Introduction
In this introductory chapter, I will outline what this book is about and aims to achieve, which is to continue what I started in a prequel book, A Mind for Language: An Introduction to the Innateness Debate (ML). Both books share the same central theme, namely the so-called Innateness Hypothesis for language, which is the conjecture proposed by the linguist Noam Chomsky many decades ago that children acquire language being guided by an innate, genetically based mental system that is specifically dedicated to this task. Both ML and this book critically examine arguments that have been used, or could be used, to support this idea. Where ML considered arguments coming from linguistics proper, the present book delves into arguments from neighboring fields that overlap with linguistics in various ways. This chapter concludes with a review of the linguistic arguments in support of Chomsky’s Innateness Hypothesis that formed the focus of ML. While the present book shares its subject with its prequel, each book can be read independently. Nevertheless, because the books do share the same central theme, in this chapter I must go over some of what I wrote in ML, chapter 1.
Our central theme is the so-called (and seemingly never-ending) “nature–nurture” debate, the beginning of which can be traced back to the earliest written sources more than two millennia ago, especially in the work of the Greek philosopher Plato. Since then, this subject has been of continuous interest to philosophers throughout the ages (see ML, chapter 3).
The main question in this debate is how people come to “know” well … everything; this question can also be asked for other creatures, but for the time being I’m limiting the discussion to humans; see Chapters 8 and 9 for attention to nonhuman animals. Here the term “knowing” is meant to cover everything that makes up the human mind, including both the conscious and subconscious parts of it. Conceivably, there could be two completely opposing answers which are (somewhat simplistically stated): (a) all human knowledge, and thus the behavior that is dependent on this knowledge, is innate (which in modern terms means that it all somehow comes from our genes) or (b) all knowledge and behavior is learned, which means that it is due to environmental influences (i.e., parental input, education and life experience). As I review in Chapter 3, this debate occurs and evolves in all disciplines that study human or nonhuman animal behavior, with various viewpoints dominating the discussion at different times, depending on which discipline we focus on. Strikingly, the arguments that are given to support the roles of nature and nurture, as well as their interaction, are very similar across disciplines, allowing nevertheless for angles that are specific to each discipline. Being a linguist, I have chosen to examine the debate with respect to “knowledge of language.” Here this phrase does not refer to what linguists have come to know about human languages but to what enables every living person to use their language (or languages). Being able to “do” language has to be based on possessing a “mental grammar” of that language. Interestingly, we are not consciously aware of the content of this mental grammar. (If we were, the task of linguists who want to know what its precise content is would be so much easier.) My choice for taking knowledge of language as a case study – asking how people get to have it – is not only opportunistically due to me being a linguist. Here I must repeat what I said about this in ML, chapter 1.
Within linguistics (the science that studies all aspects of human language), the nature–nurture debate has been especially lively, ever since Noam Chomsky suggested in the late 1950s that “most of language is innate.” This was a shocking idea! Ask any person how they “learned” their language and they will say: from my parents (or broadly “my caregivers”). It seems so obvious, doesn’t it, that knowing languages is dependent on the environment, on the language(s) that you grow up with. If you grow up in Italy, you will speak Italian. Being born and raised in The Netherlands makes you a speaker of Dutch. How can “most of language” be innate and what does that even mean? Chomsky’s bold conjecture met with a lot of controversy, not only because it clashed with how ordinary people think they got their language, but also because it went against a central thesis of the predominant (at least in the US) psychology school of behaviorism, which regarded language (and all other behavior) as something that is completely learned, being due to “stimuli” that are present in the environment. Of course, Chomsky never meant that people are born with complete knowledge of all languages such that they would simply have to select the one that fits the environment (even though the notion of “choosing” became part of his theory of the innate language system, as we will see in Chapter 2). Rather, Chomsky offered an idea that would explain why children can acquire (rather than “learn”) languages so easily, without receiving explicit instruction and based on what he claimed are rather “poor” language stimuli that they experience casually in daily interactions with caregivers, siblings, and other individuals. Thus, he tried to provide a solution to what is known as “Plato’s problem” which is: How is it possible that humans know so much based on so little experience (see ML, chapter 3). The idea was that children are born with a “manual” that guides them toward the construction of an appropriate mental grammar which allows them, albeit not instantaneously, to speak and comprehend the surrounding language. Chomsky’s views inspired many linguists to look at language and language acquisition in a different way, and made the question of precisely how children get to know their language the central question of linguistics, which it has been for the last (more than) half a century.
