The Language Spiral: How Society Evolved Language

The Language Spiral
How Society Evolved Language


Claire Ceriani
Spring, 2010

Senior Thesis
Adviser: Dr. Paul Grobstein
Bryn Mawr College


Table of Contents

I.    Introduction
II.   The Neurological Basis of Language
III.  Examining Social Evolution
IV.   Language as Created by Social Interactions
V.    An Example of Modern Language Development
VI.   Language and Social Deprivation
VII.  Conclusion
        Bibliography


I.    Introduction
If there is any human trait with the power to unite and divide large groups of people, it is language.  Human language is far more than communication.  Communication allows animals to exchange information about food and predators.  Language allows people to exchange ideas, emotions, theories, and stories.  It is clear that language sets humans apart from animals, but it is not clear how such a defining skill of our species could have evolved.  How have humans developed a form of communication so complex that no other form of animal communication even comes close to it?  Because language is an integral part of the human social structure, it is necessary to consider both neurological development and social development.  The human capacity for language emerged slowly over time as emerging social structures favored greater communication skills.  Such skills in turn enabled humans to create even more complex societies, resulting in a positive feedback loop that eventually created the modern language capability.  Once this capability was sophisticated enough to support modern complex language, individual languages developed rapidly.

Language is frequently viewed as a particular skill that is exclusive to humans.  Noam Chomsky’s famous theory of Universal Grammar has frequently been used to explain how language arose.  According to this theory, human beings possess a language acquisition device that allows us to analyze the language we hear and extract from it certain grammatical rules that are hard-wired into our brains.  Every language is therefore constructed on the framework of this Universal Grammar.  Chomsky also claimed that these rules are too complex for children to grasp, which indicates that they must somehow be inborn and innately understood (Stokoe 2001).  This theory suggests that the capacity for language evolved relatively quickly as the result of purely neurological changes that would be due to genetic mutations.  Other theories propose that language is the byproduct of the intersection of several different skills: the spandrels described by Stephen Jay Gould (R. Botha 2003).  Spandrels are not the result of natural selection and have no evolutionary value.  They emerge as the result of other adaptations. 

Both of these theories ignore the social value of language.  This paper will describe how the evolution of language was the inevitable result of an evolving society, not the product of Universal Grammar or the side-effect of other skills.  Human language is more sophisticated than animal communication, because it allows humans to work cooperatively to reach goals and solve problems.  It is not a single skill, and it is not the byproduct of other cognitive abilities.  It is the manifestation of problem-solving and interpersonal skills that allow people to understand the thoughts of others in order to live and work in concert with each other.  Human language also makes use of grammar, which no other animal does, regardless of how many “words” (such as the wanring calls of chimpanzees) it uses or can learn to use.  This is a key difference between human language and animal communication that likely arose out of the human ability to observe patterns in another person’s behavior and make generalizations.  Grammar did not come from a set of rules that are somehow hard-wired into the brain.  It is more likely that humans needed to solve the social problem of ensuring that everyone understood each other, and universal solutions were found for this universal problem.  Social skills like these  are evolutionarily advantageous in a large society, and are therefore subject to natural selection as the emerging society creates a more complex environment for itself.
 

II.    The Neurological Basis of Language
Tracing language evolution through neurological evolution is a difficult, but important, part of understanding the origins of language.  Knowing which parts of the brain are necessary for learning and producing language makes it possible to differentiate between the brain of an ape and the language-ready brain of a human.  When the brains of humans are compared to the brains of other animals, including apes, it is obvious that the human brain devotes proportionally more neurons to the mouth and lips than any other animal (Loritz 1999).  This explains why humans are capable of the fine motor skills required to produce speech, but it does not explain why humans speak in the first place, nor does it address other forms of language, such as sign language.  Studies of people with aphasia indicate that speech production is related to Broca’s area, and word comprehension is related to Wernicke’s area (Ardila 2009).  They do not, however, give any indication of how language was originally created.

The mirror system hypothesis (MSH) provides an interesting explanation for language acquisition.  This theory, described by Michael Arbib, applies specifically to how gestural language may have evolved, assuming that gestures preceded speech.  He states that “the brain mechanisms which support language evolved atop a mirror system for grasping” (M. A. Arbib 2009, 118).  This mirror system is made up of neurons that are active both when the subject is grasping and when observing another grasping.  Such neurons exists in humans as well as apes and monkeys, explaining how tool use is learned.  Arbib goes on to explain that complex imitation of a gesture leads to a protosign, which leads to a protolanguage and ultimately to a true language.  Mirror neurons have been found via PET in Broca’s area (Rizzolatti and Arbib 1998), suggesting that this part of the brain may actually play a part in language acquisition if the MSH is true.

