The Dragons of Eden

by Carl Sagan

  Effective defense against predators and the hunting of game were both necessarily cooperative ventures. The environment in which man evolved—in Africa in Pliocene and Pleistocene times—was inhabited by a variety of terrifying mammalian carnivores, perhaps the most awesome of which were packs of large hyenas. It was very difficult to defend oneself alone against such a pack. Stalking large animals, either solitary beasts or herds, is dangerous; some gestural communication among the hunters is necessary. We know, for example, that shortly after man entered North America, via the Bering Straits in the Pleistocene Period, there were massive and spectacular kills of large game animals, often by driving them over cliffs. In order to stalk a single wildebeest or stampede a herd of antelope to their deaths, hunters must share at least a minimal symbolic language. Adam’s first act was linguistic—long before the Fall and even before the creation of Eve: he named the animals of Eden.

  Some forms of gestural symbolic language, of course, originated much earlier than the primates; canines and many other mammals who form dominance hierarchies may indicate submission by averting the eyes or baring the neck. We have mentioned other submissive rituals in primates such as macaques. The human greetings of bow, nod and curtsy may have a similar origin. Many animals seem to signal friendship by biting, but not hard enough to hurt, as if to say, “I am able to bite you but choose not to do so.” The raising of the right hand as a symbol of greeting among humans has precisely the same significance: “I could attack you with a weapon but choose not to wield one.”* Extensive gestural languages were employed by many human hunting communities—for example, among the Plains Indians, who also used smoke signals. According to Homer, the victory of the Hellenes at Troy was conveyed from Ilium to Greece, a distance of some hundred miles, by a series of signal fires. The date was about 1100 B.C. However, both the repertoire of ideas and the speed with which ideas can be communicated in gestural or sign languages is limited. Darwin pointed out that gestural languages cannot usefully be employed while our hands are otherwise occupied, or at night, or when our view of the hands is obstructed. One can imagine gestural languages being gradually supplemented and then supplanted by verbal languages—which originally may have been onomatopoeic (that is, imitative in sound of the object or action being described). Children call dogs “bow-wows.” In almost all human languages the child’s word for “mother” seems imitative of the sound made inadvertently while feeding at the breast. But all of this could not have occurred without a restructuring of the brain.

  We know from skeletal remains associated with early man that our ancestors were hunters. We know enough about the hunting of large animals to realize that some language is required for cooperative stalking. But ideas on the antiquity of language have received a measure of unexpected support from detailed studies of fossil endocasts made by the American anthropologist Ralph L. Holloway of Columbia University. Holloway’s casts of fossil skulls are made of rubber latex, and he has attempted to deduce something of the detailed morphology of the brain from the shape of the skull. The activity is a kind of phrenology, but on the inside rather than on the outside and much more soundly based. Holloway believes that a region of the brain known as Broca’s area, one of several centers required for speech, can be detected in fossil endocasts; and that he has found evidence for Broca’s area in a Homo habilis fossil more than two million years old. The development of language, tools and culture may have occurred roughly simultaneously.

  The development of human language was a crucial turning point in the evolution of man. Among its highest peaks, as here, were story-telling cultures before the invention of writing.

  Photo by Nat Farbman, Life.

  Courtesy of Time-Life Picture Agency, © Time Inc.

  There were, incidentally, manlike creatures who lived only a few tens of thousands of years ago—the Neanderthals and the Cro-Magnons—who had average brain volumes of about 1,500 cubic centimeters; that is, more than a hundred cubic centimeters larger than ours. Most anthropologists guess that we are not descended from Neanderthals and may not be from Cro-Magnons either. But their existence raises the question: Who were those fellows? What were their accomplishments? Cro-Magnon was also very large: some specimens were well over six feet tall. We have seen that a difference in brain volume of 100 cubic centimeters does not seem to be significant, and perhaps they were no smarter than we or our immediate ancestors; or perhaps they had other, still unknown, physical impediments. Neanderthal was a lowbrow, but his head was long, front to back; in contrast, our heads are not so deep, but they are taller: we can certainly be described as highbrows. Might the brain growth exhibited by Neanderthal man have been in the parietal and occipital lobes, and the major brain growth of our ancestors in the frontal and temporal lobes? Is it possible that the Neanderthals developed quite a different mentality than ours, and that our superior linguistic and anticipatory skills enabled us to destroy utterly our husky and intelligent cousins?

