even those very different from us.
An example of this can be found in research into the language of Caribbean reef squid (Moynihan 1991). Caribbean reef squid speak with their skin. Pigment cells in their skin called chromatophores are attached to muscles that can be contracted or relaxed. This either exposes the pigment or makes it invisible, which allows the squid to change the color patterns on their skin very rapidly. In doing so they create complex visual patterns ranging from white to camouflage, which send sophisticated signals to other squid. Males, for example, use specific color patterns to flirt with females, who in turn use other patterns to respond. When there are other males around, the male can use half of his body to signal to the female, and the other half to tell his opponent to back off. Many different patterns are possible, and they can change in the blink of an eye. Because of the subtlety and speed of the changes, most of the patterns have not yet been deciphered. In addition to the color patterns, squid also use body postures to create meaning. Biologist Moynihan (1991) argues that the visual patterns, together with the postures, constitute a proper language, with nouns, verbs, adjectives, and adverbs. Nouns and verbs are most important; they are, for example, used to establish whether the other wants to mate. Adjectives and adverbs are then used to describe the intensity of the desire to mate. Because of the difficulty in understanding all the elements of this visual language, the precise rules of this grammar are still unknown, but the broad meaning can be grasped from the context. Studying these expressions as a language with a grammar helps us to get a better grasp of how they function; seeing their grammar as grammar can also help us to get a richer view of what grammar can entail.
Another example is bird song. The songs and calls of many species of birds have been studied extensively, and it was long assumed that the most important functions of song were to attract females and to defend territory. However, recent research focusing on grammar shows that bird languages are far more complex than was supposed, both with regard to the content of messages and their structure (Slobodchikoff 2012). Many aspects once thought to be unique features of human language have also been found in bird languages. Humans can, for example, produce new sounds that have meaning for speakers of the same language because they follow certain syntactic rules. A recursive, hierarchical embedding, needed for new utterances to make sense, requires a context-free grammar. Recursion has been found in the language of many birds (and other non-human animal species, such as elephants), including chickadees (Kerschenbaum et al. 2014). Chickadee language consists of a variety of different sounds that can be combined creatively. Single units are combined, like words, into patterns and sentences, of which the combinations become more complex as the intensity of the communication increases (Slobodchikoff 2012). For the Carolina chickadee, the meaning of sentences changes when the order of the elements changes (Kerschenbaum et al. 2014). Starlings have recently been found to classify sentences from embedded, context-free grammar (Gentner et al. 2006). The syntax of the black-chinned hummingbird also has an open system similar to that of starlings and humans (Slobodchikoff 2012).
Grammar is also being studied in the languages of other animals. The songs of humpback whales (Suzuki et al. 2006), which sound improvised and chaotic to the human ear, are formed like sentences, consisting of smaller units that are combined to form songs containing up to 400 elements. Mexican free-tailed bats are currently seen as the species of non-human mammals who have the most complex forms of vocal communication (Gillam and Fenton 2016). Because most of their vocalizations are beyond the range of the human ear, humans long thought their vocal communication was limited. But new technologies show that their songs are complex both in content—they discuss everything from territory to social status, love, raising children, and other social affairs—and in structure, with fixed elements combined using grammar. They are creative as well; males each develop their own songs to sing to females. Technology helps us perceive and interpret the complexities of the languages of other species. Dolphin researcher Denise Herzing has studied dolphin languages for decades, and uses technologically advanced equipment to translate their language into human language, and vice versa. She first managed to communicate a word in this manner—sargassum, a type of seaweed—in 2013, and emphasizes the importance of studying behavior in parallel with language (Herzing 2016). Elephants use low-pitched sounds to communicate over long distances, and these infrasounds give them a private communication system that plays an important role in their complex social life. Researchers from the Elephant Listening Project use recordings to decipher their languages, and have found that they communicate not only information, but also emotions and intentions. They have different words for categories (such as groups of humans, and bees) and for individuals, in which they also express family relations (Elephant Listening Project 2017).
The use of recordings and technology can help to categorize animal vocalizations and map the structure of their languages, but, as has been explained, to only study structures is not enough if we want to understand what they mean. Lizards have four ways to express themselves: by their posture, the number of legs they have on the ground, nodding their head, and displaying or inflating their chin. This may seem fairly simple, but there are 6,864 possible combinations, of which 172 are frequently used (Slobodchikoff 2012). We can map these movements, but to grasp what they mean we need to study the grammar of the wider context in which they are used, including how these expressions stem from and shape social relations. In linguistics, grammar is usually regarded as the set of rules that governs the composition of words, phrases, and clauses in a natural language. It also refers to the study of these rules. Wittgenstein (1958) reminds us of the relevance of the wider network of rules, linked to social practices, that determines whether or not use of language is meaningful. Meaning does not simply spring from technical instructions for the use of words and sentences; it is always also tied to a given context.
In studying non-human animal language games, we should therefore focus on their structure and on context. In both of these aspects we must also avoid taking human language as the blueprint for what qualifies as proper language, and investigate how non-human animals create meaning.
Meta-Communication: Play and Greeting
Non-human animals use language to express and shape social relations. In a similar way to humans, they can also communicate about communication: they are capable of meta-communication, which plays a major role in developing relations with others. We find meta-communication in different language games—humor between humans is one. In this section I will discuss two non-human animal or interspecies language games in which we find meta-communication, play and greeting, in order to shed further light on the connection between using language and constituting social rules, and to show that non-human animal language games that do not involve human language can still be complex and enable non-human animals to discuss situations that transcend the here and now. These examples shed light on the relations between language and world, which I discuss in more detail in the next chapter.
Play behavior is found in many species, not only in placental mammals, but also in marsupials, birds, reptiles, and fish. Play-like behavior has furthermore been found in different invertebrates, such as crustaceans, cephalopods, and insects, including ants, bees, and cockroaches (Burghardt 2005). In play, non-human animals use behaviors and movements that usually form part of other social situations, such as fights, flights, attacks, and sexual advances. Animals of many species use special play behaviors to indicate that they want to play. Dogs, wolves, and coyotes, for example, use the play bow as an invitation to play; they also use it during play, for example, in order to make amends when something rough or unintended happens. The meaning of the bow might be “I want to play” or “sorry about that, I still want to play.” During play, dogs often change roles; dominant dogs adopt submissive postures and vice versa, and stronger dogs sometimes self-handicap to make play possible. In dog play, however, certain social conventions remain intact (Smuts 2006); for example, dominant dogs will never lick the mouth of a subordinate dog.
Play can be a form of competition and a form of cooperation. Dogs need to play to learn social rules, but it is more than a learning mechanism; dogs are creative in play, they express themselves and enjoy themselves. Furthermore, as we have seen, dogs in play communicate about communication. When the play gets rough and they
