The Making of the Mind: The Neuroscience of Human Nature (11 page)

What seems to prevent chimpanzees from relying on imitation as a primary means of social learning could well be their inability to recognize other chimpanzees as intentional agents.
³²
The goal or intention of a model is readily picked up by a human being, as is the specific means used to achieve the goal. The means and the end are separable in the human's mind. By contrast, the intentions of the model and the behavioral means used to achieve the goal are probably not part of the chimpanzee's experience in witnessing the whole event. Instead, the chimpanzee possibly only perceives changes in the environment, and the demonstrator's actions are just part of these changes. Unlike human beings, chimpanzees seem unable to perceive these environmental changes as parts of a behavioral strategy that can be copied.

Although human beings possess an advanced form of social intelligence, efforts to enculturate apes by training them in imitative learning have shown some success. Even though wild chimpanzees do not show signs of the capacity for joint attention, there is sufficient continuity between the two species for intensive training to yield some positive results. For example, wild apes do not appear to point to an object for others to look at or to hold up an object to show others. Yet these skills can be trained to a degree, most likely because “in a human-like cultural environment…they are constantly interacting with humans who show them things, point to things, encourage (even reinforce imitation), and teach them special skills—all of which involve a referential triangle between human, ape, and some third entity.”
³³
When in close contact with humans, it appears that chimpanzees can gain some access into our social world and even our symbolic world. Training apes to learn some aspects of American Sign Language illustrates this point. Their achievements in these settings, however, do not alter the conclusion that cultural learning is an emergent and distinctive feature of human evolution. Only human beings invent elaborate cultures that their offspring learn through immersion as part of the natural course of cognitive development.

Episodic Culture

How, then, have the capacities of invention and social learning changed across phylogeny in evolutionary time? How have such changes affected the kinds of cultures that we observe in the historical record? Archeologists have studied cultural changes in terms of the artifacts created by early hominids. Change in the sophistication of stone tools is a good example. However, it is also instructive to speculate about the cognitive capacities that have evolved in modern humans. Both cognition and culture set us apart from all other species in biological evolution and, at the same time, characterize the human journey through historical time, from the Upper Paleolithic to today.

The cultural world of the chimpanzee provides a clouded glimpse, perhaps, into the mind of our common ancestor from five to seven million years ago. The neocortex of the chimpanzee is well developed and no doubt serves the function of conscious awareness, just as it does in human beings. However, unlike human beings, the ape's mind, and the mammalian mind more generally, would be limited to representations of its perceptions and actions. Lacking language, an ape cannot name and reflect upon abstractions about what it sees, hears, and feels. The thought of apes is tied to the concrete situation, the here and now of perception and action, rather than the abstract symbolic representations. The ape also cannot talk to itself, using language as a means of inner dialogue and contemplation. The behavioral traditions that apes invent and learn are linked to the episodes that they experience from day to day. Because grooming and backscratching are common episodes in a chimpanzee's life, it is not surprising that the methods used become traditional. The tools invented to fish for termites show the impressive problem-solving capacities of the chimpanzee, but, again, they arise from concrete experiences and reflect what is called episodic culture.
³⁴

If we assume that the common ancestor of chimpanzees and humans exhibited episodic culture, then what changed in hominid ancestors that led to the culture of modern human beings? It has already been argued that an advanced form of working memory and advanced social intelligence paved the way in part. However, an even more radical change also occurred—the invention and propagation of language within a human population and from
one generation to the next. When human beings were bestowed the gift of naming, we opened a door to a world of abstraction that is closed to our primate ancestors. To name meant the capacity to utter not just a sound but also an abstract symbol that referred to something entirely and arbitrarily different from the sound itself. The ability to learn and use a name to refer to a concrete object by itself moved human beings beyond the episodic world of perception and action into a world of abstraction.

