Evolution of Human Speech and Language in Hominids

Speech Articulation and the Vocal Tract

Articulation means movement. In speech, articulation is the process by which speech sounds are formed. The articulators are the movable speech organs, including the tongue, lips, jaw, velum, and pharynx. These organs, together with related tissues, comprise the vocal tract — the resonating cavities of speech production that extend from the larynx (voice box) to the lips or nostrils.

Probably the most important factor distinguishing humans from apes and other animals is the remarkable capacity for language. The ability to communicate with others of one's own kind in abstract, symbolic speech is unique to humans, and evolutionists have never been able to bridge the tremendous gulf between this ability and the grunts, barks, and chattering of animals.

Some researchers have made extravagant claims about the potential for teaching chimpanzees to speak, or have developed highly imaginative speculations as to how animal noises may have evolved into human languages. Such notions, however, are not based on real scientific observation or evidence. Human speech production is accomplished by the coordination of muscular actions in the respiratory, laryngeal, and vocal tract systems. Typically, the word "articulation" refers to the functions of the vocal tract, but speech production requires the action of all three systems. A full account of speech production would go beyond articulation to include such topics as intonation and emotional expression.

The story begins about 3.5 million years ago with the appearance of a group of animals collectively known as australopithecines. Australo means "southern" and pithecines means "apes." These "southern apes," initially discovered in South Africa, were small, apparently upright-walking apes. Around 2 million years ago, a new creature appeared that is now placed in the genus Homo: Homo habilis.

Homo habilis possesses the same stature as the australopithecines but with a slightly larger brain. It is also suggested that he used a few primitive tools. Next appears the real star of human evolution, Homo erectus. Homo erectus possesses the skeletal frame of modern humans, though somewhat more robust, and his brain capacity is closer still to that of humans. Homo erectus also used more advanced tools.

Hominid Evolution and the Fossil Record

This "almost" human persisted, we are told, for over 1.5 million years, after which nearly modern humans (Homo sapiens) began to appear. Soon the offshoot Neanderthals arose, and at about the same time thoroughly modern humans appeared within the last 100,000 years. Evolutionists as well as creationists have in recent years come to believe in the monophyletic origin of all the tribes and races of humankind.

Most earlier evolutionists, however, believed in humanity's polyphyletic origin, thinking that each of the major "races" had evolved independently from a different hominid line. This idea easily leads to racism — the belief that one race is innately superior to another. If each race has a long, independent evolutionary history, slowly developing its distinctive character through random mutation and natural selection, then it is nearly certain that there has been a differential rate of evolution between the different races, with some evolving to higher levels than others.

The word "hominid" refers to members of the family of humans, Hominidae, which consists of all species on our side of the last common ancestor of humans and living apes. Hominids are included in the superfamily of all apes, the Hominoidea, whose members are called hominoids. Although the hominid fossil record is far from complete and the evidence is often fragmentary, there is enough to give a good outline of the evolutionary history of humans.

The time of the split between humans and living apes used to be thought to have occurred 15 to 20 million years ago, or even up to 30 or 40 million years ago. Some apes occurring within that time period, such as Ramapithecus, were once considered hominids and possible ancestors of humans. Later fossil finds indicated that Ramapithecus was more closely related to the orangutan, and new biochemical evidence indicated that the last common ancestor of hominids and apes occurred between 5 and 10 million years ago, probably toward the lower end of that range (Lewin 1987). Ramapithecus is therefore no longer considered a hominid. The field of science that studies the human fossil record is known as paleoanthropology — the intersection of paleontology (the study of ancient life forms) and anthropology (the study of humans).

Although evolutionists are now in practically complete agreement that all present groups of humans came originally from one single population of ancestral humans, they are currently in considerable disarray as to exactly what that lineage may have been. The australopithecines and the Homo erectus group of supposed hominids are no longer considered humanity's progenitors, since fossils of true humans have been found that are dated earlier than any of these.

Not only do these discoveries indicate that humanity's unique bodily structure has — so far as actual fossil evidence goes — always been distinct from that of apes, but also that humans have always possessed their unique capacity for communication. As Donald Johanson has suggested, there is even the possibility that early hominids had "some kind of social cooperation and some sort of communication system." Back to the very beginning of human existence, therefore, insofar as it can be elucidated by archaeological excavation and anthropological analysis, humans have always been human — culturally and linguistically as well as physically and mentally.

