Chimps & the Language of Signs

From: Neuropsychiatry, Neuropsychology, Clinical Neuroscience
by Rhawn Joseph, Ph.D.
(Plenum Press, New York, 1993)

Chimps, Gorillas & the Language of Signs


By Rhawn Joseph, Ph.D.

CHIMPS, GORILLAS & THE LANGUAGE OF SIGNS Hans was born in Berlin Germany early in this century and long amazed the local citizens with his ability to rapidly perform mathematical calculations. It was not the difficulty of the problems which was so astounding but the fact that Hans was a horse. For example, after a math problem was written on a blackboard, Hans would count out the answer by tapping his left forefoot to indicate 10, 20, 30, and so on, and with his right forefoot to indicate 1-9. In this way he was able to indicate if the answer were 17, 24 or whatever. Trickery was ruled out because Clever Hans could solve the problems even when his owner was out of sight. However, when the owner and the audience were not shown the problem or the answer, Hans suddenly lost his amazing prowess. This is because the audience tended as a body to move forward as they watched Hans feet and would signal him via their movements as to how to respond. For example, they would tense as he approached the correct answer and would then move their heads when he reached it, signaling him to stop. When he did as their subtle body language suggested he was rewarded by a nice treat. Hence, it was well worth his while to act on their unconscious bidding.


Originally (and beginning in prehistoric, preverbal times) infants and adults communicated many of their likes, dislikes, desires, and needs with little reliance on words but instead used gestures and facial expressions which were innate and natural in origin and understood across cultures 15. Indeed, children are said to employ over 150 natural gestures and signs, many of which they unlearn or modify as they grow older 16.

Due to their innate origins, many forms of body language serve as a silent, non-verbal means of complex signaling that are universally understood. Regardless of culture, people smile the same and a smile accompanied by raising of the eyebrows and a nod of the head is a universal greeting gesture 17. A similar gesture passed between men and women is often seen as flirtatious. Conversely, the balled fist, flexed arm, furrowed brow, open mouthed or tight lipped expression is an indication of anger be it monkey, ape or human. Of course, not all signs are universal.

Because many natural signs are a manifestation of the hardware of the brain and have little or nothing to do with learning, we see that even children who are born blind and deaf still smile and emit appropriate sounds when happy. Similarly, when sad or upset they will frown, stamp their feet, and clench their fists. Severely retarded children with no language capabilities who are extremely limited in their ability to learn or even mimic what they see, can still laugh, smile, weep, and show signs of rage by yelling and screaming and stamping their feet in anger. Chimpanzees and gorillas respond likewise when angry, including baring the teeth in an open mouth posture of rage.

Many complex depictive gestures which are employed predominantly by adult human beings, have common biological roots as they are related to the functioning of the body. It is these gestures which are more or less expressed similarly or have the same meaning across cultures. For example, touching the ear with a single finger to indicate that one does not understand or hear what is being said, holding one's nose and wrinkling one's face and mouth may indicate the presence of a disagreeable odor, rubbing the tummy may indicate hunger or a stomach ache, touching one's temple or forehead with the index finger may indicate thinking, turning the same finger in a cork screw fashion may indicate craziness (a "mixed up" mind), and slicing a finger across the throat may indicate an upcoming death by decapitation, or the need for the opposing party to shut up.

Natural (biologically rooted) signs are first and foremost rooted in emotional displays and thus have common limbic origins 18. However, many gestures, although originally natural and seemingly shaped by innate physical and biological predispositions, also come to be shaped by the cultural and social environment in which one is raised. Natural signs and gestures, like spoken language, are subject to modification, and abbreviation or they become stylized to various degrees as they become part of a common currency of exchange 19. For example, in a military culture the open (empty, non-threatening) hand above the eyes (which decreases the threating nature of direct visual contact) has become a military salute.

Just as dialects and languages have evolved from common roots, many gestures have also differentially evolved so as to form distinct gestural languages as well. Nevertheless, many gestures and facial expressions such as feelings of puzzlement, doubt, contempt, anxiety, insecurity, or haughtiness are easily understood between most cultures 20. Many gestures in fact circumvent language and illuminate or make unnecessary an exchange of dialogue; e.g. blowing a kiss, shaking hands, kissing on the cheek. In fact, certain gestures convey meaning that are very hard to put into words, such as demonstrating versus explaining how a corkscrew works and what it is shaped like. In many ways, spoken language, being a more recent acquisition, still lags behind gesture and specific body movements as a form of intellectual and social currency. In many situations it is clearly not as efficient as gesture for communicating.