Another neurological feature associated with language is that of hemisphere asymmetry, with the left hemisphere usually being dominant for language.  A study by Helen J. Neville investigated the cerebral specialization of hearing children identifying line drawings of common objects.  The evoked potential (EP) of each hemisphere was measured and compared.  Older children showed asymmetry between the EPs of the right and left hemispheres, indicating the cerebral specialization commonly associated with language.  Younger children were more symmetrical, indicating that specialization develops with age.  When deaf children were tested, those who had learned American Sign Language from a deaf parent also showed cerebral specialization.  Those without spoken or signed language did not.  This suggests that the acquisition of a language may shape the development of the brain as one hemisphere (usually the left) becomes more specialized to interpret and produce language (Neville and Bellugi 1978).  The human brain may be physically influenced by language acquisition in addition to evolution.  Therefore, as early humans began using early forms of language, their brains would have changed, possibly triggering further cognitive development that could have lead to increased complexities in their societies through improved problem-solving and interpretation skills.  Considering the effect of language on society is just as important as considering the effect of society on language.


 

III.    Examining Social Evolution
Social evolution considers how communities develop, and how that development contributes to the evolution of the individuals within that community.  Language is clearly a social function.  It allows us as human beings to exchange ideas and information with a complexity beyond the level seen in other animal species.  Our communities are also far more complex than those observed in even our closest primate relatives.  Greenspan and Shanker (2004) propose a timeline suggesting when specific cognitive functions developed in human ancestors and what effects those developments had on society.  They describe modern rhesus monkeys as being able to engage each other in early signing, and baboons as using purposeful two-way interactions.  Chimpanzees and bonobos are described as being capable of the same type of communication used by Australopithecus as long as 5.3 million years ago: affective signaling and shared problem solving.  Archaic H. sapiens and Early Moderns (600,000-60,000 years ago) could express ideas symbolically and linguistically, and H. sapiens sapiens (starting 130,000 years ago) began connecting ideas together and thinking logically.  This timeline serves to illustrate the evolution of communication into modern language, and can be used to consider how certain cognitive skills played a role in increasingly complex societies.

What is striking about this timeline is the difference between modern nonhuman primates and early humans.  Other primates may live in groups and communicate basic information with each other, but they have never evolved language.  What caused human beings to develop this ability?  If, like other features that distinguish one species from another, language were the result of a random genetic mutation favored by natural selection, communication would have leapt forward to language fairly quickly.  This was long believed to be the case, due to a “symbol explosion” observed in the fossil record that seemed to indicate that early humans began using language in a relatively short period of time.  Such early symbols include iconic drawings and indications of rituals.  More recent discoveries, however, suggest that the use of symbols goes back farther than originally thought, pointing to a more gradual change. 

One of the most significant discoveries was that of a Neanderthal who appeared to have been deliberately buried with his arms folded across his body.  According to Arensberg who made the discovery, the body had an intact hyoid bone that would have allowed it to speak (Greenspan and Shanker 2004).  The fact that Neanderthals might have been capable of vocal communication and had a society sophisticated enough to consider a particular way of treating their dead pushes back the original estimate of when language might have developed.  Though it is still uncertain if Neanderthals did actually use language, the fact that they could have is significant.  Michael Arbib proposes that “a brain that could support protolanguage could also support language,” but only if there is a rich enough culture to foster to development of sophisticated communication (M. A. Arbib 2009, 120).  Early human ancestors may have been capable of learning a fully developed language, but that would not matter if they did not have the cultural need to develop such a language in the first place.

The evolution of the society becomes just as important as the evolution of the species when considering communication skills.  Such skills require interaction with others.  The more sophisticated the interaction, the more sophisticated the communication must be to adequately share information.  Communication has a clear evolutionary advantage; being able to warn other members of the group of approaching danger ensures survival.  But every other species alive today is proof that a fully developed language is not necessary for survival.  What led humans to develop the ability to create and use language?  It has been suggested by Robin Dunbar that language in humans plays the same role as grooming in chimpanzees (Dessalles 2007).  Chimpanzees use grooming as a ritual to establish social bonds.  They frequently groom the same individuals within their group, and never seem to find anything except the occasional twig, indicating that this practice has little practical value.  Early human beings, through shared communication with each other, may have established family and community ties.  It does not matter that the information they exchanged may not have been vital to survival.  Just by spending time together, they created social ties that would have fostered a sense of loyalty to one’s community.  For an animal living in a large group and engaging in activities such as group hunting, loyalty is an important part of survival.