The idea of postulating such an innate language ability, which clearly leans toward the nature pole, had a profound influence in the field of linguistics, as well as in “neighboring” fields such as philosophy, psychology, anthropology and, more generally, all fields that deal with human behavior (leading to the emergence of a new field called Cognitive Science; see ML, chapter 4).1 This, however, does not mean that Chomsky’s ideas were or are uncontroversial. While they certainly contributed to the demise of behaviorism and a simultaneous boost in acknowledging the role of nature in human development, those who opposed the view that knowledge of language arises due to an innate capacity that is specific to language have continuously tried to show that such knowledge can emerge from general cognitive capacities (which, as such, are innate) that guide the learning of many things, including language. It would seem, then, that an investigation of the nature–nurture debate in linguistics offers a good case study.
As I point out in ML, chapter 1, there are additional reasons for choosing language as our focus. First, the mind is invisible and elusive. Brain-imaging techniques, such as CT scans or EEGs, can make broad and sometimes very specific actions of a working brain visible on a computer screen, but this is still a far stretch from visualizing how the mind works (see Chapter 6). Many researchers claim that we can learn most about the mind by observing what people do and how they behave. In this light, human language, being a widespread, indeed universal, form of behavior, can be a “window on the mind.” More than any other form of behavior, with the possible exception of body language and facial expression, language is used by people “to speak their mind,” thus revealing what “is going on up there.” A further good reason for choosing language as our testing ground is that our understanding of this phenomenon, once more due to the influence of Chomsky’s ideas, has grown tremendously over the last sixty years. Finally, linguistic behavior can be studied quite easily; it is easier to gather and analyze linguistic behavior than many other things that people do because “language (like love) is all around.”
With these two books (ML and the present one, which I will henceforth refer to as GBE, for Genes, Brains, Evolution and Language), I do not intend to offer a grand new theory that claims to put an end to the nature–nurture debate (not even just with reference to language), nor will I try to defend an extreme view. There is no final answer here (nor will any such answer be forthcoming anytime soon, although, as we will see in the course of the book, there is light at the end of the tunnel). Why then do I think that writing two books on this issue is warranted? The goal of these books is to offer a guide through the various viewpoints and arguments. My intention is to help the reader in becoming an informed participant in this ongoing debate, although I would prefer to call it a dialogue. While a typical debate aims at stating and defending one’s own position, a dialogue involves an attempt to understand other viewpoints. I will try to state the relevant issues, explaining terms and theories, while sharing with the reader information about some rather amazing phenomena that bear on the phenomenon of human language. From the start, it is crucial to see that the nature–nurture dialogue is not just an “academic dialogue,” to be held exclusively in the ivory towers of learned societies. I will make it clear that specific viewpoints (or implicit assumptions) about the nature and origin of our minds have direct consequences for your opinions concerning many aspects of daily life, such as raising children, school education, sexual orientation and gender choice, political views, economic systems, up to and including “the American Dream” (Is it really true that all people can become anything they want to be?).
Even though I will focus on language, I will try to show that almost all arguments can also be brought to bear on the same question with reference to other mental capacities that are characteristically human, as well as debates “in daily life” about matters that cause serious conflicts among all citizens, including politicians. It is my hope that the present book, and its prequel, will provide the reader with enough background to participate in the never-ending debate with an educated, open (although not blank) mind, no matter what the focus of the debate is.
There are people who claim that the nature–nurture debate is dead, while others are convinced that it refuses to go away. After reading this book, the reader may have developed an informed opinion on this matter as well.
