The Consequences of Language: The Biological Basis For Language? Chapter 4a Page XXX
The Consequences of Language
Chapter 4. The biological Basis of Language
The purpose of this chapter is to provide an evolutionary perspective of the evolution of biological structures that enable language.Questions about the Origin and Evolution of Language; Establishing a Biological Perspective; How did the vocal tract develop? How did the brain develop? (include contributions of cognitive neuroscience to this understanding.; The Evolution of Language Structure
1. Questions about the Origin and Evolution of Language
Because language is one of the most salient features that separates humans from other animals, the origin and evolution of language has been and remains a crucial question for it may provide important insights into what we are as human beings and how we got that way. One of the earliest recorded views of language origins is the biblical story of Babel. According to this view, people wanted to build a tower so tall that they could come closer to God. God considered this a poor idea and declared that the people should speak different languages to make it impossible for them to communicate and thus prevent them from building the tower.
In 1855, The Linguistic Society of Paris proclaimed that they were no longer going to publish articles that addressed questions of language origins, as the papers previously submitted and published were highly speculative and the evidence upon which they were based extremely limited. As a result, they concluded that they concluded that it was all a waste of time, because such theories, while interesting, did not advance our understandings of language origins beyond the earlier biblical explanation.
Since that time, the question has been reopened with Hockett’s 1960 Scientific American article on the origin and evolution of language. Hockett’s article brought out that today we now have much more information at our disposal than did the French linguistics writing for the Linguistic Society of Paris in 1855 and, just as importantly, we have different ways of approaching the question than we did earlier. For example, we now have a richer understanding of evolution, note that Darwin published his theory of evolution in The Origin of the Species in 1859. We now have a richer fossil record of our human ancestors, an understanding of how language structure works, along with that an understanding of how the vocal tract and the brain contribute to the production and comprehension of language. Comparative anatomy helps us to understand how our anatomy differs from our nearest phylogenetic relatives. These developments surely justify the reopening of the investigation of the origin and evolution of language.
It may be noted that in the biblical version of language origins, it was assumed that Adam and Eve (and possibly God) spoke a language quite similar to that spoken today, though we do not know what that language was, nor what it looked like. While the Babel story accounts for the diversification of language, it does not recognize any sort of evolution from some earlier form. However, from an evolutionary perspective, one would not expect modern human language to emerge as a full-blown set of semiological systems, but rather develop in stages, as did the human physical form. This chapter explores the evolution of the biological capacity for language. We return to the question of the evolution of the semiological system in chapter 15.
Establishing a biological perspective
Physical anthropology, one of the four branches of anthropology seeks to understand the physical (biological) evolution of our species. This perspective asks us to stand back and look at ourselves as animals, to be sure different from other animals, but animals just the same. We know that human beings, technically known as homo sapiens sapiens (= wise, wise humans), are most closely related to the great apes and specifically the chimpanzees sharing a common ancestor (known as Dryopithecus) who lived some 40 million years ago. Even now, we share a large amount of our DNA (approximately 99%) with chimpanzees. One of the questions physical anthropology asks is: to what extent are we dependent on our biology for our language ability? To answer this question we explore, in this chapter, the workings and evolution of two of the major organs of speech, the vocal tract and the brain. In the next chapter, we explore, what Chomsky refers to as another organ of speech, the faculty of language.
Questions about the evolution of human language
Since the project of gaining a better understanding of how human language evolved is a very formidable task involving the bringing together a lot of different information in new ways, and a lot of speculation, one might ask, “why study this question?” In addition to understanding how we evolved to what we are today, there are at least two important responses to this question. First, understanding the role that language has played in our biological evolution will help us understand who we are as humans. Secondly, it can also help gain a better understanding of the nature of language.
In this context, we need to recognize that we are not simply interested in when language began, but also we are interested in the process of how a system of communication, which must have been quite similar to that of present day chimpanzees (our nearest phylogenetic ancestor), evolved into the complex semiological system today, one consisting of three different sign systems (lexical, representational and syntactic). In addition, we want to understand how our current bodily structure reflects adaptation to language as well. And finally we want to understand what sort of relationship exists between the languages of today.
Purposefulness of adaptation and evolution
We begin with a discussion of the basics of evolutionary thinking as a foundation on which to build an appreciation for the evolution of the brain and vocal tract. Within this framework, the fundamental principle is that evolution does not have a direction or a purpose. This is because evolution is the product of two evolutionary activities: random mutation and selection.
Normal DNA reproduction. At the heart of genetic change is genetic reproduction. Every living thing is composed of fundamental building blocks known as DNA. Under normal conditions this DNA is reproduced (duplicated) without change, when the body grows new cells, either to replace dead or damaged cells in the organism’s own body or when developing reproductive cells which can produce new members of the species.[1] This process of duplication is by far the most common process occurring unceasingly, millions of times a day in an organism until death.
Random Mutation Occasionally however, something interferes with this normal process and the copied DNA may be slightly different from the original and the DNA can be said to be mutated. This process of mutation is termed random because one cannot predict either what part of the DNA will mutate, when it will mutate, or what it will mutate into. In these cases, the mutated DNA will cause a change in the cell and this may affect the viability of the cell so that it functions less well or not at all and consequently the cell (but not necessarily the organism) dies. Occasionally the cell with the mutated DNA survives.