The progression of protolanguage to language must co-evolve with the progression of early communities to complex societies.  According to Arbib’s mirror system hypothesis, humans and other primates are able to learn manual tasks from each other because mirror neurons are activated both when watching manual tasks and when performing them.  If humans began communicating through gestures before speech, this may explain how gestures, or “protosigns,” were learned.  These neurons do not fire just when they see hand movements.  They only fire when there appears to be some purpose to the movement (M. A. Arbib 2005).  A child observing an older member of the community using a particular protosign to deliberately convey meaning would be able to learn this protosign just as they learn any other manual task.  As certain gestures become more commonly used, they earn an agreed-upon meaning within the community and become signs, equivalent to spoken words.  Vocalizations may have accompanied these signs and eventually replaced them as humans began building more complex structures in groups, requiring their hands to be free to work, but still needing to communicate with each other.  Only human beings are known to have shared goals with “socially coordinated action plans” (Tomasello, et al. 2005, 676), in which a group of humans work together on a particular task, each doing a specific job.  Therefore, as humans began working towards common goals together, more sophisticated communication became necessary to coordinate everyone’s efforts.  And as communication becomes more sophisticated, more complex information can be exchanged, so more complex goals can be achieved by the community.  As society flourishes, so does language, and vice versa.  The evolution of one drives the evolution of the other.

A complex society depends on the transmission of cultural knowledge to develop.  Each generation builds on the contributions of the last.  An individual human may be extremely intelligent, but a group of humans adding further enrichment to the ideas of many previous generations of humans can achieve much more.  As society developed, the individuals with the greatest ability to communicate their ideas to other members of the group would be at an advantage.  Being able to interact socially with others through communication would make a person an effective leader, which might offer a mating advantage.  The leaders of human societies would be most likely to pass on both their genes and their ideas to the next generation.  Greenspan and Shanker describe the latter as “culturally transmitted caregiving practices from one generation to the next, across species, over millions of years” (2004, 92).  Because mating is a social activity, good communication skills are evolutionarily advantageous.  Each generation is therefore more likely than the last to be good at communicating their ideas and understanding the ideas of others.  They will learn a more complex version of the evolving communication system as a child, and add to its complexity as an adult.

At some point, this communication system become complex enough to resemble a modern language with a full lexicon and established rules of grammar, but it takes millennia to reach that point.  Language did not emerge purely as a result of genetic mutations.  It emerged as a result of developing culture.  For human beings, the drive to create social ties offers an evolutionary advantage, because humans living in large, coordinated groups would have been better protected and better able to deal with catastrophe than those living in smaller, less organized groups.  Activities like hunting and building complex shelters are more successful when carried out by cooperative groups, rather than a collection of individuals making decisions independently.  Language is the inevitable end result of increasing social communication.

Even though language depends on a strong cultural foundation to develop, there still must be some cognitive ability humans have that has enabled us to move beyond large lexicons and create complex grammar.  The theory of Universal Grammar is a popular explanation.  Humans are said to have a basic universal grammar hard-wired into their brains.  William Stokoe disagrees with this theory, citing the differences between spoken language and sign language as evidence.  The two forms of language rely on very different types of grammar owing to the different modalities in which they are expressed, yet deaf children of signing parents learn sign language just as easily as hearing children of speaking parents learn spoken language.  Sign can even be just as natural as speaking for a hearing person who has grown up using it, as Nora Ellen Groce observed in her studies of Martha’s Vineyard, which was once home to a large population of deaf people (Groce 1985).  Stokoe attests that “What is universal is that every language does what its users need it to do” (2001, 7).

Given that language can take very different forms, it is more likely that human beings possess an ability to generalize information in a way that favors community development.  A society that is somewhere between the earliest form of human communication and modern language may have a large lexicon of words expressing agreed-upon items, actions, and concepts, but may lack a set of common rules for arranging those words.  It may be possible to determine from context what a particular string of words is intended to mean, but having an established grammar allows each member of the society to communicate with every other member and be confident that everyone is interpreting the words in the same way.  It has been observed in a number of studies that chimpanzees are capable of learning a large number of symbols and using them to communicate effectively, but they never master the ability to sequence those symbols consistently according to a grammar (Ardila 2009).  Because chimpanzees do not naturally use more than a few symbols in the form of a basic gesture-call system, they have no need for grammar.  Their communication consists of simple warning calls, which do not requiring sequencing with other calls to convey complex meaning.  They do need the ability to learn the calls, so they are capable of acquiring signs taught to them by humans, but they lack the ability to generalize from the sentences they observe their trainers use to learn the rules of sequencing.

 

IV.    Language as Created by Social Interactions
The theory that language development depends as much upon social structure as it does upon cognitive ability is supported by a number of models and animal studies.  One simple, but intriguing, model was developed by James Hurford, who created a virtual world of prelanguage people, each equipped with the ability to create and learn language.  The world included specific “gods” and objects to talk about.  People within this virtual community would attempt to exchange information about these gods and objects, and could do so by choosing any simple syllable from a list of vocalizations to mean whatever they wanted (as chosen randomly by the program).  By listening to each other, these people “learned” what each word meant.  After two generations, individuals had large lexicons with single words expressing both simple and complex ideas, but no rules of syntax (Hurford 2000).  After many generations, grammatical rules for word order appeared.  Rules tended to be as general as possible.  The rules that became accepted by the society were the ones that could produce the greatest numbers of expressions without exceptions.  Hurford explains that “It has been shown here that more general linguistic rules are favoured by a completely nonbiological mechanism, namely the social transmission of language from one generation to the next” (348).

