As demonstrated by the above examples of nonhuman primate communication, one could postulate that there are certain aspects of human vocal production which are similar. Additionally, one can hypothesize that the ability to vary the arrangement of vocal elements, and to produce meaning differences, as found in gibbon duets, chimpanzee long calls and vervet alarm calls, may be the source of language origins. However, it is important to remember that nonhuman primates are not ‘unevolved’ human beings. Humans and nonhuman primates are completely different species. Behavioural and physiological traits from one may be used as an analogy for the other species. However, it makes no sense to state that chimpanzees are more evolved than macaques, nor that the vocal capabilities of humans are ‘more complex’ than that of other nonhuman primates.
Instead, one can examine which fundamental traits define the communication of nonhuman primates, and other animals: 1) the ability to recognize the vocalizations of its particular species, as distinct from other environmental noises; 2) the ability to recognize the vocalizations of kin; 3) the ability to recognize the vocalizations of allies and ‘strangers’; 3) the capacity to learn new vocalizations; 4) the capacity to discern ‘referential meaning’ contained within a species specific vocalization (i.e. the difference between a mating call and an eagle alarm call); and 5) the capacity to alter vocalizations without altering the initial referential meaning.
It is important to remember that human beings are not born as adults. We have a long, steep learning curve which takes years to master. Secondly, vocal communication is only one form of communication. Both humans and nonhuman animals rely upon visual and gestural communication, as much, if not more, than upon vocal communication. Additionally, the majority of human language is little more than ‘grunts’ of acknowledgment or other noises (umm) which fill conversational silences. Although Bickerton (1990) would say that these ‘words’ fulfill a grammatical function by occupying a ‘position’ in a sentence, one could just as simply state that it is no more complex than a chimpanzee long call response. Finally, defining human language as ‘complex’, since it is not bounded in space or time, is a bit of a stretch. Languages are fluid, their complexity arises once their vocabularies increase, which has more to do with the consensus regarding novel acoustic sounds than the so called grammatical rules of a language. In other words, if the constraints of the hypotheses fail when applied to humans, why are they employed on nonhuman primates?
