The Overall Context
In the book, Tomasello discusses a wide variety of research, from human language acquisition to the nesting behaviors of orangutans, but he does a good job of discussing the findings of much of that research, so I won't go into most of it in the introduction to the book. However, there are three things that it's important to understand in order to fully grasp the concepts in the book: the two most prominent contrasting views, namely the Chomskyan universal grammar paradigm in linguistics and Evolutionary Psychology, and what is perhaps the most important concept in the book, the concept of theory-of-mind. So in this post, I'll briefly discuss both the Chomskyan view of language and the basic beliefs of Evolutionary Psychology, and briefly define theory-of-mind. At the end, I'll provide a list of links that provide further discussion of each.
As you can probably tell from the title of the book, Tomasello believes that many aspects of modern-day human cognition evolved culturally, rather than biologically (i.e., through changes in our genetic makeup caused by the mechanisms of biological evolution, most notably natural selection). This means that we are born with a fairly plastic mind that is shaped through experience, and the experiences that modern humans have benefit from the experiences of the humans who have come before us in the form of cumulative culture. In the terminology of philosophy, Tomasello is a fairly radical empiricist. He's not a tabula rasa empiricist, but he's about as close to that as people in cognitive science come these days. His position is particularly interesting because, at the same time Tomasello began to espouse it, a group of psychologists, anthropologists, philosophers, and neuroscientists who called themselves Evolutionary Psychologists was becoming more prominent. Evolutionary Psychologists are nativists, people who believe that much of our modern-day cognition is the result of innate, biologically evolved, domain-specific mechanisms in the brain. In other words, Tomasello and Evolutionary Psychologists are in many respects polar opposites, theoretically.
While Evolutionary Psychology is not widely respected among cognitive scientists (Evolutionary Psychologists get a lot of popular press, while Tomasello gives a plenary speech at the most prestigious cognitive science conference), some of its basic ideas, in less extreme and absurd forms, are. The extreme contrast between Tomasello's work and that of Evolutionary Psychologists can therefore serve as an illustration of the generally more subtle contrasts between Tomasello and the beliefs of most cognitive scientists. To understand this contrast, then, it's important to understand the basic tenets of Evolutionary Psychology.
Here is how Stephen Pinker, one of the foremost proponents of Evolutionary Psychology, describes its purpose:
The goal of research in evolutionary psychology is to discover and understand the design of the human mind... Evolutionary psychology often investigates the adaptive functions of cognitive and emotional systems -- how natural selection "engineered" them to solve the kinds of problems faced by our ancestors in their struggle to survive and reproduce... Complex organs like eyes have many precise parts in exacting arrangements, and the odds are astronomically stacked against their having arisen fortuitously from random genetic drift or as a by-product of something else. Second, the brain, like the eyes and the feet, shows signs of good design. The adaptive problems it solves, such as perceiving depth and color, grasping, walking, reasoning, communicating, avoiding hazards, recognizing people and their mental states, and juggling competing demands in real time are among the most challenging engineering tasks ever stated, far beyond the capacity of foreseeable computers and robots. Put the premises together -- complex design comes from natural selection, and the brain shows signs of complex design -- and we conclude that much of the brain should be explained by natural selection.The idea that the brain evolved through natural selection is not a controversial one, and is part of Tomasello's view as well, but even in this short description Pinker hints at what makes Evolutionary Psychology interesting and controversial: the idea that the brain evolved, through natural selection, specific abilities to perform specific tasks, like theory-of-mind ("recognizing people and their mental states"). This is how Leda Cosmides and John Tooby put it:
[T]he reason we have one set of [brain] circuits rather than another is that the circuits that we have were better at solving problems that our ancestors faced during our species' evolutionary history than alternative circuits were. The brain is a naturally constructed computational system whose function is to solve adaptive information-processing problems (such as face recognition, threat interpretation, language acquisition, or navigation). Over evolutionary time, its circuits were cumulatively added because they "reasoned" or "processed information" in a way that enhanced the adaptive regulation of behavior and physiology.There are two important parts to these claims, against which Tomasello will argue: 1) The neural circuits that evolved did so in response to (highly) specific adaptive problems, and 2) these problems were the ones faced by our evolutionary ancestors that existed in the time between our common ancestor with modern apes. The argument for the first of these is pretty simple and intuitive. In essence, it says that there was no such thing as a "domain-general" problem in our evolutionary environment, and therefore, we could not have evolved brains that were designed with domain-general problem solving mechanisms. Our evolutionary ancestors' environment involved many specific problems that, if they were to survive, they would have to deal with adaptively. This would require the brain to develop specific mechanisms designed to deal with those specific problems. The problems that Evolutionary Psychologists often discuss in this vein include the problems of detecting cheaters and rewarding cooperators (reciprocal altruism), the problems of selecting and procuring mates, the problem of detecting when your mate is mating with others behind your back (so that, if you're male, you can know whether her offspring are actually yours), and the problem of figuring out what's going on in other people's minds (theory-of-mind).