The Notions “Language” and “Mind”
When I use the term language, I refer to human language, the specific communication system that uses words and sentences, both having a perceptible form, a meaning, and what we call categorial information (which has to do with being a noun or a verb, or forming a noun phrase or a verb phrase; see Chapter 2). All other communication systems, used by human and nonhuman animals, will be called just that: communication systems, which is not meant to imply that within this broad class important distinctions cannot be made. We will see that defining what human language is (and what it is for and how it came about) leads to a can of worms that we will open in this book. For now, let us agree on the fact that language involves two things. On the one hand, there is a mental capacity (the mental grammar) that comprises the words that we know, ways to make sentences, and “peripheral” systems for producing and understanding combinations of these, and for using them appropriately in all sorts of situations. On the other hand, language is the directly observable effect of applying the various mental language systems, which takes the form of producing audible sentences and an ability to judge whether utterances that people make are grammatical, that is, that they follow the rules of the mental grammar. (In ML, chapter 13, I discuss sign languages, such as American Sign Language, which use other processing systems for their production and perception, while, at the same time, being rooted in mental grammars that are structured very much like those for spoken languages.2)
While agreeing on what we mean by language is already hard, it is an understatement to say that it is hard to define the notion of “mind.” As is common in Cognitive Science, I will assume that the mind is: information (“data”) and information processing (“programs”). With this “working hypothesis” of what the mind is, we have to acknowledge that a large part of our mind exists subconsciously. It has often been claimed that we are not aware of most of what is going on in our mind. For example, we know that our mind controls our bodily functions, but we do not know what is going on and, frankly, we do not care either, as long as everything works well.3
With our working definition of the mind, a way to phrase the nature–nurture issue is this: How does all the information and processing that makes up our mind develop in an individual? To make the issue manageable, I break down this Big Question into several smaller questions (as I do in ML, chapter 1):
Is the mind mostly blank when people are born (like an empty hard drive, or an empty notebook), with no information present? (The mind starts developing before birth, so that is an issue that we have to consider when we ask this question.)
If so, does this mean that our mind emerges completely from learning based on experiencing the world through our senses (even prenatally), which are, in a way, like information input devices? (If so, we say that the mind is due to nurture.) Of course, information could also result from explicit instruction and teaching (mostly through language), which also falls under nurture.
Or is it the case that all information is there “from the start,” part of our biological nature, ultimately our genes? (Here some people like to say: “all knowledge is instinctual.”)
Or is it both, nature and nurture? (Just like when we come to class with a workbook that has a lot of the information already printed, with blanks for us to make additional notes, and questions that we must answer.)
That nature and nurture should not be seen as additive or complementary can be illustrated by using the following analogy. Suppose someone hears violin music and then asks you: Which part of that music comes from the violin and which part is due to the violinist? That question doesn’t make sense, right? Both are necessary to produce the music. I encourage the reader to think of the interplay between nature and nurture in the same way, although sometimes we may slip into the suggestion that they are independent of each other, as indeed many writers have done when presenting the issue.4
Finally, what do we mean by “innate”? I have loosely equated innateness with being rooted in genetic information, and I will stick with that understanding in this book. However, the route from “genes to brains and minds” is anything but clear. Neuroscientists agree that much of the working of the brain is due to experience. Also, it is often said that what some take to be innate could have somehow come about during the development from the single cell that we start out as to a baby that is ready to be born. Certainly, that development is part of our nature, but not all of it is determined by our genetic makeup. What an organism becomes is not simply dependent on genes, but also on gene expression (which involves the activation or deactivation of a gene). What this means is that whether genes have an effect is dependent on the body-internal environment in terms of neighboring cells, organisms, organs, and so on, without a necessary dependence on factors in the body-external environment of the mother (nutrition, air pollution, etc.); see Chapter 7 on epigenetic processes, which is the term for influences of the environment on gene expression. This highlights that there are two kinds of environment, one that applies to the development of all members of a certain species (here called body-internal) and one that is due to influences that are strictly dependent on circumstances that come from the outside world (which could start prenatally).5 In this book, when considering the development of language, I will limit the discussion to the external environment in terms of the sensory input that children experience mostly after being born, especially regarding language.
