Free Sample of Chapter Two of Monkey Business

What follows is a free sample from Monkey Business: A History of Nonhuman Primate Rights.

Although it may be standard to offer the first chapter of a book as a free sample, the first chapter of Monkey Business is about the history of animal rights in general, and I honestly feel it doesn't give you a true feel of what the majority of the book is like.  

The chapter I present to you below, Abilities and Intelligence, is the second chapter of the book, and gives the reader a solid background of the nonhuman primate mental capabilities and physical characteristics that later come into play when their freedoms and legal rights are discussed.

Abbreviated footnotes are used. Although the book contains all complete bibliographic notes, if anyone needs further information about any of the works sited on this blog post, please contact me for details and I will be happy to share my sources.

Enjoy, and happy reading.

2. Abilities and Intelligence

We humans commonly react with astonishment upon discovering that chimpanzees can do something we consider special to humankind. Any evidence of intelligence overlap provokes the greatest skepticism, as the uniqueness of that quality in us is our most cherished illusion.[i]

 – Geza Teleki

Modern biological and anthropological studies have created a clearly defined system of classifying primates. Almost all 230-odd species of primates share certain physical traits, such as pentadactyly (having five fingers and/or toes) and a clavicle, but there are four very distinctive physical characteristics that all primates display and that are not available in entirety on any animal that is not a primate: a bar of bone encircling or enclosing the eye sockets; nails instead of claws on most, if not all, digits; opposable thumbs; and the growth of the auditory bulla (the bone that encloses the inner ear) to the petrosal bone.[ii] Primates are some of the slowest-growing and latest-to-mature members of mammalia. In addition, they are among the few types of mammals who keep their infants near them at all times.

Despite the many similarities among primates, there are also many differences that help to differentiate the various primate species. In this regard, it is helpful to consider the two main groupings of primates: prosimians and anthropoids.

The grouping commonly referred to as prosimian (mostly suborder Strepsirrhini) includes small, nocturnal mammals native to Asia and Africa, with pointed muzzles, wet noses, naked rhinaria (a patch of bare skin around the nose), teeth that form a toothcomb (for all species except the aye-aye) and claws on at least some of their extremities. This grouping includes the following species: tarsiers, lemurs, sifakas, indris, aye-ayes, lorises, pottos, and bush babies [galagos].[iii] Prosimians tend to be solitary, but because their home ranges often overlap, there can be communication between individuals through vocalizations and scent-marking via urine and feces.[iv]

The remaining primate species are referred to as anthropoids, which include both New World and Old World primates. All New World primates are monkeys (of a parvorder called Platyrrhini) that live in Central and South America and have a wider septum and an additional bicuspid in their dental pattern.[v] Examples of New World monkeys include marmosets, tamarins, sakis, uacaris, howler, spider, capuchin, woolly, squirrel, night, and titi monkeys. These primates are arboreal and territorial and, like prosimians, communicate their presence partially by scent-marking their surroundings. One family of New World monkeys, Cebidae (which includes capuchin monkeys), has a long, prehensile tail with a bare patch of skin that is not only used in brachiation, to swing on branches, but can also be used as a limb to grab things within reach.[vi] Most New World anthropoids are not sexually dimorphic (meaning that there is not much physical differentiation between males and females).

Old World primates (parvorder Catarrhini) are principally from Asia and Africa and can be distinguished by their downward-facing nostrils and flat fingernails and toenails. All Old World monkeys have ischial callosities, which are calloused pads on their hindquarters, on which they sit,[vii] and they show a marked sexual dimorphism. In addition to humans, primates in this group include apes such as chimpanzees, bonobos, gorillas, orangutans, and gibbons, as well as monkeys such as macaques, baboons, vervets, mangabeys, guenons, and colobus and patas monkeys.[viii] Old World nonhuman primates are skilled at manipulating objects and can be trained to perform various tasks. Most of these primates can subsist on quite a varied diet, so they thrive when living near human populations, sometimes to the point at which local human cultures consider them pests.

From the smaller, nocturnal, arboreal prosimians, such as the lemurs and lorises of Madagascar, to the powerfully built, sexually dimorphic baboons of the African savannah, the physical characteristics and behaviors of primates can run the gamut. The smallest primate, the mouse lemur, can weigh as little as a few grams, while the mountain gorilla can weigh up to four hundred pounds.[ix] Primates can be nocturnal (active at night), like the tarsier, or diurnal (active during the day), like humans. Some are even cathemeral, or active only sporadically during a twenty-four hour period and otherwise at rest both day and night, such as the lemur.

Primate social groups can take many forms: monogamous pairings, like indris, siamangs, and titi monkeys; one male living with several females, such as the colobus monkeys, gelada and hamadryas baboons; or multi-male and multi-female groupings, which are the case with most New World monkeys and many Old World monkeys, as well as the African apes. An individual’s dispersal from the group upon puberty can vary, depending on the species. Some social groups are female dominated, like the ring-tailed lemurs and the bonobos; some are male dominated, such as Western lowland gorillas and baboons; and some primates don’t even have social organization in their natural habitats, such as the mostly solitary orangutans of Borneo and Sumatra. However, the species that are male dominated always reflect some sort of sexual dimorphism. For example, baboon males dominate their societies, and are almost twice the size of females, with large canine teeth that they flash in frightening and threatening displays of power.

Some primate species are completely arboreal, such as colobus monkeys, and some are terrestrial, like gorillas. Others live both in and out of the trees, like chimpanzees. In general, the larger a primate is, the more likely he is to spend time on the ground, simply on account of the basic rules of physics, which may cause him to fall from fragile tree branches. This is not necessarily species specific, as is the case with orangutans, which will live fully arboreal lives unless an individual gets too heavy (generally, only males tend to grow that large). A larger individual will increase its time on the ground out of necessity and self-preservation.

Some actions and behaviors appear to be confined to certain families or groups of similar species. For instance, monkeys do not like eye contact, but great apes do. Although direct eye contact serves as a reconciliation and social tool among apes, monkeys avoid staring at others, since to them it indicates a threat.[x] This leads anthropologists to believe that the common ancestor that humans share with chimpanzees must have been reliant on eye contact as a social cue to direct behavior.[xi]

Apes reflect displeasure by frowning, as a universal gesture with the brows furrowed.[xii] Additionally, apes all beg in the same way: With palms up, they will reach out to another individual as if asking them for a favor or to implore them to follow or join in an activity. Such manual gestures have only been observed in apes and humans. Scientists believe that these instinctive gestures may have constituted the first language developed by early humans, a sort of proto–sign language that required voluntary control and, later on, allowed for more complex communications.[xiii]

Infants of all nonhuman primates cling to the mother with a strong, instinctive grip that human babies do not exhibit. They remain in the mother’s care for the first few years of life, varying with the species. Their extreme proximity to their mothers means that they very rarely cry,[xiv] while human babies cry to get their mothers' attention because at many points throughout the day they may not be in their mother’s embrace. Nonhuman primate babies are almost always found hanging from the front or back of their mothers' bodies and, thus, have little need to cry out.

The closeness of the mother-infant relationship among nonhuman primates ensures that a mother’s offspring will develop into a healthy, well-adjusted individual. If this bond is interrupted, due to the death of the mother or outside forces, such as human involvement, the infant suffers terrible physical and emotional side effects. Infants who were not able to enjoy a normal bond with their mothers often grow up to reject their own infants, as well.

 Female primates of all species appear captivated by new infants born within their social groups, regardless of their biological connection to a particular youngster. Although various species have different customs regarding the touching of an infant not their own, females of almost all nonhuman primate species will gather around a mother and her youngster, grunting and observing as the infant moves about and learns new behaviors.[xv] The mother-child bond can persist even after death, illustrating the strength of the connection between parent and offspring. For example, the daughter of an elderly chimpanzee who was dying at a safari park in the United Kingdom held a vigil over her mother’s body. At a research site in Guinea, two different chimpanzee mothers were observed carrying and tending to the mummified corpses of their infants for up to ten weeks, including carefully shooing flies away from the bodies of their deceased offspring.[xvi]

Historical evidence illustrates many similarities and also differences between humans and the other primate species. Although primate fossils have been found dating from five million years ago, there is not yet universally accepted agreement about the moment when humans and other primates split to go their genealogically different ways. Estimates of this date vary from six to eight million years ago.[xvii] Hypotheses for what caused the split vary, as well, from diet (most primates are mainly vegetarian, but some nonhuman primates eat meat on occasion, such as chimpanzees, bonobos, and capuchins) to bipedalism (walking upright on two legs) to other evolutionary occurrences that potentially freed up hands and allowed increased caloric input to fuel cranial development. Whatever the cause, it’s important to note that the general consensus is that the split from our common ancestor, and between what we now know as humans and other great apes, occurred gradually, over time, like everything else in evolutionary history.

Divergence from this shared ancestor split traits of human and nonhuman primates and eased the transition out of the forests. Bones discovered by anthropologists Ronald Clarke and Phillip Tobias revealed a partial left foot of an Australopithecus ancestor living at least three million years ago that proved its owner was capable of bipedalism and also had a grasping, simian toe that would have allowed for arboreal locomotion.[xviii] Anatomist Randall Susman believes that similar evidence of transitional locomotive patterns can be seen in the knuckle-walking of chimpanzees and gorillas, which allows quadrumanous locomotion (four-handed walking) but also can temporarily free up the hands for food or object procurement and even for tool making and use.[xix]

It was Charles Darwin who claimed that membership in the Hominidae family was marked by bipedalism (upright posture), tool use, and a higher level of intelligence. Bipedalism allowed early humans to use their hands to make tools, and in order to create tools the brain had to be somewhat clever and creative. But it was later proven that early hominids were walking upright for more than two million years before tool use first appeared, and the increase in brain size had occurred more than four million years before that! The transition from “animal” to human, it appears, cannot be so easily explained.

Other opinions on the cause of bipedalism included the idea that standing upright made the individual appear more dominant or that it allowed increased visibility of predators over the natural environment’s grasses and other plants, and so, through natural selection, the genes continued on. Some experts have also argued that bipedalism was less calorically expensive than quadrumanous locomotion, or that it reduced body exposure to the sun, both of which permitted an easier life for individuals with the trait. Upright posture would also facilitate tree climbing. Conversely, perhaps skilled tree climbers developed a more upright posture gradually, which then evolved into upright locomotion on the ground. Whatever the origin(s) of upright posture, a bipedal individual was able to take advantage of his freed hands and more easily manipulate and use tools, which could aid his dominance over predators and, ultimately, his survival.

As similar as nonhuman primates may be to humans, just as interesting are the unique traits each separate species has developed in response to survival in its specific environment. For example, chimpanzees continued to evolve for five million years after diverging from the common ancestry shared with humans. (Humans continued to evolve, as well, albeit in different ways than did chimpanzees.) Therefore, while humans are typically considered the more highly evolved species, chimpanzees are also highly evolved, although their unique traits evolved differently from those of humans. Humans may have developed a more sophisticated language, for example, but chimpanzees developed a more sophisticated method of arboreal nesting, perhaps equally important to their survival. This begs the question, why is one highly evolved trait, such as language, considered superior to another, such as arboreal skill? Is it simply because humans have the capacity for language and thus proclaim this trait to be of greater importance?