There is good reason to see the highly developed social intelligence discussed in this chapter as the foundation for the development of language. Consider an experiment in which a human points to or gazes in the direction of hidden food in the presence of a chimpanzee. Chimpanzees, as well as all other nonhuman primates, “show little spontaneous skill at using such communicative cues to find the hidden food in this cooperative context.”
³⁵
Nor do they succeed when a member of their own species provides the communicative cues to help locate the food reward. If trained successfully after dozens of trials to use one such cue, the chimpanzees fail to use even a very similar, but slightly modified, cue of communication. It appears that the social intelligence of nonhuman primates does not enable them to learn how to communicate to solve problems, like finding food.

Armed with the innovative abilities of human working memory and the social learning and cooperation abilities of advanced social intelligence, human beings acquired the third part of the modern ensemble. Language allowed human beings to share their mental experiences with others around them who spoke the same language. Telling stories about episodes became possible in addition to actually witnessing an episode. Language also allowed the possibility of self-narration, or talking to one's self. An ongoing, incessant commentary on current perceptions or episodes remembered from the past or imagined in the future became a defining feature of the human mind. The invention of language opened the door to radically different kinds of cognitive cultures that characterized human beings for millennia up to the present day.

Of all the parts of the ensemble hypothesized here, language almost singularly creates an unbridgeable chasm between the mind of
Homo sapiens
and that of
Pan troglodytes
. As noted in
chapter 1
, Charles Darwin made this point over 150 years ago when he observed that our higher cognitive faculties are “mainly the result of the continued use of a perfect language.”
¹
Yet the hedge “almost” and the interaction of language with other ensemble parts should not be overlooked in understanding why the human mind is of a fundamentally different kind from anything found in nonhuman primates.

Language provides human beings with an ability to communicate with one another, but it is far more than a system of communication. Language is also a means of representing reality. Through language the mind found a means to represent objects and events in a symbolic manner rather than through visual-spatial images. Because of language, the ancestral mind was no longer tethered to thinking about concrete objects and events that could be imaged like a picture—a reuse of vision for seeing things in the head rather than in the immediate environment. The capacity for symbolic thought—the use of words to refer to objects, events, thoughts, and concepts—is the essence of our species. Not surprisingly, then, the beginnings of language were portrayed as part of the beginnings of humanity in the creation account of the Bible: “And out of the ground the LORD God formed every beast of the field and every fowl of the air; and brought them unto Adam to see what he would call them: and whatever Adam called every living creature, that was the name thereof” (Genesis 2:19).

THE MOTHER TONGUE

The hypothesis that modern human beings evolved first in Africa and then spread through migration to the Middle East and later throughout the world rests on both genetic and archeological evidence. Linguists have long speculated that a protolanguage once existed from which all languages subsequently evolved through historical time. Languages change relatively rapidly over time through the fast-track process of cultural evolution. Across hundreds, if not thousands, of generations, language systems appear to have grown more and more complex and differentiated in a manner analogous to the speciation of plants and animals. As with biological species, languages can also become extinct, dying off with the subpopulation of human beings who know the language. When a language is no longer taught to the next generation, it passes away.

That all human beings once spoke the same language was again an echo of the biblical book of Genesis:

Now the whole earth had one language and one speech. And it came to pass, as they journeyed from the east, that they found a plain in the land of Shinar, and they dwelt there. Then they said to one another, “Come, let us make bricks and bake them thoroughly.” They had brick for stone, and they had asphalt for mortar. And they said, “Come, let us build ourselves a city, and a tower whose top is in the heavens; let us make a name for ourselves, lest we be scattered abroad over the face of the whole earth.” But the LORD came down to see the city and the tower which the sons of men had built. And the LORD said, “Indeed the people are one and they all have one language, and this is what they begin to do; now nothing they propose to do will be withheld from them. Come, let Us go down and there confuse their language, that they may not understand one another's speech.” So the LORD scattered them abroad from there over the face of all the earth, and they ceased building the city. Therefore its name is called Babel, because there the LORD confused the language of all the earth; and from there the LORD scattered them abroad over the face of all the earth. (Genesis 11: 1–9)