The limbic system acts to analyze sensory and tactual information in regard to its potential emotional and motivational significance. It is via the neocortex of the parietal lobe that one comes to analyze the external sensory-physical properties of various objects and stimuli and to associate them together in the form of ideas. It is also the seven layered neocortex which enables us to achieve knowledge of the physical world as well as discern it's potential motivational and intellectual attributes. The neocortex, however, does not replace the old cortical nuclei. Rather it acts semi-independently to analyze the emotional as well as those non-emotional characteristics of the world which the limbic system is not concerned with. It is in this manner that we come to know, and know that we know.

All physical and tactual sensations are transmitted to the primary receiving area for somesthesis, which is located within the neocortex of the parietal lobe. The parietal lobe is sensitive and responsive to tactual stimuli regardless of where on the body it is applied. In fact, via the reception of these signals from the sensory surface of the body, the entire body surface comes to be spatially represented in the sensory neocortex. When part of the body is touched or stimulated, cells in the primary receiving area fire. Conversely, if select regions of the primary receiving area were electrically or abnormally stimulated, the person would experience a tactual sensation occurring on a circumscribed portion of the body; i.e. that body part which projects via a series of cellular relays to the neocortical cells being stimulated. Electrical stimulation of these neocortical cells can elicit well localized sensations on the opposite half of the body such as numbness, pressure, tingling, itching, tickling and warmth.

The parietal lobes are responsive to a variety of divergent stimuli. This includes tactual, kinesthetic, and proprioceptive information, sensations regarding movement, hand position, objects within grasping distance, audition, eye movement, as well as complex and motivationally significant visual stimuli 34. Moreover, the parietal lobe contains neurons which are visually sensitive to events which occur in the periphery and the lower visual field; regions where the hands and feet are most likely to be viewed. Some neurons in this area also become highly active when an individual reaches for some item, whereas other fire when the item is grasped. These latter neurons are referred to as hand-manipulation cells 35.

Analysis and guidance of the body's position and movement in visual space, the hand in particular, is a primary concern of the parietal lobe. That is, it guides the movement of the arms and hands as they move through space regardless of purpose or object of desire. In this regard it mediates eye-hand coordination. The parietal lobe, however, does not keep its "eye" on the ball (or the net, hoop, hole or whatever) but on the hands and arms. It does not receive visual information from the fovea of the retina of the eye. Rather it has only black and white peripheral vision. Again, these are the visual areas where the hands and legs are most likely to be viewed and is this regard the parietal lobes are responsible for comprehending the significance and meaning of hand movement and gesture as well as coordinating the feet as a person runs, dances, or walks about in space.

It is via the perceptual activity of the parietal lobule that we come to know that a wave of the hand means "come" or "goodbye," or that someone has balled up their fist and may punch us in the nose. In their most refined form these movements and gestures are expressed in the form of sign languages including the writing in pictures and in script, all of which is completely dependent on feedback from touch and which is made possible via select regions within the parietal lobe, specifically, the inferior parietal lobule, a structure which is largely unique to human beings.

By receiving visual as well as information regarding the limbs of the body, the parietal lobe, especially that of the right half of the brain, enables us to run, jump, do summer salts and perform gymnastics, as well as guide and program the hands so that the skills of carpentry, bricklaying, drawing, painting, and other fine arts are made possible. It is also via the parietal lobe that complex skilled temporal-sequential tasks can be performed, such as preparing a pot of coffee or brushing one's teeth 36.

Through its control over body and limb movements, the parietal lobe over the course of evolution, has become increasingly involved in gestural communication. Indeed, this brain area in fact mediates the ability to perform not only simple and "natural" signs, but complex, grammatically based, gestural sign systems such as American Sign Language (ASL). In fact, if this area of the brain were injured, the ability to comprehend ASL as well as natural signs would be compromised, although a person could still speak and understand what was said to him 37. Speaking and verbal comprehension are a product of the left frontal and temporal lobe respectively.


There once was a girl who could neither hear, nor speak, or write, nor communicate by signs. It was only through a long terrible struggle that occurred completely within her world of touch that the mind of Helen Keller's was suddenly illuminated by the world of language.
"Earlier in the day we had a tussle over the words "m-u-g" and "w-a-t-e-r." Miss Sullivan had tried to impress it upon me that "m-u-g" is mug and that "w-a-t-e-r" is water, but I persisted in confounding the two. I became impatient of her repeated attempts, and seizing my new doll, I dashed it upon the floor. I was keenly delighted when I felt the fragments at my feet. I had not loved the doll. In the still, dark world in which I lived there was no strong sentiment or tenderness....
We walked down the path to the well-house. Someone was drawing water and my teacher placed my hand under the spout. As the cool stream gushed over one hand she spelled into the other the word water, first slowly, then rapidly. I stood still, my whole attention fixed upon the motions of her fingers. Suddenly I felt a misty consciousness as of something forgotten--a thrill of returning thought; and somehow the mystery of language was revealed to me. I knew then that "w-a-t-e-r" meant the wonderful cool something that was flowing over my hand. That living word awakened my soul, gave it light, hope, joy, and set it free!...
I left the well-house eager to learn. Everything had a name, and each name gave birth to a new thought. As we returned every object which I touched seemed to quiver with life... I saw everything with the strange new sight that had come to me. On entering the door I remembered the doll... and picked up the pieces. Then my eyes filled with tears; for I realized what I had done, and for the first time I felt repentance and sorrow. Hellen Keller 38