An activity for which nonhuman primates are well known is reciprocal grooming—searching through another individual’s fur to pick out nearly invisible foreign matter. This activity may be shared between two individuals or perhaps among an entire group of primates. Grooming is an evolutionarily developed trait that is integral to the health of these primates, as it results in the removal of parasites and other unhealthful invaders that may be hidden in the fur. Of course, humans groom their children, but they don't typically groom each other as a form of social interaction.

Grooming is also very important social tool for nonhuman primates. It not only soothes and interconnects the group as a whole and reinforces existing hierarchies that define the group, as subordinates groom the more dominant members, but is also used to calm a member who may have been upset or offended during an earlier exchange. This “reconciliation hypothesis,” as defined by bonobo expert Frans de Waal, “predicts that individuals try to ‘undo’ the social damage inflicted by aggression, hence, they will actively seek contact, specifically with former opponents…. Reconciliation ensures the continuation of cooperation among parties with partially conflicting interests.”[xx] Grooming, then, can be thought of as an olive branch, a way to atone for past sins, or it can be a calming activity between two primates who simply like each other’s company and enjoy making each other feel good.

Primates are, in general, very social animals. Most species live in groups, despite the possible pitfalls of group living, which can include increased food competition and a higher likelihood of intra- and intergroup aggression. Species-specific patterns of males or females leaving their natal groups upon sexual maturity help to ensure genetic diversity within a group, as well as aiding in the genetic continuation of the individual.

It seems that one of the benefits of group living is purely mental and/or emotional: primates derive comfort from each other. Whether via grooming, physical touching, patting, hugging, or even kissing, the brains of most primates appear wired to seek out physical companionship, even during seemingly insignificant times of play. This compulsion suggests that their brains are capable of keeping track of the social rules of their groups, such as the dominance hierarchies that always exist, various warning calls, and methods of responding to an outsider who appears to the group. Some scientists have speculated that great ape and human brains evolved to their high capacities in response to the need to keep track of complex social cues and rules.[xxi]

The social networking capabilities of primate brains vary by species. Some primates, especially chimpanzees, are quickly able to recognize individuals from their past. This was evident when Boee, a chimpanzee who had been taught sign language by primatologist Roger Fouts in the 1970s, saw Fouts for the first time in 16 years and recognized him immediately, signing his name excitedly.[xxii] New World monkeys also have long-term memories of individuals and can recognize significant individuals from their past by sight, scent, and even, in the case of humans, the sound of their footsteps.[xxiii]

This mental sophistication is required to remember group history and alliances, even when pertaining to group members who have passed away. Chimpanzees in captivity have expressed behaviors that are comparable to human mourning. If a group member appears near death, others will stand vigil nearby, with increased grooming and observation practiced. Once a death has occurs, group members will caress and spend time near the deceased, and emotional behaviors of the typically expressive apes will be noticeably subdued overall. Earlier in this chapter it was mentioned that chimpanzee mothers whose infants have died were observed carrying around the mummified corpses for up to ten weeks. These actions in the face of death have been compared with similar denial behaviors in humans facing loss and coping with extreme grief.

Primate sociality, for most species, is also fluid: not every member of a particular species has the identical social patterns of its same-species peers. This is likely the reason that dominance hierarchies preside over so many primate communities. Just as with human beings, some nonhuman primates have greater aptitude in particular activities than others, and the value of specific strengths may affect both an individual’s worth in a given society and his survival in the wild.

Mental abilities vary widely among primate species. Advanced mental capabilities permitted humans to differentiate themselves clearly from the rest of the primate world. Because primates resemble each other in so many ways, researchers commonly study primate intelligence and abilities in search of surprises amidst the folds and curves of the brain. Cognitive ethologists, scientists who study the processes of animal intelligence, often focus on the multifaceted minds of great apes because they offer the greatest range of abilities and because there has already been much prior research on those species. Great apes such as chimpanzees are relatively easy for laboratories to procure, and as they are biologically closer to humans than are monkeys, this research has wider application to human culture and greater worth to scientific-grant-awarding institutions.

In the 1920s, early research by psychologist Wolfgang Köhler tested the problem-solving abilities of chimpanzees as they attempted to obtain bananas hung above them. When Köhler described their capabilities as evidence of foresight, the anthropomorphism alarms went off, as people were shocked when asked to consider that animals could display such an elevated level of thought.[xxiv] (Anthropomorphism, the assessment of human characteristics, abilities, and behaviors in nonhuman beings and a consequent assumption of attendant human feelings, thoughts, and motives, is often hurled at biologists as an insult. Generally considered to be anti-scientific and unprofessional, anthropomorphist may see human emotion and reasoning where no more than biological or instinctual cause-and-effect exists. This inclination will be discussed at greater length throughout subsequent chapters.) The threat of anthropomorphism didn’t fully discredit Köhler’s work; however, while his findings gained a greater following, many scientists appeared reluctant to leave behind the accepted belief that their research subjects were more than a bundle of nerves and muscles. For example, physiologist Ivan Pavlov (of the “Pavlov’s dogs” operant conditioning research) deemed Köhler’s conclusion “disgusting.”[xxv]

A prominent figure in the early days of primatology was Nadezhda Ladygina-Kohts, a Russian researcher who studied chimpanzee cognition in the 1930s. She deduced that ape empathy was stronger than monkey empathy (a conclusion that has been supported by additional research in more recent years). Ladygina-Kohts described what would happen every time she pretended to cry: This behavior caused a young chimpanzee subject to stop what he was doing immediately, approach her, visually examine her face, and attempt to make her feel better with light touches.[xxvi] This type of consolation behavior is common among great apes, as is grooming, and it is compelling to note that when it occurs, the agent does not gain anything tangible from the consoling behavior. Evolutionarily speaking, this behavior is confusing, for why would a wild animal engage in conduct that does not directly improve his chances for survival?

Further research by primatologist Frans de Waal has shown that the advanced mental capabilities of apes permit them to understand the viewpoint of an outsider (and to a greater degree than the abilities of a monkey allow).[xxvii] Numerous other examples exist of chimpanzees living in captivity that intuit the desires of other group members and altruistically help them achieve their goals. This impulse can even cross the species barrier: In 1996 a gorilla named Binti-Jua gently carried to safety a four-year-old boy who had fallen into her enclosure at the Brookfield Zoo in Illinois, fending off other gorillas with a threatening growl.[xxviii]

Although the higher intelligence of such social animals seems to be related to their involvement in a community, it’s important to note that less social primates, such as orangutans, do not appear to suffer intellectually for lack of interaction. Much in the way that chimpanzee intelligence has been compared and contrasted with human intelligence, orangutan thought processes have been studied as well. Anne Russon, a primatologist and professor at Toronto’s York University, studies the orangutans of the Nyaru Menteng sanctuary in Borneo and compares their intelligence to that of a three-year-old human, but with a caveat: “They don’t have a child’s mind.”[xxix] According to Russon (who has been observing the same group of orangutans every summer for more than thirty years), the slower-moving orangutans are not slower intellectually; they appear to be constantly storing their experiences for future reference.

Because of scarcity of food in their home ranges, Bornean orangutans live and travel alone (except when a mother has a youngster, as it takes years to raise the infant to a state of independence), although there may be temporary groupings at a particularly dense feeding spot. The slightly smaller Sumatran orangutans, now recognized as a species distinct from orangutans in Borneo, have less sparse feeding spots and thus are more likely to form social groups around meals (groups that tend to consist of numerous females with one dominant male for protection).[xxx]

Borneo orangutans have developed their own unique set of smarts that benefit them in ways appropriate to their lifestyle. For instance, although they have no need to remember social alliances and hierarchies, evidence shows that they can recall the fruiting patterns of trees that they visit for food only once every eight years. Additionally, their seemingly innate ability to mimic detailed physical tasks has become a topic of great interest to scientists studying the human mind, as their level of observational skill and applied creativity is thought to be what also facilitates education and comprehension in human beings. Orangutans can be seen observing actions and then seem to break down the separate movements in their minds, and only when they have figured out a sort of internal plan of attack do they attempt to recreate the action they originally observed.[xxxi] Known to be thoughtful and precise in captivity, orangutans will often act out an internal script in order to deceive those around them into giving them something they desire, usually access to something clandestine via a glitch that had gone unnoticed by the human eye.

The impulsive, emotional outbursts of young human children, which also seem so recognizable in chimpanzees, have no place in orangutan life. They have been found to point at items with their eyes, rather than with their hands, and do much communicating with subtle eye and body movements.[xxxii] Detail oriented and clean, they tend to prefer order and patterns, evidenced by the way they will often arrange sticks and leaves in particular configurations around their nests and living areas, for no apparent reason other than decoration or to satisfy some internal need for order in their jungle home.[xxxiii]

Precision rules orangutan society. Their relationships, like their fruit trees, have been described as being dispersed over time and space. Says primatologist Carel van Schaik, “[They] don’t have to meet every day. There is a lot more structure than meets the eye."[xxxiv] The subtle social networks of orangutans are the antithesis of the explosive, dramatic relationships of chimpanzees, but that does not imply that one is better or more advanced than the other. Rather, they have developed in response to very specific environmental needs.

Primates as a whole have a relatively larger ratio of brain size to body size, when compared to most other mammals.[xxxv] The frontal lobe of the brain’s cortex (the neocortex) is the center of many thought processes—including creative thought, decision making, memory, and emotion—and is almost the same size in chimpanzees and humans.[xxxvi] Psychologist Steven Walker admitted that “much work has been done since Huxley emphasized 100 years ago that ‘every principle gyrus and sulcus of a chimpanzee brain is clearly represented in that of a man,’ but there is nothing that contradicts his conclusion that the differences between the human and chimpanzee brains are remarkably minor by evolutionary standards.”[xxxvii] Evidence of this similarity is found throughout the field of cognitive research.

Developmental psychologist Michael Tomasello and his colleagues at the Max Planck Institute for Evolutionary Anthropology tested the learning abilities of chimpanzees versus those of small children. When a child was shown a simple task, the child would mimic the trainer to achieve the proper result. This process of imitation is one of the most integral ways that humans learn to survive to adulthood.