The tower referenced in Genesis was in all likelihood a staged temple tower, known as a “ziggurat,” and the “Tower of Babel” could only be the
ziggurat erected in Babylon.
²
Babylonian literature refers to the construction of a large ziggurat known as Etemenanki, which was described as a temple to the god Marduk that would reach to the heavens. Archeologists have discovered a tablet giving the precise dimensions of each of the structure's seven stories, and the Greek historian Herodotus provided a description of Etemenanki after his visit to Babylon in 460 BCE.
³

Theologians and scholars of language have for centuries sought to discover the mother tongue of all humanity, the source from which existing languages descended through cultural evolution in historical time. However, interest in the topic exploded in scientific circles after the publication of Darwin's
Origin of Species
in 1859. Questions about the origin of human nature—including languages—proved irresistible. Yet there was little if any tangible scientific evidence that could be advanced to test theorists’ speculations. And so, by 1866, the
Société de Linguistique de Paris
was obliged to ban all discussions of the evolution of language from their meetings.
⁴
This indeed chilled debate, for it was not until more than a century later that cognitive scientists returned in earnest to investigate the topic.

One intriguing hypothesis is that a common prehistoric language was spoken in Asia around fifteen thousand years ago by modern humans living in the territory between the Black Sea and the Caspian Sea.
⁵
Called Nostratic—after the Latin
noster
for “our”—it was hypothesized to be a superfamily of languages, including the family of Indo-European languages as well as other linguistic families such as the Afro-Asiatic languages spoken by, for example, Ethiopian and southwestern Asian populations and the Altaic languages spoken by Korean and Japanese populations. Linguists sought to reconstruct the proto-languages or a hypothetical ancestral language from which modern language families descend (e.g., proto-Indo-European). The reconstruction of a proto-language involves specifying the set of consonants and vowels it used, the words it employed, the grammatical endings appended to nouns or verbs, and even the allowable word orderings, such as whether an adjective precedes or follows a noun.

Instead of trying to reconstruct proto-languages, the linguist Joseph Greenberg attempted to build a taxonomy of existing languages by comparing their similarities and differences. He selected words that change the
least over time, such as the numbers one, two, and three, parts of the body, personal pronouns, and so on.
⁶
The picture that emerged from Greenberg's classification turned out to be in many ways similar to the Nostratic hypothesis. Greenberg concluded that a Eurasiatic superfamily included the Indo-European and Altaic languages—essentially all of Europe and Asia along with Eskimo-Aleut in the American Artic. It differed from Nostratic by excluding the Afro-Asiatic family, which Greenberg concluded had split from and evolved as a separate lineage at an earlier point in time.
⁷

Greenberg's classification of languages shows that Africa contains within it the greatest diversity of languages. There are four highly diverse families of languages in Africa alone, whereas the entire European peninsula is coextensive with all of Asia in spawning a single family of languages—Eurasiatic.
⁸
In fact, this same family extends around the world, across the Alaska and the northern zones of Canada, and as far east as Greenland. In much the same way, a single family of languages known as Amerind covers the vast majority of both North and South America. In short, all the languages of Europe, Asia, and the Americas taken together can be classified within only two families; by contrast, the continent of Africa alone has twice that many families. This pattern of greater linguistic diversity within Africa suggests that languages have been evolving for a longer period of time there than anywhere else. Just as greater genetic diversity implies an African origin of modern humans, the diversity of human languages suggests the same conclusion.