  So far as we know, nothing like human intelligence appeared on Earth before a few million, or at least a few tens of millions of years ago. But that is a few tenths of a percent of the age of Earth, very late in December in the Cosmic Calendar. Why did it appear so late? The answer clearly seems to be that some particular property of higher primate and cetacean brains did not evolve until recently. But what is that property? I can suggest at least four possibilities, all of which have already been mentioned, either explicitly or implicitly: (1) Never before was there a brain so massive; (2) Never before was there a brain with so large a ratio of brain to body mass; (3) Never before was there a brain with certain functional units (large frontal and temporal lobes, for example); (4) Never before was there a brain with so many neural connections or synapses. (There seems to be some evidence that along with the evolution of the human brain there may have been an increase in the number of connections of each neuron with its neighbor, and in the number of microcircuits.) Explanations 1, 2 and 4 argue that a quantitative change produced a qualitative change. It does not seem to me that a crisp choice among these four alternatives can be made at the present time, and I suspect that the truth will actually embrace most or all of these possibilities.

  A Pleistocene summit. Left to right: Homo habilis (in an inadequate state of repair), Homo erectus, Neanderthal man, Cro-Magnon man, and Homo sapiens.

  Photograph by Chris Barker. Copyright © Marshall Cavendish Ltd.

  The British student of human evolution Sir Arthur Keith proposed what he called a “Rubicon” in the evolution of the human brain. He thought that at the brain volume of Homo erectus—about 750 cubic centimeters, roughly the engine displacement of a fast motorcycle—the uniquely human qualities begin to emerge. The “Rubicon” might, of course, have been more qualitative than quantitative. Perhaps the difference was not so much an additional 200 cubic centimeters as some specific developments in the frontal, temporal and parietal lobes which provided us with analytical ability, foresight and anxiety.

  While we can debate what the “Rubicon” corresponds to, the idea of some sort of Rubicon is not without value. But if there is a Rubicon anywhere near 750 cubic centimeters, while differences of the order of 100 or 200 cubic centimeters do not—at any rate to us—seem to be compelling determinants of intelligence, might not the apes be intelligent in some recognizably human sense? A typical chimpanzee brain volume is 400 cubic centimeters; a lowland gorilla’s, 500 cc. This is the range of brain volumes among the tool-using gracile Australopithecines.

  The Jewish historian Josephus added to the list of penalties and tribulations that accompanied Mankind’s exile from Eden the loss of our ability to communicate with the animals. Chimpanzees have large brains; they have well-developed neocortices; they, too, have long childhoods and extended periods of plasticity. Are they capable of abstract thought? If they’re smart, why don’t they talk?

  * Modern rocket technology and space exploration owes an incalculable debt to Dr. Robert H. Goddard, who through many decades of devoted an
d lonely research was singlehandedly responsible for the development of essentially all important aspects of the modern rocket. Goddard’s interest in this subject originated in a magic moment. In the New England autumn of 1899, Goddard was a seventeen-year-old high school sophomore who had climbed a cherry tree and, while idly looking down at the ground around him, experienced a kind of epiphanal vision of a vehicle that would transport human beings to the planet Mars. He resolved to devote himself to the task. Exactly one year later, he climbed the tree again, and on every October 19th for the rest of his life, made a special point of recollecting that moment. Can it be an accident that this vision of voyages to the planets, which has led directly to its own historical fulfillment, was glimpsed in the limbs of a tree?

  * God’s judgment on the serpent is that henceforth “upon thy belly shalt thou go”—implying that previously reptiles traveled by an alternative mode of locomotion. This is, of course, precisely true: snakes have evolved from four-legged reptilian ancestors resembling dragons. Many snakes still retain anatomical vestiges of the limbs of their ancestors.