On the other hand, chimpanzees, when shown how to complete the same simple task, would often go about it in a different way; they would achieve the same result but through a unique process, which they determined for themselves. Tomasello called this emulation (as opposed to imitation) and inferred that the act of imitation is uniquely human and that the inability to mimic the steps (and to understand the reasons to mimic the steps) to achieve a specific goal is something that separates other species from humans.[xxxviii]

Although orangutans can easily imitate typically human tasks, primatologist Biruté Galdikas has an interesting theory for why this occurs. She thinks that they do this as a social mechanism to bond with whichever human first exhibited the task. This sort of copycat behavior is a way to equalize two individuals and to show a relationship between them that otherwise might be prevented from expression due to a communication barrier.[xxxix]

Cognitive mapping, the ability to form mental representations of items that might be hidden in various locations, usually occurs in human children prior to turning three years old. Evidence in captivity and in the wild shows that adult chimpanzees and bonobos have this ability, as well,[xl] and capuchins and gorillas have been shown to pass tests involving concepts such as object permanence (the ability to know an object is present even if hidden from sight).[xli] Additional tests have proven that some nonhuman primates are capable of recognizing mirror images and rotations of symbols, as well as the relationships between scale models and full-size objects,[xlii] and of sorting, comparing, and classifying objects.[xliii] Research by Sally Boysen through the Primate Cognition Project showed that language-trained chimpanzees may be able to comprehend what is called a second-order relationship (the more abstract relationships among seemingly very similar objects, such as metal nails and screws, or fresh apples and oranges) because the language itself gives them an additional level at which to organize their thoughts about the world around them.[xliv]

Further evidence of higher thought among great ape species can be found once again in chimpanzees and orangutans, who use a simplistic barter system in the wild. High value is placed both on sexual access to ovulating females and on meat, and at times one may be exchanged for the other. This is evidence of higher thought processes such as representation (x amount of meat is equal to copulation with female x), reciprocation (if I give you meat, I deserve sexual access in return), and alternative planning for future options (if I don’t eat this meat, I can give it to this female in return for sex), among others. [xlv]

A Japanese study by the researcher Tetsuro Matsuzawa, featuring a chimpanzee named Ai and a computer math program, showed that not only could Ai distinguish distinct numbers she viewed on a screen, she could also understand the relationships between numbers. She was easily able to select randomized numbers in ascending order, accurately and without prompting from the researchers. Ai's son Ayumu has regularly completed numerical tasks with even more accuracy than Ai, and researchers believe this is due to greater eidetic memory in youngsters—that they are better at making accurate mental images of complicated puzzles.[xlvi] Not only are young chimpanzees better than older chimpanzees at such tests, but they outperform adult human beings, as well. In testing on color recognition, not only can chimpanzees differentiate various colors, they can match them accurately with their correct Japanese symbols.[xlvii]

Other experiments have shown that chimpanzees can understand the relationships between numbers and also add fractions, and they can even understand more advanced concepts such as conservation (the idea that a piece of clay possesses the same mass regardless of its shape).[xlviii] Chimpanzees also display an understanding of reciprocity: It was found that an individual who had received grooming from another individual was more likely than usual to share food later in the day with the groomer. Although this behavior could be explained using the theory that the groomed individual was in a better mood after receiving so much attention and was thus more likely to share food in general, it appears that groomees tend to share food specifically with their groomers after a session. This behavior requires abilities involving memory and the conception of gratitude, which may not be as well developed in other primates.[xlix]

Although great apes such as chimpanzees may have mental abilities greater than many other primate species, it’s not only the higher primates who are able to comprehend basic mathematics. Marc Hauser of Harvard University proved that rhesus macaques were able to add one plus one and, when presented with two items, were also aware if one was subsequently removed.[l] These results and others like them prove, at a minimum, that some primate species show greater comprehension of number relationships than do very young human children.

When reviewing accounts of the intelligence of certain primate groups, it’s not uncommon to encounter a related discussion of their culture, be it pertaining to child-rearing practices or location-specific methods of cracking open nuts. What is culture, exactly? Primatologist Carel van Schaik defines it as socially transmitted behavior that is customary or habitual (exhibited by most members of a group, or at least most of the relevant members of a group) in one location but is absent from another group at another location and cannot be explained genetically.[li]

Evidence of culture can be found in the following categories: labels (ways of recognizing objects like food or predators), signals (socially transmitted variations of displays), skills (such as tool use), and symbols (variations of signals that have become unique to a social unit or population).[lii] Van Schaik believes that although chimpanzees and orangutans show cultural evidence with labels, signals, and skills, only human beings have continued on to show evidence of symbol use in cultures, due to humanity’s advanced communication and education systems. This definition of culture seems to be generally accepted in the field of anthropology.

Primatologist William McGrew of Miami University in Ohio has created a guideline consisting of specific behaviors that groups must exhibit, which qualify as evidence of culture:

Innovation (A new pattern is invented.)

Dissemination (The pattern spreads to other individuals.)

Standardization (The pattern is consistent among individuals.)

Durability (The pattern is performed even when others are not around.)

Tradition (The pattern is transferred over generations.)

Diffusion (The pattern spreads to other groups.)

While evidence of each step has been observed in various primate studies, as of yet there has been no nonhuman population to meet all six requirements with one single action or pattern.[liii] Nonetheless, it’s important to note that some human populations might also fail to meet all six criteria definitively, and McGrew believes that a more basic interpretation of culture is still acceptable in such cases.

Many cultural anthropologists would argue that culture is, by definition, a purely human attribute. Culture, they say, uses symbols, and the behavior of animals is not symbolic, thus nonhuman beings are unable to have culture. Perhaps the disagreement between cultural anthropologists and primatologists can be resolved if semantics are taken into account. The word culture was originally developed by humans and for humans; thus, it may be fundamentally impossible to claim that nonhumans have cultures, per se. Of course this use is purely literal, and there seems to be a good deal of evidence of nonhumans exhibiting their own versions of what we consider to be cultures.

Anthropologist and philosopher Barbara Noske analyzed the habit of anthropologists (by definition, scholars of humans) to ignore any signs of culture, community, or general intelligence in animal communities. She observed that even though the characteristics listed above may be very obviously present in nonhumans, anthropologists don’t look for them because they’re operating under the presumption that only humans have cultures and enriched social communities. She concluded, “If one preconceives humans to be the sole beings capable of creating society, culture or language, one will thereby have pre-empted ‘ape’ forms of society, ‘ape’ culture and ‘ape’ language almost by definition.”[liv] That assumption is a risky business that could result in the ignorance of possible cultures in other species.

Primatologists have discovered, for example, unique methods of tool use that have developed in geographically separate communities of chimpanzees. East African chimps have created tools to fish through termite and insect mounds, whereas West African chimps have created hammers to crack the hard shells of nuts. Although both coasts of Africa share the same food resources of insects and nuts, the groups of chimpanzees living on each side developed different methods of obtaining that food. As these methods were passed down from one generation to the next, the behavior stuck.

Explaining away such unique location-specific behavior as simple “behavioral variation” indirectly reinforces a stereotype of nonhumans as acting purely on instinct and without any particular intentions or forethought; but the fact that the environments in which these two behaviorally diverse chimpanzee populations live are similar may instead lead to the conclusion that environmental factors are likely not a hidden cause of what appears to be cultural, and the same finding holds true for orangutan behavior differences.[lv] Many scientists are quite content to label such occurrences as evidence of culture. For instance, in a 1999 article in Nature, leading chimpanzee experts including Jane Goodall, William McGrew, Toshisada Nishida, Richard Wrangham, and Christophe Boesche found among their assorted research more than three dozen instances of cultural variations among social groups.[lvi]

Reasons have been developed to explain the geographical differences in chimpanzee tool use (and refute the existence of chimpanzee culture), such as the proposal that genetic differences result in the development of varying food procurement traits, or that different environments simply make it easier for chimps in one area to use sticks instead of rocks. Such theories are often refuted, because chimpanzee groups are genetically identical in broad terms., and in similar environments, chimpanzees will seek out the specific tools their communities favor. Rocks to use as hammers are not more easily found in West Africa, but the chimps that live there seek them out, and chimps in East Africa do not.

There are many other examples of such behavior in nonhuman primates. Capuchin monkeys have been observed not only using hammers and anvils to crush found nuts, but also purposely transporting selected hammers to proper anvil sites, showing evidence of forethought and planning.[lvii] On the island of Koshima in Japan, macaque communities will wash sweet potatoes both in a freshwater stream and in the salty ocean before consumption, something that has been dubbed “seasoning behavior” by the observing primatologists.[lviii]

Chimpanzees in Fongoli, Senegal, fashion and use tools not only to catch termites, as Jane Goodall observed, but also as spears with which to hunt meat (specifically bush babies hidden in hollow tree trunks), the first instance of nonhumans creating and using deadly weapons.[lix] Chimpanzees at Goodall's research site at Gombe have been observed selecting and carrying termite-fishing tools even when not near a termite mound,[lx] proving the depth and scope of their abilities of mental representation and planning for future activities. They have also been observed seeming to cooperate during group colobus monkey hunts and, in a study at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, using water as a tool to float out-of-reach peanuts within grasping distance of their hands.[lxi]

Chimpanzees, orangutans, and gorillas have demonstrated self-awareness in mirror tests,[lxii] something that no other species but humans has thus far exhibited. This awareness is equivalent to that of a 2-year-old human child. Macaques, gibbons, and baboons are able to recognize the existence of an animal in a mirror reflection but so far have not exhibited behavior showing that they realize it is themselves being reflected.[lxiii] In these cases, although pygmy marmosets and cotton-top tamarins have shown precursory evidence of self-recognition in mirrors,[lxiv] most other primates tend to search behind the mirror, looking for an animal that they believe is staring at them through the glass.[lxv] Psychologist Gordon Gallup, head of the first mirror self-recognition tests of nonhuman primates, in the 1960s, wrote that “these data would seem to qualify as the first experimental demonstration of a self-concept in a subhuman form.”[lxvi]

It’s important to note that tool use among nonhuman primates does not exist solely to find or prepare food. Orangutans will swing on flexible tree branches and use leaves as napkins or towels to clean their bodies.[lxvii] Chimpanzees sometimes use leaves as cups to trap, collect, and pour rainwater. They also use branches and leaves to cover themselves when it rains. They may use small sticks to protect feet when climbing prickly trees, and also in nostrils, as humans would use a Q-tip in a stuffy nose. Female chimpanzees will even play and cuddle with sticks, acting as if they were infants, in the way that human children play with dolls.[lxviii]

Bonobos will drag sticks through the dirt, signifying to the group that it’s time to move on to a new resting site. Capuchins use leaves to sponge up water and have been observed beating deadly snakes with sticks. Macaques have been observed soaking in natural hot springs and throwing snowballs for entertainment in the winter. The significance of findings such as these illustrate that the inventiveness of primates is not limited solely to food but also to comfort, pain avoidance, protection, and self-medication.

Music appreciation and creation is one of the cornerstones of human culture, and evidence increasingly supports this trait in apes as proof of yet another way they exhibit culture. Great apes in the wild and in captivity have been found to be very receptive to music. When a musician played a guitar in various ape sanctuaries, he found that the chimpanzees and orangutans were captivated by the music and were enthralled with the guitar producing the sounds. They participated in the performance by bobbing their heads and softly hooting along, which sounded to him like an attempt to harmonize with the song. Musicians Peter Gabriel and Paul McCartney have played music with bonobos, who supposedly have a good handle on rhythm and pitch. Some sanctuaries will play recorded music as a surefire way to calm their primate inhabitants when they are especially riled. Likewise, chimpanzee groups in the wild have been observed moving rhythmically and vocalizing at times of high emotion, such as during thunderstorms and grass fires.[lxix]

There are many clear, documented cases of traditional behavior passed through members of primate societies, often surviving after generations. Craig Stanford of the University of Southern California believes this is evidence of the existence of nonhuman primate cultures.[lxx] Each new group that adopts a particular behavior also adapts it. Often started by younger members of a group and then traveling to the older members, it moves from individual to individual, morphing and meandering through a community. Conversely, some activities are believed to be taught by elder members to the younger members of a group, particularly if the behavior involved is detailed or exacting, requiring practice and learned expertise to perfect it.

The fact that certain behaviors are learned via nurture instead of nature, ingrained and not instinctual, is often presumed to be evidence of primate culture. Compared with other species, primates happen to be good at imitating others, a skill that may appear basic on the surface but which is actually very complex, involving planning, consideration of cause and effect, and the physical dexterity to recreate the behaviors observed. It may or may not be influenced by environment.

The similarities between human and nonhuman primates include not only intelligence and occasional benevolence; there are additional behavioral characteristics shared between primate species that are not things to celebrate. One such trait occurs in chimpanzee society, where sexual dominance and beating of females is common (something that, unfortunately, also happens all too frequently among humans). 

