Read more: Instant Expert: The evolution of language
Different linguistic traits must have appeared at different times, perhaps for different reasons. But which of these “protolanguages” came first?
When viewing language as a collection of many distinct components, it becomes clear that the different linguistic traits must have appeared at different periods of human evolution, perhaps for different reasons. But while most theorists agree that early humans passed through multiple stages en route to modern language, there are major differences of opinion concerning the order in which the different components appeared.
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A system which possesses some, but not all, components of language can be termed a “protolanguage” – a term introduced by anthropologist Gordon Hewes in 1973. Three potential protolanguages dominate theories of language evolution.
The protolinguistic ape?
The earliest writing, providing clear evidence of modern language, dates from just 6000 years ago, but language in its modern form emerged long before then. Because all modern humans come from an ancestral African population, and children from any existing culture can learn any language, language must have preceded our emigration from Africa at least 50,000 years ago. But can we put a date on the emergence of the first rudimentary protolanguages?
Whether gestural, musical or lexical, protolanguage considerably surpassed modern ape communication in the wild. With all the cognitive challenges, and benefits, this would bring, we would expect these early humans to differ considerably from their forebears in both anatomy and culture. Using this logic, Homo erectus, which originated almost 2 million years ago, appears to be the most likely candidate.
H. erectus were larger than their predecessors, and had brain sizes of 900 to 1100 cubic centimetres. These approach the size of our own brains, which average about 1350 cubic centimetres. This suggests a capability for flexible intelligence and culture. Their stone tools were vastly more sophisticated than those of Australopithecus, suggesting they may have had more advanced communication, though the tools were less sophisticated than tools made by Neanderthals and modern humans.
Importantly, the H. erectus tools appeared to reach a kind of stasis – their iconic Achulean hand axe, which was a symmetrical all-purpose tool, persisted for a million years. This suggests they did not have full language, which would have accelerated cultural and technological change. Hence they might have had some, but not all, of the linguistic capacities modern humans possess – a protolanguage, in other words.
Musical beginnings
This prominent model of protolanguage was offered by Darwin in 1871, and focused on the origins of vocal learning, a capability assumed (but not explained) by word-based, or lexical, protolanguage. Darwin realised that in most vocal learning species, complex learned vocalisations are not used to communicate detailed information, but rather provide a display of the singer’s virtuosity. While the songs of some birds or whales rival human speech in acoustic complexity, they convey only a very simple message, roughly “I’m an adult of your species and want to mate.”
Based on this analogy, Darwin suggested that human vocal learning originated in the context of sexual selection, territoriality and mate choice, and initially resembled song more closely than speech. Only later, by this model, did the individual notes and syllables of these vocal displays take on meaning, probably in an initially holistic manner. Since Darwin, many others have taken up the musical protolanguage hypothesis, and it is attracting increasing support today. One virtue of this hypothesis is that it also provides an explanation for music: another universal characteristic of our species. By this model, music is a living reminder of an earlier stage of human evolution, preceding true language.
Eloquent gestures
Another well-established model of protolanguage suggests that language was originally conveyed by gestures, rather than speech. One avenue of evidence comes from observations of apes, which lack vocal learning and speech, but use manual gestures in an intentional, flexible and informative way. While attempts to teach apes spoken language fail completely, efforts to teach apes to communicate via manual gesture have been much more successful.
Although no ape has ever mastered a full sign language, apes can learn and use hundreds of individual manual gestures communicatively. The visual/manual mode is clearly adequate for full human language, as sign languages convincingly demonstrate. These two features make gestural protolanguage a popular alternative view today.
One prominent version of gestural protolanguage, offered by neuroscientist Michael Arbib at the University of Southern California, Los Angeles, suggests that signs did not, initially, refer to individual objects or actions, but rather to whole thoughts or events. This is an example of what is called a holistic protolanguage, in which whole complex signals map directly onto whole complex concepts, rather than being segmented into individual words. This is precisely how early gestures and utterances are understood and used by infants in early language acquisition. In such holistic models, whole sentences came first, and were only divided up into words during a later “analytic” stage of biological evolution and cultural development. This approach contrasts with the “synthetic” models of protolanguage, which have individual words from the very beginning.
Gestural models face the difficulty of explaining why our species switched to using speech so thoroughly. It may have been due to the need to communicate in darkness, or because hands became occupied by tools. But speech has disadvantages too. Speaking aloud, we cannot safely communicate with our mouths full, or in the presence of dangerous predators, or in loud environments like waterfalls or storms. The selective pressures that might have driven humans to rely so heavily on speech alone remain elusive.
First words
One highly intuitive model suggests that early humans had words, but did not arrange them into syntactically structured sentences. This model of “lexical protolanguage” parallels language development in children, who start out with single-word utterances, move on to a two-word stage, and then begin forming more complex sentences with syntax.
Linguist at the University of Hawaii, Manoa, is one of the main proponents of this model. He once suggested that the addition of syntax in all of its complexity might have occurred quite suddenly, due to a mutation with large effects on brain wiring, quickly catapulting our species into full language. But linguist at Tufts University in Medford, Massachusetts, suggests a much finer and more gradual path to modern syntax, starting with simple word order and progressing steadily to fine points of grammar that make modern languages difficult for adults to learn.
Despite various other disagreements, all proponents of lexical protolanguage agree that language began with spoken words, referring to objects and events. Most also agree that the purpose of protolanguage was the communication of ideas. Although each of these assumptions seems intuitive, they are challenged in other models of the evolution of language.