At what point in the lineage leading to modern humans did our ancestors become capable of something we would recognize as speech? The question is one that has intrigued scientists for decades, and though the answer is likely to be complex, there have been some tentative steps toward understanding the conundrum.
One of the main problems for researchers is the fact that the organs responsible for producing speech sounds — including the tongue, larynx and diaphragm, as well as their related nerves — are comprised of soft tissue that is extremely unlikely to fossilize. Therefore scientists are forced to study the next best thing — the bony structures of the body that encase the nerves leading to the organs in question. A 1998 study by Kay, Cartmil & Balow showed that the size of the hypoglossal canal, through which the tongue’s main nerve passes, is larger in modern humans, early Homo sapiens, and Neanderthals than the equivalent structure in modern chimpanzees and gorillas. A smaller hypoglossal canal also characterizes fossils of Homo habilis and the australopithecines, leading Kay et al to conclude that the ability to speak must have evolved roughly 400,000 years ago. A similar study of the thoracic vertebral canal, undertaken by McLarnon and Hewitt in 1999, had similar results. From this it can be concluded that speech ability was probably present in the common ancestor of Homo sapiens and Neanderthals. This does not necessarily mean that the hominids present at that time actually did speak, but it is likely the structures for speech were in place by that time.
Ape Speech
While captive great apes have shown varying degrees of skill in learning human sign languages, and even appear to understand some human speech, efforts to teach chimpanzees and orangutans to speak as humans do have been largely unsuccessful. This is partly due to a difference in anatomy; the vocal tract of the great apes consists of a single tube, while that of humans comprises two linked tubes, giving humans the ability to produce a larger repertoire of sounds. In addition, humans have better control over their breathing and the articulation of their tongues. Apes, of course, can produce a wide array of calls that communicate information to their brethren, and gibbons in particular have shown a marked complexity in combining their calls in a way resembling a simple language. Humans, however, seem to have taken this ability and run with it, producing a dazzling array of sounds that comprise the thousands of languages that have existed throughout human history.
Other Animal Languages
Some other species can also have quite complicated languages, including dolphins, humpback whales, and various types of songbirds. Because these animals are obviously far more distantly related to humans than apes are, it is almost certain that the languages these species exhibit are cases of convergent evolution; this goes to show that animals besides humans have found the ability to communicate with their fellows helpful to their survival.
Genetic Research
There has been some recent research involving the Foxp2 gene, which some scientists believe may be partly responsible for our language ability, but other scientists, including MIT’s Robert Berwick, argue that language itself is too complex a phenomenon to be laid at the door of a single gene, or even a group of genes. His own work involves studying the many similarities between human language and bird songs, and though he feels the language puzzle may never be completely solved, he continues to work in a direction that he thinks will yield interesting insights.
Jenny Ashford - Jenny Ashford is a writer and graphic artist from central Florida. Her main area of interest in her Suite 101 articles is science, with a ...
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