Some nonhuman primate species practice infanticide, including monkeys, chimpanzees, and gorillas. For example, when a dominant male langur monkey takes control over an already existent group of females, he systematically kills all the infants. This morbid practice is actually supported by evolution, for the infants’ deaths allow the mothers to be fertile sooner than they would have been, so the dominant male can impregnate them sooner and ensure continuation of his genes. Additionally, there will be no youth in the group to compete with his own progeny for dominance. The numbers of infants killed in such attacks are relatively high: 35% in grey langur monkeys, 37% in mountain gorillas, 43% in red howler monkeys, and 29% in blue monkeys.[lxxi]

In 1925, when Raymond Dart discovered Australopithecus africanus, the ancient human-ape ancestor who proved Charles Darwin’s evolutionary theories correct and provided a physical record of what early man was like, Dart postulated that this being was a carnivore who ate his prey alive, violently tearing up the carcasses and drinking the blood. Scientific theories such as Dart’s helped encourage the bloodthirsty ape imagery in popular culture and also encouraged humans to ascribe their war and violent tendencies to some link from their not-so-distant past.[lxxii] Dart’s theories were later proved incorrect, as evidence from examination of Australopithecus skulls revealed injuries not from man-to-man combat but from larger animals, proving that early man was easy prey.[lxxiii]

It’s interesting to consider that if Dart’s theories had more quickly been disproved, nonhuman primates might have been seen through more compassionate and less fearful eyes. Ethologist Karl Lorenz noted that although most other animals in the world do not participate in interspecies warfare and genocide, humans do.[lxxiv] It’s as if humanity’s strength and violence evolved faster than its system of Darwinian checks and balances.

On the other side of humanity’s affiliation with the animal world, consider the bonobo, the species to which humans are most closely related and which separated from us genealogically only six million years ago. These typically peaceable beings live in a matrilineal society ruled by cooperation and social comforting, where sexual couplings placate disputes and where dominance and cannibalism don’t exist. In fact, “the use of sex to promote sharing, to negotiate favors, to smooth ruffled feathers, and to make up after fights is enough to make it the magic key to bonobo society.”[lxxv]

For bonobos, sex is a recreational and social pleasure, not used just to assert dominance and conceive offspring but also serving the function of allaying competitive aggression and calming excited nerves. It’s an integral part of bonobo daily life, more so than with any other primate species, and can occur in unconventional pairings, such as homosexual and intergenerational, and in numerous positions as well.[lxxvi]

Bonobo peacefulness even extends across the species barrier. Whereas chimpanzees will hunt and eat monkeys in the wild, bonobos have been observed catching monkeys and keeping them as playthings for their own entertainment. They will groom and swing the smaller animals like toys and even mount them sexually, acting confused and playing a little rough when the monkeys don’t cooperate as expected.[lxxvii] Their diet does include a small amount of animal protein (mainly insects, and rarely small rodents and duikers), although studies have shown that 99 percent of their protein is plant based.[lxxviii] All this being said, primatologist and bonobo expert Frans de Waal notes that it’s important not to romanticize bonobos as an ideally peaceful relative: “Even if strikingly pacific, they are not the long-lost noble savages. All animals are competitive by nature and cooperate only under specific circumstances and specific reasons, not because of a desire to be nice to one another…bonobo society is not all rosy. The species is no exception to the rule that cooperative tendencies are best understood in conjunction with competitive ones, even though I agree that in bonobos the emphasis seems to have shifted to the former.”[lxxix]

Bonobos, first referred to as pygmy chimpanzees, were not recognized as a separate species until 1929.[lxxx] Their slimmer frames, more upright posture, and less furry bodies illustrate how much closer relations they are to humans than are chimpanzees. Had they been noticed and studied earlier, perhaps their genetic proximity to humanity might have influenced human culture and attitudes more than traits of other apes that were observed or assumed. Sexual expression, sexual equality, and social networks might have been seen more as activities preferable to war, territoriality, and other aggressive mainstays of human culture.

It’s been proposed that perhaps the bonobo’s natural reliance on pleasure and bonding through physical touch could begin to convince humans that such traits are innate in us, as well, and perhaps ought to be considered more praiseworthy in the modern world. After all, if morality is based at least in part on what is natural behavior for us, perhaps humans could be more accepting of the physical liberties displayed by our closest relatives.

The various nonhuman primate species’ differences and similarities to humankind has given rise to innumerable studies that research not just what primates do, but how they do certain things. After years of field studies of wild chimpanzees in Bossou, Guinea, primatologist Tetsuro Matsuzawa believes that one of the key differences between human beings and other primates lies in how skills are passed down from one generation to another. Primates, he claims, do not teach (despite research by other primatologists that seems to prove otherwise). Youngsters may watch their parents perform an action, he says, but when the youngsters try to complete that same action themselves, they must rely on trial and error to guide them, not the correction or encouragement of a parent.[lxxxi] Evidence discovered by Christophe Boesch of chimpanzee parents possibly teaching their infants how to crack nuts with an anvil has been rare—only twice in more than 70 hours of observation[lxxxii]—lending credence to Matsuzawa's theory of primate societies being void of true education.

The variety of theories presented in this chapter reveals just how difficult it is for humans to know what drives nonhuman behaviors. Some of the most well-known biological theories derive from Charles Darwin’s work on evolution, and although his popularity has helped promote protections of nonhuman primates (due to their close relation to humans) it has also promoted an undercurrent of presumptions about animal behavior.

Evolution through natural selection implies that a being (human or animal) acts the way it does so as best to protect its reproductive future. Any behavior that is exhibited throughout generations is there because genes so dictated. Does this mean that all behavior is genetic? To assume this would in a sense deny all forms of intentionality and culture among nonhumans. Of course this can only be assumed if one conveniently leaves humans out of the equation, which is most likely to happen anyway, even if it makes little sense. This notion would imply that culture, tool preparation, altruistic behavior, and even sign language is only observed in nonhuman primates because they are acting on behalf of their genetic codes, like unconscious machines following a program. It’s not too difficult to see how closely this image mimics the soulless automaton of the Cartesian era and promotes separation of human from nonhuman primates.

On the other side of the scale is anthropomorphism (assigning human characteristics and/or thought to a nonhuman). The proscription of granting other species undeserved inclusion into the sphere of humanity leaves researchers in a tough space, especially when the animal behavior under question is entirely mental or is so subtle as to be difficult to measure. The intentionality of a nonverbal being will always remain something of a mystery. As Barbara Noske writes, “No scientist can ever totally transcend his anthropocentrism, in that he cannot leap over his own humanity and the typically human perspective. In that sense our fellow apes remain unknowable.”[lxxxiii]

What’s the solution, then? Perhaps, as Noske suggests, researchers should learn from the apes not by teaching them our language and imposing our cultural norms on them, but by immersing themselves in the ape culture and becoming one of them.[lxxxiv] Living in their communities, eating their foods, learning their communications, and practicing their behaviors might really be the best way to understand nonhuman primates. It would be the truest, purest form of observation and certainly more direct than teaching primates human behaviors in order to learn about primate behaviors.

When it comes to discussions of primate culture, intentionality, and intelligence, much of what has been studied, proposed, argued, and conjectured strives to reveal something quite mysterious: what animals are thinking (and how they are thinking it). Nevertheless, there does not yet exist any objective method of determining exactly what animals are thinking at any given moment. For example, chimpanzees and capuchins have been observed in situations where it appears they are taking part in an organized hunt, although opinions vary on whether the individuals intentionally cooperate, with a shared desire for hunting success, or if perhaps the behavior is something more random or coincidental. The hunt's success does increase with the size of the hunting group, which may suggest that perhaps this is evolutionarily intentional. If primates are indeed cooperating, though, it would mean much in terms of evolution and anthropology, because it’s widely believed that mankind has been so successful in mastering his environment partially due to early humans’ ability to cooperate among themselves in pursuit of a larger goal.

It’s important to note that, in cooperation research at the Great Ape Research Institute in Japan, chimpanzees would not cooperate together to reach a shared food goal, but they would work with a human being to reach the same goal,[lxxxv] and they would help human beings reach a goal, as well, even if the reward were not something desired by the chimpanzee. But to blindly assume cooperation between individuals of another species is a huge assumption, because it implies an impossible reading of intentions and comparisons to human thought processes. Since these primates are not humans, one cannot make decisions about mental status based merely on comparing resulting behaviors with human behaviors.

It would seem that a simple solution to unlocking the mysteries of nonhuman primates’ minds would be solved with a shared language whereby they could communicate to humans their wants, desires, and even thoughts. This is where the much-debated sign-language studies of the mid-1900s came into play. These began in the late 1940s with Viki, a chimpanzee who was trained over three years, through much labor and physical molding of her lips, by Keith and Katherine Hayes to vocalize four words (momma, poppa, up, and cup). It is generally agreed that Viki spoke the words not because she understood their meanings but because she learned that if she spoke the words she would be rewarded with food. Human language did not come naturally to Viki, nor did she seem able to speak with any sort of ease or comprehension.[lxxxvi]

The experience with Viki, and other similar early studies in which chimpanzees were raised as humans to see if they would pick up human language naturally, simply cemented the concept that apes cannot use a spoken language due to the natural formation of their larynxes. Specifically, nonhuman primates are lacking a bend in the vocal tract that is required to make the sounds of a spoken human language.[lxxxvii] Humans are capable of uttering and comprehending about a hundred different phonemes (the sounds that comprise language), even though most languages use only half that amount. Chimpanzees, it has been found, are only able to create twelve distinct phonemes.[lxxxviii]

As an alternative method of communication, researchers thought perhaps American Sign Language (ASL) would be a perfect fit for primates, due to their high intelligence, social natures, and dexterous hands. In 1964 William Lemmon, a primatologist at the Institute for Primate Studies in Norman, Oklahoma, purchased an infant chimpanzee named Lucy from the owners of an exotic animal show. Maurice Temerlin, a clinical psychologist and psychotherapist, was chosen (along with his wife, Jane) to raise young Lucy as a human child in an effort to see just how much of its innate chimpanzee qualities a youngster could lose in such a situation. Working with the first chimpanzee to be reared by humans past sexual maturity, Temerlin was especially interested in Lucy’s sexual development and the degree to which it would be influenced by these circumstances.

Lucy had typical human childhood experiences, such as wearing clothes, receiving immunizations, learning to eat with utensils, and surviving as a member of a family unit, and she excelled at them all, perhaps even better than a human child would have. She was adept at preparing drinks for herself (both alcoholic and virgin) and using tools such as screwdrivers to disassemble objects. As she got older, Lucy’s behavior continued to mimic that of a human, albeit a human without inhibitions, as she was fond of masturbating and staring at human male centerfolds in adult magazines that were supplied to her as part of the investigation. When she was later introduced to a male chimpanzee, she was understandably frightened, never before having seen another member of her own species.[lxxxix]

Graduate students of the Institute for Primate Studies, including Roger Fouts, who would later work with another signing chimp named Washoe, were hired to teach Lucy sign language, and she eventually learned to incorporate more than a hundred signs into her vocabulary. As other primates did after her, she would create combinations of signs to signify things for which she didn’t know the proper words, such as signing “cry fruit” to express onion.[xc]

As Lucy grew larger and stronger, special considerations had to be made for what Dr. Temerlin considered to be his "daughter." A special room was built for her, reinforced with concrete and steel. Although most parents wouldn’t allow it for a human child, Temerlin permitted Lucy to drink alcohol, calling her an “ideal drinking companion...[who] never gets obnoxious, even when smashed to the brink of unconsciousness.”[xci] Temerlin tested Lucy’s comfort zones by engaging in various forms of sexual activity in front of her. Many of Temerlin’s methods are considered outdated and inappropriate by modern standards, and they would likely have seemed questionable to most conservative people at the time.

