Exploring Language in Humans: Larynx, Pharynx, and Steven Pinker

The larynx, positioned near and attached to the hyoid bone, functions primarily "to provide a patent (open) airway and to act as a switching mechanism to route air and food into the proper channels. Because it houses the vocal cords, the function of the larynx is voice production" (Marieb, 2004). The larynx is best termed as the "voice box" of speech manipulation. It receives air from the lungs which is further directed and manipulated by the pharynx, which "extends from the base of the skull to the level of the sixth cervical vertebra" (Marieb, 2004). The pharynx is our anatomical "throat" and when lengthened, as it is in humans, the result is a modification of sound that can be further modified by manipulation of the tongue. Not surprisingly, despite the benefits of language use, this "anatomical arrangement also impedes the ability to breathe and swallow simultaneously - which is why, regrettably, almost every one of us knows someone who choked to death" (Tattersall, 1998). It appears that even the best of evolutionary adaptations come at a price. Nevertheless, the relatively lower position of the larynx and an elongated throat provide humans with an array of sound that other primates are not capable of producing.

From a genetic standpoint, language revolves around a series of genes that make language possible. Of particular note, is FOXP2. FOXP2 is a gene found on chromosome 7 that is thought to have had some impact on the human ability to speak and does have some involvement in the motor areas that control speech. "The FOXP2 gene differs by two amino acids in humans, compared to chimps and other apes" (Raven, 2005). Despite the attempts made by researchers to facilitate speech in nonhuman primates, it appears humans are the only living species that are hard-wired from the start to produce the sounds necessary for complex language.(1)

Possible theories for the origin of language are nearly as elaborate as brain morphology. Steven Pinker (1994), a well known professor and linguist in the cognitive sciences, suggests "language could have arisen, and probably did arise, by a revamping of primate brain circuits that originally had no role in vocal communication" (p. 360). In vervets, for example, there are "homologues to Wernicke's and Broca's areas and a band of fibers connecting the two, just as in humans. [...] The monkey seems to use the regions corresponding to Wernicke's area and its neighbors to recognize sound sequences and to discriminate the calls of other monkeys from its own calls" (p. 360). Further, Broca's area, albeit a proportionally much smaller region in monkeys than in humans, is used to coordinate motor functions, such as the larynx and tongue. However, why vervets have the same cognitive arrangement as humans is anyone's guess. We really do not know. The only conclusion that can be made at this point is that the common ancestor primates share with humans possessed this trait, and it evolved to the extent that it did in the human lineage only.(2)

Returning to the warning calls of vervets, Steven Pinker continues:

"Perhaps a set of quasi-referential calls like these came under the voluntary control of the cerebral cortex, and came to be produced in combination for complicated events; the ability to analyze combinations of calls was then applied to the parts of each call" (p. 362).

It is here that one must define what might entail a "complicated event." It is conceivable that the manufacture of stone tools implies some degree of cooperation that results in communication between individuals. However, what about tool assemblages constructed of non-lithic materials not so easily seen in the fossil record? In Pinker's mind, these would surely obscure "linguistic competence from future archaeologists" (p. 363). Without a doubt, there are many such human groups, both past and most certainly present, that engage in complicated tasks that are never imprinted upon the archaeological record, and, at least in terms of archaeology, a correlation between tool use and language capability would not be warranted.

Brain morphology presents another dilemma...

(1) Our closest, nonliving relative, Homo neanderthalensis, may also have been at a disadvantage: "The Neanderthal vocal tract cannot produce a, i, or u. The absence of these vowels from the vowel systems of chimpanzee, newborn infant, and Neanderthal man is an indirect way of showing that the vocal tracts of these creatures cannot form the abrupt area functions that are necessary for these vowels" (Lieberman, 1972).

(2) "The validity of such an inference must be tested by a series of criteria, such as position in relation to neighboring organs, the presence of intermediate stages in related taxa, similarity of ontogeny, existence of intermediate conditions in fossil ancestors, and agreement with evidence provided by other homologies. Homology cannot be proven; it is always inferred" (Mayr, 2001).

References

Lieberman, P. (1972). Phonetic Ability and Related Anatomy of the Newborn and Adult Human, Neanderthal Man, and the Chimpanzee. American Anthropologist, 74, 287-307.

Marieb, E. (2004). Human Anatomy and Physiology. San Francisco: Pearson.

Mayr, E. (2001). What Evolution Is. New York: Basic.

Pinker, S. (1994). The Language Instinct. New York; HarperCollins

Raven, P. (2005). Biology. New York: McGraw-Hill.

Tattersall, I. (1998). Becoming Human. Orlando: Harcourt.