  † Cherubim is plural; Genesis 3:24 specifies one flaming sword. Presumably flaming swords were in short supply.

  * In the West. There are, of course, many insightful and profound myths on the origin of mankind in other human cultures.

  * The upraised and open right hand is sometimes described as a “universal” symbol of good will. It at least runs the gamut from Praetorian Guards to Sioux scouts. Since those wielding weapons are, in human history, characteristically male, it should be and is a characteristically male greeting. For these reasons, among others, the plaque aboard the Pioneer 10 spacecraft—the first artifact of mankind to leave the solar system—included a drawing of a naked man and woman, the man’s hand raised, palm out, in greeting (see illustration on this page). In The Cosmic Connection I describe the humans on the plaque as the most obscure part of the message. Nevertheless, I wonder. Could the significance of the man’s gesture be deduced by beings with very different biologies?

  5

  THE

  ABSTRACTIONS

  OF BEASTS

  I demand of you, and of the whole world, that you show me a generic character … by which to distinguish between Man and Ape. I myself most assuredly know of none. I wish somebody would indicate one to me. But, if I had called man an ape, or vice versa, I would have fallen under the ban of all the ecclesiastics. It may be that as a naturalist I ought to have done so.

  CARL LINNAEUS,

  the founder of taxonomy, 1788

  EASTS ABSTRACT NOT,” announced John Locke, expressing mankind’s prevailing opinion throughout recorded history. Bishop Berkeley had, however, a sardonic rejoinder: “If the fact that brutes abstract not be made the distinguishing property of that sort of animal, I fear a great many of those that pass for men must be reckoned into their number.” Abstract thought, at least in its more subtle varieties, is not an invariable accompaniment of everyday life for the average man. Could abstract thought be a matter not of kind but of degree? Could other animals be capable of abstract thought but more rarely or less deeply than humans?

  We have the impression that other animals are not very intelligent. But have we examined the possibility of animal intelligence carefully enough, or, as in Francis Truffaut’s poignant film The Wild Child, do we simply equate the absence of our style of expression of intelligence with the absence of intelligence? In discussing communication with the animals, the French philosopher Montaigne remarked, “The defect that hinders communication betwixt them and us, why may it not be on our part as well as theirs?”* There is, of course, a considerable body of anecdotal information suggesting chimpanzee intelligence. The first serious study of the behavior of simians—including their behavior in the wild—was made in Indonesia by Alfred Russel Wallace, the co-discoverer of evolution by natural selection. Wallace concluded that a baby orangutan he studied behaved “exactly like a human child in similar circumstances.” In fact, “orangutan” is a Malay phrase meaning not ape but “man of the woods.” Teuber recounted many stories told by his parents, pioneer German ethologists who founded and operated the first research station devoted to chimpanzee behavior on Tenerife in the Canary Islands early in the second decade of this century. It was here that Wolfgang Kohler performed his famous studies of Sultan, a chimpanzee “genius” who was able to connect two rods in order to reach an otherwise inaccessible banana. On Tenerife, also, two chimpanzees were observed maltreating a chicken: One would extend some food to the fowl, encouraging it to approach; whereupon the other would thrust at it with a piece of wire it had concealed behind its back. The chicken would retreat but soon allow itself to approach once again—and be beaten once again. Here is a fine combination of behavior sometimes thought to be uniquely human: cooperation, planning a future course of action, deception and cruelty. It also reveals that chickens have a very low capacity for avoidance learning.

  Until a few years ago, the most extensive attempt to communicate with chimpanzees went something like this: A newborn chimp was taken into a household with a newborn baby, and both would be raised together—twin cribs, twin bassinets, twin high chairs, twin potties, twin diaper pails, twin babypowder cans. At the end of three years, the young chimp had, of course, far outstripped the young human in manual dexterity, running, leaping, climbing and other motor skills. But while the child was happily babbling away, the chimp could say only, and with enormous difficulty, “Mama,” “Papa,” and “cup.” From this it was widely concluded that in language, reasoning and other higher mental functions, chimpanzees were only minimally competent: “Beasts abstract not.”