Humans have employed gestures and movements to mime and dance, to pantomime and to convey the symbolic, the sublime, the abstract, the mythical, magical, and mystical (which is why many religions utilize symbolic gestures in their rituals and liturgies) long before the development of written or complex grammatical spoken language. Gesture may have not only been a forerunner to spoken language, but provided the context in which it could develop.

Because gesture is a precursor to the development of speech, it is commonly employed by those without speech but who possess highly developed social brains. Apes, monkeys, dogs, wolves and other animals are able to gesture through eye and body movement, and facial expression and are even able to mime and dance 39. Even unrelated species make several of the same gestures which essentially have the same meaning; a puppy will sometimes naturally raise it's paw as if to shake and show friendliness when confronted appropriately and apes and monkeys commonly make hand to hand contact as a signal of appeasement and friendliness.

Given that so many postures, facial expressions, and arm and hand movements are understandable not only between cultures but between animals and man, certainly raises the possibility that the neurological foundations of gesture are similar between species. These similarities could also be due to the possibility that they were subject to similar environmental pressures in order to survive. This is why, perhaps, that dogs and humans both feel guilt, shame, depression, anger, jealousy, and love. Both share a very similar limbic system, have similar brains, and have lived quite comfortably together for at least 10,000 years.

However, dogs don't rhyme, curse and use foul language or put much effort into describing their world though they are certainly not lacking in curiosity. In contrast, as has been shown with the chimpanzees Washoe and Lucy, Koko the gorilla, and other apes (see below), these capacities are not limited to human beings as these primates possess similar aptitudes.

How do we know this? First via the extensive observations of Jane Goodall on wild chimpanzees living in the Gombe field reserve in Africa complied over a 30 year time period, and through the efforts of the Gardners of the University of Nevada, Francine Patterson of Stanford, and many other scientists 40. Indeed, the Gardners and Dr. Patterson were able to teach these creatures American Sign Language and were thus able to "talk" with them.


American Sign Language (ASL) is a complex gestural language utilized by the deaf as their primary means of communicating with others. It is composed of natural as well as artificial signs which have been forged into a grammatical gestural language that is thus visual and verbal, but not auditory. However, unlike natural signs, ASL is a bit cumbersome and it takes about twice as long to indicate a word via gesture as to say it out loud.

In general, there are two structural levels to signing 41. The first level includes the rules which govern the relations between signs within sentences. The second level is concerned with the internal structure of the lexical units.

ASL makes use of space patterns and the contours of movement; i.e. hand shape, movement, and spatial location which is actively manipulated in regard to indicating syntax, nominals and verbs. For instance, nominals are assigned locations in the horizontal plane, and verb signs move among these spatial loci so as to indicate the grammatical relations between the subject and object. Moreover, the same hand shape presented in different motions or at different spatial locations, conveys different grammatical and semantic information.

Although highly grammatical and dependent on temporal contrasts, ASL is very sensitive to spatial contrasts. However, these spatial contrasts are heavily dependent on verbal described relationships such as "right" vs "left", "up" vs "down." Space and movement become subordinate to verbal labels and coordinates. Unlike gestures, be they cultural or natural in origin, ASL employs linguistic, temporal sequential, and visual referents, and thus represents a multidimensional as well as grammatical means of complex communication via movement.


To be capable of learning and producing this formalized system of gestural interrelationships considerable evolutionary adaptation and development in the parietal lobes was required. Some of this development occurred in the superior parietal lobe which is concerned with the movement of the hands and arms in visual space. However, with the evolution of parietal tissue at the juncture of the occipital (vision), temporal (auditory) and inferior frontal (motor) areas the development of a complex grammatical gestural language including the temporal sequencing of sound was made possible 42. The appearance of the angular gyrus of the inferior parietal lobule helped make possible the creation of human speech and all associated nuances of language, e.g. reading, writing and arithmetic.

Grammatical, denotative spoken language is in part a secondary acquisition which follows the development of the superior and inferior parietal regions and thus the ability to gesture in temporal sequences. Nevertheless, animals that cannot speak but who possess some of the same brain structures as humans are also able to learn and employ complex systems of gesturing and signing so as to communicate their own interests and desires.

