution of human language, only primate communication is relevant as a predecessor. The brain of non-human primates displays homologues to certain areas of the human brain. Monkeys and apes have a counterpart to Broca's aerea. It contains a mirror-neuron system and is responsible for the coordination of manual actions (Lieberman 2002: 48, 53), including communication by gestures, and is also active in the emission of vocal signals to mates (Tagliatela et al. 2008). Thus, the neural basis for communication by gestures and sounds is already present in primates.

Source: Graham & Hobaiter 2023

As for vocal signals, primates (just like many other animals) issue contact calls to ensure perceptual contact, and alarm calls to warn their group. Vervet monkeys (Chlorocebus pygerythrus) give calls at least in two different contexts, when they attack mates and when they perceive a predator. In the former context they terrify the adversary, in the latter, they warn their mates. Calls used in one context are partly similar to calls used in the other; but within each context, the calls are unique. The alarm calls distinguish between a predator approaching from above or from below. Members of the troop react to them accordingly by fleeing downwards or upwards. In the category of terrestrial predators, calls to snakes differ from calls to leopards. These calls are interpreted depending on the situation context and learnt during maturation (Price et al. 2015). Other species give food calls and different social calls. However, these calls are confined to a rather narrow acoustic range; nor do they allow for fine-tuned differentiation. Chimpanzees combine a subset of their call repertoire in sequences of two or at most three calls (Girard-Buttoz et al. 2022).

Primates' phonatory and articulatory apparatus, on the one hand, and their auditory equipment, on the other are sufficiently similar in their physiological constitution to their human counterpart to be physically capable of producing and perceiving speech sounds. Nevertheless, non-human primates do not succceed in this. The neural network has not yet developed the necessary motor and sensory control capability (Fitch et al. 2016).

There are several examples of individual apes – and occasionally of individuals of other species – who learnt to communicate with humans by an exchange of signs resembling human words. Most successful were experiments that taught young chimpanzees American Sign Language. Even these apes, however, were unable to productively combine signs to form sentences. All their utterances were directive speech acts (Terrace 2019). In general, whatever these individuals succeeded in learning is less representative of animal communication abilities and more of forms of domestication.

All in all, non-human primate communication differs from human language in some crucial respects:

1. Calls differ by acoustic parameters like duration, intermittence, pitch and intensity. There are, however, no units of signs which could be combined. In other words, these signs lack double articulation.
2. Communication is situation-bound; i.e., it refers to features of the speech situation or of the wider situation surrounding communicators. Thus, it lacks effability.

These two properties of animal communication systems hang together: effability is only to be had with double articulation.