This model, though deliberately simple, emphasizes the importance of considering social development in language evolution.  Natural selection may have favored early humans who were capable of learning from each other and living in organized groups, but it has no influence over the way a language develops.  It gives a species with good communication skills an advantage, but it has no effect on the structure of that communication.  In this model, grammar emerges because the virtual people know how to pick out patterns and prefer having a few rules that each explain a lot of patterns, rather than a lot of rules that each explain a few.  This is a part of living in a society.  Human beings living and working together need to be able to interpret each other’s behavior in order to understand another person’s intentions.  Two people attempting to build a house together who are unable to understand each other’s actions and intents will have a hard time reaching their goal.  The ability to imagine what another person is thinking is a social skill.  This is related to how a child figures out what an adult is trying to communicate.  A child needs to be able to figure out the rules that govern another person’s speech so they can communicate with each other.  The more general the rules, the more easily they can be passed from generation to generation.

Virtual models for language are useful for examining specific aspects of language, but no computer program can accurately create a virtual society with all the complexity of human society.  To examine the effects of society on language acquisition, researchers have turned to other social animals.  For most of human history, it had been believed that no other animals were capable of learning a human language.  Studies that had attempted to teach chimpanzees to speak had failed.  Then in 1966, Gardner and Gardner began a ground-breaking study known as Project Washoe.  This was the first study to attempt to teach sign language to a chimpanzee.  More importantly, it made use of cross-fostering rather than operant conditioning, meaning that an emphasis was placed on treating Washoe as if she were an ordinary human child, including living in the Gardners’ home.  Within 51 months, Washoe had acquired 132 signs (Gardner and Gardner 1989).  The goal of the project was more than just investigating language.  The Gardners’ wanted to determine how much of our cognitive abilities as human beings are dependent on living in a human society.  They enforced a strict no-speaking rule around Washoe; everyone had to use American Sign Language in her presence, just as deaf parents would sign to a deaf child.  Through this constant exposure to ASL, Washoe began learning signs at a rate comparable to that of young children.  She even practiced signs on her own, just as small children babble to themselves.

As other chimpanzees were added to the cross-fostering laboratory, the results became more remarkable.  The chimpanzees were observed (by remote camera) to sign to each other, even when no humans were around to prompt them.  When Washoe adopted an infant chimpanzee named Loulis, Roger Fouts suggested that they stop signing in front of him.  Because Washoe was nursing Loulis at the time, they were almost always together, so she lost nearly all signed input from humans.  The cross-fostered chimpanzees continued to sign to each other, even when the humans no longer signed.  Washoe was observed signing to Loulis and molding his hands into the correct shape, just as the Gardners had done to teach her.  Loulis acquired more than fifty signs that he could only have learned from the other chimpanzees.  Though the chimpanzees never acquired consistent grammar, this is evidence that they do possess the ability to understand and use a much larger number of symbols than they are seen to use in the wild.  This suggests that it is the social environment with models actively involved in encouraging language acquisition that is crucial to language.  As Oliver Sacks describes it, “It is impossible to acquire language without some essential innate ability, but this ability is only activated by another person who already possesses linguistic power” (Sacks 1989, 49-50).

Around the time of Project Washoe, a team led by Sue Savage-Rumbaugh was attempting to teach language to bonobos using operant conditioning.  A keypad with symbols on it was used in place of ASL.  The study was unsuccessful for many years.  One bonobo named Matata was nursing an infant named Kanzi at the time of the study, so Kanzi was always present during her training sessions.  Though Matata made little progress, Kanzi began playing with the keypad unprompted, and demonstrated an understanding of some of the symbols.  The team abandoned the operant conditioning and food rewards and focused on interacting with Kanzi as if he were a human child (Gardner and Gardner 1989).  Kanzi learned a large number of symbols, and was even observed to attempt vocalizations, squeaking a high-pitched “oñynn” sound before picking up an onion (Greenspan and Shanker 2004).  Like Washoe, he demonstrated a sort of babbling, never actually saying a word, but making vocalizations to himself.  The results of the Kanzi study were duplicated with Panbanisha, where “it became clear that the explanation for their development lay in the language-enriched environment in which they were raised” (153).  They even developed improved planning and motor skills, suggesting that learning these new communication methods stimulated other types of cognitive development as well.