Apes and humans are all blessed with well developed parietal lobes and limbic systems. Apes, however, possess only the first hint of what in humans is referred to as the angular gyrus which along with the marginal gyrus makes up the inferior parietal lobule. These neocortical structures are extremely important in the acquisition of language. Sitting at the junction where visual, auditory and tactual sensations are processed, they are able to integrate these different signals so that multiple categories can be assigned to a single sensation or idea 43.

Primates are able to make considerable use of their face, hands and arms for the purposes of gesturing and this has been made possible via the tremendous evolutionary development that has occurred in the parietal lobes. Thus the ability to gesture with the hands and arms as a means of communication is most developed in primates. Similarities in gestures and the brain, however, are also a function of both species being subject to similar evolutionary pressures early in their history, especially in regard to the development of the upper arm and hand, and the ability to grasp and manipulate objects. It is also for these reasons that humans and apes are in fact capable of acquiring and communicating via complex systems of gesturing, such as via ASL.


The Gardners began training Washoe in ASL in 1966. They used the method of molding the hands while he was also looking at the appropriate action or object, followed by giving him a rewarding treat 44. Given the complexity of ASL he made surprising progress.

After two years of training Washoe had learned over 30 signs which he was able to use in appropriate two word combinations. In fact, he was capable of using two word gestures before his first year of training was up, such as, "give food." Washoe picked up signs through imitation as well and was also able to correctly invent certain signs such as a gesture indicating a "bib," and made up gestural combinations to accurately describe items he had no name for. For example, for some time he mystified his caretakers by repeatedly asking for a "rock berry," which later they discovered meant a Brazil nut. He also called Alka-Seltzer a "listen drink," and a cucumber a "green banana." After three years of training he was able to use correctly over 85 signs, and after four years he had progressed to over 130 signs.

Washoe, in fact, not only learned signs and could communicate proficiently, but actively engaged in tutoring a young chimpanzee, Louis, as how to sign as well. On one occasion when a human presented a bar of chocolate, Washoe became very excited and started signing "food." However, noticing the eager and curious look of Louis, Washoe walked over and took his hand, pointed at his mouth and then molded the child's hand in the form of the appropriate sign which was then readily learned.

Nevertheless, when the Gardners first presented their evidence on Washoe, they were attacked by many "scientists" who ridiculed their findings. Indeed, great efforts were extended to deny their evidence and even ruin their reputation. Unfortunately, throughout history, it has not at all been uncommon for a few scientists, like temple priests, to strive at all costs to maintain the faith of the status quo. Nevertheless, the efforts of the Gardners have been replicated by many others.

Lucy, another chimpanzee who was taught ASL and raised like a child in the home of the Temerlins, not only learned to communicate, but in some ways became more human-like than chimpanzee like 45. She learned how to turn on the TV to watch her favorite shows (which says something of the intellectual level television is aimed at), and learned to go to the cupboard and then the refrigerator so as to mix herself a gin and tonic. Lucy also liked to flip through magazines and comment through ASL, on what she saw.

Such human like behavior in a chimpanzee is probably not all that surprising given their proficiency for aping humans in so many other contexts. In this regard, they are just like children. Indeed, Washoe's proficiency at signing has often been favorably compared to the language capability of a young child. On the otherhand, chimpanzee behavior is also very complex.

As Dr. Goodall and her colleagues have demonstrated, Chimpanzees in the wild live very multifaceted lives and many of their social interactions involve complex gesturing 46 They use elaborate facial, hand, arm, and body gestures to convey their needs and goals, develop long lasting best friend relationships with other chimps, learn strategies for achieving dominance including the formation of coalitions, and engage in deception so as to do things in secret without the interference of more dominant chimps. They also engage in prolonged child care with mother son and especially mother daughter bonds lasting a lifetime.

Chimpanzees greet each other with hugs and kisses, hold hands, pat each other affectionately, engage in long periods of mutual grooming, seek reassurance by hugging and embracing each other, and will even risk their own lives to help friends or family members who are in distress or danger. They will punish estrus females for faithless sexual indiscretions, reconcile after an argument, will care for sick family members, and will cooperatively hunt monkeys or small animals which they kill, eat, and share 47.

Moreover, when chimpanzees are frightened or alarmed they will clasp hold of one another. Humans often behave similarly, and wolves and dogs too will seek the close proximity of each other or their master, sometimes even climbing into laps.

When a lower ranking chimpanzee wants to pass by a more dominant animal they may reach out their hand and wait for the dominant male to reach out and touch it so as to provide reassurance. The dominant chimp will open up his hand, stretch it out and sometimes take the hand of the less dominant animal and give it a squeeze.

