Gestural Origins of Language

It’s widely theorised that man’s first language was gestural. Most theories attribute the development of spoken language to man’s superior intelligence.

Chimpanzees have been taught sign language. So, it’s reasonable to assume that some australopithecines, evolutionary predecessors of humans, could have acquired a similar language.

Though primates have the ability to produce vocalisations, these aren’t under close voluntary control. They are triggered by internal or external, mainly social, stimuli.

Human speech is deliberate and manipulative. It’s a result of sharper and deeper cognitive analyses of sensations. Lieberman suggests that articulate speech is a fairly recent human acquisition.

Preliminary inspection of casts of Homo Erectus and australopithecine skull and mouth parts indicates that these hominids were probably incapable of producing human speech sounds¹. 

The beginnings of a language system could have been elaborated from the fundamental finger-pointing gestures exhibited by chimpanzees, with consciousness of self derived from self-referential pointing². 

Though chimpanzees exhibit gestural behaviour, consisting of attention-orientation toward leading individuals, some arm and hand gestures, facial expressions, body postures, and incipient locomotion, any of which may be accompanied by vocalisation³, the gestures lack the complexities and rules of language.

Consistently, primates have the ability to interpret gestures. This consists of predicting others’ intentions by watching head and neck positions, flicking of the ears or tail, body stance, movements, and gait.

Modern primates imitate gestures too. The young tend to mimic the old. Propagating gesturing, the imitation cements patterns of behaviours which the primates can be identified by.

Construction and use of tools and weapons have also been attributed to the origin of speech⁴. It is generally claimed that transmission of tools had to be based on speech. Others have proposed that the sounds emitted while making or using tools would have led to onomatopoeic symbols for such tools or processes³.

Just as the imitation of the characteristic motor behaviour of another animal can come to stand as a sign for that animal, the gesture or characteristic motor sequence associated with the making or use of a tool or weapon can come to serve as a sign for it³.

Hand and finger movements are often accompanied by tongue thrusts and twists⁵. Tasting and testing objects is a fundamental way to construct meaning around objects.

Though we evolutionarily elaborated the correlates between speech and gestures, the transition from gestural to spoken language remains under-substantiated and granularly unexplained.

Making manual gestures is slower than speaking, requires more energy, and prevents the use of the hands for any other activity while the message is being transmitted³. Consistently, decoding gestures is more time-consuming than interpreting heard speech. Given these limitations, speech seems developmentally natural.

The limit of signs in modern sign language is 1500-2000 signs. All spoken languages have a wider vocabulary. Given cultural and technological development, gestural languages may have reached the capacity to communicate. So, expression flourished in speech.

References
1. Crelin, personal communication
2. Tran DuCc Thaio (1966, 1969a, b, 1970)
3. Hewes, 1973
4. Greenberg, 1968
5. Darwin, 1872