  But in thinking over these experiments, two psychologists, Beatrice and Robert Gardner, at the University of Nevada realized that the pharynx and larynx of the chimp are not suited for human speech. Human beings exhibit a curious multiple use of the mouth for eating, breathing and communicating. In insects such as crickets, which call to one another by rubbing their legs, these three functions are performed by completely separate organ systems. Human spoken language seems to be adventitious. The exploitation of organ systems with other functions for communication in humans is also indicative of the comparatively recent evolution of our linguistic abilities. It might be, the Gardners reasoned, that chimpanzees have substantial language abilities which could not be expressed because of the limitations of their anatomy. Was there any symbolic language, they asked, that could employ the strengths rather than the weaknesses of chimpanzee anatomy?

  The Gardners hit upon a brilliant idea: Teach a chimpanzee American sign language, known by its acronym Ameslan, and sometimes as “American deaf and dumb language” (the “dumb” refers, of course, to the inability to speak and not to any failure of intelligence). It is ideally suited to the immense manual dexterity of the chimpanzee. It also may have all the crucial design features of verbal languages.

  There is by now a vast library of described and filmed conversations, employing Ameslan and other gestural languages, with Washoe, Lucy, Lana and other chimpanzees studied by the Gardners and others. Not only are there chimpanzees with working vocabularies of 100 to 200 words; they are also able to distinguish among nontrivially different grammatical patterns and syntaxes. What is more, they have been remarkably inventive in the construction of new words and phrases.

  On seeing for the first time a duck land quacking in a pond, Washoe gestured “waterbird,” which is the same phrase used in English and other languages, but which Washoe invented for the occasion. Having never seen a spherical fruit other than an apple, but knowing the signs for the principal colors, Lana, upon spying a technician eating an orange, signed “orange apple.” After tasting a watermelon, Lucy described it as “candy drink” or “drink fruit,” which is essentially the same word form as the English “water melon.” But after she had burned her mouth on her first radish, Lucy forever after described them as “cry hurt food.” A small doll placed unexpectedly in Washoe’s cup elicited the respon
se “Baby in my drink.” When Washoe soiled, particularly clothing or furniture, she was taught the sign “dirty,” which she then extrapolated as a general term of abuse. A rhesus monkey that evoked her displeasure was repeatedly signed at: “Dirty monkey, dirty monkey, dirty monkey.” Occasionally Washoe would say things like “Dirty Jack, gimme drink.” Lana, in a moment of creative annoyance, called her trainer “You green shit.” Chimpanzees have invented swear words. Washoe also seems to have a sort of sense of humor; once, when riding on her trainer’s shoulders and, perhaps inadvertently, wetting him, she signed: “Funny, funny.”

  Washoe (left) signaling in Ameslan “hat,” for a woolen cap.

  Washoe (left) signaling in Ameslan “sweet,” for a lollipop.

  Lucy was eventually able to distinguish clearly the meanings of the phrases “Roger tickle Lucy” and “Lucy tickle Roger,” both of which activities she enjoyed with gusto. Likewise, Lana extrapolated from “Tim groom Lana” to “Lana groom Tim.” Washoe was observed “reading” a magazine—i.e., slowly turning the pages, peering intently at the pictures and making, to no one in particular, an appropriate sign, such as “cat” when viewing a photograph of a tiger, and “drink” when examining a Vermouth advertisement. Having learned the sign “open” with a door, Washoe extended the concept to a briefcase. She also attempted to converse in Ameslan with the laboratory cat, who turned out to be the only illiterate in the facility. Having acquired this marvelous method of communication, Washoe may have been surprised that the cat was not also competent in Ameslan. And when one day Jane, Lucy’s foster mother, left the laboratory, Lucy gazed after her and signed: “Cry me. Me cry.”