The Arguments in Support of the Innateness Hypothesis
Many different arguments have been advanced to test the predictions that we make if we say that the knowledge that people have of their language, or languages, is rooted in an innate system that guides the construction of their mental grammars. We can make a broad distinction between two types of arguments that I call linguistic arguments and “other” arguments. Linguistic arguments are based on the study of language proper, that is, its structure, how it changes over time, how children acquire it, and how it can be manifested in different modalities, such as speech and sign. The class of “other” arguments draws into the discussion a variety of other disciplines, such as computational approaches, neuroscience, genetics, the study of animal communication systems (both as used in nature and as taught in language experiments), and evolutionary biology. To combine both classes of arguments into one book (and one course) turned out to be inadvisable, which led to the decision to divide the original project into two books.6 I do not assume that readers of either book have read the other one or have taken an introductory course in linguistics. Chapter 6 of ML offers a model of the mental grammar (providing necessary linguistic terminology and ideas about which aspects of these grammars might come for “free” to the learner because they are innately specified), which is briefly summarized in Chapter 2 of the present book.7
The Linguistic Arguments in a Nutshell
From within linguistics proper, a variety of phenomena supply arguments that could potentially support the Innateness Hypothesis (IH) for language. We can make a distinction between static aspects of language (the way languages “are,” i.e., their universal design and their manifestations as different languages) and dynamic aspects. The latter appear in three varieties. Firstly, language “grows” in the individual, as part of its ontogenetic development. From this domain, we extracted several arguments, starting with the poverty of the stimulus argument, which is based on the idea that the language input that children are exposed to underdetermines the rich mental grammar that they have to construct to become fluent language users; this instantiates the linguistic version of Plato’s problem. Secondly, the study of how languages change over time also leads to an argument in favor of the IH if it can be shown that certain properties of languages are immune to change. Thirdly, and related to processes of change, there are phenomena that involve the spontaneous emergence of new languages, either in the spoken modality or in the gestural modality, which are hard to explain, unless it is believed that those who spontaneously create these new languages are guided by an innate “manual.” I here list the arguments in the order in which they were presented in ML.8
Arguments for the Innateness Hypothesis
b. Language change (ML, chapter 8)
c. Language acquisition
Logical aspects
Poverty of the stimulus (ML, chapter 9)
Convergence (ML, chapter 10)
Developmental aspects
Speed of the process (ML, chapter 10)
Critical period (ML, chapter 11)
Spontaneous emergence (ML, chapter 12)
Pidgin and creole languages
Home Sign
d. Sign languages (ML, chapter 13)
Chapter 7 of ML deals with static properties of languages, homing in on the question as to whether there are linguistic universals (i.e., properties that are shared by all languages) and, if so, to what extent such universals support the notion of an innate so-called Universal Grammar (UG). In other words, in this chapter, we evaluate the force of the argument from universals (for the Innateness Hypothesis). The IH predicts that there are properties that all languages share. Nativists (scholars who accept that people are born with innate, domain-specific knowledge modules), also often called rationalists,9 have hypothesized, based on the study of many languages, that there seem to be properties that all languages might share. Such properties may be overt in that they simply state (after some analysis) patterns that can readily be observed in the language utterances (such as the order in which words occur in a sentence, or the speech sounds that they use), but they can also be more covert or hidden in the sense that they state abstract properties of the mental grammars that underlie the languages of the world. Covert properties, which are what nativists focus on, are hard to falsify because, as nativists say, they can be obscured or shielded in the actual language utterance due to a variety of “performance” factors. Empiricists (who reject the nativist stance), focusing on more overt, directly perceptible properties of language, conclude that there is not a single alleged language universal that has not been falsified by one or more languages. The “shielding” of the relevant predictions by nativists and the empirical evidence from surface data that empiricists look at have the combined result that the argument from universals must be handled with some care. Nevertheless, despite all the differences between languages and the difficulties in stating universals, whether overt or covert, it is hard to deny that all languages seem to follow the same grammar plan (which I have tried to characterize in ML, chapter 6, summarized in Chapter 2 of the present book), which is perhaps comparable to the body plan that is shared by all members of a species. The question is then whether the universality of this grammar plan can be explained if it is claimed that children construct their mental grammar based on general, rather than language-specific, learning capacities.