The results of these primate studies were surprising, but explainable.  Chimpanzees and bonobos are very closely related to humans.  It is believable that they might have cognitive abilities advanced enough to learn some basic language skills, even if they cannot truly acquire human language.  But a study by Irene Pepperberg with Alex, the African Grey parrot, was even more remarkable.  Pepperberg made use of the model-rival technique to teach Alex to speak.  This technique uses two trainers, one acting as the teacher, and the other as the learner.  The teacher asks the learner to name a desired object.  If the learner is correct, the teacher gives him the object as a reward.  The rationale behind this technique is that language will be best learned if the observer (Alex) can see that not only does the object have a name, but that knowing it has some social benefit.  The observer then becomes the learner once the target word has been modeled several times (I. M. Pepperberg 1999). 

Operant conditioning relies on unrelated rewards (food) to encourage a right answer, and punishment to discourage a wrong one.  The model-rival technique demonstrates that language has a purpose; being able to name the object allows the learner to obtain that object.  Pepperberg writes in her personal memoir Alex & Me, “isn't it blindingly obvious that communication is a social process, and that learning to communicate is a social process, too?” (I. M. Pepperberg 2008, 69)  She explains more scientifically in her study that a subject needs social interaction understand why he is supposed to be learning this word and what use it actually has to him.  Alex learned a large number of words throughout the study, and demonstrated that he understood how they were meant to be used (such as using color, shape, number, and material words correctly when describing objects) (I. M. Pepperberg 1997).  Alex was also used to model words for other parrots, and was observed to speak more slowly and clearly when he was doing so, suggesting that he understood his role as a language model.

The results of these studies demonstrate the importance of social context in language learning.  Chimpanzees, bonobos, and African Greys are all social animals, but none of them live in societies as fully developed as humans do.  They also all use some form of communication to convey information to each other in the wild, but none of them use language.  But when these species are placed in human environments with complex social interactions, their cognitive abilities take a huge leap forward.  They do not obtain true language, but they prove themselves capable of learning a large number of words and using them appropriately, even though they never used that broad a range of communication in the wild.  This indicates that the ability to learn a large, agreed-upon code of symbols that stand for real objects, traits, and actions may be present in many other animals besides humans.  Our complex social interactions allow us to develop rich lexicons and pass them on from generation to generation.  The fact that these animals did not acquire true grammar indicates that the ability to generalize and learn sequencing rules may be exclusive to humans.  But what if many generations of Washoes continued to pass on signs to each other and develop an even larger lexicon?  What if they continued to live in a complex human-like society?  Would they eventually develop the generalizing ability of humans as a result of social evolution?  If they did, language among these chimpanzees might become possible.  It is this cognitive skill that allows humans to create and learn true language over many generations.
 

V.    An Example of Modern Language Development
The emergence of Nicaraguan Sign Language (NSL) among deaf children illustrates the natural tendency of human beings to learn and to create language.  NSL is the language used by children at a school for the deaf that was established in the 1970s.  With mainly hearing adults teaching the classes, a signed form of Spanish was originally used, but the students failed to become truly fluent.  William Stokoe describes similar difficulties he observes when Signed English is used in place of American Sign Language in American schools.  He explains that signed versions of spoken languages are merely codes that lack “a history of natural evolution” that would be shaped by the social needs of the community (Stokoe 2001, 165).  As more children joined the Nicaraguan school, a community grew, and out of it came a new language created by the students to meet their own social needs.  The starting materials for this language were the various homesign systems each student had already established.  Such systems consist of gestures created by deaf children to communicate with their families.  They may follow very general rules, but do not have the richness and complexity of true language (R. Botha 2007).  Ann Senghas, who led a significant study of NSL, describes the first generation of students as providing their homesigns as the language models which subsequent students would use to create complex language (Senghas 1995).

The work of Ann Senghas focused on the effects of age on a student’s ability to sign fluently.  Students of different ages were asked to describe cartoon clips in sign.  Younger singers produced more units of meaning, or morphemes, per sign, and more than twice as many morphemes per minute.  They also used fewer mimetic signs than their older peers (Senghas 1995).  This indicates that younger signers are capable of putting more meaning into their signs efficiently, and are not relying on simple mime as homesigners often do.  Even though the younger signers are learning from the older signers, they are more fluent, meaning that the language must be evolving from year to year.  Senghas describes the loss of mimetic signs as “preference for a system of grammatical regularity and productivity” (66), meaning that younger signers are sacrificing the clarity of mime for agreed-upon signs that are easy to produce and reassemble into different sentences. 