Luigi Luca Cavalli-Sforza and his colleagues explored the parallel between genetic and linguistic evolution in fine detail. Might the picture of human origins and migration out of Africa to the Near East and beyond, indicated by similarities in the genomes of diverse human populations, also be supported by comparisons of their languages? The approximately five thousand languages still spoken today can be clustered into seventeen different phyla.
⁹
The languages sharing a phylum use similar sounding words to refer to the same concept. They are thus related linguistically in a manner that parallels the biological relationships of brothers, sisters, and cousins. For example, Italian, Spanish, and French are related linguistically because they descended from and diversified around the common ancestor, ancient Latin. The DNA results have shown a major split in the phylogenetic tree between Africans and
non-Africans. The second split separates, in terms of their genetic similarity, the Caucasoids, East Asians, Artic populations, and American natives, on the one hand, from the Southeast Asians, Pacific Islanders, New Guineans, and Australians on the other.

Strikingly, the linguistic similarities confirm the DNA evidence, almost without exception. Each and every linguistic phylum maps onto only one of the six major clusters of human beings classified on the basis of genetic similarity.
¹⁰
For example, Niger-Kordofan, Nilo-Saharan, and Khoisan linguistic phyla are all linked to biologically defined populations in Africa. The Indo-European languages, out of which English descended, are tied to the Caucasoid populations, as defined by their genetic similarity. The few exceptions that failed are not too difficult to explain from what is known about the biological history of the groups in question. For example, Ethiopians speak Afro-Asiatic languages found in North Africa and the Middle East, where populations are genetically identified as Caucasoid. But genetic mixing of the African and Caucasoid lines is also evident in the Ethiopian population. Similarly, the Tibetans are closest to the Northeast Asian cluster in terms of genetic similarity, but linguistically they align with the Sino-Tibetan phylum spoken in all of China. The Tibetans are thought by historians to have originated from nomadic groups from the steppes north of China, a fact that could account for their connection to the Northeast Asian genetic cluster.

That languages are evolutionarily related to one another was suggested first by Sir William Jones in the eighteenth century. As an avocation, Jones mastered and classified on the basis of their similarities numerous languages while serving as a Supreme Court justice in India. In 1786, in his
Third Discourse to the Asiatic Society
, he proposed that
Greek, Latin
, and
Sanskrit
, the language of Northern India from the first millennium BCE, were remarkably similar and must have descended by modification from a common ancestor.
¹¹
This linguistic insight came seventy-two years before the explanation of biological evolution in the
Origin of Species
, but it was Darwin's book that was widely read and spread throughout the culture.

DEFINING LANGUAGE

At the core of language is the human capacity for symbolic reference: the use of an arbitrary sound to refer to something else. A word, a sound or combination of sounds, can refer to a concrete object that exists in the external world, such as a dog. Although a seemingly simple example of symbolic reference, it reveals a profound capacity for abstract thought. It reveals an ability to think with symbols rather than with visual-spatial images that are grounded in the objects and events of the physical world. We can think visually about objects and events that have been perceived in the real world. This capacity is certainly shared by other primates endowed with a visual system similar to our own. Yet human beings alone can also think using words that refer to objects and events.
Dog
can be a constituent of thought without any imagery of a particular dog. In short, human beings can think symbolically and abstractly, as seen in the example of naming.

As a symbol, a word is purely an abstract carrier of information, an arbitrary but agreed upon convention among the speakers of a language, a tool to help one think of a particular concept when the word is heard and comprehended. Where speakers of English say “the dog,” speakers of German (
das Hund
), French (
le chien
), Spanish (
el perro
), or Italian (
il cane
) use different combinations of sounds to mean the same thing. The arbitrariness of the connection between symbol and referent is all the more striking because English is closely related to both German and French. Similarly, French, Spanish, and Italian are closely related Romance languages with their origin in Latin.

The concept itself is also an abstraction in that a wide variety of four-legged mammals that bark, sleep, wag their tails, and live with human beings all fit the word dog. The reference or extension of the concept in the external world includes a very large and diverse population of concrete entities that we can be see, hear, smell, pet, and at times be bitten by. But the meaning of the concept—what philosophers call its intension—is an abstraction that the mind represents and indexes to all dogs and only to dogs. Such conceptual capacity provides a second example of the human ability for abstract thought.