Male chimps also often form coalitions which enables them to assume dominant status. However, if they fail in these endeavors or when harmony is broken the trouble maker may eventually make conciliatory gestures by grinning nervously, stretching out his hand and begging to make up, sometimes by bowing and grunting submissively while the dominant male may stare or approach with lips pressed together firmly and with the body inflated. Frequently, the dominant will take the offered hand and either touch or kiss it, sometimes taking the whole hand in his mouth. Then the dominant male and the trouble maker might approach and kiss each other and then embrace 48. Sometimes, however, the dominant will mount the subordinant as if he is about to engage in sexual intercourse. Similar sexual mountings to indicate dominance or submission are employed by gorillas, monkeys, dogs, and humans, and this is one of the reasons that human males respond aversively or quite aggressively in response to the sexual overtures of homosexuals. It is not just a mindless bias but a biological predisposition.

Nevertheless, among apes, when dominance or appeasement is not forthcoming and a fight ensues, it has an extremely excitatory effect on the others who hurry over to watch the scene, and give high pitched barks of encouragement. Spectators may also be drawn into the fight by one of the adversaries who begs for reinforcement. Those who are fighting draw attention by screaming at the top of their lungs; they may put an arm around a friend's shoulders to get him or her to join in; with open hand they may beg for help from bystanders; and if they start to lose the fight they may flee to a protector and, in safe proximity, shout and gestulate at their opponent. In consequence, large scale confrontations between different sections of society may result.

Moreover, in attempting to build a coalition so as to increase their status and power, males will seek female support which is accomplished by grooming the female and playing with their infants, much like a politician feels a need to kiss and hug babies. This is valuable for if their position is challenged, those females whose support he has won may assist him. However, females are likely to provide support only with their closest of friends or with kin. Male chimps, however, will form coalitions even with former enemies with whom they've fought, if perchance it will help them gain power. In contrast, females are less interested in power and status and instead will engage in cooperative behavior not for the purposes of obtaining power or some advantage but to maintain a cooperative relatinship with kin and those they like. The parallels with human behavior are surprisingly similar.

"Adult male chimpanzees seem to live in a hierarchical world with replaceable coalitions partners and a single permanent goal: power. Adult females, in contrast, live in a horizontal world of social connections. Their coalitions are committed to particular individuals whose security is their goal...for them it is of paramount importance to keep good relationships with a small circle of family and friends." However, "a female chimpanzee may, for example, instigate an attack by a male friend on another female. She will sit next to the male, arm around his shoulder, directing a few high pitched barks at her rival until the male obliges by charging at the other female." 49


Humans are not the only species that derive enjoyment from killing one another. Chimpanzees show a surprisingly human-like propensity for murder, mayhem, and gang attacks on both male and female chimps who are not or no longer part of their group. This latter behavior occurs while the males of a group, sometimes accompanied by a female, patrol the outskirts of their territory 50.

Chimpanzees will viciously assault other chimps who stray into their territory, including former friends, strange females, or infants, even when the stranger attempts to be friendly by holding out a hand or trying to touch them. If a strange male or female actually makes contact, this may be completely rejected by the patrolling chimpanzee gang member who not only moves away but will take leaves and scrub the spot where he has been touched. The stranger is then usually severely beaten or killed. Chimpanzees also sometimes engage in sneak attacks on their leaders, sometimes castrating them and biting off fingers and toes 51.

These types of behavior, however, should be completely distinguished from that of a natural predator. Although a predator such as a wolf or a lion may find even the prospect of the hunt exciting, hunting for humans and apes seems to be a derivative of the desire to kill. In my opinion humans do not engage in the killing of other humans because they are hunters and predators. Rather, they became hunters because they enjoyed killing. The same, I believe, can be said of chimpanzees who kill not for the sake of obtaining meat, but for the thrill of killing which has a terribly excitatory effect on the whole troop who may then beg and beg for just a tiny morsel of the still warm and bloody flesh of the victim.

Like humans, chimpanzees also engage in tool use and construction, and will often utilize tree branches, rocks, or other handy items in their displays. For example, they may sneak up on their compatriots, and then suddenly charge while dragging or waving huge branches which they rattle or strike against the ground. They may also pick up rocks and throw them (sometimes with punishing accuracy), stamp on the ground or drum loudly on a tree trunk, as well as pick up cans or other noisy objects that he can bang on, and even swat others who happen to be in their way. Moreover, they show a surprising capacity to think about and plan their attacks, often spending much time looking for the right size rock and then waiting again for the right moment to strike.

These similarities between humans and chimpanzees, (and the other apes, the orangutan, and the gorilla) should probably be not all that surprising particularly in light of chimpanzees being the closest living relative to human beings. In fact, Chimpanzees are genetically more similar to humans than they are to Gorillas. Indeed, human DNA differs from chimpanzee DNA by only one percent. Moreover, biochemically, chimps and humans possess an identical order of amino acid molecules.