The study also compared the signing of students who entered the school prior to 1983 to those who arrived later in order to determine the effects of year of entry on signing.  Signers with a later year of entry produced more morphemes per minute, indicating that each new class of children further shaped the developing language.  Certain types of inflectional markers may be observed occasionally in older signers, but only the youngest use them consistently.  This is likely because each new class observes the older classes signing, and interprets common features as rules that they then use as a regular part of the language.  Because there is no adult model to correct them, the changes they make stay.  This is similar to an English-speaking child hearing her parents use many different verbs in the past tense and noticing that a lot of them end with the “-ed” sound.  She assumes this a rule without exception and says “goed,” despite having heard and understood the word “went” thousands of times.  Her parents correct her, and she learns that “to go” does not fit the pattern.  But the children learning NSL do not have adults around with grammar textbooks.  Whatever rules they decide upon are the ones the next class will learn.  If there is no decided rule for a particular aspect of language when they get to the school, they will reanalyze the signing of their older peers, find the most consistent pattern, and make it a rule.  As anyone who has ever raised a child knows, young children are wired to learn language.  The emergence of NSL makes it clear that children need to learn language and will create one of their own if there is not an adequate model around them.

This idea may lead to the theory that language is somehow hardwired into the brain, and that all languages were created using this “language center.”  Universal Grammar is used by some to explain the similarities between certain languages such as Creoles, and is dismissed by others.  The observations of the NSL study offer support to both sides of the argument.  Two significant features of NSL that conform to the basic structure of spoken languages are segmenting and sequencing.  Part of the study consisted on comparing the signing of NSL-fluent students to those of hearing, Spanish-speaking adults.  Both groups were asked to use their hands to describe the motion of a cartoon cat swallowing a bowling ball and then rolling down a hill.  Those who spoke Spanish and had no knowledge of NSL made single mimetic gestures to signify the idea of something rolling downwards.  Those who were NSL-fluent made separate signs, the NSL words for “down” and “roll,” indicating that they were using complex language rather than mime.  This suggests that segmenting and sequencing are innate linguistic properties that naturally emerge when humans create language, and are not the result of cultural transmission (Siegal 2004).  These individual signs can be separated from each other and still retain their meaning, and can be sequenced with other signs to express new ideas.  The same is true of equivalent words in spoken languages.  But if these properties were culturally transmitted, they probably would not have arisen in NSL, because the children who created it had extremely limited knowledge of another culture’s language.

The same experiment, however, also revealed some significant differences between NSL and other languages that cast doubt on the idea of Universal Grammar.  While it is certainly true that most spoken languages do separate manner and path (in this case, “rolling” and “down”) into separate words, not all sign languages do (M. A. Arbib 2009).  Though other aspects of language may be separated and sequenced, manner and path are expressed simultaneously.  NSL may therefore be similar to spoken languages in this sense, but not to other sign languages.  If this observation is to be used as evidence for universal grammar, NSL and all other sign languages would have to fit this pattern.  One could argue that signed languages are generated using different universal rules due to their different modalities of expression.  NSL may be more similar to spoken languages because a few students did have a limited understanding of Spanish, and this was enough to influence its development.  If that is true, then we would expect to find other similarities between NSL and spoken Spanish.  But another difference was observed between the signs of the hearing adults and the NSL-fluent students.  The students not only made separate gestures for manner and path, they also “nested” them by signing one sign, then another, and then the first sign again to indicate simultaneity.  The idea of “cat rolling down” was expressed as cat [roll descend roll].  This is a novel construction completely unlike spoken Spanish.  NSL may share some features with many languages, but it also contains significant features of its own that are difficult to explain with Universal Grammar.

A better interpretation might be that humans have an innate need to form social groups and use a particular set of universal problem-solving skills to figure out how to communicate with each other.  Laura Helmuth (2001) describes the need to communicate in a group as a social problem that group members must solve.  A complex community needs to be able to build together, establish ownership, share knowledge and skills, and create family ties.  Simple gesture can communicate very simple ideas, but to exchange more complicated ideas such as laws, social hierarchies, and emotions, language becomes necessary.  Senghas, Kita, and Özyürek (2004) hypothesize that “children naturally possess learning abilities capable of giving language its fundamental structure” (1779).  Note that it is not “language-learning abilities.”  The idea is that humans are capable of learning complex skills from each other, and that language is a skill that arose as a solution to the problem of communication. 

In the case of sign language, the mirror neurons described in the MSH would be the most likely way humans learn this skill.  It is through complex imitation of signs that children learn a sign language, a learning method that is not specific to language (M. A. Arbib 2009).  The brain centers involved in complex manual activity are nearly the same as the ones involved in speaking activity (Stokoe 2001).  This has led some researchers, most notably Stokoe, to conclude that sign language evolved before spoken language.  Early humans were able to learn manual skills from each other through observation.  Simple gesture was first used to convey very basic ideas, and was learned using the same observational skills.  Those who learned these skills the best would have been able to communicate better and would have had an evolutionary advantage in a society built on communication.  According to Stokoe (2001), verbal language may have replaced signs when it became more convenient to show how to perform a particular manual skill with the hands and explain how to do it with spoken words.