In ML, chapter 7, which focuses on language change, we ask whether there are certain properties of languages that are immune to change and if so, whether this could be explained if we were to assume that these properties are built into the innate language system. This discussion thus deals with the argument from language change. What supports this argument is, once more, that the grammars of all languages submit to a shared fundamental design (the grammar plan), a point that gets extra weight once we compare human language with communication systems elsewhere in the animal kingdom. (We will deal with this latter point in detail in Chapter 8 of the present book.)
The majority of linguistic arguments in support of the IH come from the study of language acquisition. The first argument that Noam Chomsky formulated directly addressed what was called “Plato’s problem,” which raises the question how people come to know so much on the basis of so little experience. Chomsky formulated a linguistic version of that problem: How do children come to have such rich knowledge of language (i.e., a mental grammar) while being exposed to primary linguistic data that are of “poor” quality? This is also often called the logical problem of language acquisition. The crucial point here is that despite the lack of negative evidence (information about which words and sentences are not grammatical), the child succeeds in becoming a successful language user, able to tell whether or not a word or sentence is grammatical for their language. The “logic” of the problem focuses on the claim that for any finite set of data, whatever its quality, there are many, perhaps infinite, ways of constructing a grammar that accounts for the data. If there is no guidance to home in on a specific grammar, we would predict that different children would arrive at different grammars while making all sorts of mistakes along the way of adjusting their grammar to new input. Nativists emphasize that children do not make mistakes that would be expected if language acquisition was a trial-and-error process and they claim that children converge on the same grammar for any given language.10 The conclusion drawn is that children must be guided by an innate system toward the correct grammar. In Chapter 2 of this book, I offer a “dialogue” that examines the poverty of the stimulus argument in more detail.
Further support for the IH comes from the developmental aspects of language acquisition. The argument from stages is based on the observation that children’s language acquisition shows similar stages with specific properties that reflect their grammatical competence at each stage, which, while deviating from the ambient language, are systematic in their own right. These stages occur at roughly comparable ages, although there is considerable variation in this respect, as critics have emphasized. The nativist argues that a stage-by-stage, maturational development is expected when development is rooted in our biological nature.
Some nativists emphasize that language acquisition is fast. Considering the enormous complexity of human languages, it should amaze both researchers and parents that children find their way into language while still being unable to make simple calculations (like 2 + 5). Of course, young infants and children do, and seem to know, many amazing things and the general idea among nativists is that whatever children know or do early on and with ease, with only limited experience, is likely rooted in innate systems (“instincts”). In contrast, when children have more trouble with tasks that are relatively simple (like addition, writing, tying their laces), the idea is that there are no domain-specific, innate guiding hands and that brute-force learning is at play, based on general learning capacities (which as such are innate) and usually a lot of practice.
A Mind for Language, Chapter 11 deals with the critical period argument. This argument is based on another characteristic of the maturational nature of language acquisition. The central idea is that exposure to language input must occur within a so-called critical (or sensitive) period, which, for human language, has been suggested to end around puberty. Nativists point to the fact that critical period effects are common in the animal kingdom at large and are as such attributed to “innately guided learning.” Support for postulating a critical period for language learning comes from evidence of extreme deprivation of language input, removal of brain tissue (in operations or accidents) that are important for language, or from the fact that second language acquisition after puberty appears to be much harder than second language acquisition before puberty. As shown in ML, chapter 11, there has been a lot of discussion, based on empirical research, that the critical period may differ for different modules of the grammar and may end several years before puberty. Even deprivation in very early stages of development can have lasting effects in phonological and syntactic skills.