After ten years of habituating Lucy into every aspect of their lives, the Temerlins grew tired of the experiment, and it was terminated. Although Lucy was now a media darling (while interviewed for a New York Times article in 1974, she invited the ASL-signing interviewer, Boyce Rensberger, up into a tree[xcii]), she was sent to live at Niokolo Koba National Park in Senegal, something that the Temerlins felt was in her best interest (despite the fact that their “daughter” had actually been born into captivity in the state of Florida). Although one of her teachers stayed with her at her new home, Lucy grew depressed at the loss of her normal life and family, and she became seriously ill. She refused to drink, climb, and eat like the other chimps in her assigned social group in Africa, asking in sign language for help when she grew frustrated at not having enough food.[xciii]

As her human helper tried to draw away for fear of retarding any potential progress Lucy could make in her new life as a wild chimpanzee, Lucy learned to manipulate her emotions by signing every time she was hurt, pulling out her fur in desperation, and growing emaciated from starving herself. After this low point, Lucy did eventually learn to accept her new life. She started eating leaves and slowly growing more confident in living outdoors. After ten years of living as a wild chimpanzee in Senegal, Lucy was killed and her skeleton found near the compound, with the hands and feet missing, likely from poaching activity.[xciv] Lucy died at age 22, having lived her short life first as half human, then half chimpanzee.

The first successful ape sign-language study involved Washoe, a chimpanzee who was also raised by humans. The project was started in 1966 at the University of Nevada by Allen and Beatrix Gardner and then spearheaded by a young graduate student named Roger Fouts (who later also worked with Lucy), with the goal of designing Washoe’s curriculum in response to the previous failures at teaching primates to speak a human language. The Gardners suspected (correctly) that nonhuman primates were physically unable to produce speech and, considering their physical and manual dexterity, might be more successful communicating with signs.

Although Washoe was raised as a human child, no spoken language was used in her presence; only ASL was used to communicate. During the five years that she lived with the Gardners and Fouts, Washoe’s language ability progressed as would a human child’s language skills. She not only used language to gain access to food, but also in more abstract ways that highlighted her desires and opinions, such as to ask for playtime or describe something for which she didn’t know the proper sign. She learned more than 130 signs, and her researchers estimated that she understood three times that number.[xcv] Video footage of Washoe playing by herself revealed private signing (Washoe signing to herself, the equivalent of a human talking to himself), animation (pretending that an inanimate object is alive), and substitution (giving an object a new identity). The discovery of Washoe engaging in private signing and labeling (such as signing “cat” when she saw a photo of a cat[xcvi]) disproved centuries of philosophical decrees that only humans are capable of thought.

At five years old, Washoe was forced to leave her human family when the study supporting her sign language lost funding. The project was moved to the Institute for Primate Research at the University of Oklahoma under the direction of controversial director Dr. William Lemmon. It was here that Washoe first saw other chimpanzees. She described them as “black cats” and “black bugs,”[xcvii] revealing just to which species Washoe felt she belonged. Over time, however, Washoe grew increasingly comfortable with the other chimpanzees, even reacting with true altruism and compassion when she rescued a fellow chimpanzee that was drowning in the moat surrounding their enclosure.[xcviii]

At this point in the study, Washoe’s closest human confidante, Roger Fouts, began to doubt the efficacy of the old-school, dominance-heavy scientific community and its relationship to its animal subjects. This nagging feeling would not go away and eventually would cause Fouts to turn his back on animal research in general, but not before moving the Project Washoe chimpanzees to Central Washington University, where he was able to demand a new level of respect and freedoms for the chimpanzees he had grown to love and value in their own right.[xcix]

Later in life, Washoe was found to have taught sign language to her adopted son, Loulis, via modeling with his hands and signing on his body. (It’s important to note that Washoe’s caretakers were careful not to sign in the presence of Loulis, so they could see if he would learn sign language from Washoe. He started signing within eight days of being “adopted” by her.[c]) Chimpanzees in the wild rely heavily on teaching and modeling to pass down cultural and survival skills to successive generations, so it is not surprising that Washoe taught her adopted infant the language she herself grew up using to communicate, but this also proved that not only those chimpanzees raised in human homes could successfully learn a human language.

Skeptics of Project Washoe claimed that the findings could not be presented as true of general chimpanzee intelligence and ability, but only proved something about cross-fostered chimpanzees. Luckily, little Loulis (who was not cross-fostered) learned sign language the same way he learned other skills from his mother, such as grooming and nest-making, and the scientific community soon had to admit that these chimps’ language abilities were indicative of their entire species, and not just a rare coincidence.

Washoe and Loulis were eventually joined by other chimpanzees whom the Gardners had taught sign language—Moja, Dar, and Tatu—allowing the researchers to examine how the chimpanzees, as a group, used sign language in their daily lives. It was discovered that Loulis had a tendency to sign to his playmate Dar on certain topics and sign with his mother on other topics. When play between Loulis and Dar got too rough, Loulis would scream for his mother and then point to Dar and sign, “Good good me,” as if to incriminate Dar as the guilty party of the fight.[ci] Both applications—the topic specificity and blame games—illustrate that Loulis had a concept of the mental states of others, something he tried to use to his own advantage.

With Project Washoe, it was discovered that the majority of chimpanzee signing fell into one of three categories: play, social interaction, and reassurance (which is generally true of other chimpanzee communication in captivity, as well). Surprisingly, food was not one of the main topics of discussion, so the chimpanzees were not simply mimicking signs in order to gain access to meals. The chimpanzees’ signing revealed how far back their memories could stretch. For example, Tatu asked for the annual Christmas tree during an early November snowstorm,[cii] and Washoe greeted her old human family, whom she hadn’t seen for eleven years, by signing their names.[ciii]

In 1971, a more conventional scientific study was embarked upon by Duane Rumbaugh at the Yerkes Regional Primate Center in Atlanta, Georgia, with a chimpanzee named Lana. Out of concern that the more casual, family-style primate language studies would not be accepted by the scientific community, he instead relied on empirical methods in his experiment and tried to minimize any subjectivity.

Lana was taught to communicate via a computerized keyboard. The benefit of the computer was that it removed all subjectivity from the research, since it would only reply to Lana’s requests if they were formed correctly. Any type of body language and unspoken inference (potential influences that had peppered the critiques of previous primate language studies) were meaningless to the computer.

Soon Lana was not only able to use the symbols correctly to ask for things she desired but also to describe things for which she did not know signs and to argue with her trainers when she felt they were teasing her.[civ] While it’s not surprising that Lana learned to use this language to her own benefit, it is interesting to note that she also learned to read output from the machine and to complete puzzles in which key words were missing from a sentence.[cv]

Begun in 1973, Project Nim was a four-year attempt to teach sign language to an  infant chimpanzee called Nim Chimpsky (cleverly named after Noam Chomsky, a famed linguist who had proclaimed language to be the result of innately human qualities). Psychologist Herbert S. Terrace undertook the experiment in the hopes that it would help define the boundaries of humanity and its culture by exploring the development of human language in another species.

Nim was raised as if he were a human child, surrounded by a human family that was constantly supervising and recording his actions and under the tutelage of sixty different teachers. It was hoped that his close ties with the humans around him would inspire him to learn sign language as a way of communicating with and appeasing them. Unfortunately the project was plagued with instability—with many changes in personnel and locations where Nim was taught, as well as lack of funding—problems that surely did not help to calm the inquisitive and observant young chimp and most likely impeded his learning potential.

In the first four years of the project, Nim learned 125 signs, starting at four months of age.[cvi] The speed and accuracy of his learning depended greatly on the tenure of the teachers who were working with him. The longer they had been there to develop a relationship with Nim and the more patient and talented they were, the faster he learned novel signs.

Like other primates in language studies, Nim would combine signs to describe objects whose proper signs had not yet been taught to him. New signs were learned either by having his hands physically molded by a teacher or by his imitation of a teacher’s signing. Because his teachers constantly communicated with and around Nim via sign language, it was easy to show that Nim was not using signs only in anticipation of a food reward. For instance, Nim used signs to ask for a specific color of crayon he wanted for an art project, to describe certain teachers by name, and even to identify himself in mirrors. When one of his teachers caught him about to drink some poisonous cleaning fluid that had accidentally been left out, her frantic signing of “No stop don’t eat” halted Nim in his tracks and surely prevented a disaster.[cvii] Nim’s sense of self and awareness of others appeared to be very well developed and documented.

Although Project Nim was later criticized for using outdated research methods and animal handling, including corporal punishment in times of extreme defiance, some interesting moments occurred that shed light on the development of young Nim. For example, his caretakers apparently felt that he was rather self-centered, acting as if everything in his environment existed solely for his use and enjoyment. Once his caretakers taught him the concept of taking turns and sharing, Nim began using the sign for me frequently; however, it wasn’t until he had a tantrum one day after having to share yogurt with a teacher, when he angrily began using the new sign to chastise the teacher who (he felt) wasn’t sharing adequately, that he added you to his vocabulary. From that point on, his signing reflected his adjusted view of the world, as one where actions and experiences could be shared between beings and where he was no longer the center of his universe.[cviii] This is a developmental step clearly delineated in human children, as well.

Other instances revealed Nim trying to teach sign language to human children he met outside, and he would also play tricks on his caretakers (such as hiding important objects they wanted) that revealed his clear sense of awareness of the points of view of others. He enjoyed cleaning and household chores so much that he would throw a tantrum when he wasn’t allowed to participate.[cix] During potty-training episodes, Nim was so accustomed to wearing pants that when they were removed to facilitate his use of the toilet, he covered himself up as if embarrassed by his nudity.[cx]

Despite his seemingly human characteristics, Nim wasn’t afraid to reveal his chimp-ness (for lack of a better word), whether it was by testing the will of newcomers with physical displays or screaming in defiance when he was displeased, which led to physical attacks on unfamiliar people. As revealed in the study, “Undoubtedly Nim saw a teacher who could not control him as an opportunity to assert his own meager dominance...."[cxi] "Most of the time, however, Nim expressed his feelings and intentions directly…This was true whether Nim was expressing affection, curiosity, fear, aggression, wonder, or determination.”[cxii]

 An interesting side effect of his sign language usage was that a few times when Nim was acting aggressive, he would approach the object of his aggression, generally a teacher, and sign the words “bite” or “angry” while looking as if he were about to attack the person physically.[cxiii] This could be viewed as the language equivalent of a threat, something that is very pervasive in wild chimpanzees, albeit typically in the form of puffing out of body hair, physical displaying, and swaggering from side to side. Certainly, getting in the faces of his teachers, grimacing, and signing about how angry he was would instill fear in the humans around him. But Nim’s use of “bite” and “angry” can also be considered as tools, as if his ability to express himself stopped him from relying on pure physical reactions—almost as if some of his chimp-ness had been suppressed and redirected into language by the human culture in which he was submerged.