On the other hand, some gestural and behavioral similarities also exist between humans and dogs (which is why they form close relationships), as well as between humans and gorillas. In fact, perhaps about 100 million years ago, the predatory canide line and a herbivorous line branched off from the end of the therapsid, repto-mammalian line, with the canides taking control of the ground and the herbivores the trees. There they lurked and lived until a cataclysmic event 65 million years ago turned the world to both their advantage.


Gorillas are generally very peaceful creatures who maintain their massive bulk predominantly through a vegetarian diet, although they also like to eat meat on occasion, including bird eggs and termites. Like dogs and humans they are very social and roam through Central Africa in bands of up to thirty individuals which are led by a single dominant male. Their predominant mode of auditory communication is through barking, roaring, grunting, whining, whimpering, grumbling, humming, and purring. Many of their sounds, however, can convey different meanings depending on the context in which they are elicited, as well as through variations in pitch and quality. It has been estimated that their calls range from twenty to more than thirty. Often, however, their vocalizing seems to have no effect on other gorillas who may not even bother to look up 56.

Another primary means of communication is through complex gestures. This includes facial expressions and a variety of postures, including chest beating, and tearing limbs from trees or waving branches in a threatening manner.

Chest beating is one of the more obvious and most easily observed gestures they employ and it usually is part of a temporal sequence of movements, calls, and actions. That is, before they beat their chest, they begin to "hoot" and will then suddenly grab some leafy vegetation and stuff it in their mouth while just as suddenly they will rise up and throw the remainder into the air. Then the chest beating occurs, the sound of which can carry up to a mile away. While so engaged they will kick their leg into the air, and then begin running sideways while they snatch a tree limb and wave it menacingly. This whole sequence is then brought to a conclusion by the gorilla holding both hands clasped together over his shoulder like a boxer who has just won his prize fight. He then slaps and thumps his hand forcefully against the ground. One could only imagine that if he held a football, he would substitute spiking for thumping.

It seems any number of events can trigger the chest thumping display, such as the presence of a human, or that of another gorilla, in response to the movement of some animal or object the identity of which they cannot completely discern, or in response to displays by other gorillas. They also engage in this display in play and in fun, or just for the heck of it. In this regard this behavioral sequence can express irritation, anger, lonesomeness or even boredom.

Another means of communicating to the group is walking in a very rigid and stiff legged fashion, moving very abruptly or lunging with the body, staring, head shaking, cowering, and even mock biting. However, what these gestures mean depends on context and the status of the gorilla who employs them.

In comparison to chimps, the tool making capabilities of the gorilla are sorely lacking. In part, this may be due to their larger, more clumsily shaped hands which reduces their ability to perform fine motor tasks. Indeed, the thumb is very small and they still use their upper extremities for knuckle walking.

Nevertheless, they frequently handle and carry objects, will construct elaborate nests for resting during the day and sleeping at night, and will tear up vegetation or yank apart tree branches as part of their display. On the other hand, those in the wild seem to lack any inclination to explore.


One might assume from these observations that gorillas may not seem to be the brightest of our fellow apes. However, this may be due in part to problems inherent in the observational method. As demonstrated by Dr. Francine Patterson, gorillas possess tremendous mental powers as well as the ability to converse in depth via gesture or to even play practical jokes, such as with a plastic alligator 57.

For example, Koko the gorilla apparently likes to sneak up on some (supposedly) unsuspecting human with a little toy alligator hidden behind her back. When she is near her victim, Koko will abruptly spring up, brandishing the alligator wildly. The human is expected to assume a terrified look, scream, and run. Koko knows the whole thing is a charade, but she thinks it is vastly funny. Nevertheless, as pointed out by Dr. Patterson, it is rather amazing to think that "a gorilla might even for a moment think that it needs a prop like a toy alligator in order to scare a human." 58

Koko the gorilla began her formal training in 1972 at the age of one and for the next several years underwent a grueling full time educational regimen in ASL acquisition. This was accomplished by molding her hands to form the appropriate signs, and then by giving her a reward if she did so correctly. Before giving her a drink from her bottle, Dr. Patterson would show her the sign for drink, which is shaping the hand as if hitch hiking and placing the thumb in the mouth.

Surprisingly, Koko began to learn signs almost immediately, although admittedly they were sloppily made and often consisted of demands for food. Indeed, by her second month of training she was able to use about 16 different two word combinations. "Pour that hurry drink hurry.... me me eat... you me cookie me me... gimme drink thirsty, " and so on. Like Washoe, she invented and utilized natural signs, such as "give me" which looks like a beckoning gesture. Again this is a gesture that not only primates and humans understand, but which is comprehensible to a dog as meaning "come here."