Natural selection. When the altered DNA is part of a chromosome, the mutation can be passed on to future generations. This is where the process known as selection goes to work. Selection is a process which statistically favors individuals and groups with a specific genetic make up, if that make up proves successful in the given environment. If a mutation lessens the organism’s ability to adapt to the environment then the organism and its genetic material is less likely to survive. On those infinitesimally rare occasions that the mutation assists in adaptation, the individuals carrying that genetic material are more likely to survive than those without it and as a result, the percentage of individuals in the population carrying that mutation will increase.[2]
Direction and Progress. The long-horned grasshopper pictured sitting on the right looks like an ordinary insect that has been the product of random mutation and selection just like any other animal. However, one will see that it has a special organ on its forelegs; this is an organ for hearing, commonly called an ear.
This strikes most of us as unusual for we expect to find ears in one’s head and some have argued (wrongly) that the ears are on the head so that they can be close to the brain. But finding hearing organs elsewhere on the body, should not be surprising when we recall the key points about evolution supported by the processes of random mutation and selection. One of the consequences of this process is that evolution does not have a direction, and consequently we cannot talk of progress, only change. While it is no doubt true that being able to hear would be likely to increase one’s adaptability and hence one might find in nature a variety of hearing organs that have evolved in different ways, this does not argue for the inevitability for hearing organs. Because evolution lacks a direction, we cannot predict what will happen next. We can however trace the “history” of the evolutionary developments to see how we got to where we are today. In this chapter we will examine three evolutionary developments that are related to writing: the evolution of writing, the evolution of the vocal tract and the evolution of the brain.
When we carry this perspective over to the evolution of the organs of speech, we will see that they too support the principles that development of language is not inevitable.
2. How did the Vocal Tract develop?
The primary representational system of human language uses the acoustic channel. More precisely it is vocal which means that it uses the vocal apparatus. But what is this vocal tract and what makes’s it so remarkable? Etymologically speaking, the word vocal is related to the words vowel and voice. And not too surprisingly, vowels are the most salient component of the human voice, that is speech. I say this, because when we hear human language, we rely most heavily on hearing the vowels, for once they are identified we can identify the consonants with which they are associated (note that consonants mean literally ‘with sonants’ (i.e., vowels). Thus before we can examine the evolution of the vocal tract, we need to understand what vowels are and how they are produced.
The Nature of Vowels
Listen to the vowels in the following words: beet /bit/, bit /bIt/, bait /bet/, bet /bt/, bat /bæt/, bought /bt/, but /bt/, Bert /bt/, boat /bot/ boot /but/. Notice, that when you hear these vowels, your perception is probably that they are discrete entities quite different from each other. Yet in the physical world, vowels are much like colors, there is a wide range of variation in type, but when we identify them as part of a system, we see them as discrete entities: we see seven basic colors and hear ten distinct vowels. This is because, as was pointed out in chapter 3, these vowels (in English) represent discrete, phonemic contrasts called phonemes.
The adjacent figure shows the distribution of one speaker’s production of the various vowels in a reading of a short text. The vowels were drawn by graphing the frequencies (given in kilo Herz) of the first formant (horizontal axis) and second formant (vertical axis). Although the vowel tokens for each vowel are in the same general area, one can see that there is a good deal of variation in the production of each vowel phoneme.
Acoustically speaking, formant is a concentration of sound energy in the sound spectrum. For example, as shown in the spectrogram[3] in the sidebar, the vowel /i/ as in the word beet has a first formant somewhere between 200 and 300 Herz and a second formant around 2000 to 3000 Herz. If we were to drop the second formant to somewhere between 600 and 1200 Herz without changing the first formant, we would recognize the sound as the vowel /u/ as in boot. If we were to raise the first formant to around 800 to 1000 Herz and drop the second formant to around 1000 to 1200 Herz, we would hear the vowel /a/ as in hot.
How are formants produced acoustically?
The source-filter theory offers a straightforward explanation of how formants are produced. The source refers to the source of the sound to be filtered, while the filter is a tube which acts to reinforce some frequencies and dampen others. According to this theory, sound is produced by a vibrating object, a larynx, a violin string, etc. The most prominent sound is the fundamental frequency. When we hear an "A" on the piano, we recognize it as an "A" because of its fundamental frequency. In addition, most sounds are not single waveforms, but consist of multiple waves of differing frequencies and amplitudes. For example, in addition to the fundamental frequency of a sound (the one which gives its characteristic pitch) are a set of harmonics, each of which have is a sound wave whose frequency is a multiple of the fundamental frequency. These harmonics arise because of the physical properties of the vibrating sound source and are what make a piano sound different from a violin, a trumpet or a human voice.
The musical note "A" has a fundamental frequency of 446 Herz (cycles per second). By cycles per second, we mean the number of cycles that a sound accomplishes each second - the more cycles, the higher the frequency. To understand what a cycle is, we need to recognize that sound only exists by traveling through a medium (air, water, etc.). It does so as a wave, that is, as a sequence of compressions and expansions (see figure 5).