Evolutionary timeline
[edit] Primate language
Not much is known about great ape communication in the wild. The anatomical structure of their larynxes does not enable apes to make many of the sounds that modern humans do. In captivity, apes have been taught rudimentary sign language and the use of lexigrams—symbols that do not graphically resemble their corresponding words—on computer keyboards. Some apes, such as Kanzi, have been able to learn and use hundreds of lexigrams.
The Broca's and Wernicke's areas in the primate brain are responsible for controlling the muscles of the face, tongue, mouth, and larynx, as well as recognizing sounds. Primates are known to make "vocal calls," and these calls are generated by circuits in the brainstem and limbic system.[16] Howewer, modern brain scans of chattering chimpanzees prove that they use Brocas area to chatter [17] and there is evidence that monkeys hearing monkey chatter use the same brain regions as humans hearing speech.[18]
In the wild, the communication of vervet monkeys has been the most extensively studied.[19] They are known to make up to ten different vocalizations. Many of these are used to warn other members of the group about approaching predators. They include a "leopard call", a "snake call", and an "eagle call". Each call triggers a different defensive strategy in the monkeys that hear the call and scientists were able to elicit predictable responses from the monkeys using loudspeakers and prerecorded sounds. Other vocalizations may be used for identification. If an infant monkey calls, its mother turns toward it, but other vervet mothers turn instead toward that infant's mother to see what she will do.[20]
Similarly, researchers have demonstrated that chimpanzees (in captivity) use different "words" in reference to different foods. They recorded vocalizations that chimps made in reference, for example, to grapes, and then other chimps pointed at pictures of grapes when they heard the recorded sound.
[edit] Early Homo
Regarding articulation, there is considerable speculation about the language capabilities of early Homo (2.5 to 0.8 million years ago). Anatomically, some scholars believe features of bipedalism which developed in australopithecines around 3.5 million years ago would have brought changes to the skull, allowing for a more L-shaped vocal tract. The shape of the tract and a larynx positioned relatively low in the neck are necessary prerequisites for many of the sounds humans make, particularly vowels. Other scholars believe that, based on the position of the larynx, not even Neanderthals had the anatomy necessary to produce the full range of sounds modern humans make.[21][22] Still another view considers the lowering of the larynx irrelevant to the development of speech.[23]
The term proto-language, as defined by linguist Derek Bickerton, is a primitive form of communication lacking:
- a fully developed syntax
- tense, aspect, auxiliary verbs, etc.
- a closed-class (i.e. non-lexical) vocabulary
That is, a stage in the evolution of language somewhere between great ape language and fully developed modern human language. Bickerton (2009) places the first emergence of such a proto-language with the earliest appearance of Homo, and associates its appearance with the pressure of behavioral adaptation to the niche construction of scavenging faced by Homo habilis.[24]
Anatomical features such as the L-shaped vocal tract have been continuously evolving, as opposed to appearing suddenly.[25] Hence it is most likely that Homo habilis and Homo erectus during the Lower Pleistocene had some form of communication intermediate between that of modern humans and that of other primates.[26]
[edit] Archaic Homo sapiens
Steven Mithen proposed the term Hmmmmm for the pre-linguistic system of communication used by archaic Homo, beginning with Homo ergaster and reaching the highest sophistification in the Middle Pleistocene with Homo heidelbergensis and Homo neanderthalensis. Hmmmmm is an acronym for holistic (non-compositional), manipulative (utterances are commands or suggestions, not descriptive statements), multi-modal (acoustic as well as gestural and mimetic), musical, and memetic.[27]
[edit] Homo heidelbergensis
H. heidelbergensis was a close relative (most probably a migratory descendant) of Homo ergaster. H. ergaster is thought to be the first hominid to vocalize,[28] and that as H. heidelbergensis developed more sophisticated culture proceeded from this point and possibly developed an early form of symbolic language.
[edit] Homo neanderthalensis
The discovery in 2007 of a Neanderthal hyoid bone suggests that Neanderthals may have been anatomically capable of producing sounds similar to modern humans. The hypoglossal nerve, which passes through the canal, controls the movements of the tongue and its size is said to reflect speech abilities. Hominids who lived earlier than 300,000 years ago had hypoglossal canals more akin to those of chimpanzees than of humans.[29][30][31]
However, although Neanderthals may have been anatomically able to speak, Richard G. Klein in 2004 doubted that they possessed a fully modern language. He largely bases his doubts on the fossil record of archaic humans and their stone tool kit. For 2 million years following the emergence of Homo habilis, the stone tool technology of hominids changed very little. Klein, who has worked extensively on ancient stone tools, describes the crude stone tool kit of archaic humans as impossible to break down into categories based on their function, and reports that Neanderthals seem to have had little concern for the final form of their tools. Klein argues that the Neanderthal brain may have not reached the level of complexity required for modern speech, even if the physical apparatus for speech production was well-developed.[32][33] The issue of the Neanderthal's level of cultural and technological sophistication remains a controversial one