The MSH depends on a social environment in which people are driven to learn things from each other.  They observe each other’s actions to learn how to make a spear.  Children observe adults to learn how to use gestures to express their needs.  Gesture systems may evolve into languages as more people learn the existing system and add to it.  It is not that language creation itself is innate, but that the need to exchange information with others causes humans to solve this problem using the same skills.  One issue to consider in the case of NSL is how language already existed within this community of children.  The homesigns that made up the raw materials of NSL cannot be considered true language, but did they have a basis in a language model?  Botha says that the deaf children who create homesigns are not exposed to language at all (R. Botha 2007), making these systems purely products of the mind of the child.  Michael Arbib (2009) argues that homesigners still learn from their family that things can be identified by pointing, and still observe their family members interacting and communicating with each other, even if they cannot hear what is being said. 

It must also be remembered that the students at this school knew that language existed.  Parents and teachers had attempted to teach them to lip-read and to understand signed and written Spanish.  These children did not come up with the idea of language on their own.  They needed a community of people who were willing to communicate with them the way they wanted to communicate: through a language that makes sense visually, not aurally.  Keeping this in mind, we can use the example of NSL to understand how complex languages may have developed in early cultures with reasonably well-developed communication systems, but we cannot use it to draw conclusions about the very beginnings of human communication.  This was a community with a limited knowledge of language, not isolation from it.
 

VI.    Language and Social Deprivation
If language acquisition is responsible for further social development, we might think that language therapy could help children with social difficulties.  This is indeed what is frequently observed in children with autism.  Autism is marked by social, emotional, and cognitive difficulties.  Because they seem to have a hard time engaging with others, autistic children generally develop little to no language skills.  Greenspan and Shanker explain this via the Attention Diathesis Hypothesis, which states that “a child uses his affect to provide intent (or direction) for his actions and meaning for his symbols or words” (Greenspan and Shanker 2004, 301).  If a child does not know how to engage with his caregivers and understand their emotions and intents, he will not understand their use of language.  An autistic child lacks the ability to follow the patterns of communication, never acquires language, and becomes even more socially withdrawn as a result. 

Greenspan and Shanker devised a program to engage autistic children in activities focusing on problem-solving, spatial/motor/sensory relations, and speech therapy.  58% of the children involved in the program learned abstract thinking, empathy, and impulse control, but most significantly, they began using language creatively and spontaneously in social situations.  As their language skills developed, the ability to understand the ideas and emotions of others emerged, and peer relations improved.  These results were only observed, however, when caregivers spent a large amount of time engaging their children in long conversational exchanges, rather than just simple question-answer exchanges.  By engaging them in basic social interactions, caregivers and teachers were able to foster language abilities in many of the autistic children.  When further language development was encouraged, more sophisticated cognitive and social behaviors were observed.

Such results have been seen in a number of studies that focused on getting autistic children to understand and use language.  Many of the most successful studies have used sign language in place of or in addition to spoken language, capitalizing on the fact that though autistic children seem to have difficulties understanding sounds, they often have strong visual abilities (Goldstein 2002).  Some children who learn signs will go on to learn spoken words as well.  Roger Fouts famously worked with an autistic boy named David, guiding him through gestures, then gesture phrases, and finally to clear speech (Fouts 1997).  Though not all children benefit from such programs, most make at least some improvement in language use.  The ones who are most successful improve their social skills, learn to control impulse behavior and tantrums, and may even seek out social interactions independently (Kelly 2008, Bonvillian and Nelson 1978).  A program developed by Anne Toth called Bridge of Signs uses sign language to teach language to children with autism, Down syndrome, and other forms of mental retardation that impede verbal communication (Toth 2009).  Even the children who learned the fewest signs still learned to direct their attention to their teachers and control their behavior.  Many of them only learned from live teachers; videos teaching the signs were used, but were ineffective for many children.  The social interaction was apparently a key part of learning the signs.

Similar patterns are seen even in children of normal intelligence and cognition who have lacked early language input.  Oliver Sacks describes his experience with a boy named Joseph (Sacks 1989).  Joseph was deaf from birth, but was born to hearing parents who did not know sign language.  At the age of eleven and with no language skills, he entered a school for the deaf.  He learned sign language, and though he did communicate well about literal ideas, he seemed to have a hard time with abstract concepts.  He did not seem to understand what a question is, and he was unable to communicate ideas about the past or the future.  It seemed that he had passed the critical age to develop these skills, which normally would have developed as he learned language.  But it also seems that social interaction may be a part of developing advanced cognitive skills.  Sacks made visits to a number of deaf schools, and found that the children at Joseph’s school, which was not residential, were shy and lacked confidence and spontaneity.  Most only achieved a 4th grade reading level by graduation.  At the residential California School for the Deaf in Fremont, Sacks found the students to be academically and socially equal with their hearing peers.  The social aspect is clearly a crucial part of learning it.  Jean Aitchison describes the case of Vincent, a hearing child of deaf parents who learned ASL as a first language (Aitchison 1996).  Though he watched TV, he did not attempt vocalization until his first live exposure to English at the age of three.  Even a child who knew that language existed and had acquired a manual form of it with no difficulty could not acquire a verbal form without live personal interaction.