One of the prevailing questions that Herbert Terrace aimed to answer with Project Nim was whether or not a primate was able to consistently and accurately create sentences with sign language. Although preliminary evidence seemed partially to support the hypothesis that Nim was understanding and creating proper sentences, this was never able to be examined in depth, and Terrace wrote that at times Nim’s signing was more imitative and used solely to obtain positive feedback from his teachers. [cxiv]

Project Nim ran out of funding in 1977, and the project was disbanded. The star of the show, Nim, had to be returned to the Institute for Primate Studies in Oklahoma, where he joined Washoe, who was also living there after being raised as a human and taught sign language.

At this point, successful experimental language studies, both with and without the usual scientific methods, had begun drawing attention, and that, plus federal funding, helped promote further investigations. After the relative failure of Project Nim, Herbert Terrace became skeptical of other ape language studies and was frequently asked to review video tapes and search for signs of prodding and imitation that were similar to those exhibited by Nim and his teachers. Terrace admitted that Nim was not taught true American Sign Language but a pidgin version; thus, even if Nim had learned it word for word, he would never have been considered the master of a previously recognized language.[cxv] Additionally, Terrace was very often skeptical of any investigation into animal language use that seemed to have positive results, although he was never able to explain certain events occurring in the chimpanzee language studies, such as the spontaneous signing of Washoe when alone with her dolls, or the signing of her son, Loulis, who used fifty-seven distinct signs, despite humans near him using only seven special signs.[cxvi]

The year 1972 saw the first time that a gorilla was taught a human language. Francine "Penny" Patterson started teaching an infant lowland gorilla named Koko sign language as part of a research program through the psychology department at Stanford University. It took only a week for Koko to begin using signs to request food and drink, and as of this writing she has learned more than a thousand signs.[cxvii]

As with other apes that have been taught to communicate using sign language, Koko’s intelligence has been examined closely. She not only understands spoken English, as well as American Sign Language (she actually understands many more words than she is able to sign on her own), but she is learning to distinguish letters of the alphabet and has been tested as having an IQ of approximately 80 (which is considered low-average for humans.)[cxviii] She recognizes herself in a mirror, has an active imagination, creates artwork and can communicate in the abstract about events that have happened in the past, using words to indicate a sense of time. [cxix]

Apparently quite empathetic, Koko expressed emotion when she saw photos of other gorillas or other animals that appeared to be suffering or in pain, and she bonded with kittens that she was allowed to keep as pets and deeply grieved their deaths. It’s important to note that she wasn’t merely grieving the absence of her beloved kittens; she actually understood the concept of death. When asked by her teacher where gorillas went when they die, Koko signed “comfortable hole bye,” and when asked how they feel when they die, she signed “sleep.”[cxx] Koko had never seen a burial before, but this is consistent with the instinct of gorillas and other primates to cover the deceased in either earth or vegetation in the wild.

As Koko gained worldwide attention and admiration for her bright and gentle demeanor, Dr. Patterson established The Gorilla Foundation in an effort to guarantee funding for the duration of the research. Eventually two more gorillas named Michael and Ndume joined Koko at her home in California. Both additional gorillas learned sign language later in life and relied on it to communicate between themselves and to their human caretakers. The gorillas have become so proficient that they have been known to sign slowly to humans who don’t understand sign language as well as they, also using modulation or the exaggeration of words to prove an especially compelling point, in much the same way that humans will slow their speech and overemphasize words to non-native speakers of their language.[cxxi]

Among other items of interest, Patterson’s work has shown that gorillas most enjoy eating; trees also make them happy, and work makes them angry.[cxxii] Her gorilla subjects appear to harbor amazing creativity and keen observational skills regarding what’s going on around them. For instance, Koko described the events of an earthquake as “Darn darn floor bad bite. Trouble trouble.”[cxxiii] When asked how she had slept last night (a colloquial turn of phrase), instead of replying with a descriptive term about the quality of her sleep, as had been anticipated by the human questioner, Koko replied factually and literally with the physical description “floor blanket.”[cxxiv] During a different exchange, Koko revealed her understanding of words in both concrete and abstract terms when she answered the question “What is hard?” with the signs for both “rock” and “work.”[cxxv] When someone jokingly refers to Koko as a goofball or some other such term, she corrects them and signs “no, gorilla.”[cxxvi]

One of the most fascinating instances of ape humor was described in the following exchange between Koko and Barbara Hiller, one of her assistant caretakers.

Koko was nesting with a number of white towels and signed "that red," indicating one of the towels. Barbara corrected Koko, telling her that it was white. Koko repeated her statement with additional emphasis, "that red." Again Barbara stated that the towel was white. After several more exchanges, Koko picked up a piece of red lint, held it out to Barbara and, grinning, signed "that red."[cxxvii] [italics mine]

Ever the humorist, when Koko played jokes on humans, she would chuckle, sometimes even in anticipation of the actual events.

Koko and Michael have engaged in wordplay, using signs that were almost homonyms for the signs they actually should have used. “Knock” was used for “obnoxious," “tickle” for “ticket," “lip stink” for “lipstick” and “berry bottom” for “belly button,”[cxxviii] much in the way that young children will sometimes mispronounce or mistake a word for a similar-sounding choice. A study of Koko’s language skills revealed that of the 876 signs she used during the first ten years of the study, six percent (or 54 signs) were invented by her. Two percent were compound signs she created of known signs, and one percent were considered “natural gorilla gestures.”[cxxix] Patterson says that “conversations with gorillas resemble those with young children and in many cases need interpretation based on context and past use of signs in question.”[cxxx]

Previous testing revealed that Koko could correctly identify and classify words and items, such as differentiating between light and dark colors or even describing some colors as warm and others as sad. Ninety percent of her matches were considered correct by the project's standards (by comparison, seven year-old humans taking the same study answered correctly just 82 percent of the time).[cxxxi] She continues to show self-awareness via self-recognition in mirror tests, converses about the differences between herself and others, and gets embarrassed when others observe her signing to her dolls in play.

The skills of Koko and Michael have not been considered exceptional or coincidental, as each came from different upbringings, and other gorillas in zoos have exhibited similar language aptitudes, albeit in naturally occurring gorilla gestures. Rather, it is believed that all gorillas have the aptitude to converse in American Sign Language if living in an environment that supports its development.

Chantek, an orangutan who was born in 1977 at the Yerkes Regional Primate Research Center in Atlanta, Georgia, was part of an American Sign Language study conducted by Dr. H. Lyn White Miles at the University of Tennessee at Chattanooga.[cxxxii] The research started when Chantek was just nine months old and proved that orangutans, in addition to chimpanzees, bonobos, and gorillas, were capable of learning a human language. Yet Miles was certainly not the first to recognize that orangutans may possess increased intelligence akin to that of humans. Lord James Burnett Monboddo, a linguist and anthropologist of the late 1700s, declared in his book Of the Origin and Progress of Language, “I still maintain, that his [the orangutan] being possessed of the capacity of acquiring it [language], by having both the human intelligence and the organs of pronunciation, joined to the dispositions and affections of his mind, mild, gentle, and humane, is sufficient to denominate him a man.”[cxxxiii] It wasn’t until Miles’ experiment that Lord Monboddo’s theories could be proven.

Chantek ended up learning approximately 150 signs that were both unique and self-instigated.[cxxxiv] He used the signs to gain things he wanted and to control the conditions around him, and when he did not know the particular sign for an object, he would combine known signs in a way to best describe the object he was discussing. Much like the other apes in sign language studies, and like humans learning language, Chantek would use specific words to describe a large range of related items: For example, dog could mean a canine or something with four legs or a picture of a dog or a noise approximating that which a dog would make. Chantek also showed signs of utilizing displacement, discussing things which were not in his immediate physical world (something which is held as a marker of intelligence, as it requires symbolic and abstract thought as well as considerable memory).[cxxxv]

He developed a value system and could label what he considered to be good or bad, illustrating his ability to be enculturated into the norms of human society and what is and is not allowed by human individuals living among others. Chantek also learned deception and would often use signs to trick those around him into thinking something or acting in a certain way. He was able to think empathetically and consider the points of view of others, so as to best control his environment. Additionally, he would use animism and pretend that inanimate objects were alive. [cxxxvi]

Unintentionally, Chantek also learned to understand spoken English and would respond to spoken inquires with sign language answers.[cxxxvii] When prompted, Chantek could slow down his signing and deliberately make his language clearer to others[cxxxviii] (like gorillas Koko and Michael would do). He also began to use his feet, as well as objects nearby, to sign. When he was eager to learn the correct sign for something, he would offer up his hands to the researchers as a plea for help, so that they might shape his hands into the appropriate positions.[cxxxix]

After nine years of living at the research site at the University of Tennessee, Chantek outgrew the facilities and was moved back to the Yerkes Center where he was born, where he stayed until 1997 when he was placed at Zoo Atlanta.[cxl] Although one assumes that Miles’s work with Chantek was begun with an open mind and lack of preconceptions regarding the personhood of nonhuman primates, she admits that “like my colleagues doing similar research, I have found myself unconsciously experiencing them [the orangutans] as persons.”[cxli] Miles believes that evidence of Chantek’s language usage is sufficient as proof of rational thought,[cxlii] and thus he meets the criteria for Descartes’s definition of personhood.

A less rigid language study was performed in the late 1970s. Gary Shapiro was a young student who had been schooled in the methods and experiments of Allen and Beatrix Gardner and Roger Fouts during their work with the chimpanzee Washoe. He had also had experience working with Aazk, an orangutan being studied at a zoo in Fresno, California. He was nominated for a position teaching sign language to orangutans at primatologist Biruté Galdikas’ study site at Camp Leakey in Borneo.

Shapiro arrived at Camp Leakey in 1978 and eventually established an emotional bond with a young orangutan named Princess, a former pet who had successfully been reintroduced into the wild and who ended up learning thirty-seven signs in nineteen months.[cxliii] It’s important to note that, in this setup, Princess was able to leave Shapiro and go off into the jungle at any point in time; thus, the project lacked many controls and structures that were deemed important in previous language studies, and Princess may have been able to learn and use more signs under different circumstances if there had been fewer diversions.

A few other researchers tried various methods to compensate for nonhuman primates’ inability to utter the sounds of human language. In the late 1970s, David Premack, a psychologist from the University of California at Santa Barbara, pioneered a study that involved Sarah, a chimpanzee, learning language based not on spoken sounds or signs but on plastic chips. These chips acted as symbols for words, and throughout the study Sarah was taught not only to use the chips correctly but also to arrange them in a grammatical fashion, considering things like word order and ways to differentiate how some items were similar or different from each other.[cxliv]

In another study, a bonobo named Kanzi, who now resides at The Great Ape Trust in Iowa, learned to communicate using an electronic board filled with various symbols. Each symbol stands for a unique word or concept, and primatologist Sue Savage-Rumbaugh, who heads the study, has documented that Kanzi has learned to use 350 words to express himself and has been able to combine them into a sort of “proto grammar.”[cxlv] He is very proficient at understanding spoken English and comprehends a vocabulary of approximately 3,000 spoken words.[cxlvi] Further, Kanzi's sister, Panbanisha, was captured on video using chalk to draw one of the symbols on the ground in order to communicate to her keepers that she wanted to go outside.[cxlvii]

Savage-Rumbaugh has explained that bonobo symbol acquisition was only successful after humans stopped trying to teach the bonobos and, instead, simply used language around them. “The driving force in language acquisition is to understand what others (that are important to you) are saying to you. Once you have that capacity, the ability to produce language comes rather naturally, and rather freely.”[cxlviii]

More recently, Panbanisha’s infant, Nyota, has proven to be even more advanced than Kanzi and Panbanisha were at the same age.[cxlix] This is most likely due to Nyota’s growing up since birth among both educated, signing, human caretakers and signing bonobo family members, allowing him to live in a truly enriched environment that supports language acquisition. Savage-Rumbaugh’s research with Kanzi and other bonobos has since been applied to helping autistic human children communicate with lexigram boards.