In any case, after three years of training Koko had acquired and was regularly employing over 125 words and had utilized an additional 150. This included words such as "pillow, love, necklace, baby, hot, up down, in, out, finished, yes, no, don't, can't"

Koko could also understand many spoken words as well, and sometimes would ease drop on conversations, or answer questions that were asked out loud. For example, one day a visitor asked Dr. Patterson what might be the appropriate sign for the word "good." Before Dr. Patterson could respond, Koko made the sign for her.

Sometimes she would also demand some item, like candy, that the humans had been talking about. To keep Koko from knowing what they were discussing, these experimenters had to often resort to spelling and even then Koko figured out, for example, that c-a-n-d-y, spelled her favorite treat.

Many of Koko's comments and questions were spontaneous, and she soon learned to use words in an insulting fashion. For example, Koko did not like birds and hated the blue jays who screeched outside her window. Hence, when she dealt with someone or something she didn't like, she would call it "bird." Later she progressed to calling certain individuals "stupid devil", or "Devil head," and began using filthy language to insult Dr. Patterson or her friends, by signing at them, "dirty toilet," "stupid toilet," or "Penny dirty toilet devil."

Koko, like Washoe, also learned to combine signs to describe animals or objects, the signs for which she had not yet been taught. This includes, "barefoot head" to describe a bald man, "Giraffe bird," to describe an ostrich, "finger bracelet" to describe a ring, "eye hat" to describe a mask, and "fine animal gorilla" to describe herself.


Given some of the social and neurological similarities between apes, dogs and humens, as well as their advanced methods of expressing and comprehending complex gestures, it may seem curious that no other species save humans, has learned to converse as does man. If these creatures can gesture why can't they learn to talk or understand complex spoken commands?

There have been attempts to teach dogs and apes to speak, but they have failed. For example, Keith and Catherine Hayes spent many years trying to teach spoken language to a chimpanzee by the name of Viki. Although seemingly as intelligent as many young children, Viki could only speak 6 words, most of which were not all that easily understood.

Similarly, Alexander Graham Bell attempted to teach his dog to speak and was able to make it say "How are you, Grandma?" This was accomplished by training it to growl at a steady rate while moving its jaws and throat in a certain fashion. That is, he did it by shaping. However, what the dog said actually sounded more like "ow ah ooh gwahh mahh."

Apes and dogs are not well equipped for producing the sounds of speech because of the shape of their mouths and throats. In addition to lacking the mechanisms necessary to make speech sounds, they also lack the temporal-sequential perceptual capabilities so as to hear the individual units and sounds of speech and are unable to string words together so that they are grammatical and make syntactical sense. Although apes are able to sign, their ability to employ grammar even in their gestures is all but non-existant.

Washoe was never able to understand the rules of grammar and his ability to use grammatical relationships did not even approximate that of a 3 year old human child. For example, if Washoe wanted to ask to be tickled, he would sign, "tickle you, me tickle, or you tickle" as if all meant the same thing. In this regard, Washoe's understanding of grammar may be similar to that of the right brain of an adult human. Grammar is a left brain function.

However, David Premack showed with his chimpanzee named Sara that she was able to learn some aspects of grammar and to read and write simple words using a system of language based on variously colored and sizes and shapes of plastic chips which she would arrange. For example, she could manipulate these chips to say: "Put the apple in the pail and the banana in the dish." However, she would make errors on 1 of 4 trials indicating that her understanding of grammar remained rudimentary and incomplete.

Dogs have also been trained to manipulate plastic chips and various objects in order to communicate their needs. In fact, a German investigator, H. Subbok early in this century taught his dog to read, or at least to recognize certain written words. This particular dog would be shown four cards with different words written on them and when that particular word was uttered by his master, he would reach out and point with his paw to the correct word regardless of the order in which it was arranged. Nevetheless, this dog was unable to rearrange these written words to make meaningful sentences.


The reason apes do not understand grammar or use spoken language is because they are almost completely lacking a recent neurological evolutionary acquisition. Indeed, evolution did not stop with the apes, and humans possess a significantly increased expanse of highly evolutionary advanced parietal tissue near the juncture of the occipital and temporal lobes. This expanse of tissue is referred to as the inferior parietal lobule and contains the famous landmark, the angular gyrus, a structure almost wholly unique to humans. It is the inferior parietal lobule which makes not only fully formed ASL possible, but the evolution of grammatically correct language, be it spoken, or gestural in the form of drawing, painting, or writing.