The results of these studies further emphasize the interrelation between language development and social development.  Social interaction is obviously necessary for a child to acquire language.  It is not enough to just observe language being used remotely.  The child has to be an active participant in the communication.  If something prevents that child from participating, such as deafness, mental retardation, or the emotional difficulties of autism, language does not develop.  But if efforts are made to interact with that child or to teach him how to interact with and understand others, language skills emerge.  Language use seems to unlock more advanced cognitive skills, perhaps by creating new neurological pathways (Greenspan and Shanker 2004).  Most important, children who are able to acquire language often overcome their behavioral difficulties.  Learning even just a few signs or words may be enough to alleviate a child’s frustration over not being able to communicate at all.  In all of the previously mentioned studies, researchers indicated a sense that the children wanted to communicate, and that learning a few words gave them pleasure.  The increased cognitive capabilities granted by language may also allow social skills to flourish.  Once a child masters some language skills, he may be more driven to interact with others.  Language is the tool that allows individuals to interact beyond sharing basic information.  Language allows children to tell stories and share thoughts and emotions, which are necessary for playing with peers and making friends.
 

VII.    Conclusion
In The Runaway Brain, Christopher Wills claims that by creating complex societies, human beings created new evolutionary pressures that favored further cognitive development (Wills 1993).  This is not unlike the sort of co-development seen between language and society.  Each needs the other to evolve further levels of complexity, driving each other in a spiral.  Language is not a cognitive skill that appeared as the result of a single mutation, or that emerged as a byproduct of other adaptations.  Language requires a social environment with people interacting, sharing ideas, and working cooperatively.  Studies have shown that animals can be taught more complex communication when they are placed in a social environment, indicating that a large part of human language is the product of society.  But to generalize the basic patterns of that code without being consciously taught by those fluent in it is a distinctly human skill that allows us to live and work in large, complexly organized groups.  This is what makes our code a true language.

The development of NSL provided researchers with a rare opportunity to watch a modern language evolve.  It is evidence that people living in a complex society need a complex language to communicate with each other.  The modern human brain is capable of not only learning an existing language, but also of creating one to fill a linguistic void.  In fact, it seems driven to do so.  Language can only be created, however, if enough people are actively engaged in trying to communicate with each other.  The human brain needs language in order to fully develop.  A lack of language cuts a person off from society, and gaining it allows them to connect to others in ways they never have before.  The social and linguistic functions of the human brain are intricately tied together.  Social connection is vital for the natural acquisition of language, but if social interaction is impaired, teaching the affected individual even a few words can unlock social skills.

Understanding the connection between social and linguistic development is a crucial part of understanding our species.  A person without language has a far greater disability than a person without hearing or sight.  Language allows us to connect with other people, and this connection is necessary for proper emotional, psychological, and neurological development.  We know at what ages children typically develop particular social and linguistic skills, but we need to determine how the acquisitions of these skills affect each other in order to properly help children with developmental disorders.  Is a theory of mind necessary for language acquisition?  Or does language acquisition allow the theory of mind to develop?  By looking at language as a cognitive process that needs other people to exist, we change the way we see language in the brain.  There is no “language center” in the brain.  There are areas of the brain specifically involved in language production, but the creation, acquisition, and use of language are the result of the cognitive processes we use to understand the beliefs, wants, and intentions of others.  This changes the way we might think about helping someone with aphasia regain language use, or the way we teach secondary languages.  Using language is more than memorizing a lexicon and a list of grammar rules.  It is a social function.

Social evolution requires many generations.  It is not something that is passed down biologically.  It is something that emerges over time as each generation teaches the next about the society they live in, including its communication code.  As the community becomes more developed, its code needs to convey a broader range of information.  As more information can be shared, more complicated goals can be shared by the community, allowing further development to the society.  This can be seen even in our recent history.  Complex societies created laws along with legalese.  Poetry became an art form, creating new ways of thinking and of using words and grammar.  The internet brought about netspeak.  All of these developments influenced the way language is used, but they are also the products of people using language to create them in the first place.  Our use of language is dependent on a complex social environment that gives us shared goals and intentions that require complex communication.  Our shared intentions drive us to create social bonds, and these bonds inspire us to use language to share more than just vital information.  We use language to share social and emotional information.  Simple communication is the product of Darwinian evolution.  Human language is additionally the product of social evolution.

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