In ML, chapter 12 some “extreme” instances of the poverty of the stimulus argument are used to reinforce this argument in favor of an innate language capacity. The creolization argument focuses on cases in which children, when exposed to a so-called pidgin (a relatively primitive system of communication created by adults who do not share a common language), do not simply imitate what they hear. Instead, their own utterances display grammatical structure that is not present in the input that they get from their pidgin-speaking caregivers. The idea is that children convert pidgins into creole languages which differ from pidgins in being much more grammatically structured. How can children do this? Nativists have argued that children can do this because they are born with an innate “manual” that dictates the construction of a mental grammar, no matter how impoverished the input. Another example of the power that children have to impose grammatical structure where there is none in the input concerns so-called home sign systems which are created by deaf children who are not exposed to a sign language, their input being merely the gestures of their caregivers. Home sign leads to the argument from spontaneous emergence.
Chapter 13 of ML presents the view that the very existence of sign languages testifies to the likelihood of an innate capacity for language. In other words, we here see the sign language argument, which is based on the striking parallelisms between signed and spoken languages in developmental stages, and in their functions and formal, grammatical organization (which is not to say that there are no grammatical differences). These parallelisms strongly suggest that both types of languages are instantiations of the same mental language system that is not geared toward modality-specific aspects of speech and sign (i.e., the specific perception/production channel). This idea is supported by the fact that spoken languages and sign languages are processed, at least in a significant part, in the same brain areas, and that language breakdown (for example in aphasia) proceeds in parallel ways. This suggests a biological predisposition of these brain areas for language, which in turn suggests a genetic basis for language.
The arguments that are summarized here are presented and critically evaluated in ML. Further arguments are provided in the present book, an outline of which is offered in the next section.
An Outline of This Book
This book is divided into six parts. As indicated in the Table of Contents, several longer chapters are divided in two sections.
Part I: Introduction. Chapter 1 outlines the aims and contents of the present book and its prequel ML. Chapter 2 (“The Organization of the Mental Grammar”) presents a model of the mental grammar. Chapter 3 (“The Nature–Nurture Debate across Disciplines”) shows how the nature–nurture issue has played out in a variety of other disciplines, albeit often focused on other human capacities than language or addressing the issue in more general terms.
Part II: Third Factors and Formal Languages Theory. Chapter 4 discusses whether the mental grammar is solely dependent on the innate Universal Grammar and the language input, called the first and second factor, respectively. We review a number of ideas about the role of so-called third factors, such as general learning capacities which can be observed in other systems than language. The role of such factors has always been stressed by empiricists, who claim that there is no need to appeal to an innate UG, but within the nativist camp, recognition of such factors has also increased significantly over the last two decades. Other than general learning capacities, several other third factors have been suggested, involving general physical laws. An important focus of this chapter is to show how Chomsky’s views on what is innate for language have evolved from “most of it” (in the 1960s) to “very little” (since 2000) and how this shift entails an important reduction in what drives nativists and empiricists apart. Chapter 5 (“Formal Languages Theory and the Mental Grammar”) builds on a major contribution that Noam Chomsky made to the study of human language, which was to consider language as a formal grammar that can be compared to other formal grammars that are either mathematically conceivable or actually occurring as computer languages or other so-called artificial languages. By considering the various components of the mental grammar, the question can be asked how their formal design differs in complexity from each other and from other actual or conceivable formal systems. The field of Formal Languages Theory has undergone changes since the 1960s which will be discussed. This chapter will then ask what bearing such formal theories have on the content of the innate Universal Grammar and language acquisition.
Part III: Brains and Genes. Chapter 6 introduces the argument from brain localization. This argument rests on the observation that specific cognitive functions, like language, seem to be supported by neural circuits that tend to be in the same locations in the brains of almost all people. Such (near-)identical locations across the species could not be a coincidence. These commonalities suggest that these brain areas are biologically and thus genetically “reserved” for specific cognitive functions, language being one of them. This is not to deny that there is also plasticity, which allows brain areas to be (re-)dedicated to other, even new functions, as well as the significant impact on neural circuits that is due to life experience. In this chapter, we will also consider cases in which humans have selective cognitive dysfunctions which either leave language intact while affecting other domains, or perhaps only affect language. An important class of linguistic disorders falls under the rubric of aphasia, which can take several different, and sometimes hard-to-separate, forms. While such cases are primarily meant to support the notion of modularity (which is that the mind consists of different, specialized cognitive systems; see ML, chapter 5), they have also been construed as an argument, called the argument from double dissociation, in support of innateness, on the assumption that the modularity of the mind has to be due to the innate design of the mind. Chapter 6 will present some background about the structure of the brain and instrumental techniques to measure brain activities that bear on language which are used in a field called neurolinguistics. Two important lessons to be drawn from this chapter are (a) that a lot of different brain areas are involved in “doing” language and (b) that brain areas that have a bearing on language always have other functions as well.