Although studies of animal behavior have revealed astonishing complexities in animal communication — including the capacity for aspects of language in certain species — humans are the only species with a natural spoken language. While apes have been able to learn sign language and other forms of symbolic communication, they are physically incapable of reproducing human speech.

The mouth, lips, and tongue are obviously important in the formation of spoken words and are more mobile in humans than in apes. Humans are also able to shape sounds more precisely because the larynx, or voice box, and the epiglottis (the cartilage that prevents food from entering the windpipe) appear to be perfectly adapted for maximum control of airflow. These anatomical features are unique to humans, although parrots and other birds can mimic human speech with their own specialized vocal apparatus. Consequently, attempts to teach apes to talk have failed.

Anatomical Foundations of Speech in Hominids

Studies with apes demonstrate that they can retain images much like human children — they are capable, for example, of identifying which box conceals a hidden banana. The question, then, is why apes are incapable of speech. Interestingly, humans and simians are born with the same laryngeal machinery, but a human infant's larynx drops at three months of age, creating a resonating chamber that makes consonant and vowel sounds possible. Apes vocalize through the nose and cannot produce the same phonetic sounds that humans make using their lips, cheeks, tongue, palate, and teeth.

Sounds alone, however, do not make a language. Sounds need meaning and signification — they must describe, distinguish, ask questions, and express tenses. When art empowered humans to associate a drawing with a real object, it became possible to make an analogy between objects and their associated sounds, a process that eventually led to the first name-sounds.

Cave art served as a reference point for humans, but animal calls have no points of reference since animals are unable to make analogies; their sounds remain instrumental but never become referential. Animals use their voices like a musical instrument — comparable to piano-playing during silent films: loud for danger, staccato for play and joy, low and mellow for courtship. Apes may lead others by the hand, but they cannot direct them to a specific destination, since they cannot place a picture into a listening mind.

Unlike the rest of the animal kingdom, human infants are not born speaking. Kittens mew and piglets grunt at birth and continue to do so throughout their lives, but modern human infants only cry at birth. Language in children does not develop until the babbling function emerges, enabling the child to copy the parent's vocal sounds. Babbling is a critical stage for true speech — one that chimpanzees do not share. This instinctive monologue of sounds without rhyme or reason seems to require vocal responses and encouragement. In the example of Viktor, the "wild boy of Aveyron," the child raised without human contact never achieved articulate speech.

The question of when the evolution of language and speech occurred within the hominid lineage has provoked fierce debate among paleoanthropologists and anatomists alike. The soft tissue of the throat does not fossilize, so scientists have not been able to trace directly the evolution of the full range of anatomical traits that allow speech production. Beginning in the 1970s, certain researchers began examining the bones of the skull — features that can preserve well in the fossil record — in order to find clues to unravel this mystery.

Fossils show that the raw brain capacity for complex language, along with the necessary mouth and throat anatomy, were probably in place before 150,000 years ago. But most of the behaviors thought to depend on language did not appear until about 40,000 years ago — the so-called Upper Paleolithic explosion most strikingly manifested in Europe. That was when tools, burials, living sites, and occasional hints of art and personal adornment revealed beings capable of planning and foresight, social organization and mutual assistance, a sense of aesthetics, and a grasp of symbols. "Everybody would accept that by 40,000 years ago, language is everywhere," says archaeologist Richard Klein.

The "flexion" of the base of the skull — the degree to which the floor of the skull is arched relative to the roof of the mouth — has been thought to have important consequences for the orientation of the voice box. The greater the degree of arch in the base of the skull, the lower the position of the larynx in the throat and, as a result, the greater the ability to produce delicate speech, especially vowel sounds.

In most mammals, the larynx and the rest of the respiratory apparatus are positioned quite high. While this orientation restricts the range of sounds one can produce, a highly positioned larynx does allow simultaneous swallowing and breathing. The human low larynx thus has its drawbacks, as one may notice when attempting to talk and eat at the same time. The rearrangement of the respiratory system must have had great adaptive value to outweigh the cost of an increased risk of choking.

Phil Lieberman of Brown University and Jeffrey Laitman of Mount Sinai School of Medicine in New York argue that "pre-humans, from the earliest australopithecines to our more recent Neanderthal cousins, did not have a larynx low enough to enable them to speak. Although Neanderthals may have been able to make certain verbal sounds, these 'words' were probably very nasalized, which would have interfered with their clarity and, as a result, their ability to be used in a precise and complex fashion." Only anatomically modern humans, who appear in the fossil record at about 100,000 years ago, seem to have had the necessary "basicranial flexion" to allow speech, according to the theory's proponents.