The idea that we evolved several specific brain mechanisms that are designed to deal with specific adaptive problems that were faced by our ancestors leads to a view of the makeup of the mind that is sometimes called "massive modularity," the view that the mind is made up of a bunch of individual modules, or tiny computers, that selectively process information that is relevant to the problems they were designed to solve. The various circuits then work together to produce complex adaptive behaviors in complex environments. Here is the substance of the massive modularity view in the words of Cosmides and Tooby:
We have all these specialized neural circuits because the same mechanism is rarely capable of solving different adaptive problems. For example, we all have neural circuitry designed to choose nutritious food on the basis of taste and smell -- circuitry that governs our food choice. But imagine a woman who used this same neural circuitry to choose a mate. She would choose a strange mate indeed (perhaps a huge chocolate bar?). To solve the adaptive problem of finding the right mate, our choices must be guided by qualitatively different standards than when choosing the right food, or the right habitat. Consequently, the brain must be composed of a large collection of circuits, with different circuits specialized for solving different problems. You can think of each of these specialized circuits as a mini-computer that is dedicated to solving one problem. Such dedicated mini-computers are sometimes called modules. There is, then, a sense in which you can view the brain as a collection of dedicated mini-computers -- a collection of modules. There must, of course, be circuits whose design is specialized for integrating the output of all these dedicated mini-computers to produce behavior. So, more precisely, one can view the brain as a collection of dedicated mini-computers whose operations are functionally integrated to produce behavior.Claim two makes involves an argument about when these domain-specific abilities evolved. We humans have only been hanging around in civilizations for about 10,000 years. That's not enough time for complex problem-solving mechanisms to evolve. So, they must have evolved earlier than that. We know that modern apes, with whom we share a common ancestor that lived about 6 million years ago, don't have the cognitive and behavioral repertoire that Evolutionary Psychologists are interested in. So, they have to have evolved within the last 6 million years. We also know that until about 2 million years ago, our ancestors were mostly various Australopithecine species that don't appear to have had many of the cognitive traits of modern humans that Evolutionary Psychologists believed have evolved through natural selection either. Therefore, most of the evolutionary work had to have been done between 2 million and 10,000 years ago, a time period called the Pleistocene. Furthermore, because most of the work was done in the Pleistocene, our brains are composed of a bunch of mini-computers, or modules, that were designed to handle the problems faced by our ancestors, but which we no longer face, or which have, in the modern world, changed so dramatically that they no longer resemble our Pleistocene problems. In the words of Cosmides and Tooby, "our modern skulls house a stone age mind."
Tomasello will argue that, in fact, the two million years in which humans have had to evolve these complex, domain-specific modules is simply not enough time. Instead, he believes that a single, fairly simple adaptation that built onto capabilities that were already present in our primate relatives. In a paper published just before the book, he wrote:
If we are searching for the origins of uniquely human cognition... our search must be for some small difference that made a big difference, some adaptation, or small set of adaptations, that changed the process of primate cognitive evolution in fundamental ways.For him, the most likely "adaptation, or small set of adaptations" are those that created in our ancestors the ability to learn and transmit cultural knowledge.
Chomsky, Universal Grammar, and the Evolution of Language
Most of you are probably familiar with Noam Chomsky, and have some level of knowledge of his contributions to linguistics. Chomsky is one of the founding fathers of cognitive science, and his work, including his criticisms of behaviorism, constituted one of the driving forces behind the cognitive revolution in the 1950s and 60s. It would be impossible to give a sufficiently detailed account of Chomsky's theories over the years, and I'm not really qualified to do that anyway. However, for the purposes of situating Tomasello's book, it will be sufficient to briefly discuss one of the foundations of Chomsky's views, the idea that humans possess an innate language faculty that house's knowledge of the underlying rule-based structure of all languages (a universal grammar). On top of that, I'll also mention some of the views of how that language faculty came to be.
The primary argument for the existence of an innate language faculty is that there simply isn't enough information in the environment to learn the complex set of rules required to be a competent user of human language. Here's a simplified version of the argument:
i. A complex set of principles and rules (grammar) underlies all human languages.Put another way, the evidence to which a child is exposed in his or her linguistic environment can be accounted for by a large, if not infinite number of possible sets of principles and rules. Figuring out which is the correct set (which one allows you to learn and use the language correctly) requires that the language faculty already contain the basics of that set. From what I can tell, the most popular version of this approach, today, is the "principles and parameters" approach that Chomsky first laid out in Lectures on Government and Binding. According to this version, we are born with a set of principles and parameters which underlie the syntax of all languages. What children learn through experience is the content of the language's lexicon, along with the values of the parameters. It is differences in these that produce the variations we see across different languages.
ii. The only information that a child receives from his or her environment about these principles and rules comes from observing people use language.
iii. There is not enough information in those observations to learn the complex set of principles and rules required to acquire a human language. The utterances a child hears are incomplete, ungrammatical, and more importantly, only a tiny fraction of the set of possible utterances (which is infinite).
iv. Therefore, in order to acquire a language through observation, the human child must come to the table equipped with an innate set of principles and rules that can be tweaked through exposure to instances of language in his or her environment.