Common to almost all the advanced primate language studies has been the use of the word dirty. Interestingly, all the apes responded well to this word, and even though there were distinctions in how the word was applied to their worlds, the primates of the language studies found “dirty” to be a very expressive and useful utterance. The chimpanzee Nim used it to alert his teachers that he had to go to the bathroom, but he also used it in jest to distract his teachers during a lesson he found especially boring.[cl] The chimpanzee Washoe used “dirty” as a curse word, to describe other primates with whom she was angry or who she felt had slighted her.[cli] The gorilla Koko signed “dirty” to express her displeasure when her toy was accidentally destroyed.[clii]

Another commonality of the language studies was the invention of novel signs to describe situations or objects. For example, Nim was sometimes given lotion to apply to dry skin on his hands. Eventually he started rubbing his hands together as a fabricated sign, which became known as his way of asking for hand lotion.[cliii] Washoe signed “water bird” the first time she saw a swan.[cliv] This, and numerous similar examples by other primates in language studies, seems to indicate that some species of primates are capable of creative expansion of language to communicate novel ideas. This ability to describe objects requires a true understanding of the language, although at times nonhuman primates, like human children, can take language too literally: When someone gave the bonobo Kanzi the task "Put some water on the carrot," Kanzi threw the carrot outside into the rain. Nobody could argue that he didn't understand the command![clv]

Depending on the source and age of the data in question, ape language studies have universally determined that nonhuman primate language is equivalent to that of a human child ranging in age from two to four years. Sue Savage-Rumbaugh claims that nonhuman primate language acquisition in studies is even more difficult than human child language acquisition because the input mode (spoken English) often does not match the output mode (ASL or lexigram buttons).[clvi]

Many characteristics of maturation revealed by the ape language studies, such as the capacity for deception, animism, and overextension of a word, were similar to stages experienced by human children of a similar developmental level but might occur with less frequency. Both the bonobo Kanzi and chimpanzee Nim failed to show the gradual increase in sentence length that is common among human infants learning language.[clvii] Kanzi's spontaneous lexigram communications revealed what his researchers referred to as a "primitive syntax or grammar…a protogrammar,"[clviii] or an ape grammar relative to Kanzi’s brain function. This protogrammar reflected partial adherence to English word order, analogous to what a human eighteen-month-old would produce. A similar protogrammar was found in use by Ai, the chimpanzee in the Japanese mathematics testing program.[clix]

The rush to explore primate intelligence through language was short-lived, however, and lasted only until the early 1980s, when general opinion asserted that language-using primates were the equivalents of highly trained performance animals and did not truly understand human language. This attitude existed despite a pivotal 1980 experiment by Sue Savage-Rumbaugh (of the Kanzi experiments) showing that chimpanzees were able to classify objects into specific categories, which proved that they understood the different meanings and uses for various objects.[clx]

It seems apparent that apes in language studies are neither just mimicking signs nor merely the products of excellent training. The order of demands, open-ended questions, and spontaneous signing illustrate that nonhuman primates can and do use language to describe their environment in much the same way humans do, with very specific and accurate word choices. By the time that Savage-Rumbaugh was proving the extent to which primates comprehend and use human language, however, many of the stars of the earlier primate language studies had moved on.

After Washoe bit off the finger of a visiting scientist, who then threatened legal action, the sign-language-trained chimpanzees residing at the Institute for Primate Studies were deemed too much of a liability, and the University of Oklahoma ended that decade-long relationship in 1979. By the early 1980s, the chimpanzees there were sold to the Laboratory for Experimental Medicine and Surgery in Primates (LEMSIP) in New York.[clxi] Media stories drew attention to the transfer, and the public grew outraged and uncomfortable at the thought of language-capable beings spending the rest of their lives in research facilities.

In the end, the two most famous chimps, Nim and another signing chimpanzee named Ally, were brought back to live in Oklahoma, and while Nim ended up at a ranch in Texas owned by an animal welfarist, Ally was later placed in a private medical research facility in New Mexico. The paperwork for Ally’s transfer has since been misplaced. The facility claims that the chimpanzee was received without a name, and he had since been renamed.[clxii] Only the language studies with Koko and her family at the Gorilla Foundation and with Kanzi’s family at The Great Ape Trust survived the skepticism of the 1980s and are producing data to this day.

The accuracy of primate language studies has been in question ever since Nim's project director concluded that what had previously been assumed to be language comprehension was more likely instructor prodding and clueing. Researchers have been accused of being insufficiently critical of language testing, using physical or verbal cues to coax proper behaviors from the primates being studied, and finding what they wanted to find—and perhaps not what was necessarily there. To a number of people it seems obvious that, in many instances, nonhuman primates have learned the meanings of specific words, signs, or symbols, but critics find it harder to swallow the concept that primates have shown the adoption of any sort of grammar. Nonhuman primates may understand the meanings of words or signs, but evidence thus far does not show that words are consistently combined in any particular order.[clxiii]

It’s been thought that the relatively quick dismissal of the early language studies was a subtle attempt to keep human beings in their assumed place of dominance over the less intelligent “other” animals. Primatologist Geza Teleki put it well when he said, “We humans commonly react with astonishment upon discovering that chimpanzees can do something we consider special to humankind. Any evidence of intelligence overlap provokes the greatest skepticism, as the uniqueness of that quality in us is our most cherished illusion.”[clxiv] Conveniently, proving that an utterance or response is language relies on vague and tenuous definitions that vary with the individual; thus, this nearly impossible task is not unlike proving that another human is a conscious being.[clxv]

In order to come to an educated conclusion about the proper use of language by nonhuman primates, it’s important to understand the basics of human language. According to George Yule, there are six special properties of human language that make it uniquely un-learnable by other beings, considered in terms of communicative and informative signals (intentional vs. unintentional communication): displacement (the language may describe places and times other than those currently being experienced in time and space), arbitrariness (there is no natural connection between a linguistic form and its meaning in a particular language), productivity (the language can be used to create almost infinite word combinations, novel sounds, and new meanings), cultural transmission (language is learned from the surrounding community and passed on generationally), discreteness (sounds used are meaningfully distinct), and duality (language is organized on both the physical level and on the level of meaning).[clxvi] Although some people may claim that the language skills of nonhuman primates are inferior and that their abilities are not sufficient proof of intelligence, it seems compelling to note that only in the last century did linguists cease judging languages of indigenous human populations to be inferior to that of “civilized” Caucasians.

 The temporal lobe of the left hemisphere is the language-making center in the brains of humans, chimpanzees, and bonobos. Studies of ape gesturing have proved brain lateralization similar to that of humans, leading scientists to consider that language-making capabilities may also be similar, despite the fact that human brains are three times as large as the average brains of other primates.[clxvii] Roger Fouts, who worked with the signing chimpanzee Washoe for many years, came to understand that great ape education must be spontaneous and that it is unpredictable, for the apes can sense when it is forced and, almost as if to prove their independence and freedom from any human-imposed restrictions, will not learn on schedule.[clxviii]

In his essay “Rational Animals,” Donald Davidson expresses difficulty imagining that animals could have much thought at all without language.[clxix] If we assume that other primates have thought, do they also have language? Critics of primate language studies, such as cognitive scientist Steven Pinker and esteemed linguist Noam Chomsky, believe that human brains are host to a physical element unique to our species, despite the fact that such a "language acquisition device" (LAD) not only has never been located in a human brain and that most scientists believe instead that language is a product of various parts of the brain working in tandem. Additionally, if there were a LAD in human brains, evolutionary theory would dictate that there be a similar element in the brains of other primates, albeit perhaps in a more primitive form.[clxx] Primatologist Tetsuro Matsuzawa lies somewhere in between the critics and the primate language proponents, explaining, "I do not say chimpanzees have language, they have language-like skills."[clxxi]

Narrowing the definition of language to the point of requiring that language use be defined as limited solely to those beings that can produce it vocally would be to disregard the vast language capabilities of mute human beings, for example. Perhaps the distinction should rest with language comprehension, which page upon page of research over the years has proved to be an ability exhibited by nonhuman primates.

What the language studies, and others pertaining to any aspect of development or life of a nonhuman primate in captivity, do show is that results will always be atypical in that they are in some way specific to the given research subject. There are many factors involved in research which, added together, conclude with a subject leading a life quite far from natural. For example, as part of Project Nim, its central study subject was taught to complete routines that were important culturally to humans but were completely worthless to a nonhuman, such as hanging his hat and coat on a hook upon entering his classroom. Nim had to concentrate on actions that were evolutionarily worthless to him and were presented to him only as vehicles to introduce new signs and also to fully enculturate him as a young human, and his resulting outbursts and lack of interest seem to illustrate that he must have experienced some frustration at being forced to complete such unnatural tasks. Frustration apparently affected his learning curve and his patience with sign language; thus, the language capabilities of a nonhuman primate brought up in a laboratory or private home might be greater than or less than a member of the same species leading a natural life in the wild.

Although some researchers credit the language research environments with being more enriched and supportive towards the growth of impressionable young primate minds, as compared with typical life in the wild, Craig Stanford proclaims, “researchers must make an a priori assumption that they are studying a socially and psychologically stunted animal.”[clxxii] Of course, there’s no way to test the language capabilities of the same being in the wild, simply because that would require them to leave the environment in question, and the results would inevitably be skewed one way or another. This is one of the great moral quandaries of using living research subjects: ironically, the more curiosity there is about animals, the more intensely they must be subjected to our scrutiny at the cost of their natural lives.

Even though the studies promote and celebrate the various levels of primate intelligence, language studies can cause controversy with animal welfarists. Experimental protocol often acclimates the subject to a comfortable life that is heavily influenced and altered by human cultures. The subjects can develop powerful emotional bonds with their teachers, especially in the case of studies that go on for decades. If a language study ends by the researcher's request or an account of a lack of funding, the study primates may be unable to acclimate to any other life, even the relatively more "natural” environment of a zoo or sanctuary. Certain primates are already so genetically similar to human beings  that it's not difficult to imagine that their behavior would grow more human-like when living among humans, completing tasks that are normal to humans but are completely abnormal to, and useless for, primate life in the wild.

Habituating a wild animal to the life of a human is also understandably controversial because if, after decades and decades of primate language studies, it is determined that primates are fundamentally unable to foster any sense of human language (an unlikely assertion), many primate lives would have been spent in vain; yet, it's possible to view primate lives as spent in vain regardless of any discoveries about primate language. Clearly primates can communicate naturally and quite well among themselves in the wild, and they certainly do not need humans to pioneer research into their language capabilities (for their own benefit).

It would be ignorant to assume that only a human language counts as evidence of the language capabilities of nonhuman primates. The high level of intelligence and sociality of nonhuman primates, especially the great apes, makes them seem prone to developing a language that would evolve over the years; yet, apparently this hasn’t happened nearly at the same rate as human beings have developed language. Reasons proposed for this include ideas such as nonhuman primates’ lacking a theory of the mind (the ability to recognize that others have awareness and thoughts), or lacking a desire to communicate because there is no evolutionary benefit to it. Primates, like many other species, have developed alternate systems to read the behavior of others so as to work together on survival.