Chapter 7 develops the argument from genetics. This line of argumentation is potentially very important, although presently the results are still limited. In a nutshell, the argument is based on the fact that there are specific genes that seem to impact certain aspects of language behavior, often while also having other, apparently unrelated, effects. An important discussion in this chapter will focus on epigenetics, which is the process in which gene expression (“nature”) can be influenced by “external” factors (“nurture”). The recognition of, and the growing interest in, epigenetic processes hold a promise for clarifying the way nature and nurture interact – which, then, suggests an avenue for finally channeling the nature–nurture debate into testable theories that explains how both factors interact. Chapter 7 will present some background about the structure of the genome and some experimental techniques to establish correlations between specific genes and behavioral traits. We will see that some evidence for the genetic impact on language is available, based on language disorders that fall under the rubric of Specific Language Impairment (SLI). An important lesson of this chapter is that (a) there is no “language gene” and (b) the route from genes to brains is not well understood.
Part IV: Animal Communication. As a prelude to our evolutionary explorations in Part V, Chapter 8 looks at communication systems in the animal kingdom at large. The study of animal communication and animal intelligence is a fascinating field in its own right. In this chapter, we will ask what it can teach us with respect to the Innateness Hypothesis for human language. We will see that different species have different systems of communication, which in all nonhuman animals seem to be largely or completely innate, which means that they have a genetic basis. This raises the obvious question as to why things should be different for humans. Perhaps postulating an innate knowledge system for human language should be the “null hypothesis.” We could take this to lead to the animal communication argument for innateness. By broadening our perspective to communication systems in nonhuman animals, we can place “what we (as humans) do” in better perspective. Another argument for innateness that we find here is thus that human language is species-specific (i.e., specific to the human species), just like the communication systems of other animals are specific to their species. In Chapter 9, we reinforce the species-specificity of human language by showing there are crucial properties of human language that other animals simply cannot grasp, even after intensive training. Despite catching headlines in the popular press, it is just not the case that nonhuman animals can master essential aspects of human languages. Arguably, these animals cannot handle human language (whether spoken or signed) because they do not have a mind for “our kind of language,” just like we cannot communicate like dolphins do, or whales, or bees, or birds.
Part V: The Evolution of Mind and Language. Assuming that we are dealing with a language-specific innate system, we must consider the plausibility of this biological system from an evolutionary point of view. Here we will enter a controversial domain because, as we will see, it is very difficult to speak confidently about the mental abilities of creatures that are no longer among us (i.e., our remote ancestors). This is an important point because it is not in dispute that human language evolved long before the earliest direct evidence that one can infer from the oldest writing systems. On the assumption that there would be no point in having language before our ancestor had a developed mind (which means that they had something to say), any account of language evolution must include an account of the evolution of the human mind. Chapter 10 turns to the evolution of language, asking some basic questions about the subject of language evolution. This is a hotly debated and studied subject these days, after having been banned from public discourse for a long time because of its unsolvable nature. It is often said that we cannot know anything about early forms of human languages because “words do not fossilize.”11
Part VI: Winding Up. Chapter 11 (Evaluating the Arguments: A Forum Discussion) will evaluate the arguments that have been examined in the book and offers a “mock” forum discussion between proponents of different and opposing views. This chapter will offer a summary of most of the topics that have been discussed in both this book and its prequel ML, asking whether something of a unifying understanding of the nature and nurture of language is in sight.