After establishing that there is a universal grammar, it becomes important to understand how it came to be. Understanding its origins may help us to understand the specifics of its content. Thus, it becomes important to understand the evolution of the language faculty. Chomsky himself has insisted that it is unlikely that the language faculty evolved through natural selection, and that if it did, it is impossible to know under what conditions, and in response to which adaptive problems, it evolved. He, along with Marc Hauser and Tecumseh Fitch articulated this position in this paper. Others within the Chomskyan tradition, most notably Derek Bickerton, Stephen Pinker, and Ray Jackendoff, disagree. Each has argued for his own version of language evolution. For Bickerton, language evolved out of a protolanguage which resembled, in some ways, modern pidgin languages. For Pinker and Jackendoff, there were a series of steps leading from the use of Saussurean signs (signs that bear only arbitrary relationships to the signified, like the word "dog" bears no nonarbitrary relationship to dogs) to complex rules for the combination of phonetic, syntactic, and semantic information into the complex utterances of human languages. There doesn't appear to be any single dominant theory of language evolution yet, but most of them assume that what evolved was some form of the Chomskyan language faculty.
The idea that humans are born with a universal grammar is pretty uncontroversial within linguistics, though it is still questioned by many outside of linguistics (especially in psychology and computer science). The poverty of stimulus argument, in particular, is still widely questioned outside of linguistics (see, e.g., this recent paper on machine learning). Tomasello himself has devoted much of his professional career to developing an alternative account of language acquisition, which he's laid out in a separate book titled Constructing a Language: A Usage-Based Theory of Language Acquisition. In that book, as well as in The Cultural Origins of Human Cognition, he argues that there is in fact sufficient information in the child's linguistic environment to acquire language. This acquisition is done not through a faculty specific to language, but using the same mechanisms that enable other forms of cultural learning. In other words, there is no innate universal grammar, and because of this, there is no need for a highly evolved language faculty. Instead, most of what constitutes modern languages evolved culturally. As you can probably imagine, this is a pretty controversial position, and it is not widely accepted, even among those who doubt the validity of the poverty of stimulus argument and the existence of a universal grammar.
Theory of Mind
The one area in which Tomasello is in agreement with most other cognitive scientists, including Evolutionary Psychologists, is in the belief that the basic capacities that allow us to infer the thoughts, beliefs, feelings, and intentions of other human beings is evolved. These capacities are generally discussed under the heading "theory of mind." The most often used test for theory of mind is the false-belief task. In a typical version of this task, a child sits in a room with two experimenters, with a pair of boxes in front of them. One of the experimenters takes an object (a toy, candy, or something else that will interest the child), shows it to the child and the other experimenter, and places it into one of the boxes. The other experimenter then leaves the room. While he or she is gone, the first experimenter takes the object out of the box, and places it in the other box (or somewhere else in the room, out of sight). The child is then asked where the experimenter who left will look for the object. The logic of the experiment is that if the child is able to reason about the mental states of other people, he or she should be able to understand that other people can have false beliefs. Therefore, if the child has theory of mind abilities, he or she should answer that the other experimenter will look in the box into which the first experimenter originally placed the object. If the child does not have theory of mind abilities, he or she will answer that the experimenter who left the room will look in the place that the object was placed after he or she left the room. Human children are able to perform this task by age 3 or 4, while most nonhuman primates are not able to perform it without extensive training.
The false belief task has many problems, and may not test for all of the aspects of theory of mind. In fact, other experimental paradigms demonstrate evidence for theory of mind abilities in nonhuman primates as well as human infants. However, there are definite differences between the theory of mind capabilities of nonhuman primates and those of young human children (perhaps even infants). Tomasello's account of the evolution of modern human cognition centers around these differences. He will argue that it is the faculties that underlie these differences that allow humans to develop, through cultural learning, a wide range of cognitive abilities, including the use of language, that no other animal has developed.
Once again, this is a very controversial position, and it has not been widely accepted, though it is garnering more and more attention in psychology and cognitive anthropology (I'm not sure what linguists think of it). I think this means that Tomasello's book, which is controversial pretty much from page 1, will spark a lot of great discussion, and will thus make for a great first book for our group. I hope this introductory post helps to situate the book. As we go along, I will try to define the concepts and explain Tomasello's positions in more depth, and may go in to more detail on the differences between his and other views in the field.