Many researchers have documented evidence of innate primate language. Bonobos have distinct hooting calls that are very different from their close relatives, the chimpanzees. These “echo” calls do not overlap and appear to be a sort of back-and-forth exchange in relation to some event, much like the language of human beings. Primatologist Frans de Waal postulates that the more peaceful nature of bonobos results in their communications being more vocal; thus they exhibit fewer physical displays (loud and violent stamping, waving and rushing emotional outbursts) than do chimpanzees.[clxxiii]

For twenty years, Dr. Klaus Zuberbühler of the University of St. Andrews in Scotland has been studying the calls of a population of Diana monkeys living on the Ivory Coast. He has found that the monkeys make specific calls for specific threats, be it a ground predator, such as a leopard, or a flying predatory bird.[clxxiv] Research by Robert Seyfarth and Dorothy Cheney of the University of Pennsylvania has proved the existence of a similar innate language system in vervet monkey and baboon communities. Individual vervets will even play a sort of practical joke on others of their community by making false land-predator calls. This compels other group members to hide in the trees, often leaving the caller free access to something he desires, be it food or a prime location at a drinking hole.[clxxv]

The innate languages of monkeys and apes do not appear to be as malleable or creative as human language. Some species such as vervets have a more stringent vocabulary, being unable to combine sounds to make new words with distinct meanings, and do not appear to have separate calls to distinguish details of, say, the proximity of a predator. Conversely, Campbell’s monkeys of the Ivory Coast have been observed to add suffixes to their calls in an attempt to differentiate calls about predators they observe themselves from those about predators they learn of via the alarm calls of a neighboring group of Diana monkeys.[clxxvi] This may be a way of separating proven fact from gossip.

Both Campbell’s monkeys and putty-nosed monkeys will also combine sounds to make words with very distinct meanings.[clxxvii] The order of calls suggests a type of grammar, as specific meanings are dependant on the order of calls emitted by the vocalizing primate. For example, when Seyfarth and Cheney played a recording of baboon calls that had been edited so as to make it appear that an infant was threatening an adult (a complete reversal of the normal hierarchical order of their society), the baboons listening to the call looked at the speaker in confusion. The language they heard was not making sense, and they understood the absurdity of the situation. However, understanding a sequential order of words does not lead them to speak or vocalize accordingly in response. “The ability to think in sentences does not lead them to speak in sentences,” the researchers explained.[clxxviii]

It seems that each time something new is discovered about the abilities and intelligence of nonhuman primates, a plethora of questions arises as a result. Does tool use imply culture? Can empathy exist in animals surviving in the wild? Language may be the result of detailed mimicry...or is it a window into the thoughts and preferences of a previously unknowable being? To answer such questions, is it best to increase funding for research, or is this quest a selfishly human desire that can have no benefit to the research subjects?

Ethical treatment of nonhuman primates is discussed at length in chapter eight of this book, but even if the entire book dealt with the subject of ethics, it would likely be impossible to come to a conclusion universally accepted by the myriad industries with an interest in nonhuman primates and their welfare. Humanity has been confounded by nonhuman primates through history, and the men of the land have still not quite figured out the best way to handle the men of the forest.

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[i] Teleki, “They,” 298.

[ii][ii] Orzech, “What.”

[iii] National Research, Psychological, 7.

[iv] Ibid., 42.

[v] Ibid., 7-8.

[vi] Ibid., 82.

[vii] Ibid., 92.

[viii] Ibid., 8.

[ix] Ibid., 7.

[x] De Waal, Family, 18.

[xi] Cohen, "Thinking," 50-57.

[xii] De Waal, Family, 27, 94.

[xiii] Ibid., 25.

[xiv] Cohen, "Thinking," 50-57.

[xv] De Waal, Family, 40.

[xvi] BBC News, "Chimps."

[xvii] Cavalieri and Singer, Great, 96.

[xviii] De Waal and Lanting, Bonobo, 26.

[xix] Ibid.

[xx] Sussman, Garber, Cheverud, “Importance.”

[xxi] De Waal and Lanting, Bonobo, 30.

[xxii] Gardner, “Smiling.”

[xxiii] National Research, Psychological, 77.

[xxiv] De Waal, Family, 136.

[xxv] Peterson and Goodall, Visions, 21.

[xxvi] De Waal, “Empathy,” .87-106.

[xxvii] De Waal, Primates, 30.

[xxviii] O'Neill, "One."

[xxix] Thompson, Intimate, 116.

[xxx] Ibid., 170.

[xxxi] Ibid., 126.

[xxxii] Ibid., 117.

[xxxiii] Ibid., 119.

[xxxiv] Ibid., 171.

[xxxv] Boyd Group, "Paper 2."

[xxxvi] Wise, Rattling, 134.

[xxxvii] Ibid.

[xxxviii] Nagell, Olguin, and Tomasello. “Processes,” 174-186.

[xxxix] Thompson, Intimate, 125.

[xl] Wise, Rattling, 183.

[xli] Ibid., 184.

[xlii] Ibid., 185.

[xliii] Ibid.,186.

[xliv] Ibid., 187.

[xlv] Grehan, “Mona.”

[xlvi] Cohen, "Thinking," 50-57.

[xlvii] Ibid.

[xlviii] Wise, Rattling, 190.

[xlix] De Waal, Primates, 43-44.

[l] Hauser and Carey. “Spontaneous.”

[li] van Schaik et al., “Orangutan,” 102.

[lii] Ibid., 105.

[liii] Sayers, “Chimpanzee,” 87-108.

[liv] Noske, “Great,” 259.

[lv] van Schaik et al., “Orangutan,” 103.

[lvi] Wise, Rattling, 180.

[lvii] Sayers, “Chimpanzee,” 87-108.

[lviii] De Waal, Family, 145.

[lix] NOVA, “Ape,” 11:05.

[lx] Wise, Rattling, 192.

[lxi] NOVA, “Ape,” 5:13.

[lxii] Diamond, “Third,” 71.

[lxiii] Boyd Group, "Paper 2."

[lxiv] National Research, Psychological, 77.

[lxv] Blum, Monkey, 7.

[lxvi] Peterson and Goodall, Visions, 23.

[lxvii] Ibid., 164.

[lxviii] PressTV, "Female."

[lxix] Thompson, “Chimpanzees.”

[lxx] Stanford, Significant.

[lxxi] De Waal and Lanting, Bonobo, 118.

[lxxii] Rice, Encyclopedia, 107.

[lxxiii] Smithsonian, “Australopithecus.”

[lxxiv] De Waal and Lanting, Bonobo, 1-3.

[lxxv] Ibid., 112.

[lxxvi] Ibid., 4.

[lxxvii] Ibid., 65.

[lxxviii] Ibid., 66.

[lxxix] Ibid., 84-85.

[lxxx] The IUCN, "Pan Paniscus."

[lxxxi] Cohen, "Thinking," 50-57.

[lxxxii] Ibid.

[lxxxiii] Noske, “Great,” 265-266.

[lxxxiv] Ibid., 259.

[lxxxv] NOVA, “Ape,” 21:47.

[lxxxvi] Terrace, Nim, 13.

[lxxxvii] Miles, “Language,” 46.

[lxxxviii] Gross, Being. Page unknown.

[lxxxix] Temerlin, Lucy.

[xc] Peterson and Goodall, Visions, 207.

[xci] Ibid., 208.

[xcii] Wade, “Deciphering.”

[xciii] Peterson and Goodall, Visions, 213-214.

[xciv] Ibid., 215.

[xcv] Terrace, Nim, 15.

[xcvi] Ristau and Robbins. “Language,” 163.

[xcvii] Fouts and Fouts, “Chimpanzees’,” 29.

[xcviii] Friends of Washoe, “Tributes.”  2013.

[xcix] Fouts and Mills, Next, 310-343.

[c] Ibid., 242.

[ci] Ibid., 300.

[cii] Ibid., 301.

[ciii] Fouts and Fouts, “Chimpanzees’,” 35.

[civ] Blum, Monkey, 15.

[cv] Terrace, Nim, 23-35.

[cvi] Ibid., 137.

[cvii] Ibid., 250.

[cviii] Ibid., 111-112.

[cix] Ibid., 116.

[cx] Ibid., 120.

[cxi] Ibid., 143.

[cxii] Ibid., 129-130.

[cxiii] Ibid., 210.

[cxiv] Ibid., 210-215.

[cxv] Wise, Rattling,173.

[cxvi] Peterson and Goodall, Visions, 220-221.

[cxvii] Koko.org, “Koko's.”

[cxviii] Patterson and Gordon. “Case,” 61.

[cxix] Ibid., 59.

[cxx] Ibid., 67.

[cxxi] Ibid., 59-60.

[cxxii] Ibid., 62.

[cxxiii] Ibid.

[cxxiv] Ibid.

[cxxv] Ibid., 64.

[cxxvi] Ibid.

[cxxvii] Ibid., 62.

[cxxviii] Ibid., 64.

[cxxix] Ibid., 65.

[cxxx] Ibid., 62.

[cxxxi] Ibid., 66.

[cxxxii] Anderson, Doctor, 284.

[cxxxiii] Miles, “Language,” 42.

[cxxxiv] Ibid., 47.

[cxxxv] Ibid., 48.

[cxxxvi] Ibid., 48-50.

[cxxxvii] Ibid., 48.

[cxxxviii] Ibid., 49.

[cxxxix] Ibid., 50.

[cxl] Chantek, “Project.”

[cxli] Miles, “Language,” 46.

[cxlii] Ibid., 52-54.

[cxliii] Thompson, Intimate, 136-146.

[cxliv] Terrace, Nim, 19-22.

[cxlv] Raffaele, “Speaking.”

[cxlvi] NOVA, “Ape,” 31:23.

[cxlvii] Savage-Rumbaugh, “Susan,” 12:04.

[cxlviii] Ibid., 13:41.

[cxlix] Wise, Rattling, 168.

[cl] Terrace, Nim, 150.

[cli] Fouts and Fouts, “Chimpanzees’,” 36.

[clii] Terrace, Nim, 231-232.

[cliii] Ibid., 268.

[cliv] Ibid., 13.

[clv] Wise, Rattling, 225.

[clvi] Ibid., 229.

[clvii] Wynne, "Aping."

[clviii] Wise, Rattling, 226.

[clix] Ibid.

[clx] Blum, Monkey, 19.

[clxi] Peterson, Jane, 612.

[clxii] Peterson and Goodall, Visions, 227.

[clxiii] Wynne, "Aping."

[clxiv] Teleki, “They,” 298.

[clxv] Wise, Rattling, 228.

[clxvi] Yule, Study 8-12.

[clxvii] De Waal and Lanting, Bonobo, 43-44.

[clxviii] Thompson, Intimate, 149.

[clxix] Bekoff, “Common,” 105.

[clxx] Wise, Rattling, 220-221.

[clxxi] Cohen, "Thinking," 50-57.

[clxxii] Stanford, Significant, 157.

[clxxiii] De Waal and Lanting, Bonobo, 33.

[clxxiv] Wade, “Deciphering.”

[clxxv] Seyfarth, Cheney and Marler, “Vervet.”

[clxxvi] Wade, “Deciphering.”

[clxxvii] Ibid.

[clxxviii] Ibid.