Situated at the junction of the temporal (auditory), occipital (visual) superior parietal (hand movement) lobes as well as inferior frontal motor areas, the inferior parietal lobule became able to sample and integrate multiple messages to create categories and concepts. It was also able to impose temporal order on what was heard and seen as well; the same temporal-sequencing that had long been refined in the course of developing skilled hand movements and gestures.

The appearance of the inferior parietal lobule was an important evolutionary advance not only in language. This made complicated tool construction possible as well as the ability to engage in complex sequential actions, such as in making a tool, constructing or sewing clothing, or even putting them on and wearing them.

Take the simple steps necessary to make a pot of coffee. From obtaining the coffee container, to heating the water, to pouring it and so on are just a few of the many steps that must be performed in a highly interrelated sequence. Take just one of these steps and perform it out of order, i.e. pouring cold water on the coffee then heating up the empty coffee pot, and one destroys the overall integrity of what one was attempting to accomplish. This condition can occur as a function of an injury to the parietal lobe. The effected person is said to suffer from apraxia.

Apraxia is a disorder of skilled temporal-sequential movement that in most cases is due to strokes or tumors that have invaded the inferior parietal lobule of the left half of the brain 59. Depending on which half of the brain which has been injured, the individual may be unable to make a pot of coffee, or put on their clothes, much less sew them together.

Necessarily, creatures such as dogs and apes, as well as our own ancient ancestors who roamed as recently as half a million years ago, are without such capabilities, and are unable to make complex tools or fashion or wear clothes. This in turn is a function of the evolutionary advanced, angular gyrus of the inferior parietal lobule, which they, and our ancient ancestors, lack. Indeed, like the bulk of the frontal lobe, the inferior parietal lobule may not have appeared until following the evolution of the Cro-Magnon people, for they were the first not only to draw, paint, and construct truly complex tools, but to sew clothes and to make the fist sewing needle. APRAXIA

Usually apraxic patients show the correct intent but perform the movement in a clumsy or disorganized fashion. There can also result gross inaccuracies as well as clumsiness when making reaching movements or when attempting to pick up small objects.

Apraxia is usually mildest when the suffer uses the actual object and performance deteriorates the most when he is required to imitate or pantomime the correct action. The patient may be asked to show the examiner how he would use a key to open a door, or hammer a nail into a piece of wood. In many cases the patient may erroneously use the body, i.e. a finger, as an object (e.g. a key). That is, rather than pretending with the finger and thumb to hold an imaginary key, they instead might stick out their index finger as if it were the key. Or he may pretend his hand is the hammer rather than he is holding and swinging a hammer with his hand. In other words, with destruction of the parietal lobe of the left half of the brain, the individual loses the capacity to make depictive movements involving temporal sequences and instead reverts back to a more primitive form of object description such that the sign, symbol, and object become fused, the body part and the object become one. That is, their ability to gesture is similar to that of a young child, who, in turns out, have a very immature inferior parietal lobule.

Moreover, a patient with apraxia may demonstrate difficulty properly sequencing his actions. If you were to pretend to place a cigarette and matches in front of the patient and ask him to demonstrate by pantomime how he would light it and take a drag, he may pretend to hold up the match, blow it out, strike it, and then pretend to suck on the cigarette and then light it. That is, he would incorrectly produce the sequence, though the individual acts may be performed accurately. They'd just be in the wrong order.

It is noteworthy that apes lack this most recently acquired neocortical tissue, the angular gyrus of the inferior parietal lobule, and that complex tool making capabilities, the capacity to draw, as well as their ability to make even the simplest of clothing, is completely lacking. Only humans make or wear clothing which in turn is also a product of this recent evolutionary neocortical acquistion. However, it is the right and not the left inferior parietal lobe which is responsible for these particular behaviors adnd when damaged or injured, these abilities suffer. Some apraxic disorder, such as constructional and dressing apraxia are often due to right parietal injuries 60.

As the name implies, when a patient suffers from dressing apraxia he has difficulty putting on his clothes. For example, a patient may attempt to put a shirt on upside down, then inside-out, and then backwards. Those with constructional apraxia lose the ability to draw accurately and they may in fact fail to attend to or notice the entire left half of visual space.

It is thus important to note that although we possess two parietal lobes, they do not perform the exact same functions. The left parietal is more concerned with temporal sequences, grammar, and language including writing, spelling and the production of signs such as in ASL. The right parietal lobe is more concerned with guiding the body as it moves through space as well as the manipulation and depiction of spatial relations such as through carpentry, masonry, as well as painting and art or even sewing together or putting on one's clothes. As such, the two parietal lobes are concerned with different aspects of language and the art of gestural communication. Indeed, it was the evolution of these two differently functioning regions of the neocortex and their subsequent harmonious interaction that made possible complex, grammatically correct, written and spoken written language.

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