The use of language is
one of the key characteristics that distinguish Homo sapiens from
other primates. Because no direct evidence of language exists in the fossil record,
researchers have had a difficult time inferring its development. Fortunately,
the evolutionary history of the human brain and throat offers some insight.
The
human brain plays a vital role in the production and comprehension of language;
therefore, the emergence of language capabilities should be reflected somehow
in changes to the brain's structure. If this is true, the fossil record can help. Although brain tissue
doesn't fossilize, surviving crania can be used to make endocasts, which reveal the shape of the
brain that the cranium being cast once held. Because studies of modern human
brains have identified the areas where speech production and language
comprehension take place, researchers using endocasts can trace the development of these areas over time.
Differences
observed in the throat anatomies of modern humans and primates have also aided
researches in making inferences about the development of language capabilities.
The larynx, for example, occupies a lower position in the human throat than it
does in the throats of other primates. This arrangement makes possible the large
human pharynx, which produces the relatively wide variety of sounds used in human
speech. There is, however, a strong disadvantage to this arrangement: a greatly
increased risk of choking while eating or drinking. Therefore, language must
have been a strongly advantageous trait; otherwise, the increased incidence of
choking would have ensured its elimination through the process of natural
selection.
Another
important indicator is the hyoid, a small throat bone only rarely preserved in
the fossil record. The discovery of a Neandertal hyoid bone at Kebara in Israel
has led some researchers to conclude, because of its humanlike appearance, that
Neandertals were capable of human speech. However, even if this were so, the capacity
to produce humanlike sounds doesn't necessarily imply the ability to communicate
symbolically.
Although
the origin of language will always be debatable because the evidence is scarce,
most researchers agree that by the Late Paleolithic, humans likely possessed a full
range of language capabilities. (The explosion of symbolic behavior found in the
archaeological record demonstrates the existence of symbolic communication at this
time.) However, some forms of communication must have existed previously. Otherwise,
early humans wouldn't have been able to pass on the complex knowledge required
to make their increasingly sophisticated tools. (‘The Bedside Baccalaureate’,
edited by David Rubel)