As evidence supporting his position Deacon pointed to the robustness of language. If language came from a big mutational leap 100 to 150 thousand years ago, we should see only a small number of genes involved in its production. These genes would be easily mutated, producing birth defects with very specific language deficits such as an inability to insert clauses within clauses. Instead there are many genetic correlates of language and language acquisition follows a predictable pattern in cultures around the world. Language is well integrated with our other cognitive abilities. These patterns all fit with an ancient and extended evolution.
This robustness leads Deacon to assume that symbolic communication began with the rise of stone tools for cutting meat, about 2.4 to 1.8 million years ago. Readers of Deacon’s book, The Symbolic Species, will know that the term “symbolic communication” is not used casually. Communication, Deacon teaches, can be iconic, indexical, or symbolic. Ionic communication is illustrative, for example making a chopping gesture is iconic, showing what an action looks like. Indexical communication depends on the larger context. Pointing at something gets its meaning from the object of the pointing. Symbolic communication lacks an intrinsic link to its reference. Pointing or mimicking will not do. Rituals can be symbolic. A blood-brother ritual in which blood flows and mixes can be powerful, but its meaning cannot be indicated by pointing or showing.
Deacon disagrees with the many linguists who insist that grammar is a system of rules for organizing a series of arbitrary signs. Grammar, he says, adds indexical signs to “ground” the symbols. Thus, “He married her in that house,” grounds the symbolic action married with a whole range of indexical signs (he, her, in, that).
This view of grammar has implications for protolanguage, which is commonly thought of as language without an organizing set of rules. In Deacon’s view protolanguage is language that is not fully grounded. To make up for the absence, ritual has to play a larger role in grounding the symbol. We still see much of this sort of thing in greetings, ceremonies, trading, and threats.
Deacon believes that originally, protolanguage was limited to pantomime and pointing with only stereotypical sounds. The basis for this position is the familiar one that apes have no voluntary control over their vocalizations but do make voluntary gestures. Thus, they would have first used gestures and only later transferred these signs to vocalizations. Why transfer them? Deacon suggests it is easier to learn a vocalization than a hand sign. Hand signs are reversed for the looker. If we face one another and I see you wave your right hand, the hand you wave is on my left. In order to imitate you and wave my right hand, I have to make a transformation, translating your action on my left as a right side action. Vocalizations, however, require no such transformation.
It was a clever argument, but it is not clear how many people were persuaded by it. First, deaf children seem to learn hand signs without the transformation problem. Second, it is not immediately clear that evolving voluntary control over one’s vocal apparatus is easier than evolving an intuitive transformation.
Although protolanguage is symbolic, it is still rooted in the here and now. To move beyond that, to talk of absent things, protolanguage had to become a full language by evolving syntax. The syntax serves the indexical functions when there is nothing to point to.Deacon also discussed at length the symbolic need that he believes created the pressure for protolanguage. This was the need to establish a way of males hunting together but mating separately. I won’t go into that argument here because readers of his book will be familiar with it, and the argument is so detailed that to give it justice would require a separate report.